Mining Information

Overburden

2010-05-29T19:21:00.001-07:00

Overburden is the material that lies above the area of economic or scientific interest (in mining and archaeology) e.g., the rock, soil and ecosystem that lies above the coal seam or ore body. It is also known as 'waste'. Overburden is distinct from tailings, the material that remains after economically valuable components have been extracted from the generally finely milled ore. Overburden is removed during surface mining, but is typically not contaminated with toxic components and may be used to restore an exhausted mining site to a semblance of its appearance before mining began. Overburden may also be used as a term to describe all soil and ancillary material above the bedrock horizon in a given area.

A related term is interburden, meaning material that lies between two areas of economic interest, such as the material separating coal seams within strata.

By analogy, overburden is also used to describe the soil and other material that lies above a specific geologic feature, such as a buried astrobleme.

From http://en.wikipedia.org/

Ore sorting

2010-04-26T07:44:00.000-07:00

Ore sorting refers to the process of separating an ore into separate constituent parts. Today, ore sorters are widely used in industrial mineral mines, diamond mines and base and precious metal mines.

Ores are typically sorted to increase the efficiency of other refining processes, by reducing the amount of material to be processed while simultaneously increasing its purity.

Modern technologies

Modern, automated sorting applies optical sensors (visible spectrum, near infrared, X-ray, ultraviolet), that can be coupled with electrical conductivity and magnetic susceptibility sensors, to control the mechanical separation of ore into two or more categories.

Commonly sorted ores

* Base and Precious Metals
o Gold
o PGMs
o Copper
o Zinc
o Nickel
* Industrial Minerals
o Pegmatites
o Limestone
o Calcite
o Dolomite
o Coal
o Magnesite
o Quartz
o Feldspar
* Gems
o Diamonds
o Tanzanite

Reasons for industrial sorting

* Pre-concentrate mill feed into high-grade and low-grade fractions
o Build a smaller mill or effectively increase the capacity of an existing mill
o Remove low-grade fraction that is actually costing money to mill
o Add previously uneconomic zones to reserves
o Manage ore blending programs more effectively
* Sort high-grade ore out of low-grade stockpiles and waste dumps
o Recover value from previously uneconomic waste
* Reduce environmental risks and costs
o Reduce mill energy consumption
o Send acid generating waste rock to appropriately designed dumps
* Optimize multiple process streams
o Send appropriate ore directly to the mill, leach heaps or smelter
* Pre-concentrate ore underground or at remote sites
o Reduce haulage and hoisting costs
o Mine satellite orebodies and sort on site
* Monitor the composition of the mill feed
o Provide real time data to operators for process optimization and work index prediction

From http://en.wikipedia.org/

Ore concentrate

2010-04-23T06:56:00.000-07:00

Ore concentrate text

Ore concentrate, dressed ore or simply concentrate is the product generally produced by metal ore mines. The raw ore is usually ground finely in various comminution operations and tailings(waste) are removed thus concentrating the metal component. The concentrate is then transported to smelters where it is used to produce useful metals.

From http://en.wikipedia.org/

Optical granulometry

2010-04-20T20:21:00.000-07:00

Optical granulometry is the process of measuring the different grain sizes in a granular material, based on a photograph. Technology has been created to analyze a photograph and create statistics based on what the picture portrays. This information is vital in maintaining machinery in various trades worldwide. Mining companies can use optical granulometry to analyze inactive or moving rock to quantify the size of these fragments. Forestry companies can zero in on wood chip sizes without stopping the production process, and minimize sizing errors.

With more photoanalysis technologies being produced, mining companies have shown an increased interest in these types of systems because of their ability to maintain efficiency throughout the mining process. Companies are saving millions of dollars annually because of this new technology, and are cutting back on maintenance costs on equipment.

In order for optical granulometry to be completely successful, an accurate photo must be taken – under sufficient lighting, and using proper technology – to obtain quantified results. If these requirements are met, an image analysis system can be implemented.

From http://en.wikipedia.org/

Oil shale industry

2010-04-16T20:27:00.000-07:00

Oil shale industry is an industry of mining and processing of oil shale—a fine-grained sedimentary rock, containing significant amounts of kerogen (a solid mixture of organic chemical compounds), from which liquid hydrocarbons can be manufactured. The industry has developed in Brazil, China, Estonia and to some extent in Germany, Israel and Russia. Several other countries are currently conducting research on their oil shale reserves and production methods to improve efficiency and recovery. However, Australia has halted their pilot projects due to environmental concerns. Estonia accounts for about 70 % of the world's oil shale production.

Oil shale has been used for industrial purposes since the early 1600s, when it was mined for its minerals. Since the late 1800s, shale oil has also been used for its oil content and as a low grade fuel for power generation. However, barring countries having significant oil shale deposits, its use for power generation is not particularly widespread. Similarly, oil shale is a source for production of synthetic crude oil and it is seen as a solution towards increasing domestic production of oil in countries that are reliant on imports.

From http://en.wikipedia.org/

NAICS 21

2010-04-10T12:13:00.000-07:00

NAICS 21 is the category within the North American Industry Classification System which is composed of establishments that extract naturally occurring mineral solids(i.e. as metals, coal and other industrial minerals), liquid minerals (i.e. crude petroleum) and gases (i.e. natural gas).

Definition of mining

NAICS 21 uses the term "mining" to include quarrying, well operations, beneficiating and other mineral preparation customarily performed at the mine sites, or as a part of mining activity and distinguishes two basic activities:

Mine operation

Mine operation includes companies that operate mines, quarries, or oil and gas wells for themselves, and companies which operate them on a contract or fee basis.

Mining support activities

Mining support activities include companies that perform exploration (except geophysical surveying) and other mining services, on a contract or fee basis, with the exception of mine site preparation and construction of oil/gas pipelines.

Further breakdown

Companies are grouped and classified according to the natural resource which is or will be mined. Industries include establishments that develop the mine site, extract the natural resources, and/or those that process the mineral mined.

Smelting and refining

Smelting and refining take place in both the "mineral processing" (NAICS 21) stages and the manufacturing stages (NACIS 31-31).

From http://en.wikipedia.org/

Mineral industry

2010-04-06T18:15:00.001-07:00

Mineral industry is the branch of industry responsible for the exploitation of minerals from soil deposits. This is achieved by mining (through underground excavations or open workings), but also by processing plants. Products of mineral industry include various building materials, such as rocks (ex. granite), but also cement, glass and ceramics.

Worldwide

* Mineral industry of Africa
* Mineral industry of Asia
* Mineral industry of Europe
* Mineral industry of North America
* Mineral industry of South America
o Mineral industry of Colombia

From http://en.wikipedia.org/

Miner's helmet

2010-04-04T04:06:00.000-07:00

A Miner's helmet is a type of helmet worn for safety purposes by miners while in the process of mining.

From http://en.wikipedia.org/

Mine Caps

2010-03-30T08:11:00.000-07:00

Mine Caps are typically used to prevent access to old, abandoned mines. People, especially the young, like to explore their surroundings but may not fully understand the dangers inherent within, and surrounding, a mine.

Why Do Mines Need To Be Capped?

Cave-ins, poor air quality, wet slippery surfaces, etc. are real dangers when entering a mine, but even the surrounding area can be dangerous. Older mines may have been covered with logs or wooden beams with loose rock and soil over the top. These fail over time, creating sinkholes, that may not be visible on the surface, until enough weight collapses it.

Law Requirements

Federal and State laws dictate certain aspects in the capping process, such as allowances for bats to have access. The type of mine, water table, geology, etc. are all considered when choosing which type of cap will be used for a given mine entrance.

Concrete Caps

Concrete continues to be the preferred method for capping vertical shafts. Considerations can be made in the design to allow for an entrance to the mine, a steel door for humans, a slot for bats, a hole for airflow. The slabs thickness can vary from as little as 6 inches to several feet.

Expanding Foam

Expanding foam is quickly replacing concrete for some vertical shafts, typically mines where an entrance for humans is no longer desired. This type of cap is sometimes referred to as a "Plug." Plugs usually have a taper to them, smaller on the bottom and wider on the top, like the cork on a wine bottle. Expanding foam plugs need to be quite thick, usually no less than 6 feet deep. Typically, loose rock and soil is placed over the top.

Steel Plates

1/4 inch or thicker steel-plating is also used, on both horizontal and vertical shafts. These allow for easier customization than concrete, cutting access holes in steel is far easier than building the concrete forms necessary for the same result. This type of cap is used where easy access is a necessity.

From http://en.wikipedia.org/

Magnetation (iron ore)

2010-03-22T18:31:00.000-07:00

Magnetation is a term referring to the processing of iron ore tailings, the waste product of iron ore mines, to recover hematite. Crushed mine tailings are mixed with water to create a slurry; the slurry is then pumped through magnetic separation chambers to extract hematite. Commercial interest in this process stems from the possibility of extracting additional iron from tailings supplied by existing mines, increasing their yield.

From http://en.wikipedia.org/

Fly-in fly-out

2010-03-16T23:03:00.001-07:00

Fly-in fly-out is a method of employing people in remote areas.

Overview

Rather than relocating the employee and their family to a town near the work site, the employee is flown to the work site where they work for a number of days and are then flown back to their home town for a number of days of rest.

Fly-in fly-out is very commonly used in the mining industry, as mines are often in areas far from towns.

Usually a fly-in fly-out job involves working a long shift (e.g. 12 hours each day) for a number of continuous days with all days off spent at home rather than at the work site. As the employee's work days are almost entirely taken up by working, sleeping and eating, there is little need for any recreation facilities at the work site. However, companies are increasingly offering facilities such as pools, tennis courts and gyms as a way of attracting and retaining skilled staff.

Generally fly-in fly-out work sites use portable buildings as typically there is no long-term commitment to the work site (e.g. the mine will close once the minerals have been extracted).

Employees like fly-in fly-out arrangements as their families are often reluctant to relocate to small towns in remote areas, due to the lack of opportunities for partner's employment, limited educational choices for children and poor recreational facilities.

Employers prefer fly-in fly-out arrangements when the cost of establishing facilities of sufficient quality to attract families to live locally will exceed the cost of creating basic facilities for a fly-in fly-out community plus the cost of airfares.

Negative effects

On the negative side, fly-in fly-out employment can put stress on family relationships and may stifle regional development.

Mining towns that once had a considerable size, like Wiluna in Western Australia, which had a population of 9,000 in 1938, have shrunk to a population of 300, with almost all employees of the local mines on fly-in fly-out rosters.

From http://en.wikipedia.org/

Face (mining)

2010-03-13T09:21:00.001-08:00

In mining, the face is the surface where the mining work is advancing. In surface mining it is commonly called pit face, in underground mining a common term is mine face.

Accordingly, face equipment is the mining equipment used immediately at the mine face used for removal and near-face transportation of the material: cutting machines, loaders, etc.

From http://en.wikipedia.org/

Exploration diamond drilling

2010-03-08T07:39:00.000-08:00

Exploration diamond drilling is used in the mining industry to probe the contents of known ore deposits and potential sites. By withdrawing a small diameter core of rock from the orebody, geologists can analyze the core by chemical assay and conduct petrologic and mineralogic studies of the rock.

History

Early diamond drilling opened up many new areas for mineral mining, and was related to a boom in mineral exploration in remote locations. Before the invention of the portable diamond drill, most mineral prospecting was limited to finding outcrops at the surface and hand digging.

Diamond drilling

Exploration diamond drilling differs from other geological drilling (see Drilling rig) in that a solid core is extracted from depth, for examination on the surface. The key technology of the diamond drill is the actual diamond bit itself. It is composed of industrial diamonds set into a soft metallic matrix. As shown in the figure, the diamonds are scattered throughout the matrix, and the action relies on the matrix to slowly wear during the drilling, so as to expose more diamonds. The bit is mounted onto a drill stem, which is connected to a rotary drill. Water is injected into the drill pipe, so as to wash out the rock cuttings produced by the bit. An actual diamond bit is a complex affair, usually designed for a specific rock type, with many channels for washing.

The drill uses a diamond encrusted drill bit (pictured on the right) to drill through the rock. The drill produces a "core" which is photographed and split longitudinally. Half of the split core is assayed while the other half is permanently stored for future use and reassaying if necessary. Although a larger diameter core is the most preferred it is the most expensive. The most common diameter sizes of core are NQ and CHD 76.

Core extraction

Merely advancing the drill by rotary action (and washing) causes a core to be extracted inside the barrel as shown. However, at a depth of perhaps 300 m, there must be a way to retrieve the core and take it to the surface. Constantly withdrawing the entire heavy drill pipe is impractical, so methods were developed to pull up the core inside the barrel. If the rock would always be solid granite, and the core would always break at the drill bit, then it would be a simple matter to stop the drilling, and lower a simple grabbing device by a wire and pull up the core. Unfortunately, many applications require an undisturbed core in fractured rock, which calls for elaborate wire-line devices.

The photo shows the extraction of a core, using a triple-tube wire-line system, capable of extracting core under the worst conditions. This is very important when exploring fault zones such as the San Andreas Fault.

Tube sizes

There are five major "wire line" tube sizes typically used. Larger tubes produced larger diameter rock cores and require more drill power to drive them. The choice of tube size is a trade-off between the rock core diameter desired and the depth that can be drilled with a particular drilling rig motor.

From http://en.wikipedia.org/

Core sample

2010-02-27T16:01:00.001-08:00

A core sample is a cylindrical section of a naturally occurring medium consistent enough to hold a layered structure. Most cores are obtained by drilling into the medium, for example sediment or rock, with a hollow steel tube called a corer. The hole made for the core sample is called a core hole. A variety of corers exist to sample different media under different conditions. More continue to be invented. In the coring process the sample is pushed more or less intact into the tube. Removed from the tube in the laboratory, it is inspected and analyzed by different techniques and equipment depending on the type of data desired. Analysis is generally non-destructive of most of the sample.

Methods

* gravity coring, in which the core sampler is dropped into the sample
* drilling exploration diamond drilling
* vibracoring, in which the sampler is vibrated to allow penetration into thixotropic media.

Management of cores and data

Coring is the method to retrieve cores samples from the ground. Coring is often utilised in ocean drilling and surveying. Scientist often using coring to acquire core samples for study.

Drilling equipment is often used for coring. Rock core is often taken during mineral exploration operations to help determine the rock type and amount of mineralisation present. A diamond impregnated core bit is used which is rotated to cut an annulus of rock, producing a rock core which extends through the bit into the core barrel. In a wireline system, the core barrel can be retrieved using a wire cable that is run inside the drill rods. Thus, the drill rods do not have to be removed from the borehole each time a core run is complete. Diamond coring can be carried out to depth of 2000m using conventional mineral exploration drilling equipment. Core can be recovered from deeper wells but the operation becomes more expensive.

The technique of coring long predates attempts to drill into the Earth’s mantle by the Deep Sea Drilling Program. The value to oceanic and other geologic history of obtaining cores over a wide area of sea floors soon became apparent. Core sampling by many scientific and exploratory organizations expanded rapidly. To date hundreds of thousands of core samples have been collected from floors of all the planet’s oceans and many of its inland waters.

Access to many of these samples is facilitated by the Index to Marine & Lacustrine Geological Samples,

"A collaboration between twenty institutions and agencies that operate geological repositories."

The above agency keeps a record of the samples held in the repositories of its member organizations. Data includes

"Lithography, texture, age, principal investigator, province, weathering/metamorphism, glass remarks and descriptive comments"

Layering

Any natural medium at or under the Earth’s surface or other body that is consistent enough to maintain a solid or semi-solid structure is layered. The layering comes from successive deposition or growth in time of structural or compositional variants of the medium.

Most familiar to us are the stratigraphic layers of the Earth’s surface on which the geologic history of the surface is based; for example, the Eocene, Oligocene, Miocene, etc. Each layer in this case contains distinctive fossils generated by the evolution of species. Layers often are divided into sublayers.

Layering is more pervasive than the broad outline of the Geologic Time Scale leads us to believe. Any change in environment causes a new layer to be deposited. A succession of plant species in a region, for example, causes a succession of layers containing different pollen in ice and mud. Variation in rainfall causes tree rings to be of different widths.

Informational value of core samples

Scientific coring began as a method of sampling the ocean floor. It soon expanded to lakes, ice, mud, soil and wood. Cores on very old trees give information about their growth rings without destroying the tree.

Cores indicate variations of climate, species and sedimentary composition during geologic history. The dynamic phenomena of the Earth’s surface are for the most part cyclical in a number of ways, especially temperature and rainfall.

There are many ways to date a core. Once dated, it gives valuable information about changes of climate and terrain. For example, cores in the ocean floor, soil and ice have altered the view of the geologic history of the Pleistocene entirely.

From http://en.wikipedia.org/

Chat (mining)

2010-02-22T20:57:00.000-08:00

Chat is a term for fragments of siliceous rock, limestone, and dolomite waste rejected in the lead-zinc milling operations that accompanied lead-zinc mining in the first half of the twentieth century. Historic lead and zinc mining in the Midwestern United States was centered in two major areas: the Tri-State area covering more than 2,500 square miles (6,500 km2) in southwestern Missouri, southeastern Kansas, and northeastern Oklahoma and the Old Lead Belt covering about 110 square miles (280 km2) in southeastern Missouri. The first recorded mining occurred in the Old Lead Belt in about 1742. The production increased significantly in both the Tri-state area and the Old Lead Belt during the mid-1800s and lasted up to 1970.

Cleanup

Currently production still occurs in a third area, the Viburnum Trend, in southeastern Missouri. Mining and milling of ore produced more than 500 million tons of wastes in the Tri-State area and about 250 million tons of wastes in the Old Lead Belt. More than 75 percent of this waste has been removed, with some portion of it used over the years. Today, approximately 100 million tons of chat remain in the Tri-State area. The EPA, the states of Oklahoma, Kansas and Missouri, local communities, and private companies continue to work together in implementing and monitoring response actions that reduce or remove potential adverse impacts posed by remaining mine wastes contaminated with lead, zinc, cadmium, and other metals.

Ore processing

Ore production consisted of crushing and grinding the rock to standard sizes and separating the ore. Ore processing was accomplished in either a dry gravity separation or through a wet washing or flotation separation. Dry processes produced a fine gravel waste commonly called “chat.” The wet processes resulted in the creation of tailing ponds used to dispose of waste material after ore separation. The wastes from wet separation are typically sand and silt size and are called “tailings.” Milling produces large chat waste piles and flat areas with tailings deposited in impoundments. Tailings generally contain higher concentrations of heavy metals and therefore present a higher risk to human health and the environment through direct contact. Chat typically ranges in diameter from 1/4 to 5/8 inch. Intermingled material such as sands measure 0.033-0.008 inches in diameter and fine tailings are less than 0.008 inches (0.20 mm) in diameter.

Uses for chat

Chat piles appear grayish white in color and impact surrounding environments severely. Chat can be used to sprinkle on snow-covered roads to improve traction, as gravel, concrete aggregate, and asphalt pavement. These chats, found as huge man-made mounds in that county, are utilized as construction aggregate, principally for railroad ballast, highway construction, and concrete production.

From http://en.wikipedia.org/

Cave-in

2010-02-08T08:32:00.000-08:00

A cave-in is a collapse of a geologic formation, mine or structure which typically occurs during mining or tunneling. Geologic structures prone to cave-ins include alvar, tsingy and other limestone formations, but can also include lava tubes and a variety of other subsurface rock formations.

In mining, the term roof fall is used to refer to a range of collapses, ranging from the fall of a single flake of shale to collapses that form sink holes that reach to the surface. Note that roof falls in mining are not all accidental. In longwall mining and retreat mining, miners systematically remove all support from under large areas of the mine roof, allowing it to settle just beyond the work area. The goal in such mining methods is not to prevent roof fall and the ensuing surface subsidence, but to control it.

From http://en.wikipedia.org/

Alicanto

2010-02-04T12:08:00.000-08:00

The Alicanto or Allicanto is a mythological bird of the desert of Atacama, pertaining to Chilean mythology.

Legend

The legend says that the alicanto's wings shine during the night with beautiful, metallic colors, and their eyes emit strange lights; making a luminous flight some would not project shade on the desert.

This bird brings luck to any miner who sees it. Alicanto live in small caves between hills containing minerals, and feed on gold and silver.

If the lucky miner follows an alicanto without being caught, they can find silver or gold. But, if the alicanto discovers them, the bird will guide the greedy miner off a cliff, causing them to fall to their death.

Alicanto should not be confused with the Alicante, a fictional Mexican snake that drinks mother's milk and impregnates women, or uses the human stomach as a living place.

From http://en.wikipedia.org/

School of mines

2010-01-22T04:09:00.000-08:00

A school of mines (or mining school) is a term used for many engineering schools established in the 18th and 19th centuries that originally focused on mining engineering and applied science. Most no longer primarily teach mining-related subjects, although some have retained the name.

Universities offering degrees in mining engineering

North America

United States (ABET-accredited Mining Engineering)

* University of Alaska Fairbanks, College of Engineering and Mines, Fairbanks, Alaska
* University of Arizona, Department of Mining & Geological Engineering, Tucson
* Colorado School of Mines, Mining Engineering, Golden, CO
* University of Kentucky, Lexington, KY
* Missouri University of Science and Technology (formerly the Missouri School of Mines & Metallurgy), Rolla, Missouri
* Montana Tech of the University of Montana (formerly Montana School of Mines), Butte, MT
* University of Nevada, Reno (formerly The Mackay School of Mines) Reno, Nevada
* New Mexico Institute of Mining and Technology, Socorro, New Mexico
* Pennsylvania State University, University Park, PA
* Southern Illinois University at Carbondale, Carbondale, IL
* University of Utah, Department of Mining Engineering, Salt Lake City, Utah
* Virginia Polytechnic Institute and State University, Blacksburg, VA
* West Virginia University, in Morgantown, WV
* South Dakota School of Mines and Technology, Rapid City, SD

United States (non ABET-accredited or other programs)

* Michigan Technological University, Houghton, Michigan, offers a graduate program (MS and PhD) in Mining Engineering
* South Dakota School of Mines and Technology, Rapid City, SD, offers a degree in Mining Engineering and Management.

Canada

* Lassonde Mineral Engineering, University of Toronto, Toronto, Ontario
* McGill University, Montreal
* Norman B. Keevil Institute of Mining Engineering, The University of British Columbia, Vancouver and Kelowna
* Queen's University, Kingston, Ontario
* Mining Engineering, Laurentian University, Sudbury, Ontario
* University of Alberta, School of Mining & Petroleum Engineering,Edmonton, Alberta
* Dalhousie University, Halifax, Nova Scotia

Europe

* Imperial College London
* University of Glamorgan (formerly the Welsh School of Mines), Pontypridd, Glamorgan, UK
* Camborne School of Mines, Cornwall, United Kingdom
* Ecole Nationale Supérieure de Géologie, Nancy
* Ecole des Mines, Paris
* École Nationale Supérieure des Mines de Saint-Étienne, Saint-Étienne, France
* Groupe des écoles des mines, seven engineering schools in France
* Technische Universität Bergakademie Freiberg, Freiberg, Germany, the oldest Academy of Mining in the world, founded in 1765
* Faculty of Mining and Geology, University of Belgrade, Serbia
* Faculty of Mining, Geology and Petroleum Engineering, University of Zagreb, Croatia
* Faculty of Mining and Geology, Silesian University of Technology, Gliwice, Poland
* Faculty of Geoengineering, Mining and Geology, Wroclaw University of Technology, Wroclaw, Poland
* Instituto Superior Técnico da Universidade Técnica de Lisboa, Lisbon, Portugal
* Escuela Técnica Superior de Ingenieros de Minas de Madrid, Universidad Politécnica de Madrid, Madrid, Spain
* Escuela Técnica Superior de Ingenieros de Minas de Oviedo/Escuela Téunica d'Inxenieros de Mines d'Uviéu, Universidad de Oviedo/Universidá d'Uviéu, Oviedo/Uviéu, Spain
* Helsinki University of Technology, Helsinki, Finland
* Technische Universiteit Delft, Delft, The Netherlands
* Department of Natural Resources, Katholieke Universiteit Leuven, Leuven, Belgium
* Faculty of Mining Engineering and Metallurgy, National Technical University of Athens, Greece
* Moscow State Mining University, Russia
* Saint Petersburg Mining Institute, Saint Petersburg, Russia
* Faculty of Mines, Istanbul Technical University, Istanbul, Turkey

Africa

* University of Pretoria, Pretoria, South Africa
* University of the Witwatersrand, Johannesburg, South Africa
* University of Dar-es-salaam, Tanzania
* The Mohammadia School of Engineering, Department of Mineral Engineering, Rabat, Morocco
* Department of Mining Engineering, University of Zimbabwe, Harare, Zimbabwe
* School of Mines, Bulawayo Polytechnic College and National University of Science and Technology, Bulawayo, Zimbabwe
* Zimbabwe School of Mines, Killarney, Bulawayo, Zimbabwe

South America

* Escola Politécnica, Universidade de São Paulo, São Paulo, Brazil
* Department of Mining Engineering, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
* Universidade Federal de Ouro Preto (formerly Escola de Minas de Ouro Preto, Minas Gerais, Brazil
* Faculdade de Engenharia, Universidade do Estado de Minas Gerais , João Monlevade, Brazil
* Department of Mining Engineering , University Federal of Pernambuco (UFPE), Recife, Pernambuco, Brazil.
* Department of Mining Engineering, Universidade Federal do Rio Grande do Sul, Rio Grande do Sul, Brazil
* Department of Mining Engineering, Universidade Federal da Bahia, Salvador, Bahia, Brazil
* Facultad de Ingenieria de Minas, Pontificia Universidad Catolica del Peru (PUCP)
* Escuela Profesional de Ingeniería de Minas, Universidad Nacional Daniel Alcides Carrión, Cerro de Pasco, Peru.
* Mining Engineering Department, University of Chile, Santiago, Chile
* Departamento de Ingeniería en Minas, Universidad de Santiago de Chile, Santiago, Chile
* Centro de Minería, Pontificia Universidad Católica de Chile, Santiago, Chile
* Faculty of Mines, Universidad Nacional de Colombia, Sede Medellín, Colombia

Asia

* Indian School of Mines University, Dhanbad, India
* IIT Kharagpur, Kharagpur, India
* NIT Karnataka, Surathkal, India
* NIT Rourkela, Orissa, India
* Visvesvaraya National Institute of Technology(NIT Nagpur), Maharashtra, India
* NIT Raipur, Chattisgarh, India
* Banaras Hindu University, Department of Mining Engineering, Varanasi, India
* Bengal Engineering & Science University, Howrah, India
* Guindy Engineering College, Anna University, Chennai, India
* Kothagudem School of Mines, Kothagudem, India
* University of Tehran, Department of Mining Engineering, Tehran, Iran
* International University of Imam Khomeini, Qazvin, Iran

Australia

* School of Civil and Resource Engineering , University of Western Australia
* School of Civil, Environmental and Mining Engineering , University of Adelaide, South Australia
* University of Wollongong, New South Wales
* School of Mining Engineering, University of New South Wales, Sydney
* School of Mining Engineering, University of Queensland, Brisbane
* School of Science and Engineering, University of Ballarat, Victoria
* Western Australian School of Mines, Kalgoorlie, Western Australia
* Melbourne School of Engineering, University of Melbourne, Victoria offers a Master of Mining Engineering
* The South Australian School of Mines and Industries, established 1889, is now part of the University of South Australia

From http://en.wikipedia.org/

Industrial Revolution

2010-01-17T15:45:00.000-08:00

The Industrial Revolution was a period from the 18th to the 19th century where major changes in agriculture, manufacturing, mining, and transport had a profound effect on the socioeconomic and cultural conditions starting in the United Kingdom, then subsequently spreading throughout Europe, North America, and eventually the world. The onset of the Industrial Revolution marked a major turning point in human history; almost every aspect of daily life was eventually influenced in some way.

Starting in the later part of the 18th century there began a transition in parts of Great Britain's previously manual labour and draft-animal–based economy towards machine-based manufacturing. It started with the mechanisation of the textile industries, the development of iron-making techniques and the increased use of refined coal. Trade expansion was enabled by the introduction of canals, improved roads and railways. The introduction of steam power fuelled primarily by coal, wider utilisation of water wheels and powered machinery (mainly in textile manufacturing) underpinned the dramatic increases in production capacity. The development of all-metal machine tools in the first two decades of the 19th century facilitated the manufacture of more production machines for manufacturing in other industries. The effects spread throughout Western Europe and North America during the 19th century, eventually affecting most of the world, a process that continues as industrialisation. The impact of this change on society was enormous.

The first Industrial Revolution, which began in the 18th century, merged into the Second Industrial Revolution around 1850, when technological and economic progress gained momentum with the development of steam-powered ships, railways, and later in the 19th century with the internal combustion engine and electrical power generation. The period of time covered by the Industrial Revolution varies with different historians. Eric Hobsbawm held that it 'broke out' in Britain in the 1780s and was not fully felt until the 1830s or 1840s, while T. S. Ashton held that it occurred roughly between 1760 and 1830. Some twentieth century historians such as John Clapham and Nicholas Crafts have argued that the process of economic and social change took place gradually and the term revolution is not a true description of what took place. This is still a subject of debate among historians. GDP per capita was broadly stable before the Industrial Revolution and the emergence of the modern capitalist economy. The Industrial Revolution began an era of per-capita economic growth in capitalist economies. Historians agree that the Industrial Revolution was one of the most important events in history.

From http://en.wikipedia.org/

Hushing

2010-01-14T16:41:00.000-08:00

Hushing is an ancient mining method using a flood or torrent of water to reveal mineral veins. The method was applied in several ways, both in prospecting for ores, and for their exploitation. Mineral veins are often hidden below soil and sub-soil, which must be stripped away to discover the ore veins. A flood of water is very effective in moving soil as well as working the ore deposits when combined with other methods such as fire-setting. It was used during the formation and expansion of the Roman Empire from the first century BC on to the end of the empire. It is now redundant except in a variant known as hydraulic mining, where jets or streams of water are used to break down deposits, especially of alluvial gold and alluvial tin.

History

The method is well described by Pliny the Elder in Book XXXIII of his Naturalis Historia from the first century AD. He distinguishes the use of the method for prospecting for ore and use during mining itself. It was used during the Roman period for hydraulic mining of alluvial gold deposits, and in opencast vein mining, for removal of rock debris, created by mechanical attack and fire-setting. He describes how tanks and reservoirs are built near the suspected veins, filled with water from an aqueduct, and the water suddenly released from a sluice-gate onto the hillside below, scouring the soil away to reveal the bedrock and any veins occurring there. The power behind a large release of water is very great, especially if it forms a single water wave, and is well known as a strong force in coastal erosion and river erosion. The method was most effective when used on steep ground such as the brow of a hill or mountain, the force of falling water lessening as the slope becomes smaller.

If veins of ore were found using the method, then hushing could also remove the rock debris created when attacking the veins. Pliny also describes the way hillsides could be undermined, and then collapsed to release the ore-bearing material. The Romans developed the method into a sophisticated way of extracting large alluvial gold deposits such as those at Las Medulas in northern Spain, and for hard rock gold veins such as those at Dolaucothi in Wales. The development of the mine at Dolaucothi shows the versatility of the method in finding and then exploiting ore deposits.

There are the remains of numerous tanks and reservoirs still to be seen at the site, one example being shown at left. It was a small tank built for prospection on the north side of the isolated opencast north of the main mine. It was presumably built to prospect the ground to one side of the opencast for traces of the gold-bearing veins extending to the north. It failed to find the veins here, so was abandoned. It probably precedes the construction of the 7 mile long aqueduct supplying the main site, and was fed by a small leat from a tributary of the river Cothi about a mile further north up the valley. The method could be applied to any ore type, and succeeded best in hilly terrain. The Romans were well experienced in building the long aqueducts needed to supply the large volumes of water needed by the method, and was probably directed by army engineers.

Earlier evidence

The earlier history of the method is obscure, although there is an intriguing reference by Strabo writing ca 25 BC in his Geographica, to gold extraction in the Val d'Aosta in the Alps. He describes the problem gold miners had with a local tribe because of the great volumes of water they had taken from the local river, reducing it to a trickle and so affecting the local farmers. Whether or not they used the water for hushing remains unknown, but it seems possible because the method requires large volumes of water to be operated. Later, when the Romans assumed control of the mining operations, the locals charged them for using the water. The tribe occupied the higher mountains and controlled the water sources, and had not yet been subdued by the Romans.

The historian Polybius, who lived from 220 to 170 BC was writing much earlier in The Histories, and he records that gold mining in the Alpine region was so successful that the price of gold in Italy fell by a third during this period. From his description of large nuggets, and the find being made only two feet below the ground level, with deposits reaching down to 15 feet, it is likely to have been an alluvial deposit where water methods such as hushing would have been very effective. Modern attempts to identify the mines point to one especially large ancient gold mine at Bessa in Northern Italy. It appears to have been worked intensively in pre-Roman days and continued to expand with Roman involvement. The scale of the aqueducts there seems to support Strabo's comments.

Later examples

The technique appears to have been neglected through the medieval period, because Georg Agricola, writing in the 15th century in his De Re Metallica, does not mention hushing at all. On the other hand, he does describe the many uses of water power, especially for washing ore and driving watermills.

However, the technique was used on a large scale in the lead mines of northern Britain from Elizabethan times onwards. The method is described in the Royal Commission on Children in Mines in 1842 in relation to children being used in the lead mines of the Pennines. The remnants of the "hush gullies" are visible at many places in the Pennines as well as at many other locations such as the extensive lead mines at Cwmystwyth in Ceredigion, and at the Stiperstones in Shropshire.

One famous and spectacular example is the Great Dun Fell hush gully near Cross Fell, Cumbria, probably formed in Georgian era in the search for lead and silver. The gully is about 100 feet deep, carries a small stream, and is a prominent landmark on the bleak moors.

Although the Cornish did not use the term "hushing", there is at least one reference to the technique being used at Tregardock in North Cornwall. Around 1580 mine adventurers used the method to work a lead-silver deposit, although lives were lost in the attempt.

From http://en.wikipedia.org/

Hurrying

2010-01-05T07:56:00.000-08:00

A hurrier, also sometimes called a coal drawer, was a child or woman employed by a collier to transport the coal that they had mined. Woman would normally get the children to help them because of the dificulty of carrying the coal. Common particularly in the early 19th century, the hurrier pulled a corf (baskets or small wagons) full of coal along roadways as small as 16 inches in height. They would often work 12 hour shifts, making several runs down to the coal face and back to the surface again.

Some children came from the workhouses and were apprenticed to the colliers. Adults could not easily do the job because of the size of the roadways, which were limited on the grounds of cost and structural integrity. Hurriers were equipped with a "gurl" belt – a leather belt with a swivel chain linked to the corf. They were also given candles as it was too expensive to light the whole mine.

Roles

Children as young as three or four were employed, with both sexes contributing to the work. The younger ones often worked in small teams, with those pushing the corf from the rear being known as thrusters. The thrusters often had to push the corf using their heads, leading to the hair on their crown being worn away and the child becoming bald.

Some children were employed as coal trappers, particularly those not yet strong enough to pull or push the corf. This job saw the child sit in a small cutting waiting for the hurriers to approach. They would then open the trapdoors to allow the hurrier and his cargo through. The trappers also opened the trapdoors to provide ventilation in some locations.

As mines grew larger the volume of coal extracted increased beyond the pulling capabilities of children. Instead horses guided by coal drivers were used to pull the corves. These drivers were usually older children between the ages of 10 and 14.

Legislation

In August 1842 the Children's Employment Commission drew up an act of Parliament which gave a minimum working age for boys in mines, though the age varied between districts and even between mines. The Mines and Collieries Act also outlawed the employment of women and girls in mines. In 1870 it became compulsory for all children aged between five and thirteen to go to school, ending much of the hurrying. It was still a common profession for school leavers well into the 1920s.

The 1969 song The Testimony Of Patience Kershaw by Frank Higgins centres around the testimony of Patience Kershaw when she spoke to the Children's Employment Commission.

From http://en.wikipedia.org/

History of coal mining

2010-01-03T06:41:00.000-08:00

Due to its abundance, coal has been mined in various parts of the world throughout history and continues to be an important economic activity today. Compared to wood fuels, coal yields a higher amount of energy per mass and could be obtained in areas where wood is not readily available. Though historically used as a means of household heating, coal is now mostly used in industry, especially in smelting and alloy production, as well as electricity generation.

Large-scale coal mining developed during the Industrial Revolution, and coal provided the main source of primary energy for industry and transportation in the West from the 18th century to the 1950s. Coal remains an important energy source, due to its low cost and abundance when compared to other fuels, particularly for electricity generation. However, coal is also mined today on a large scale by open pit methods wherever the coal strata strike the surface and is relatively shallow.

Britain developed the main techniques of underground coal mining from the late 18th century onward with further progress being driven by 19th century and early 20th century progress.

However oil and its associated fuels began to be used as alternative from this time onward. By the late 20th century coal was for the most part replaced in domestic as well as industrial and transportation usage by oil, natural gas or electricity produced from oil, gas, nuclear power or renewable energy sources.

Since 1890, coal mining has also been a political and social issue. Coal miners' labour and trade unions became powerful in many countries in the 20th century, and often the miners were leaders of the Left or Socialist movements (as in Britain, Germany, Poland, Japan, Canada and the U.S.) Since 1970, environmental issues have been increasingly important, including the health of miners, destruction of the landscape from strip mines and mountaintop removal, air pollution, and coal combustion's contribution to global warming.

From http://en.wikipedia.org/

Gold rush

2010-01-01T17:16:00.000-08:00

A gold rush is a period of feverish migration of workers into the area of a dramatic discovery of commercial quantities of gold. Gold rushes took place in the 19th century in Australia, Brazil, Canada, South Africa, and the United States.

Gold rushes were typically marked by a general buoyant feeling of a "free for all" in income mobility, in which any single individual might become abundantly wealthy almost instantly. The significance of gold rushes in history has given a longer life to the term, and it is now applied generally to denote any capitalist economic activity in which the participants aspire to race each other in common pursuit of a new and apparently highly lucrative market, often precipitated by an advance in technology.

Gold rushes helped spur permanent non-indigenous settlement of new regions and define a significant part of the culture of the North American and Australian frontiers. As well, at a time when money was based on gold, the newly-mined gold provided economic stimulus far beyond the gold fields. Gold rushes presumably extend back as far as gold mining, to the Roman Empire, whose gold mining was described by Diodorus Siculus and Pliny the Elder, and probably further back to Ancient Egypt.

There are about 13 million to 20 million small-scale miners around the world, according to Communities and Small-Scale Mining (CASM). Approximately 100 million people are directly or indirectly dependent on small-scale mining. There are 800,000 to 1.5 million artisanal miners in Democratic Republic of Congo, 350,000 to 650,000 in Sierra Leone, and 150,000 to 250,000 in Ghana, with millions more across Africa.

Life cycle of a gold rush

Within each mining rush there is typically a transition through progressively higher capital expenditures, larger organizations, and more specialized knowledge. They may also progress from high-unit value to lower unit value minerals (from gold to silver to base metals).

The rush is started by a discovery of placer gold made by an individual. At first the gold may be washed from the sand and gravel by individual miners with little training, using a gold pan or similar simple instrument. Once it is clear that the volume of gold-bearing sediment is larger than a few cubic meters, the placer miners will build rockers or sluice boxes, with which a small group can wash gold from the sediment many times faster than using gold pans. (See placer mining for details.) Winning the gold in this manner requires almost no capital investment, only a simple pan or equipment that may be built on the spot, and only simple organization. The low investment, the high value per unit weight of gold, and the ability of gold dust and gold nuggets to serve as a medium of exchange, allow placer gold rushes to occur even in remote locations.

After the sluice-box stage, placer mining may become increasingly large scale, requiring larger organizations, and higher capital expenditures. Small claims owned and mined by individuals may need to be merged into larger tracts. Difficult-to-reach placer deposits may be mined by tunnels. Water may be diverted by dams and canals to placer mine active river beds or to deliver water needed to wash dry placers. The more advanced techniques of ground sluicing, hydraulic mining, and dredging may be used.

Typically the heyday of a placer gold rush would last only a few years. The free gold supply in stream beds would become depleted somewhat quickly, and the initial phase would be followed by prospecting for veins of lode gold that were the original source of the placer gold. Hardrock mining, like placer mining, may evolve from low capital investment and simple technology to progressively higher capital and technology. The surface outcrop of a gold-bearing vein may be oxidized, so that the gold occurs as native gold, and the ore needs only to be crushed and washed (free milling ore). The first miners may at first build a simple arrastre to crush their ore; later, they may build stamp mills to crush ore more quickly. As the miners dig down, they may find that the deeper part of vein contains gold locked in sulfide or telluride minerals, which will require smelting. If the ore is still sufficiently rich, it may be worth shipping to a distant smelter (direct shipping ore). Lower-grade ore may require on-site treatment to either recover the gold or to produce a concentrate sufficiently rich for transport to the smelter. As the district turns to lower-grade ore, the mining may change from underground mining to large open-pit mining.

Many silver rushes followed upon gold rushes. As transportation and infrastructure improve, the focus may change progressively from gold to silver to base metals. In this way, Leadville, Colorado started as a placer gold discovery, achieved fame as a silver-mining district, then relied on lead and zinc in its later days. Butte, Montana began mining placer gold, then became a silver-mining district, then became for a time the world’s largest copper producer.

Gold rushes by region

Australian Gold rushes

The Victorian gold rush, which occurred in Australia in 1851 soon after the California gold rush, was the biggest of several Australian gold rushes. That gold rush was highly significant to Australia’s, and especially Victoria's and Melbourne's, political and economic development. With the Australian gold rushes came the construction of the first railways and telegraph lines, multiculturalism and racism, the Eureka Stockade and the end of penal transportation.

In 1852 alone, 370,000 immigrants arrived in Australia and the economy of the nation boomed. The 'rush' was well and truly on. Victoria contributed more than one third of the world's gold output in the 1850s and in just two years the State's population had grown from 77,000 to 540,000.

The number of new arrivals to Australia was greater than the number of convicts who had landed there in the previous seventy years. The total population trebled from 430,000 in 1851 to 1.7 million in 1871.

Gold rushes happened at or around:

* Coolgardie
* Charters Towers
* Kalgoorlie
* Bathurst
* Bendigo
* Ballarat
* Hill End

North America

The first significant gold rush in the United States was in Cabarrus County, North Carolina (east of Charlotte), in 1799 at today's Reed's Gold Mine. Thirty years later, in 1829, the Georgia Gold Rush in the southern Appalachians occurred. It was followed by the California Gold Rush of 1848–52 in the Sierra Nevada, which captured the popular imagination. The California gold rush led directly to the settlement of California by Americans and the rapid entry of that state into the union in 1850. The gold rush in 1849 stimulated worldwide interest in prospecting for gold, and led to new rushes in Australia, South Africa, Wales and Scotland.- Successive gold rushes occurred in western North America, moving north and east from California: Fraser Canyon, the Cariboo district and other parts of British Columbia, and the Rocky Mountains. Resurrection Creek, near Hope, Alaska was the site of Alaska's first gold rush more than a century ago, and placer mining continues today. Other notable Alaska Gold Rushes were Nome and the Fortymile River.

Klondike

One of the last "great gold rushes" was the Klondike Gold Rush in Canada's Yukon Territory (1898–99), immortalized in the novels of Jack London, the poetry of Robert W. Service and Charlie Chaplin's film The Gold Rush. The main goldfield was along the south flank of the Klondike River near its confluence with the Yukon River near what was to become Dawson City in Canada's Yukon Territory but it also helped open up the relatively new US possession of Alaska to exploration and settlement and promoted the discovery of other gold finds.

South Africa

In South Africa, the Witwatersrand Gold Rush in the Transvaal was important to that country's history, leading to the founding of Johannesburg and tensions between the Boers and British settlers.

South African gold production went from zero in 1886 to 23% of the total world output in 1896. At the time of the South African rush, gold production benefited from the newly discovered techniques by Scottish chemists, the MacArthur-Forrest process, of using potassium cyanide to extract gold from low-grade ore.

Notable gold rushes by date

Rushes of the 1690s

* Brazil Gold Rush, Minas Gerais (1695)

Rushes of the 1800s

* North Carolina Gold Rush, Cabarrus County, North Carolina, US (1799)

Rushes of the 1820s

* Georgia Gold Rush, Georgia, US (1828)

Rushes of the 1840s

* California Gold Rush, California (1848)

Rushes of the 1850s

* Queen Charlottes Gold Rush, British Columbia, Canada (1850); the first of many British Columbia gold rushes
* Victorian Gold Rush, Victoria, Australia
* Fraser Canyon Gold Rush, British Columbia (1858–1861)
* Rock Creek Gold Rush, British Columbia (1859–1860s)
* Pikes Peak Gold Rush, Pikes Peak, Colorado (1859)
* Northern Nevada Gold Rush (from 1850 - 1934)

Rushes of the 1860s

* Idaho Gold Rush, also known as the Fort Colville Gold Rush, near Colville, Washington state (1860)
* Cariboo Gold Rush, British Columbia (1862–65)
* Stikine Gold Rush, British Columbia (1863)
* Big Bend Gold Rush, British Columbia (1865—66)
* Omineca Gold Rush, British Columbia (1869)
* Wild Horse Creek Gold Rush, British Columbia (1860s),
* Black Hills Gold Rush, Black Hills of South Dakota and Wyoming (1863, later extending into Montana)
* Eastern Oregon Gold Rush (1860s–1870s)
* Kildonnan Gold Rush, Sutherland, Scotland (1869)
* Central Otago Gold Rush, New Zealand

Rushes of the 1870s

* Cassiar Gold Rush, British Columbia, 1871
* Palmer River Gold Rush, Palmer River, Queensland, Australia (1872)
* Black Hills Gold Rush, The Black Hills, South Dakota (1874)
* Bodie Gold Rush, Bodie, California (1876)
* Kumara Gold Rush, Kumara and Dillmanstown, New Zealand (1876)
* Hungen, Hesse, Germany (1877)

Rushes of the 1880s

* Witwatersrand Gold Rush, Transvaal, South Africa (1886); the resulting influx of miners was one of the triggers of the Second Boer War
* Cayoosh Gold Rush in Lillooet, British Columbia (1884—87)
* Tulameen Gold Rush near Princeton British Columbia

Rushes of the 1890s

* Tierra del Fuego Gold Rush, Tierra del Fuego, southern Chile and Argentina
* Cripple Creek Gold Rush, Cripple Creek, Colorado (1891)
* Westralia Gold Rush, Kalgoorlie, Western Australia
* Klondike Gold Rush, centered on Dawson City, Yukon, Canada (1896–1898)
* Atlin Gold Rush, Atlin, British Columbia (1898)
* Nome Gold Rush, Nome, Alaska (1898–99)

Rushes of the 1900s

* Fairbanks Gold Rush, Fairbanks, Alaska (1902–1905)
* Goldfield Gold Rush, Goldfield, Nevada
* Cobalt Silver Rush, 1903-5, Cobalt, Ontario, Canada
* Porcupine Gold Rush, 1909-11, Timmins, Ontario, Canada – little known, but one of the largest in terms of gold mined, 67 million ounces as of 2001

Rushes of the 1930s

* Kakamega gold rush, Kenya, 1932

Rushes of the 1970s

* Upper Amazon Gold Rush, Upper Amazon region, Brazil and Peru

Rushes of the 1980s

* Amazon Gold Rush, Amazon region, Brazil
* Mount Kare Gold Rush, Enga Province, Papua New Guinea

Rushes of the 2000s

* Great Mongolian Gold Rush, Mongolia (2001)
* Apuí Gold Rush, Apuí, Amazonas, Brazil (2006); approximately 500,000 miners are thought to work in the Amazon's "garimpos" (gold mines).

From http://en.wikipedia.org/

Geordie lamp

2009-12-26T01:41:00.000-08:00

The Geordie lamp was invented by George Stephenson in 1815 as a solution to explosions due to firedamp in coal mines.

Although controversy arose between Stephenson's design and the Davy lamp, (invented by Humphry Davy in the same year), Stephenson's original design worked on significantly different principles. If the only way air could get to the flame was restricted (a baseplate pierced by a number of small-bore brass tubes was the usual way of doing this) and the lamp body above the flame lengthened, then the same amount of air could get to the flame, but would pass through the flow restriction at a velocity higher than the velocity of the flame in a mixture of firedamp (mostly methane) and air. This, then, prevented an explosive backblast that might light the surrounding air.

Stephenson's design used glass to surround the flame, which cut out less of the light than Davy's, where the gauze surrounded it. But this also posed the danger of breakage in the harsh conditions of mineworking, which problem was not resolved until the invention of safety glass. Stephenson tried several different designs in early years and later adopted Davy's gauze in preference to the tubes and it was this revised design that was used for most of the 19th century as the Geordie lamp.

The name is possibly the route by which 'Geordie' became the familiar and affectionate epithet for Tynesiders, deriving from a diminutive form of the inventor's first name, George.

From http://en.wikipedia.org/

Freeminer

2009-12-24T01:18:00.000-08:00

A Freeminer is the ancient title given to a coal miner in the Forest of Dean, Gloucestershire, UK who has earned the right to mine personal plots known as "gales" within the royal forest.

Eligibility

In order to earn this right, an individual must be male, born within the ancient administrative district known as the "Hundred of St Briavels", (now generally considered to be contiguous with the Forest of Dean (district)), and have worked down a mine for a year-and-a-day. The officer in charge of regulating the freemines and freeminers, including allocating the gales, is known as the Gaveller, a historical post which still exists today.

The rights of the Freeminers are very ancient, and were confirmed by Edward II of England, who in doing so, claimed that the rights of the Freeminers had existed "tyme out of mynde". A plaque bearing the engraved coat of arms of the Freeminers hangs in Newland church, and another in the church of St. Michael in Abenhall.

Present day

Freeminers still operate today, though on a much reduced basis, due to several factors including the closure of mainstream commercial pits in the Forest of Dean, the low price of and demand for coal, the relatively high costs of small-scale extraction, the closure of maternity hospital facilities - such that it will be impossible to be born within the "Hundred of St Briavels" - and attempts by the UK government to exact commercial operating licence charges out of these small-scale producers. However, despite the modest level of activity, Freemining tradition remains an important part of local identity, and some Freemines operate successfully, especially through diversification into non-traditional areas, such as tourism and ochre mining at Clearwell Caves.

From http://en.wikipedia.org/

Fire-setting

2009-12-23T01:34:00.000-08:00

Fire-setting is a method of mining used mostly in antiquity. Fires were set against a rock face to heat the stone, which was then doused with water causing the stone to fracture by thermal shock. This technique was best performed in opencast mines where the smoke and fumes could dissipate safely. The technique was very dangerous in underground workings without adequate ventilation. The method became redundant with the growth in use of explosives.

History

The method is first described by Diodorus Siculus in his Bibliotheca historica written about 60 BC, about methods of mining used in ancient Egyptian gold mines. It is also mentioned in greater detail by Pliny the Elder in his Naturalis Historia published in the first century AD. In Book XXXIII, he describes mining methods for gold, and the pursuit of the gold-bearing veins underground using tunnels and stopes. He mentions the use of vinegar to quench the hot rock, but water would have been just as effective as vinegar was expensive at the time for regular use in a mine. The reference to vinegar may come from a description by Livy of Hannibal's crossing of the Alps, when it was said that the soldiers used vinegar in fire-setting to remove large rocks in the path of his army.

Pliny also says that the method was used both in opencast and deep mining. That the method was used in practice is confirmed by remains found at the Roman gold mine of Dolaucothi in west Wales, when modern miners broke into much older workings during the 1930s where they found wood ashes near worked rock faces. In another part of the mine, there are three adits at different heights which have been driven through barren rock to the gold-bearing veins for some considerable distance, and they would have not only provided drainage but also ventilation to remove the smoke and hot gases during a fire-setting operation. They were certainly much larger in section than was normal for access galleries, and the draught of air through them would have been considerable.

Fire-setting would have been used extensively during opencast mining, and is also described by Pliny in connection with the use of another mining technique known as hushing. Aqueducts were built to supply copious amounts of water to the minehead, where they were used to fill tanks and cisterns. The water was unleashed to scour the hillside below, both soil in the case of prospecting for metal veins, and then rock debris after a vein had been found. Fire-setting was used to break up the hard rocks of the vein itself and surrounding barren rock, and was much safer than use in underground workings since the smoke and fumes would be dissipated much more easily than in a confined space underground. Pliny also describes undermining methods were used to facilitate attack of the hard rocks, and probably the softer alluvial deposits too.

Agricola

The method continued in use in the medieval period, and is described by Georg Agricola in his treatise on mining and mineral extraction, De Re Metallica. He warns about the problem of the "foetid vapours" and the need to evacuate the workings while the fires are lit, and presumably for some time afterwards until the gases and smoke had cleared. The problem raises the question of ventilation means in the mines, a problem often solved by ensuring that there was a continuous path for escape of the noxious fumes, perhaps aided by artificial ventilation. Agricola mentions the use of large water-powered bellows to create a draught, and continuity of workings to the surface were essential for a stream of air to run through them.

In later times, a fire at the base of a shaft was used to create an updraught, but just like fire-setting, it was a hazardous and dangerous procedure, especially in collieries. As the number and complexity of the underground workings increased, care was needed to channel the air draught to all parts of the tunnels and faces. It was usually achieved by installing doors at key points. Most of the deaths in coal mine disasters were caused by inhalation of the toxic gases produced by firedamp explosions.

The method continued in use for many years afterwards until finally made redundant by the use of explosives. However, they also produce toxic gases and care is needed to ensure good ventilation to remove those gases, like carbon monoxide, as well as choice of the explosive itself to minimise their emission.

From http://en.wikipedia.org/

De re metallica

2009-12-21T15:45:00.000-08:00

De re metallica (Latin for On the Nature of Metals (Minerals)) is a book cataloging the state of the art of mining, refining, and smelting metals, published in 1556. The author was Georg Bauer, whose pen name was the Latinized Georgius Agricola. The book remained the authoritative text on mining for 250 years after its publication.

Agricola had spent nine years in the Bohemian town of Joachimsthal, now in the Czech Republic. (Joachimsthal is famous for its silver mines and the origin of the word "Thaler.") After Joachimsthal, he spent the rest of his life in Chemnitz, a prominent mining town in what was then Saxony. Both Joachimsthal and Chemnitz are in the Erzgebirge, or Ore Mountains.

Mining Methods

Agricola describes methods for prospecting for minerals, their occurrence in the form of alluvial deposits and the distribution of the veins or ores. He follows these sections by a description of the methods of deep mining, the building of shafts to extract the ore, and tunnels to follow the veins. The book is illustrated copiously with often very detailed woodcuts of the various operations. The use of water for washing ores is discussed in great detail, such as the use of launders and washing tables, especially needed for heavy ores such as those of gold and tin, together with various machines needed to crush the vein ore, many of which were worked by water mills. He makes frequent reference to classical authors, such as Pliny the Elder who wrote about mining methods in his Natural History published in the 77 AD.

One of the primary problems this book addressed was the removal of water from the mines. The limit Agricola documents for raising water from the mines via a pump is 32 feet. It could then be dumped into another level and pumped from there. The investigation of this problem (and its popularization) would spark a discussion leading to the discovery of air pressure. Also included in this volume are discussions of the geology of ore bodies, surveying, mine construction, and ventilation. He describes the method of breaking hard rocks using fire-setting, which involved making a fire against a rock-face, and then quenching the rock with water to induce cracking by thermal shock.

De Re Metallica was not limited to mining. It also covered assaying, refining, smelting, and marketing. It covered the creation of saltpeter, and the use of different acids in the refining process, as well as alchemy, timbering, and even some on the diseases of miners and smelters.

Publication history

Although Agricola died in 1555, the publication was delayed until the completion of the extensive and detailed woodcuts. The book was costly and limited in distribution: in many areas it was chained in churches, so that the priest could translate from Latin for parishioners. One of the rare editions (printed in 1657 in Italy) of this book can be found.

In 1912, the first English translation of De Re Metallica was privately published in London by subscription. The translators were Herbert Hoover, a mining engineer (and later President of the United States), and his wife, Lou Henry Hoover, a geologist and Latinist. The translation is notable not only for its clarity of language, but for the extensive footnotes, which detail the classical references to mining and metals, such as the Natural History of Pliny the Elder, the history of mining law in England, France, and the German states; safety in mines, including historical safety; and known minerals at the time that Agricola wrote De Re Metallica.

Subsequent translations into other languages, including German, owe much to the Hoover translations, as their footnotes detail their difficulties with Agricola's baroque vocabulary.

From http://en.wikipedia.org/

Davy lamp

2009-12-19T16:51:00.000-08:00

The Davy lamp is a safety lamp with a wick and oil vessel burning originally a heavy vegetable oil, devised in 1815 by Sir Humphry Davy. It was created for use in coal mines, allowing deep seams to be mined despite the presence of methane and other flammable gases, called firedamp or minedamp.

Davy had discovered that a flame enclosed inside a mesh of a certain fineness cannot ignite firedamp. The screen acts as a flame arrestor; air (and any firedamp present) can pass through the mesh freely enough to support combustion, but the holes are too fine to allow a flame to propagate through them and ignite any firedamp outside the mesh. The first trial of a Davy lamp with a wire sieve was at Hebburn Colliery on 9 January 1816.

Gas Detector

The lamp also provided a crude test for the presence of gases. If flammable gas mixtures were present, the flame of the Davy lamp burned higher with a blue tinge. Miners could also place a safety lamp close to the ground to detect gases, such as carbon dioxide, that are denser than air and so could collect in depressions in the mine; if the mine air was oxygen-poor (asphyxiant gas), the lamp flame would be extinguished (black damp or chokedamp).

Comparison with Geordie lamp

There was some controversy, since George Stephenson also produced a similar safety lamp in 1816 called the Stephenson generally and locally within the North East coalfields the Geordie.

Supporters of each man seem to have regarded the other as having plagiarised their man's idea. The Geordie lamp had a glass inside the tubular gauze with a copper cap; the air was fed from below. The Davy lamp was simpler and cheaper, and was popular with mine owners.

There were safety arguments on both sides: in principle, a poorly maintained (or badly designed) Davy lamp could overheat the gauze if it met a high concentration of methane. The gauze rusted easily in the damp mines, making the lamp hazardous. The Geordie lamp could become unsafe if the internal glass was broken (as it became an oversize Davy). Both original lamps were faulty, and led to attempts at improvement, by using multiple gauzes above the flame, and with a glass surround to improve illumination. They were poor sources of light and the situation did not improve until the introduction of electric hand lamps in the Victorian period.

Accident rate

The introduction of the Davy lamp actually led to an increase in accidents in mines, as the lamp encouraged working mines that had previously been closed for safety reasons.

One reason why the lamp caused an increase in the accident rate was that the men continued to work in unsafe conditions due to the presence of methane gas. The other reason why there was an increase was that there should have been an installation of extractor ventilation fans installed at each mine to reduce the concentration of methane in the air. This would have been expensive, and thus they were not installed by mine owners. The lamps also had to be provided by the miners themselves, not the owners, as traditionally the miners bought their own candles at top price in the company store. The installation of fans became required after laws requiring minimum air quality standards were introduced.

Modern Lamps

The modern day equivalent of the Davy lamp is the Protector Garforth GR6S flame safety lamp which is used for firedamp testing in all UK coal mines. A modified version of this lamp is used to transport the Olympic Flame for the torch relays. They have recently been used for the Sydney, Athens, and Turin torch relays and have been used for the Special Olympics Beijing relay, they will also be used for the London 2012 relay. The lamps are still made in Eccles.

From http://en.wikipedia.org/

Stamp mill

2009-12-17T15:59:00.000-08:00

A stamp mill (or stamp battery or stamping mill) is a type of mill machine that crushes material by pounding rather than grinding, either for further processing or for extraction of metallic ores. Breaking material down is a type of unit operation.

Cornish stamps are stamp mills that were developed in Cornwall for use in tin mining in around 1850. Cornish stamps were used to crush small lumps of ore into sand like material. Constructed from heavy timber or iron lifters with iron "heads" at the bottom were raised by cams on a rotating axle, and fell on the ore and water mixture, fed into a box beneath. The heads normally weighed between 4 and 8 cwt vague each, and were usually arranged in sets of four, in timber frames. Small stamps were commonly powered by water wheels and larger ones by steam engines.

Californian stamps were based on Cornish stamps and were used in the Californian gold mines. They were more rapid in action, and the heads and lifters were made to rotate so that they wore more evenly. The other advantage of the Californian stamp was that a single head could crush 1.5 tons of ore as opposed to the Cornish stamps which could only crush 1 ton.

Arrangement

A stamp mill consists of a set of heavy steel (iron-shod wood in some cases) stamps, loosely held vertically in a frame, in which the stamps can slide up and down. They are lifted by cams on a horizontal rotating shaft. On modern mills, the cam is arranged to lift the stamp from the side, so that it causes the stamp to rotate. This evens the wear on the shoe at the foot of the stamp. As the cam moves from under the stamp, the stamp falls onto the ore below, crushing the rock, and the lifting process is repeated at the next pass of the cam. Each one frame and stamp set is sometimes called a "battery" or, confusingly, a "stamp" and mills are sometimes categorised by how many stamps they have, i.e. a "10 stamp mill" has 10 sets. They usually are arranged linearly, but when a mill is enlarged, a new line of them may be constructed rather than extending the line. Abandoned mill sites (as documented by industrial archaeologists) will usually have linear rows of foundation sets as their most prominent visible feature as the overall apparatus can exceed 20 feet in height, requiring large foundations. Stamps are usually arranged in sets of five.

Some ore processing applications used large quantities of water so some stamp mills are located near natural or artificial bodies of water. For example, the Redridge Steel Dam was built to supply stamp mills with process water.

History

The main components for water-powered stamp mills - water wheels, cams, and hammers - were already known by the Greeks in Hellenistic times. Ancient cams are in evidence in early water-powered automata from the third century BC. A passage in the Natural History of the Roman scholar Pliny (NH 18.97) indicates that water-driven pestles had become fairly widespread in Italy by the first century AD: "The greater part of Italy uses an unshod pestle and also wheels which water turns as it flows past, and a trip-hammer mola". These trip-hammers were used for the pounding and hulling of grain. Grain-pounders with pestles, as well as ordinary watermills, are also attested as late as the middle of the fifth century in a monastery founded by Romanus of Condat in the remote Jura region, indicating that the knowledge of trip hammers continued into the early Middle Ages. Apart from agricultural processing, archaeological evidence also strongly suggests the existence of trip hammers in Roman metal working. In Ickham in Kent, a large metal hammer-head with mechanical deformations was excavated in an area where several Roman water-mills and metal waste dumps have also been traced.

The widest application of stamp mills, however, seems to have occurred in Roman mining, where ore from deep veins was first crushed into small pieces for further processing. Here, the regularity and spacing of large indentations on stone anvils indicate the use of cam-operated ore stamps, much like the devices of later medieval mining. Such mechanically deformed anvils have been found at numerous Roman silver and gold mining sites in Western Europe, including at Dolaucothi (Wales), and on the Iberian peninsula, where the datable examples are from the 1st and 2nd century AD. At Dolaucothi, these stamp mills were hydraulic-driven and possibly also at other Roman mining sites, where the large scale use of the hushing and ground sluicing technique meant that large amounts of water were directly available for powering the machines.

Stamp mills were used by miners in Samarkand as early as 973. They were used in medieval Persia to crush mineral ores. By the 11th century, stamp mills were in widespread use throughout the medieval Islamic world, from Islamic Spain and North Africa in the west to Central Asia in the east.

Water-powered and mechanised trip hammers reappeared in medieval Europe by the 12th century. Their use was described in medieval written sources of Styria (in modern-day Austria), written in 1135 and another in 1175 AD. Both texts mentioned the use of vertical stamp mills for ore-crushing. Medieval French sources of the years 1116 and 1249 both record the use of mechanised trip hammers used in the forging of wrought iron. Medieval European trip hammers by the 15th century were most often in the shape of the vertical pestle stamp-mill. The well-known Renaissance artist and inventor Leonardo de Vinci often sketched trip hammers for use in forges and even file-cutting machinery, those of the vertical pestle stamp-mill type. The oldest depicted European illustration of a martinet forge-hammer is perhaps the Historia de Gentibus Septentrionalibus of Olaus Magnus, dated to 1565 AD. In this woodcut image, there is the scene of three martinets and a waterwheel working wood and leather bellows of the Osmund bloomery furnace. The recumbrent hammer was first depicted in European artwork in an illustration by Sandrart and Zonca (dated 1621 AD).

Water-powered stamp mills are illustrated in book 8 of Georg Agricola's De Re Metallica, published in 1556. The mills Agricola shows were largely wooden construction, excepting the use of iron shoes on the end of each stamp. The camshaft was set directly on the axle of the waterwheel, and stamps were typically arranged in gangs of three, with each wheel driving one or two gangs.

The first stamp mill in the U.S. was built in 1829 at the Capps mine near Charlotte, North Carolina. They were common in gold, silver and copper mining regions of the US in the latter 19th and early 20th centuries, in operations where the ore was crushed as a prelude to extracting the metals. They were superseded in the second half of the 19th century in many applications by more efficient methods. However their simplicity meant that they were used in remote areas for ore processing well into the 20th century. (19th century advertisements for some mills highlighted that they could be broken down, packed in by mule in pieces, and assembled on site with only simple tools)

Other stamping mills

Stamp mills were used in early paper making for preparing the paper-stuff (pulp), before the invention of the Hollander beater. They were used in mining for breaking ore, and in oil-seed processing for prior to pressing the oil from the milled seeds. Early mills were water powered but mills can be steam, water, or electric powered.

A stamping mill may refer to a factory that performs stamping.

From http://en.wikipedia.org/

Subsidence

2009-12-15T17:28:00.000-08:00

Subsidence is the motion of a surface (usually, the Earth's surface) as it shifts downward relative to a datum such as sea-level. The opposite of subsidence is uplift, which results in an increase in elevation. Ground subsidence is of concern to geologists, structural engineers and surveyors.

Dissolution of limestone

Subsidence frequently occurs in karst terrains, where dissolution of limestone by fluid flow in the subsurface causes the creation of voids (i.e. caves). If the roof of these voids becomes too weak, it can collapse and the overlying rock and earth will fall into the space, causing subsidence at the surface. This type of subsidence can result in sinkholes which can be many hundreds of meters deep.

Mining-induced

Several types of sub-surface mining, and specifically methods which intentionally cause the extracted void to collapse (such as pillar extraction, longwall mining and any metalliferous mining method which utilises "caving" such as "block caving" or "sub-level caving") will result in surface subsidence. Mining induced subsidence is relatively predictable in its magnitude, manifestation and extent, except where a sudden pillar or near-surface underground tunnel collapse occurs (usually very old workings). Mining induced subsidence is nearly always very localised to the surface above the mined area, plus a margin around the outside. The vertical magnitude of the subsidence itself typically does not cause problems, except in the case of drainage (including natural drainage) - rather it is the associated surface compressive and tensile strains, curvature, tilts and horizontal displacement that are the cause of the worst damage to the natural environment, buildings and infrastructure.

Where mining activity is planned, mining-induced subsidence can be successfully managed if there is co-operation from all of the stakeholders. This is accomplished through a combination of careful mine planning, the taking of preventative measures, and the carrying out of repairs post-mining.

Extraction of natural gas

If natural gas is extracted from a natural gas field the initial pressure (up to 600 bar) in the field will drop over the years. The gas pressure also supports the soil layers above the field. If the pressure drops, the soil pressure increases and this leads to subsidence at the ground level. Since exploration of the Slochteren (Netherlands) gas field started in the late 1960s the ground level over a 250 km² area has dropped with a current maximum of 30 cm. See also this subsidence lecture.

This type of subsidence can similarly be caused by extraction of other resources, e.g. ground water, petroleum or rock salt.

Groundwater-related

The habitation of lowlands, such as coastal or delta plains, requires drainage. The resulting aeration of the soil leads to the oxidation of its organic components, such as peat, and this decomposition process may cause significant land subsidence. This applies especially when ground water levels are periodically adapted to subsidence, in order to maintain desired unsaturated zone depths, exposing more and more peat to oxygen. In addition to this, drained soils consolidate as a result of increased effective stress. In this way, land subsidence has the potential of becoming self-perpetuating, having rates up to 5 cm/yr. Water management used to be tuned primarily to factors such as crop optimisation but, to varying extents, avoiding subsidence has come to be taken into account as well.

Faulting induced

When differential stresses exist in the Earth, these can be accommodated either by geological faulting in the brittle crust, or by ductile flow in the hotter and more fluid mantle. Where faults occur, absolute subsidence may occur in the footwall of normal faults. In reverse, or thrust, faults, relative subsidence may be measured in the hangingwall.

Isostatic rebound

The crust floats buoyantly in the plastic asthenosphere, with a ratio of mass below the "surface" in proportion to its own density and the density of the asthenosphere. If mass is added to a local area of the crust (e.g. through deposition), the crust subsides to compensate and maintain isostatic balance.

Seasonal effects

Many soils contain significant proportions of clay which because of the very small particle size are affected by changes in soil moisture content. Seasonal drying of the soil results in a reduction in soil volume and a lowering of the soil surface. If building foundations are above the level to which the seasonal drying reaches they will move and this can result in damage to the building in the form of tapering cracks. Trees and other vegetation can have a significant local effect on seasonal drying of soils. Over a number of years a cumulative drying occurs as the tree grows, this can lead to the opposite of subsidence, known as heave or swelling of the soil, when the tree declines or is felled. As the cumulative moisture deficit is reversed, over a period which can last as many as 25 years, the surface level around the tree will rise and expand laterally. This is often more damaging to buildings unless the foundations have been strengthened or designed to cope with the effect.

From http://en.wikipedia.org/

Mining accident

2009-12-13T08:24:00.000-08:00

A mining accident is an accident that occurs in the process of mining minerals.

Thousands of miners die from mining accidents each year, especially in the process of coal mining and hard rock mining. Most of the deaths today occur in developing countries, especially China, and rural parts of developed countries.

Causes

Mining accidents can have a variety of causes, including leaks of poisonous gases such as hydrogen sulphide or explosive natural gases especially firedamp or methane, dust explosions, collapsing of mine stopes, mining-induced seismicity, flooding, or general mechanical errors from improperly used or malfunctioning mining equipment.

Accidents by country

Canada

Probably the most famous accidents in Canada are collectively referred to as the Springhill mining disasters.

China

The worst coal mining disaster in the world took place on April 26, 1942 in Benxihu Colliery, located at Benxi, Liaoning. A coal-dust explosion killed 1,549 miners working that day.

China currently accounts for the largest number of coal-mining fatalities, accounting for about 80% of the world’s total, although it produces only 35% of the world’s coal. Between January 2001 to October 2004, there were 188 accidents that had a death toll of more than 10, about one such accident every 7.4 days. After the 2005 Sunjiawan mine disaster, which killed at least 210 miners, a meeting of the State Council was convened to work on measures to improve work safety in coal mines. The meeting's statement pointed out serious problems such as violation of safety standards and overproduction in some coal mines. Three billion yuan (36 million US dollars) were earmarked for technological renovation on work safety, gas management in particular, at state-owned major coal mines. The government also promised to send safety supervision teams to 45 coal mines with serious gas problems and invite colliery safety experts to evaluate safety situations in coal mines and formulate prevention measures.

In 2006, according to the State Work Safety Supervision Administration, 4,749 Chinese coal miners were killed in thousands of blasts, floods, and other accidents. For example, a gas explosion at the Nanshan Colliery killed 24 people on November 13, 2006; the mine was operating without any safety license and the Xinhua News Agency claimed the cause was incorrect usage of explosives. However, the 2006 rate was 20.1% less than 2005 despite an 8.1% rise in production.

The New York Times reported that China's lack of a free press, independent trade unions, citizen watchdog groups and other checks on official power has made cover-ups of mining accidents more possible, even in the Internet age. As a result, Chinese bureaucrats habitually hide scandals (such as mine disasters, chemical spills, the 2003 SARS epidemic, and tainted milk powder) for fear of being held accountable by the ruling Communist Party or exposing their own illicit ties to companies involved. Under China’s authoritarian system, superiors reward subordinates for strict compliance with targets set from above, like reducing mine disasters. Indeed, should a mining accident occur, the incentive to hide it is often stronger than the reward for handling it well, as a disaster on a bureaucrat’s watch is almost surely a blot on his career, while successfully concealing it means that it may never be uncovered.

In November 2009, a mining accident in Heilongjiang killed at least 104. It is thought to have been caused by a methane explosion followed by a coal dust explosion. Three top officials involved with the mining company have been promptly fired.

France

The Courrières mine disaster was the worst ever pit disaster in Europe. It caused the death of 1,099 miners (including many children) in Northern France on 10 March 1906. It seems that this disaster was surpassed only by the Benxihu Colliery accident in China on April 26, 1942, which killed 1,549 miners. A dust explosion, the cause of which is not known with certainty, devastated a coal mine operated by the Compagnie des mines de houille de Courrières (founded in 1852) between the villages of Méricourt (404 killed), Sallaumines (304 killed), Billy-Montigny (114 killed), and Noyelles-sous-Lens (102 killed) about two kilometres (one mile) to the east of Lens, in the Pas-de-Calais département (about 220 km, or 140 miles, north of Paris).

A large explosion was heard shortly after 06:30 on the morning of Saturday 10 March 1906. An elevator cage at Shaft 3 was thrown to the surface, damaging pit-head workings; windows and roofs were blown out on the surface at Shaft 4; an elevator cage raised at Shaft 2 contained only dead and unconscious miners.

New Zealand

The most notable mining accident in New Zealand is the 1896 Brunner Mine disaster.

Poland

Several major mining accidents happened in Poland. See List of mining disasters in Poland.

Russia

Several major mining accidents happened in Russia, particularly the Ulyanovskaya Mine disaster.

United Kingdom

Over the period 1850 to 1930 the South Wales coalfield had the worst disaster record. This was due to the increasing number of mines being sunk to greater depths into gas-containing strata, combined with poor safety and management practices. As a result there were nearly forty underground explosions in the Glamorgan and Monmouthshire areas of the coalfield during this time. Each accident resulted in the deaths of twenty or more men and boys - either directly during the explosion or by suffocation in the poisonous gases formed. The total death toll from these disasters was 3,119.

The four worst accidents were:

* 439 deaths at the Senghenydd Colliery Disaster at Universal Colliery in Senghenydd, Glamorgan in a gas explosion in 1913
* 290 deaths at the Albion Colliery in Cilfynydd, Glamorgan in a gas explosion on 25 June 1894
* 266 lives lost in the Gresford Disaster near Wrexham in North Wales on 22 September 1934
* 259 deaths at the Prince of Wales Mine, Abercarn, Monmouthshire in an explosion on 11 September 1878.

Some collieries e.g. Morfa Colliery, near Port Talbot, Glamorgan and Black Vein Colliery, Risca, Monmouthshire suffered three disasters before it was decided to close them for being unsafe.

In England, The Oaks explosion remains the worst mining accident, claiming 388 lives on 12 December 1866 near Barnsley in Yorkshire. The Hulton Colliery explosion, Westhoughton, Lancashire in 1910, claimed the lives of 344 . An explosion in 1878, at the Wood Pit, Haydock, Lancashire, killed over 200 men and boys, however, only 189 were included in the 'official list'.

In the metalliferous mines of Cornwall, some of the worst accidents were at East Wheal Rose in 1846, where 39 men were killed by a sudden flood; at Levant mine in 1919, where 31 were killed and many injured in a failure of the man engine; 12 killed at Wheal Agar in 1883 when a cage fell down a shaft; and seven killed at Dolcoath mine in 1893 when a large stull collapsed.

The worst mining accident in Scotland is the Blantyre mining disaster in Blantyre, Lanarkshire which claimed 207 lives in 1877.

United States

The Monongah Mining Disaster was the worst mining accident in American history; 362 men and young boys were killed in an underground explosion on December 6, 1907 in Monongah, West Virginia.

From 1880 to 1910, mine accidents claimed thousands of fatalities. The U.S. Bureau of Mines was created in 1910 to investigate accidents, advise industry, conduct production and safety research, and teach courses in accident prevention, first aid, and mine rescue. The Federal Coal Mine Health and Safety Acts of 1969 and 1977 set further safety standards for the industry. Where annual mining deaths had numbered more than 1,000 a year in the early part of the 20th century, they decreased to an average of about 500 in the late 1950s, and to 93 during the 1990s. In addition to deaths, many thousands more are injured (an average of 21,351 injuries per year between 1991 and 1999), but overall there has been a downward trend in deaths and injuries.

In 2006, 72 miners lost their lives at work, 47 in coal mining. The majority of these fatalities occurred in Kentucky and West Virginia, including the Sago Mine Disaster.

From http://en.wikipedia.org/

Energy law

2009-12-10T09:51:00.000-08:00

Energy laws govern the use and taxation of energy, both renewable and non-renewable. These laws are the primary authorities (such as caselaw, statutes, rules, regulations and edicts) related to energy. In contrast, energy policy refers to the policy and politics of energy.

In the twentieth century, energy law focused mostly on natural gas regulation, but was expanded to include other areas of energy regulation as well. It also includes the legal provision for oil, gasoline, and "extraction taxes."

From http://en.wikipedia.org/

Whitedamp

2009-12-09T01:57:00.001-08:00

Whitedamp is a noxious mixture of gases formed by the combustion of coal, usually in an enclosed environment such as a coal mine. The most toxic constituents are carbon monoxide and hydrogen sulfide. Coal frequently starts to burn slowly in mines when it is exposed to the atmosphere.

Detection

Traditionally, whitedamp was detected by its effect on canaries, who succumb much more quickly than humans. However, there are gas detectors available now which detect toxic gases at very low levels. The levels of gas detection depend on the methods used.

From http://en.wikipedia.org/

Hydrogen sulfide

2009-12-07T16:09:00.000-08:00

Hydrogen sulfide (or hydrogen sulphide) is the chemical compound with the formula H2S. This colorless, toxic and flammable gas is partially responsible for the foul odor of rotten eggs and flatulence.

It often results from the bacterial break down of sulfites in nonorganic matter in the absence of oxygen, such as in swamps and sewers (anaerobic digestion). It also occurs in volcanic gases, natural gas and some well waters. The odor of H2S is commonly misattributed to elemental sulfur, which is in fact odorless. Hydrogen sulfide has numerous names, some of which are archaic (see table).

Production

Hydrogen sulfide is obtained by its separation from sour gas, which is natural gas with high content of H2S. It can be produced by reacting hydrogen gas with molten elemental sulfur at about 450 °C. Hydrocarbons can replace hydrogen in this process.

Sulfate-reducing bacteria produce hydrogen sulfide under ambient conditions by the reduction of sulfate from elemental sulfur.

The standard lab preparation is to gently heat iron sulfide (FeS) with a strong acid in a Kipp generator.

A less well known and more convenient alternative is to react aluminium sulfide with water:

3 H2O + Al2S3 → 3 H2S + Al2O3.

Hydrogen sulfide is also a byproduct of some reactions and caution should be used when production is likely as exposure can be fatal.

Occurrence

Small amounts of hydrogen sulfide occur in crude petroleum but natural gas can contain up to 90%. Volcanoes and some hot springs (as well as cold springs) emit some H2S, where it probably arises via the hydrolysis of sulfide minerals, i.e. MS + H2O → MO + H2S.

About 10% of total global emissions of H2S is due to human activity. By far the largest industrial route to H2S occurs in petroleum refineries: the hydrodesulfurization process liberates sulfur from petroleum by the action of hydrogen. The resulting H2S is converted to elemental sulfur by partial combustion via the Claus process, which is a major source of elemental sulfur. Other anthropogenic sources of hydrogen sulfide include coke ovens, paper mills (using the sulfate method), and tanneries. H2S arises from virtually anywhere where elemental sulfur comes into contact with organic material, especially at high temperatures.

Hydrogen sulfide can be present naturally in well water. In such cases, ozone is often used for its removal. An alternative method uses a filter with

hydrogen sulfide converts to alkali hydrosulfides such as sodium hydrosulfide and sodium sulfide, which are used in the degradation of biopolymers. The depilation of hides and the delignification of pulp by the Kraft process both are effected by alkali sulfides.

In analytical chemistry

Hydrogen sulfide used to have importance in analytical chemistry for well over a century, in the qualitative inorganic analysis of metal ions. For such small-scale laboratory use, H2S was made as needed in a Kipp generator by reaction of sulfuric acid (H2SO4) with ferrous sulfide FeS. Kipp generators were superseded by the use of thioacetamide, an organic solid that converts in water to H2S. In these analyses, heavy metal (and nonmetal) ions (e.g. Pb(II), Cu(II), Hg(II), As(III)) are precipitated from solution upon exposure to H2S. The components of the resulting precipitate redissolve with some selectivity.

A precursor to metal sulfides

As indicated above, many metal ions react with hydrogen sulfide to give the corresponding metal sulfides. This conversion is widely exploited. In the purification of metal ores by flotation, mineral powders are often treated with hydrogen sulfide to enhance the separation. Metal parts are sometimes passivated with hydrogen sulfide. Catalysts used in hydrodesulfurization are routinely activated with hydrogen sulfide, and the behavior of metallic catalysts used in other parts of a refinery is also modified using hydrogen sulfide.

Miscellaneous applications

Hydrogen sulfide is also used in the separation of deuterium oxide, i.e. heavy water, from normal water via the Girdler Sulfide process.

Safety

Hydrogen sulfide is a highly toxic and flammable gas. Being heavier than air, it tends to accumulate at the bottom of poorly ventilated spaces. Although very pungent at first, it quickly deadens the sense of smell, so potential victims may be unaware of its presence until it is too late. For safe handling procedures, a hydrogen sulfide material safety data sheet (MSDS) should be consulted.

Toxicity

Hydrogen sulfide is considered a broad-spectrum poison, meaning that it can poison several different systems in the body, although the nervous system is most affected. The toxicity of H2S is comparable with that of hydrogen cyanide. It forms a complex bond with iron in the mitochondrial cytochrome enzymes, thereby blocking oxygen from binding and stopping cellular respiration. Since hydrogen sulfide occurs naturally in the environment and the gut, enzymes exist in the body capable of detoxifying it by oxidation to (harmless) sulfate. Hence, low levels of sulfide may be tolerated indefinitely.

At some threshold level, the oxidative enzymes will be overwhelmed. This threshold level is believed to average around 300–350 ppm. Many personal safety gas detectors, such as those used by utility, sewage and petrochemical workers, are set to alarm at as low as 5 to 10 ppm and to go into high alarm at 15 ppm.

An interesting diagnostic clue of extreme poisoning by H2S is the discoloration of copper coins in the pockets of the victim. Treatment involves immediate inhalation of amyl nitrite, injections of sodium nitrite, inhalation of pure oxygen, administration of bronchodilators to overcome eventual bronchospasm, and in some cases hyperbaric oxygen therapy (HBO). HBO therapy has anecdotal support and remains controversial.

Exposure to lower concentrations can result in eye irritation, a sore throat and cough, nausea, shortness of breath, and fluid in the lungs. These symptoms usually go away in a few weeks. Long-term, low-level exposure may result in fatigue, loss of appetite, headaches, irritability, poor memory, and dizziness. Chronic exposures to low level H2S (around 2 ppm) has been implicated in increased miscarriage and reproductive health issues amongst Russian and Finnish wood pulp workers, but the reports have not (as of circa 1995) been replicated. Higher concentrations of 700–800 ppm tend to be fatal.

* 0.0047 ppm is the recognition threshold, the concentration at which 50% of humans can detect the characteristic odor of hydrogen sulfide , normally described as resembling "a rotten egg".
* Less than 10 ppm has an exposure limit of 8 hours per day.
* 10–20 ppm is the borderline concentration for eye irritation.
* 50–100 ppm leads to eye damage.
* At 150–250 ppm the olfactory nerve is paralyzed after a few inhalations, and the sense of smell disappears, often together with awareness of danger,
* 320–530 ppm leads to pulmonary edema with the possibility of death.
* 530–1000 ppm causes strong stimulation of the central nervous system and rapid breathing, leading to loss of breathing;
o 800 ppm is the lethal concentration for 50% of humans for 5 minutes exposure(LC50).
* Concentrations over 1000 ppm cause immediate collapse with loss of breathing, even after inhalation of a single breath.

Hydrogen sulfide was used by the British as a chemical agent during World War One. It was not considered to be an ideal war gas, but while other gasses were in short supply it was used on two occasions in 1916.

A series of suicide cases in Japan in which the victims killed themselves by producing toxic hydrogen sulfide fumes by mixing common household cleaning products have highlighted the danger posed by commonly used substances and prompted censorship of internet sites who posted advice for aspiring suicides.

Function in the body

Hydrogen sulfide is produced in small amounts by some cells of the mammalian body and has a number of biological functions. It is produced from cysteine by various enzymes. It acts as a vasodilator and is also active in the brain, where it increases the response of the NMDA receptor and facilitates long term potentiation, which is involved in the formation of memory. Eventually the gas is converted to sulfites and further oxidized to thiosulfate and sulfate.Due to its effects similar to NO (without its potential to form peroxides by interacting with superoxide), hydrogen sulfide is now recognized as a potential cardioprotective agent.Vasoactivity of garlic is caused by catabolism of the polysulfide group in allicin to H2S, a reaction which could depend on reduction mediated by glutathione. In trisomy 21 (the most common form of Down syndrome) the body produces an excess of hydrogen sulfide.

Induced hypothermia

In 2005 it was shown that mice can be put into a state of suspended animation-like hypothermia by applying a low dosage of hydrogen sulfide (81 ppm H2S) in the air. The breathing rate of the animals sank from 120 to 10 breaths per minute and their temperature fell from 37 °C to just 2 °C above ambient temperature (in effect, they had become cold-blooded). The mice survived this procedure for 6 hours and afterwards showed no negative health consequences. In 2006 it was shown that the blood pressure of mice treated in this fashion with hydrogen sulfide did not significantly decrease.

A similar process known as hibernation occurs naturally in many mammals and also in toads, but not in mice. (Mice can fall into a state called clinical torpor when food shortage occurs). If the H2S-induced hibernation can be made to work in humans, it could be useful in the emergency management of severely injured patients, and in the conservation of donated organs. In 2008, hypothermia induced by hydrogen sulfide for 48 hours was shown to reduce the extent of brain damage caused by experimental stroke in rats.

As mentioned above, hydrogen sulfide binds to cytochrome oxidase and thereby prevents oxygen from binding, which leads to the dramatic slowdown of metabolism. Animals and humans naturally produce some hydrogen sulfide in their body; researchers have proposed that the gas is used to regulate metabolic activity and body temperature, which would explain the above findings.

Two recent studies cast doubt that the effect can be achieved in larger mammals. A 2008 study failed to reproduce the effect in pigs, concluding that the effects seen in mice were not present in larger mammals. Likewise a paper by Haouzi et al noted that there is no induction of hypometabolism in sheep, either.

Participant in the sulfur cycle

Hydrogen sulfide is a central participant in the sulfur cycle, the biogeochemical cycle of sulfur on Earth. As mentioned above, sulfur-reducing and sulfate-reducing bacteria derive energy from oxidizing hydrogen or organic molecules in the absence of oxygen by reducing sulfur or sulfate to hydrogen sulfide. Other bacteria liberate hydrogen sulfide from sulfur-containing amino acids. Several groups of bacteria can use hydrogen sulfide as fuel, oxidizing it to elemental sulfur or to sulfate by using dissolved oxygen, metal oxides (e.g. Fe oxyhydroxides and Mn oxides) or nitrate as oxidant. The purple sulfur bacteria and the green sulfur bacteria use hydrogen sulfide as electron donor in photosynthesis, thereby producing elemental sulfur. (In fact, this mode of photosynthesis is older than the mode of cyanobacteria, algae and plants which uses water as electron donor and liberates oxygen.)

H2S implicated in mass extinctions

Hydrogen sulfide has been implicated in some of the several mass extinctions that have occurred in the Earth's past. The Permian mass extinction (sometimes known as the "Great Dying") may have been caused by hydrogen sulfide. Organic residues from these extinction boundaries indicate that the oceans were anoxic (oxygen depleted) and had species of shallow plankton that metabolized H2S. The formation of H2S may have been initiated by massive volcanic eruptions, which emitted CO2 and methane into the atmosphere which warmed the oceans, lowering their capacity to absorb oxygen which would otherwise oxidize H2S. The increased levels of hydrogen sulfide could have killed oxygen-generating plants as well as depleted the ozone layer causing further stress. Small H2S blooms have been detected in modern times in the Dead Sea and in the Atlantic ocean off the coast of Namibia.

From http://en.wikipedia.org/

Firedamp

2009-12-05T05:29:00.000-08:00

Firedamp is a flammable gas found in coal mines. It is actually the name given to a number of flammable gases, including methane. It is particularly commonly found in areas where the coal is bituminous.

Firedamp is explosive at concentrations between 4% and 16%, with most violence at around 10%, and caused much loss of life in coal mines before the invention of the Davy lamp. Even after the safety lamps were brought into common use, firedamp explosions could still occur from sparks produced when coal contaminated with pyrites was struck with metal tools. The presence of coal dust in the air increased the risk of explosion with firedamp, and indeed could cause explosions itself.

The Tyneside coal mines in England had the deadly combination of bituminous coal contaminated with pyrites, and a great number of lives were lost in accidents due to firedamp explosions, including 102 dead at Wallsend in 1835. A continuous flame was produced at Whitehaven sometime before 1733, described as being "a yard wide and two yards long." The miners dealt with it by piping it to the outside.

Rather than the Davy lamp, Tyneside miners used a Geordie lamp, a similar safety lamp designed by George Stephenson.

Damps

Gases (other than air) in coal mines in England were collectively known as "damps". This comes from the German word Dampf (meaning "vapour"), and was probably introduced when German miners and mine engineers were brought to England in the 17th century to help in the development of deep mining.

Other damps included blackdamp (carbon dioxide and other gases), and the insidiously lethal afterdamp (carbon monoxide and other gases) produced following explosions of firedamp or coal dust.

Accident at Courrières in Pas-de-Calais

1906, the firedamp killed 1200 Workers in a coal mine at the town of Courrières in Pas-de-Calais, France. The explosion propagated itself in the galleries, thanks to the dust, which served as a fuel source. A number of workers were trapped in the coal mine for several weeks, eating their own excrement, drinking urine, and eating horses, in an effort to survive.

From http://en.wikipedia.org/

Blackdamp

2009-12-03T22:25:00.000-08:00

Blackdamp (also known as stythe or choke damp) is a mixture of unbreathable gases formed when oxygen is removed from an enclosed atmosphere and largely replaced by nitrogen, argon, carbon dioxide and water vapour. The gas displaces oxygen in the air, lowering the available oxygen content to a level which is incapable of sustaining human or animal life; it is thus an asphyxiant.

The name black damp is believed to derive from the German word for vapors ("dampf"). The word damp is used in similar mining terms such as white damp (carbon monoxide), fire damp (typically methane) and stink damp (hydrogen sulfide).

Sources

Blackdamp is encountered in enclosed environments such as mines, sewers, wells, tunnels and ships holds. It occurs with particular frequency in abandoned or poorly ventilated coal mines. Coal, once exposed to the air of a mine, naturally begins absorbing oxygen and exuding carbon dioxide and water vapor. The amount of blackdamp exuded by a mine varies based on a number of factors, including the time of year (coal releases more carbon dioxide in the summer months), the amount of exposed coal, and the type of coal, although all mines with exposed coal produce gas.

Hazards

Blackdamp is considered a particularly pernicious type of damp (especially in a historical context), due to its omnipresence where exposed coal is found, and slow onset of symptoms. It produces no obvious odor (unlike stinkdamp), is constantly being reintroduced to the air (instead of being released in pockets from actively mined sections), and does not require combustion in order to be released (unlike whitedamp or afterdamp). Many of the initial symptoms of oxygen deprivation (dizziness, light-headedness, drowsiness and poor coordination) are relatively innocuous and can easily be mistaken for simple fatigue, a far from unlikely diagnosis in the physically-strenuous job of coal mining. The time between the onset of initial symptoms and the start of frank asphyxiation (and rapid unconsciousness) can be as short as seconds. Thus, if the warning signs are missed, a large number of miners can be rapidly incapacitated in the same short period of time, leaving no one to summon help.

In addition to the danger inside the mine, blackdamp can be "exhaled" in large quantities from mines (especially long-abandoned coal mines with few outlets for escaping gas) during sudden changes in atmospheric pressure, potentially causing asphyxiation on the surface.

Detection and Countermeasures

In active mining operations, the threat from blackdamp is addressed with proper mineshaft ventilation as well as various detection methods, typically using miner's safety lamps or hand-held electronic gas detectors. The safety lamp is merely a specially-designed lantern with a flame that is designed to automatically extinguish itself at an oxygen concentration of approximately 18% (normal atmospheric concentration of oxygen is ~21%). This low detection threshold gives miners an unmistakable warning and allows them to escape before any potentially incapacitating effects are felt.

From http://en.wikipedia.org/

Afterdamp

2009-12-01T06:17:00.001-08:00

Afterdamp is the toxic mixture of gases left in a mine following an explosion caused by firedamp, which itself can initiate a much larger explosion of coal dust. It consists of carbon dioxide, carbon monoxide and nitrogen. Hydrogen sulfide, another highly toxic gas, may also be present. Afterdamp was the deadly gas which caused the majority of casualties in the many pit disasters of the British coalfields, and elsewhere in the world. Such disasters continue to afflict working mines, especially in mainland China.

Detection

Gas detectors are available now which detect toxic gases at very low levels. The levels of gas detection depend on the methods used.

From http://en.wikipedia.org/

Damp (mining)

2009-11-29T02:46:00.001-08:00

Historically, gases (other than breathable air) in coal mines in Britain were collectively known as "damps". This comes from the Middle Low German word dampf (meaning "vapour"), and was in use by 1480.

Damps included:

* After damp, a mixture of gases (carbon monoxide, carbon dioxide, nitrogen and others) produced following explosions of firedamp or coal dust
* Black damp, stythe or choke damp, a suffocating mixture of nitrogen and carbon dioxide
* Fire damp, any mixture of flammable gases, principally methane
* Stink damp, usually hydrogen sulfide; toxic and explosive, but easily detectable by the smell
* White damp, carbon monoxide, highly dangerous due to being both toxic and explosive

The term damp also gives rise to damp sheet, a heavy curtain used to direct air currents and prevent the buildup of dangerous gases.

From http://en.wikipedia.org/

Wallarah 2 Coal Project

2009-11-27T15:35:00.000-08:00

The Wallarah 2 Coal Project (W2CP) is a proposal by Korea Resources Corporation (owned by the South Korean government) and other major leading Korean and Japanese mining companies that comprise the Wyong Areas Coal Joint Venture to construct a modern and environmentally advanced longwall mine near Wyong, New South Wales, Australia. The exploration areas within which the mining proposal occurs was awarded to the Wyong Areas Coal Joint Venture by the NSW State Government in 1995 following a competitive tender. Extensive exploration drilling, geological surveys, environmental investigations, stakeholder consultations and other initiatives totalling $80 million have been undertaken by the Wyong Areas Coal Joint Venture since 1995. A Community Liaison Committee has been operating for approximately 10 years and includes two representatives from Wyong Council, community groups and NGOs and Government agencies.

The proposed mine will have an annual coal production of 4 to 5 million tonnes of export quality thermal coal per year, over 42 years, with initial construction expected in 2010 and longwall coal production in 2012. The New South Wales State Government is the major land owner in Central Coast, through land holding of Landcom.

The coal loader, coal stockpile and rail link will be at least 3 kilometres away from one of the largest urban growth areas on the Central Coast, including the proposed Warnervale town centre and potential support industries to the mining project. The coal loader proposed for Tooheys Road is a minimum of 2.4 kilometres from Warnervale, which is the Central Coast's largest proposed growth centre. Under the Government's development strategies, Lake Macquarie and Wyong will be increasingly urbanised.

Opposition

The Australian Coal Alliance has formed to oppose the project. State Labor MP for Wyong David Harris said: "My vision is for job growth through clean technology." "The Wyong Employment Zone has the potential to provide about 6000 jobs and we mustn't put that at risk. It's about what sort of future we want for the Central Coast and it's not mining." said Harris. He was concerned about the noise and dust impacts on the community and for the future of the Wyong Employment Zone at Warnervale.

From http://en.wikipedia.org/

Bootleg mining

2009-11-18T15:37:00.000-08:00

Bootleg mining is illegal coal mining.

The term originated around the 1920s, though the practice probably predates that. Generally, a bootleg mine (sometimes called a Bootleg Pit) is a small mine dug by a handful of men. They were frequently dug by coal miners off official tunnels in order to procure additional, free coal for themselves, a practice that causes additional ramifications when fighting mine fires. Sometimes small pits are hidden under houses or outbuildings. Usually, the mine is not large enough to turn around in. The pits are known for being unsafe, and often causing collapse.

The practice has died away in the United States; an American with simple equipment cannot dig enough coal in a day to reach a living wage. Bootleg mines in China are very common, as are the fatalities resulting from unregulated mining.

From http://en.wikipedia.org/

Acid mine drainage

2009-11-16T18:17:00.000-08:00

Acid mine drainage (AMD), or acid rock drainage (ARD), refers to the outflow of acidic water from (usually abandoned) metal mines or coal mines. However, other areas where the earth has been disturbed (e.g. construction sites, subdivisions, transportation corridors, etc.) may also contribute acid rock drainage to the environment. In many localities the liquid that drains from coal stocks, coal handling facilities, coal washeries, and even coal waste tips can be highly acidic, and in such cases it is treated as acid rock drainage. Acid rock drainage occurs naturally within some environments as part of the rock weathering process but is exacerbated by large-scale earth disturbances characteristic of mining and other large construction activities, usually within rocks containing an abundance of sulfide minerals.

Occurrence

Sub-surface mining often progresses below the water table, so water must be constantly pumped out of the mine in order to prevent flooding. When a mine is abandoned, the pumping ceases, and water floods the mine. This introduction of water is the initial step in most acid rock drainage situations. Tailings piles or ponds may also be a source of acid rock drainage.

After being exposed to air and water, oxidation of metal sulfides (often pyrite, which is iron-sulfide) within the surrounding rock and overburden generates acidity. Colonies of bacteria and archaea greatly accelerate the decomposition of metal ions, although the reactions also occur in an abiotic environment. These microbes, called extremophiles for their ability to survive in harsh conditions, occur naturally in the rock, but limited water and oxygen supplies usually keep their numbers low. Special extremophiles known as acidophiles especially favor the low pH levels of abandoned mines. In particular, Acidithiobacillus ferrooxidans is a key contributor to pyrite oxidation.

Metal mines may generate highly acidic discharges where the ore is a sulfide mineral or is associated with pyrite. In these cases the predominant metal ion may not be iron but rather zinc, copper, or nickel. The most commonly-mined ore of copper, chalcopyrite, is itself a copper-iron-sulfide and occurs with a range of other sulfides. Thus, copper mines are often major culprits of acid mine drainage.

Chemistry

For further information, see Acidophiles in acid mine drainage

The chemistry of oxidation of pyrites, the production of ferrous ions and subsequently ferric ions, is very complex, and this complexity has considerably inhibited the design of effective treatment options.

Although a host of chemical processes contribute to acid mine drainage, pyrite oxidation is by far the greatest contributor. A general equation for this process is:

2FeS2(s) + 7O2(g) + 2H2O(l) → 2Fe2+(aq) + 4SO42-(aq) + 4H+(aq)

The oxidation of the sulfide to sulfate solubilizes the ferrous iron (iron(II)), which is subsequently oxidized to ferric iron (iron(III)):

4Fe2+(aq) + O2(g) + 4H+(aq) → 4Fe3+(aq) + 2H2O(l)

Either of these reactions can occur spontaneously or can be catalyzed by microorganisms that derive energy from the oxidation reaction. The ferric irons produced can also oxidize additional pyrite:

FeS2(s) + 14Fe3+(aq) + 8H2O(l) → 15Fe2+(aq) + 2SO42-(aq) + 16H+(aq)

The net effect of these reactions is to release H+, which lowers the pH and maintains the solubility of the ferric ion.

Effects

Effects on pH

In some acid mine drainage systems temperatures reach 117 degrees Fahrenheit (47 °C), and the pH can be as low as -3.6.

Acid mine drainage causing organisms can thrive in waters with pH very close to zero. Negative pH occurs when water evaporates from already acidic pools thereby increasing the concentration of hydrogen ions.

About half of the coal mine discharges in Pennsylvania have pH under 5 standard units. However, a significant portion of mine drainage in both the bituminous and anthracite regions of Pennsylvania is alkaline, because limestone in the overburden neutralizes acid before the drainage emanates.

Acid mine drainage has recently been a hindrance to the completion of the construction of Interstate 99 near State College, Pennsylvania, but this acid rock drainage didn't come from a mine: pyritic rock was unearthed during a road cut and then used as filler material in the I-99 construction. A similar situation developed at the Halifax airport in Canada. It is from these and similar experiences that the term acid rock drainage has emerged as being preferable to acid mine drainage, thereby emphasizing the general nature of the problem.

Yellow boy

When the pH of acid mine drainage is raised past 3, either through contact with fresh water or neutralizing minerals, previously soluble Iron(III) ions precipitate as Iron(III) hydroxide, a yellow-orange solid colloquially known as yellow boy. Other types of iron precipitates are possible, including iron oxides and oxyhydroxides. All these precipitates can discolor water and smother plant and animal life on the streambed, disrupting stream ecosystems (a specific offense under the Fisheries Act in Canada). The process also produces additional hydrogen ions, which can further decrease pH. Research is currently being conducted as to the feasibility of recovering yellow boy and other iron precipitates for use as commercial pigments.

Trace metal and semi-metal contamination

Many acid rock discharges also contain elevated levels of potentially toxic metals, especially nickel and copper with lower levels of a range of trace and semi-metal ions such as lead, arsenic, aluminium, and manganese. In the coal belt around the south Wales valleys in the UK highly acidic nickel-rich discharges from coal stocking sites have proved to be particularly troublesome.

Treatment

Oversight

In the United Kingdom, many discharges from abandoned mines are exempt from regulatory control. In such cases the Environment Agency working with partners has provided some innovative solutions, including constructed wetland solutions such as on the River Pelenna in the valley of the River Afan near Port Talbot and the constructed wetland next to the River Neath at Ynysarwed.

Although abandoned underground mines produce most of the acid mine drainage, some recently mined and reclaimed surface mines have produced ARD and have degraded local ground-water and surface-water resources. Acidic water produced at active mines must be neutralized to achieve pH 6-9 before discharge from a mine site to a stream is permitted.

In Canada, work to reduce the effects of acid mine drainage is concentrated under the Mine Environment Neutral Drainage (MEND) program. Total liability from acid rock drainage is estimated to be between $2 billion and $5 billion CAD. Over a period of eight years, MEND claims to have reduced ARD liability by up to $400 million CAD, from an investment of $17.5 million CAD.

Methods

Lime neutralization

By far, the most commonly used commercial process for treating acid mine drainage is lime precipitation in a high-density sludge process. In this application, a slurry of lime is dispersed into a tank containing acid mine drainage and recycled sludge to increase water pH about ~9. At this pH, most toxic metals become insoluble and precipitate, aided by the presence of recycled sludge. Optionally, air may be introduced in this tank to oxidize iron and manganese and assist in their precipitation. The resulting slurry is directed to a sludge-settling vessel, such as a clarifier. In that vessel, clean water will overflow for release, whereas settled metal precipitates (sludge) will be recycled to the acid mine drainage treatment tank, with a sludge-wasting side stream. A number of variations of this process exist, as dictated by the chemistry of ARD, its volume, and other factors. Generally, HDS-generated sludge also contains gypsum and unreacted lime, which enhance both its settleability and resistance to re-acidification and metal mobilization.

Less complex variants of this process, such as simple lime neutralization, may involve no more than a lime silo, mixing tank and settling pond. These systems are far less costly to build, but are also less efficient (i.e., longer reaction times are required, and they produce a discharge with higher trace metal concentrations, if present). They would be suitable for relatively small flows or less complex acid mine drainage.

Carbonate neutralization

Generally, limestone or other calcareous strata that could neutralize acid are lacking or deficient at sites that produce acidic rock drainage. Limestone chips may be introduced into sites to create a neutralizing effect. Where limestone has been used, such as at Cwm Rheidol in mid Wales, the positive impact has been much less than anticipated because of the creation of an insoluble calcium sulfate layer on the limestone chips, binding the material and preventing further neutralization.

Ion exchange

Cation exchange processes were investigated as a potential treatment for acid mine drainage. Not only would ion exchangers remove potentially toxic heavy metals from mine runoff, there was also the possibility of turning a profit off of the recovered metals. However, the cost of ion exchange materials compared to the relatively small returns, as well as the inability of current technology to efficiently deal with the vast amounts of mine discharge, renders this solution unrealistic at present.

Constructed wetlands

Constructed wetlands systems have been proposed during the 1980s to treat acid mine drainage generated by the abandoned coal mines in Eastern Appalachia. Generally, the wetlands receive near-neutral water, after it has been neutralized by (typically) a limestone-based treatment process. Metal precipitation occurs from their oxidation at near-neutral pH, complexation with organic matter, precipitation as carbonates or sulfides. The latter results from sediment-borne anaerobic bacteria capable of reverting sulfate ions into sulfide ions. These sulfide ions can then bind with heavy metal ions, precipitating heavy metals out of solution and effectively reversing the entire process.

The attractiveness of a constructed wetlands solution lies in its relative low cost. They are limited by the metal loads they can deal with (either from high flows or metal concentrations), though current practitioners have succeeded in developing constructed wetlands that treat high volumes (see description of Campbell Mine constructed wetland) and/or highly acidic water (with adequate pre-treatment). Typically, the effluent from constructed wetland receiving near-neutral water will be well-buffered at between 6.5-7.0 and can readily be discharged. Some of metal precipitates retained in sediments are unstable when exposed to oxygen (e.g., copper sulfide or elemental selenium), and it is very important that the wetland sediments remain largely or permanently submerged.

An example of an effective constructed wetland is on the Afon Pelena in the River Afan valley above Port Talbot where highly ferruginous discharges from the Whitworth mine have been successfully treated.

Precipitation of metal sulfides

Most base metals in acidic solution precipitate in contact with free sulfide, e.g. from H2S or NaHS. Solid-liquid separation after reaction would produce a base metal-free effluent that can be discharged or further treated to reduce sulfate, and a metal sulfide concentrate with possible economic value.

As an alternative, several researchers have investigated the precipitation of metals using biogenic sulfide. In this process, Sulfate-reducing bacteria oxidize organic matter using sulfate, instead of oxygen. Their metabolic products include bicarbonate, which can neutralize water acidity, and hydrogen sulfide, which forms highly insoluble precipitates with many toxic metals. Although promising, this process has been slow in being adopted for a variety of technical reasons.

Metagenomic study of acid mine drainage

With the advanced of Large-scale sequencing strategies, genomes of microorganisms in the acid mine drainage community are directly sequenced from the environment. The nearly full genomic constructs allows new understanding of the community and able to reconstruct their metabolic pathways. Our knowledge of Acidophiles in acid mine drainage remains rudimentary: we know of many more species associated with ARD than we can establish roles and functions.

List of selected acid mine drainage sites worldwide

This list includes both mines producing acid mine drainage and river systems significantly affected by such drainage. It is by no way complete, as worldwide, several thousands of such sites exist.

North America

* Argo Tunnel, Idaho Springs, Colorado, USA
* Berkeley Pit superfund site, covering the Clark Fork River and 50,000 acres (200 km²) in and around Butte, Montana, USA
* Britannia Beach, British Columbia, Canada
* Clinch-Powell River system, Virginia and Tennessee, USA
* Iron Mountain Mine, Shasta County, California, USA
* Monday Creek, Ohio, USA
* The Irwin Syncline in Southwestern Pennsylvania
* Pronto mine tailings site, Elliot Lake area, Ontario, Canada
* North Fork of Kentucky River, Kentucky, USA
* Cheat River Watershed, West Virginia, USA
* Copperas Brook Watershed, from the Elizabeth Mine in S. Strafford, Vermont, impacting the Ompompanoosuc River
* Davis Pyrite Mine in NW Massachusetts
* Hughes bore hole, Pennsylvania

Europe

* Avoca, Wicklow, Ireland
* Aznalcollar mine on the Agrio River, Spain
* Wheal Jane, Cornwall, England
* Tinto River, Spain

Oceania

* Queen River, Tasmania, Australia
* King River, Tasmania, Australia

From http://en.wikipedia.org/

Winding engine

2009-11-11T17:23:00.001-08:00

A winding engine is a stationary engine used to control a cable, for example to power a mining hoist at a pit head. Electric hoist controllers that have replaced proper winding engines in modern mining but use electric motors are also traditionally referred to as winding engines.

Most proper winding engines have been stationary steam engines. They differ from most other stationary steam engines in that, like a steam locomotive, they need to be able to stop frequently and also reverse. This requires more complex valve gear and other controls than are needed on engines used in mills or to drive pumps.

From http://en.wikipedia.org/

Wheel tractor-scraper

2009-11-08T01:18:00.000-08:00

In civil engineering, a wheel tractor-scraper is a piece of heavy equipment used for earthmoving. The rear part has a vertically moveable hopper (also known as the bowl) with a sharp horizontal front edge. The hopper can be hydraulically lowered and raised. When the hopper is lowered, the front edge cuts into the soil or clay like a cheese slicer and fills the hopper. When the hopper is full (8 to 34 m³ (10 to 45 yd³) heaped, depending on type) it is raised, and closed with a vertical blade (known as the apron). The scraper can transport its load to the fill area where the blade is raised, the back panel of the hopper, or the ejector, is hydraulically pushed forward and the load tumbles out. Then the empty scraper returns to the cut site and repeats the cycle.

On the elevating scraper the hopper is filled by a type of conveyor belt with cutting edges.

Scrapers can be very efficient on short hauls where the cut and fill areas are close together and have sufficient length to fill the hopper. The heavier scraper types have two engines ('tandem powered'), one driving the front wheels, one driving the rear wheels, with engines up to 400 kW (550 horsepower).
A Caterpillar towed scraper parked up

Self propelled scrapers were invented by R. G. LeTourneau in the 1930s. His company called them Tournahoppers.

Two scrapers can work together in a push-pull fashion but this requires a long cut area.

From http://en.wikipedia.org/

Wellhead

2009-11-05T17:30:00.000-08:00

A wellhead is a general term used to describe the pressure containing component at the surface of an oil well that provides the interface for drilling and production equipment.

The main purpose of a wellhead is to provide a pressure barrier connecting the casing strings that run from the bottom of the hole sections to the surface pressure control equipment.

Whilst drilling the oil well the surface pressure control is provided by a Blowout preventer or 'BOP'. If the pressure is not contained during drilling operations by the casings, wellhead and BOP, then a well blowout can occur.

Once the well has been drilled, a completion is placed in the well to provide the conduit for the well fluids. The surface pressure control is provided by a christmas tree which is installed on top of the wellhead, and has isolation valves and choke equipment to control the well fluids.

Wellheads can be located on the facility oil platforms/onshore called a surface wellhead, or subsea subsea wellhead/mudline wellhead.

A wellhead system provides the following basic functionality:

* connection for a blowout preventer or bop
* support of the casing and tubing strings (the tubing string may also be suspended in the Christmas tree;
* providing a seal between the different strings;
* allowing for access to annuli between the different casing/tubing strings.

Components

The primary components of a wellhead system are:

* casing head
* casing spools
* casing hangers
* packoffs and isolation seals
* bowl protectors
* test plugs
* mudline suspension systems
* tubing heads
* tubing hangers
* tubing head adapters

Specification

The basic requirements for materials, dimensions, test procedures and pressure ratings for wellheads and wellhead equipment are defined on API Spec 6A: Specification for Wellhead and Christmas Tree Equipment. Wellheads are cemented in place and are generally permanently kept in place, although in exploration wells they may be recovered for use again.

Design factors

Wellheads are manufactured for numerous different purposes.

The main oil industry specifications are :

1. API 6A Specification for Wellhead and Christmas Tree Equipment
2. ISO 10423 Wellhead and Christmas Tree Equipment

Functions

A wellhead serves numerous functions. Some of these are:

1. Means of casing suspension. (Casing is the permanently installed pipe used to line the well hole for pressure containment, collapse prevention, etc.)
2. Means of casing pressure isolation when multiple casing strings are used
3. Means of attaching a blowout preventer during drilling
4. Means of attaching a tree for well control during production, injection, or other operations
5. Means of well access
6. Means of pump attachment
7. Means of tubing suspension (Tubing is removable pipe installed in the well)

From http://en.wikipedia.org/

Trommel

2009-11-01T16:11:00.000-08:00

A trommel (from the Dutch word for drum, "trommel") is a screened cylinder used to separate materials by size - for example, separating the biodegradable fraction of mixed municipal waste or separating different sizes of crushed stone.

Portable trommels (also called portable trommel screens) are often used in the production of organic products from various types of waste.

For example, excavation contractors may screen their site debris into two fractions; a saleable topsoil for farms, nurseries and site-work, as well as cleaned rock for aggregates or landscaping work. This allows the contractor to resell their waste, instead of incurring the cost of sending it for disposal.

The same principle applies to the production of compost, sand/gravel, lumber mill by-products and municipal waste.

From http://en.wikipedia.org/

Subsea

2009-10-26T11:03:00.000-07:00

Subsea is a general term frequently used to refer to equipment, technology, and methods employed to explore, drill, and develop oil and gas fields that exist below the ocean floors. This may be in "shallow" or "deepwater".

Deepwater is a term often used to refer to subsea projects located in water depths greater than 1,000 feet, and may include floating drill vessels, semi-sub rigs or Semi-submersible Platforms.

"Shallow" or shelf" is used for shallower depths and can include standing Jackup Rigs or similar.

Background and history

Oil and gas fields reside in deep water and shallow water around the world. When they are under water and tapped into for the hydrocarbon production, these are generically called subsea wells, fields, projects, development, or other similar terms.

The first subsea well was in one of the Great Lakes in the USA and was in only a few feet of water.

Systems

Subsea production systems can range in complexity from a single satellite well with a flowline linked to a fixed platform, FPSO or an onshore installation, to several wells on a template or clustered around a manifold, and transferring to a fixed or floating facility, or directly to an onshore installation.

Subsea production systems can be used to develop reservoirs, or parts of reservoirs, which require drilling of the wells from more than one location. Deep water conditions, or even ultradeep water conditions, can also inherently dictate development of a field by means of a subsea production system, since traditional surface facilities such as on a steel-piled jacket, might be either technically unfeasible or uneconomical due to the water depth.

The development of subsea oil and gas fields requires specialized equipment. The equipment must be reliable enough to safe guard the environment, and make the exploitation of the subsea hydrocarbons economically feasible. The deployment of such equipment requires specialized and expensive vessels, which need to be equipped with diving equipment for relatively shallow equipment work (i.e. a few hundred feet water depth maximum), and robotic equipment for deeper water depths. Any requirement to repair or intervene with installed subsea equipment is thus normally very expensive. This type of expense can result in economic failure of the subsea development.

Subsea technology in offshore oil and gas production is a highly-specialized field of application with particular demands on engineering and simulation. Most of the new oil fields are located in deepwater and are generally referred to as deepwater systems. Development of these fields sets strict requirements for verification of the various systems’ functions and their compliance with current requirements and specifications. This is because of the high costs and time involved in changing a pre-existing system due to the specialized vessels with advanced onboard equipment. A full scale test (System Integration Test – SIT) does not provide satisfactory verification of deepwater systems because the test, for practical reasons, cannot be performed under conditions identical to those under which the system will later operate. The oil industry has therefore adopted modern data technology as a tool for virtual testing of deepwater systems that enables detection of costly faults at an early phase of the project. By using modern simulation tools models of deepwater systems can be set up and used to verify the system's functions, and dynamic properties, against various requirements specifications. This includes the model-based development of innovative high-tech plants and system solutions for the exploitation and production of energy resources in an environmentally-friendly way as well as the analysis and evaluation of the dynamic behavior of components and systems used for the production and distribution of oil and gas. Another part is the real-time virtual test of systems for subsea production, subsea drilling, supply above sea level, seismography, subsea construction equipment and subsea process measurement and control equipment.

Remotely Operated Vehicles

Remotely Operated Vehicles (ROV's) are robotic pieces of equipment operated from afar to perform tasks on the sea floor. ROV's are available in a wide variety of function capabilities and complexities from simple "eyeball" camera devices, to multi-appendage machines that require multiple operators to operate or "fly" the equipment.

Organizations

A number of professional societies and trade bodies are involved with the subsea industry around the world. Such groups include Subsea UK, Society of Petroleum Engineers (SPE), American Petroleum Institute (API), American Society of Mechanical Engineers (ASME), National Association of Corrosion Engineers (Nace).

Government agencies administer regulations in their territorial waters around the world. Examples of such government agencies are the Minerals Management Service (MMS, US), Norwegian Petroleum Directorate (NPD, Norway), and Health & Safety Executive (HSE, UK). The MMS administers the mineral resources in the US (using Code of Federal Regulations (CFR)) and provides management of the country's hydrocarbon resources.

Safety

Subsea hydrocarbon (oil and gas) extraction has an exceptionally safe record and has been going on for approximately 100 years.

From http://en.wikipedia.org/

Safety lamp

2009-10-18T19:52:00.000-07:00

A safety lamp is any of several types of lamp, which are designed to be safe to use in coal mines. These lamps are designed to operate in air that may contain coal dust, methane, or firedamp, all of which are potentially flammable or explosive. The use of open lamps, rather than the safety lamps that were then available, was one cause of the Naomi Mine explosion and the Darr Mine Disaster in Pennsylvania in December 1907.

First Safe Lamps

The first safety lamp was invented by William Reid Clanny, an Irish physician, who announced his discovery on May 20, 1813 at the Royal Society of Arts in London, but it was not tried out in a colliery until 1815. Within months of this demonstration, two improved designs had been announced: one by George Stephenson, which later became the Geordie lamp, and the Davy lamp, invented by Sir Humphry Davy. Most later lamps are constructed on the principle discovered by Davy, that a flame enveloped in wire gauze of a certain fineness does not ignite firedamp

Both the Davy and Stephenson lamps were fragile. The gauze in the Davy quickly rusted in the moist air of a coal pit, and so became unsafe, while the glass in the Stephenson was easily broken, and could then allow the flame to ignite firedamp in the atmosphere. Later designs, the Gray, Mueseler, Marsaut, and other lamps, tried to overcome these problems by using multiple gauze cylinders, but the glass remained a problem until toughened glass became available.

Also, the light that all these gave was poor and this was not solved until the introduction of electric lighting in mines around 1900. But it took until 1930 for the introduction of battery-powered helmet lamps to finally solve the problem.

Early Illumination

Prior to the invention of these safety lamps, miners used candles with open flames or phosphorescent sources of light and later flint or steel mills designed by 'Spedding.' Later, barometers were used to tell them if atmospheric pressure was low (in which case more methane seeped out of the coal seams into the mine galleries).

The use of small mammals or birds was used much later at the end of the Victorian age to warn of the presence of the deadly carbon monoxide present after underground fires or explosions, the so-called afterdamp. The method was introduced by the noted physiologist and disaster investigator, John Scott Haldane after the Laxey lead mine disaster. Such animals are much more susceptible to the gas, and will die before a human, so giving an early warning of the problem. There were numerous deaths casued by carbon monoxide from a small fire near one of the shaft bottoms. An alternative method of removing a different gas, known as firedamp (methane) involved igniting the gas deliberately to cause explosions, thus evacuating the mines of the majority of explosive or easily flammable material present.

The lack of good lighting was a prime cause of a painful eye affliction (nystagmus).

Modern Lamps

Nowadays, safety lamps are mainly electric, and traditionally mounted on miners' helmets (such as the wheat lamp) or the Oldham headlamp, sealed to prevent gas penetrating the casing and being ignited by electrical sparks.

Although its use as a light source was superseded by electric lighting, the flame safety lamp has continued to be used in mines to detect methane and blackdamp, although many modern mines now also use sophisticated electronic gas detectors for this purpose.

LED safety Lamp

As a new light source, LED has many advantages for safety lamps, including longer burn time and less energy required. Combined with new battery technologies, such as the lithium battery, it gives much better performance in safety lamp applications. It is replacing conventional safety lamps.

From http://en.wikipedia.org/

Pumpjack

2009-10-09T01:07:00.000-07:00

A pumpjack (also known as 'nodding donkey, pumping unit, horsehead pump, beam pump, sucker rod pump (SRP), grasshopper pump, thirsty bird and jack pump) is the overground drive for a reciprocating piston pump installed in an oil well.

It is used to mechanically lift liquid out of the well if there is not enough bottom hole pressure for the liquid to flow all the way to the surface. The arrangement is commonly used for onshore wells producing relatively little oil. Pumpjacks are common in many oil-rich areas, dotting the countryside and occasionally serving as local landmarks.

Depending on the size of the pump, it generally produces 5 to 40 litres of liquid at each stroke. Often this is an emulsion of crude oil and water. The size of the pump is also determined by the depth and weight of the oil to be removed, with deeper extraction requiring more power to move the heavier lengths of sucker rods (see diagram at right).

A pumpjack converts the rotary mechanism of the motor to a vertical reciprocating motion to drive the pump shaft, and is exhibited in the characteristic nodding motion. The engineering term for this type of mechanism is a walking beam. It was often employed in stationary and marine steam engine designs in the 1700s and 1800s.

Above ground

Pumpjacks are powered by a "prime mover". This is commonly an electric motor, but combustion engines are used in isolated locations without economic access to electricity. The most common "off-grid" pumpjack engines run on casing gas produced from the well, but pumpjacks have been run on many types of fuel, such as propane (LPG) and diesel. In harsh climates such motors and engines may be housed inside a shack to protect them from the elements.

The prime mover of the pumpjack runs a set of pulleys to the transmission which in turn drives a pair of cranks, generally with counterweights on them to assist the motor in lifting the heavy string of rods. The cranks in turn raise and lower one end of an I-beam which is free to move on an A-frame. On the other end of the beam, there is a curved metal box called a Horse Head or Donkeys Head, named so due to its appearance. A cable made of steel (or, occasionally, fiberglass) called a bridle, connects the horse head to the polished rod, a piston that passes through the stuffing box. The polished rod has a very close fit to the stuffing box, letting it move in and out of the tubing without fluid escaping. (The tubing is a pipe that runs to the bottom of the well through which the liquid is produced.) The bridle follows the curve of the horse head as it lowers and raises to create an almost completely vertical stroke. The polished rod is connected to a long string of rods called sucker rods, which run through the tubing all the way to the down-hole pump, usually positioned near the bottom of the well.

Down-hole

At the bottom of the tubing is the "down-hole pump". This pump consists of two ball check valves: a stationary valve at bottom called the "standing valve", and a valve on the piston connected to the bottom of the sucker rods that travels up and down as the rods reciprocate, known as the "traveling valve". Reservoir fluid enters from the formation into the bottom of the borehole through perforations that have been made through the casing and cement (casing is a larger metal pipe that runs the length of the well, which has cement placed between it and the earth). The tubing, pump and sucker rods are all inside the casing). When the rods at the pump end are traveling up, the traveling valve is closed and the standing valve is open (due to the drop in pressure in the pump barrel). Consequently, the pump barrel fills with the fluid from the formation as the traveling piston lifts the previous contents of the barrel upwards. When the rods begin pushing down, the traveling valve opens and the standing valve closes (due to an increase in pressure in the pump barrel). The traveling valve drops through the fluid in the barrel (which had been sucked in during the upstroke). The piston then reaches the end of its stroke and begins its path upwards again, repeating the process.

Often, gas is produced through the same perforations as the oil. This can be problematic if gas enters the pump, because it can result in "gas locking", where insufficient pressure builds up in the pump barrel to open the valves (due to compression of the gas) and little or nothing is pumped. To preclude this, the inlet for the pump can be placed below the perforations. As the gas-laden fluid enters the well bore through the perforations, the gas bubbles up the annulus (the space between the casing and the tubing) while the liquid moves down to the standing valve inlet. Once at the surface, the gas is collected through piping connected to the annulus.

Water well pump jacks

Pumpjacks can also be used to drive what would now be considered "old fashioned" hand-pumped water wells. The scale of the technology is much smaller than for an oil well, and can typically fit on top of an existing hand-pumped well head. The technology is very simple, typically using a parallel-bar double-cam lift driven from a very low horsepower electric motor.

Although the flow rate for a water well pumpjack is very low compared to a modern jet pump and the lifted water is not pressurized, the water well pumpjack does at least have the option of falling back to hand pumping in an emergency, by simply hand-rotating the pumpjack cam to its lowest position, and attaching a manual handle to the top of the wellhead rod.

From http://en.wikipedia.org/

Power shovel

2009-09-10T01:51:00.000-07:00

A Power shovel (also stripping shovel or Front Shovel or Electric Mining Shovel) is a bucket equipped machine, usually electrically powered, used for digging and loading earth or fragmented rock, and mineral extraction.

Design

Shovels normally consist of a revolving deck with a power plant, driving and controlling mechanisms, usually a counterweight, and a front attachment, such as a boom or crane which supports a handle with a digger at the end. The machinery is mounted on a base platform with tracks or wheels. The bucket is also known as the dipper. Modern bucket capacities range from 8 m3 to nearly 80 m3.

Use

Power shovels are used principally for excavation and removal of overburden in open-cut mining operations, though it may include loading of minerals, such as coal. They are the modern equivalent of steam shovels, and operate in a similar fashion.

Operation

The shovel operates using several main motions:

* hoist - pulling the bucket up through the bank (i.e. the bank of material being dug)
* crowd - moving the dipper handle out or in to control the depth of cut and when positioning to dump
* swing - rotating the shovel between digging and dumping
* propel - moving the shovel unit to different locations or dig positions

A shovel's work cycle, or digging cycle, consists of four phases:

* digging
* swinging
* dumping
* returning

The digging phase consists of crowding the dipper into the bank, hoisting the dipper to fill it, then retracting the full dipper from the bank. The swinging phase occurs once the dipper is clear of the bank both vertically and horizontally. The operator controls the dipper through a planned swing path and dump height until it is suitably positioned over the haul unit (e.g. truck). Dumping involves opening the dipper door to dump the load, while maintaining the correct dump height. Returning is when the dipper swings back to the bank, and involves lowering the dipper into the tuck position to close the dipper door.

From http://en.wikipedia.org/

Movement and Surveying Radar

2009-09-08T19:25:00.000-07:00

In open pit mining operations, people and equipment are constantly at the base of a steep, man-made slope (the highwall or pit-wall). Instances where this slope fails resulting in a rock or earthfall can result in loss of life, injuries and damage or destruction of equipment (see mining). It has been found that, over the last few hours preceding a slope failure, there is nearly always a small movement, or alteration in the movement pattern in the rock face of that section.

The system is intended to monitor mine slopes to detect this movement and generate a warning of impending failure (slope stability), so that personnel and equipment may be removed prior to the failure. The radar element provides very accurate, real-time, all weather slope movement measurements with sub millimetre detection ability, and is able to provide an alarm if the detected movement reaches a predetermined level, thereby permitting evacuation of the unstable area, and enhancing safety.

All radar measurements are fully geo-referenced to an accuracy that allows easy integration with standard digital terrain mapping (DTM) tools.

A second function of the Movement and Surveying Radar is to determine the absolute range to the electromagnetic reflective centroid of an area on a body of material or geographical feature. This functionality, combined with the accurately surveyed position of the measurement origin of the Movement and Surveying Radar and the positioning system’s angular measurement information, may be used to generate survey data of geographical features such as mine walls and rubble dumps. The survey data collected may be used for applications such as the calculation of material removal volumes.

A Movement and Surveying Radar combines simultaneously the execution of slope stability and surveying measurements, which together with high-speed external data links makes it a near real-time tool for mining safety, planning and productivity improvement.

From http://en.wikipedia.org/

Man engine

2009-09-05T15:00:00.000-07:00

A man engine is a mechanism of reciprocating ladders and stationary platforms installed in mines to assist the miners’ journeys to and from the working levels. It was invented in Germany in the 19th century and was a prominent feature of tin and copper mines in Cornwall until the beginning of the twentieth.

Operation

In the Cornish examples the motive power was provided by waterwheels, or one of the mine's beam engines. Originally operating without a flywheel, this offered a reciprocating motion of, typically, twelve to fifteen feet (three to five metres). The engine would be linked to a series of beams – known as "rods" – fastened together and reaching to the bottom of the mineshaft. Small platforms would be attached to the rods at the same distance apart as the engine stroke. Fixed platforms were built onto the shaft walls, spaced to coincide with the top and bottom positions of each of the moving platforms. In a common variation a pair of rods was used, with one on its upstroke as the other descended. The miner hopped from one to the other, rather that waiting at a fixed rest, as they changed direction. Counterweights – large boxes filled with stones attached through "see-sawing" horizontal beams – were installed in order to avoid the full weight of the shaft and men bearing on the engine beam. In the deepest mines, which could sink to more than 350 fathoms (640 metres), extra counterweights were provided in side-shafts at regular intervals.

To go up or down, the miner would step onto the travelling platform and allow himself to be carried to the next fixed platform, where he would step off and wait. At the end of the next stroke the next moving platform would line up and he could step onto it and repeat the process. Although the footholds were often small, grab handles were fitted above each one. Miners may ascend and descend at the same time: the pause at the changeover point is made long enough for two men to change places.

Safety

The miners took to these devices without hesitation as their pay was not calculated until they had reached their underground workplace. Contemporary safety studies concluded that, although intrinsically dangerous, the use of a man engine was in practice safer than climbing long ladders: it was less risky to be carried up at the end of a hard shift than to climb a ladder and risk falling because of exhaustion. In some mines, particularly in Germany, wedges or collars placed just above close-fitting rollers, or chains, were installed to limit any drop should a breakage occur.

Levant mine accident

In the afternoon of 20 October 1919 an accident occurred on the man engine at the Levant Mine, St Just, Cornwall. More than 100 miners were on the engine being drawn to the surface when a metal bracket at the top of the rod broke. The heavy timbers crashed down the shaft, carrying the side platforms with them, and thirty-one men lost their lives. The man engine was not replaced and the lowest levels of the mine were abandoned.

History

The earliest known examples of this device were from the silver mining area of the Harz mountains, Germany, where they were driven by cranks connected to water wheels, although bucket hoists using the same method of operation had been used in Swedish iron mines since the 17th century. They appear to have evolved from an informal modification to the beam pumps, where the miners stuck spikes into the wooden pump rods to get themselves carried up the shaft. As beam pumps were universal in deep mines, it was a then simple development to make proper platforms to carry the miners. The first formal engine was installed in 1833 at a mine at Clausthal, Lower Saxony, where inspector Wilhelm Albert and manager Georg Dörell (1793–1854) fastened foot platforms and hand-holds to adjacent, reciprocating pump rods, using a waterwheel-driven pump put out of use when a new drainage adit was made at a lower level. The 1837 man engine at Grube Samson in Sankt Andreasberg in the same region is still in use, although converted from water to electric power in 1922.

The device was introduced to Cornwall in 1842, following the award of a premium for the best design, by the Royal Cornwall Polytechnic Society. The winner, Michael Loam, built one for the proprietors of the Tresavean Mine, in Lanner near Redruth. He used a double-rod design, driven by a waterwheel. The miners' journey time (in either direction) was reduced from about an hour to twenty-four minutes and output per shift increased by one fifth. More than a dozen examples were installed in Cornish mines by the end of the century, but these were usually of the single-rod type, which was perceived as safer in use.

When cable operated winding gear became available the man engines continued in use, particularly in cases where the mineshaft was not truly vertical and winding engines drawing suspended cages could not be used: with the provision of a few well-place rollers, and “fend offs” mounted on trunnions, the rods could reach the bottom of a shaft even at a substantial deviation from the vertical. Economics also played a part: the rods needed for pumping could be used for this extra function at little increased cost. Even when skips or “kibbles” were used in such shafts, (running on “skipways”) the tipping motion would make them impractical for carrying men.

From http://en.wikipedia.org/

Loader (equipment)

2009-09-03T08:32:00.000-07:00

A loader is an engineering vehicle (often used in construction) that is primarily used to "load" material (asphalt, demolition debris, dirt, feed, gravel, logs, raw minerals, recycled material, rock, sand, wood chips, etc.) into or onto another type of machinery (dump truck, conveyor belt, feed-hopper, rail-car, etc.).

Heavy equipment front loaders

A loader (also known as: bucket loader, front loader, front end loader, payloader, scoop loader, shovel, skip loader, and/or wheel loader) is a type of tractor, usually wheeled, sometimes on tracks, that has a front mounted square wide bucket connected to the end of two booms (arms) to scoop up loose material from the ground, such as dirt, sand or gravel, and move it from one place to another without pushing the material across the ground. A loader is commonly used to move a stockpiled material from ground level and deposit it into an awaiting dump truck or into an open trench excavation.

The loader assembly may be a removable attachment or permanently mounted. Often the bucket can be replaced with other devices or tools--for example, many can mount forks to lift heavy pallets or shipping containers, and a hydraulically-opening "clamshell" bucket allows a loader to act as a light dozer or scraper. The bucket can also be augmented with devices like a bale grappler for handling large bales of hay or straw.

Large loaders, such as the Kawasaki 95ZV-2, John Deere 844J, Caterpillar 950H, Volvo L120E, Case 921E, or Hitachi ZW310 usually have only a front bucket and are called Front Loaders, whereas small loader tractors are often also equipped with a small backhoe and are called backhoe loaders or loader backhoes or JCBs, after the company that first invented them.

The largest loader in the world is LeTourneau L-2350. Currently these large loaders are in production in the Longview, Texas facility. The L-2350 uses a diesel electric propulsion system simlilar to that used in a locomotive. Each rubber tired wheel is driven by its own independent electric motor.

Loaders are used mainly for uploading materials into trucks, laying pipe, clearing rubble, and digging. A loader is not the most efficient machine for digging as it cannot dig very deep below the level of its wheels, like a backhoe can. Their deep bucket can usually store about 3-6 cubic meters (exact number varies with the model) of earth. The front loader's bucket capacity is much bigger than a bucket capacity of a backhoe loader. Loaders are not classified as earthmoving machinery, as their primary purpose is other than earthmoving.

Unlike most bulldozers, most loaders are wheeled and not tracked, although track loaders are common. They are successful where sharp edged materials in construction debris would damage rubber wheels, or where the ground is soft and muddy. Wheels provide better mobility and speed and do not damage paved roads as much as tracks, but provide less traction.

In construction areas loaders are also used to transport building materials - such as bricks, pipe, metal bars, and digging tools - over short distances.

Loaders are also used for snow removal, using their bucket or a snowbasket, but usually using a snowplow attachment. They clear snow from streets, highways and parking lots. They sometimes load snow into dump trucks for transport.

High-tip buckets are suitable for light materials such as chip, peat and light gravel and when the bucket is emptied from a height.

Unlike backhoes or standard tractors fitted with a front bucket, many large loaders do not use automotive steering mechanisms. Instead, they steer by a hydraulically actuated pivot point set exactly between the front and rear axles. This is referred to as "articulated steering" and allows the front axle to be solid, allowing it to carry greater weight. Articulated steering provides better maneuverability for a given wheelbase. Since the front wheels and attachment rotate on the same axis, the operator is able to "steer" his load in an arc after positioning the machine, which can be useful. The tradeoff is that when the machine is "twisted" to one side and a heavy load is lifted high, it has a greater risk of turning over to the "wide" side.

Front loaders gained popularity during the last two decades, especially in urban engineering projects and small earthmoving works. Many engineering vehicle manufacturers offer a wide range of loaders, the most notable are those of John Deere, Caterpillar, Case, Volvo, Komatsu, Liebherr,JCB and Kawasaki, being the longest, on-going manufacturer of articulated wheel loaders in the world.

The term "loader" is also used in the debris removal field to describe the boom on a grapple truck.

In Pakistan first tractor loader was manufactured by JIC JIC

Tractor front loaders

These loaders are a popular addition to tractors from 50 to 200hp. It's current 'drive-in' form was originally designed and developed in 1958 by a company called Quicke A history of Quicke loader development.They were developed to perform a multitude of farming tasks, and are popular due to their relavitely low cost (compared to Telehandler) and high versatility. Tractor loaders can be fitted with many attachments such as hydraulic grabs and spikes to assist with bale and silage handling, forks for pallet work, and buckets for more general farm activities.

Compact front end loaders

Popular additions to compact utility tractors and farm tractors are Front End Loaders, also referred to as a FEL. Compact utility tractors, also called CUTs are small tractors, typically with 18 to 50 horsepower (37 kW) and used primarily for grounds maintenance and landscape chores. There are 2 primary designs of compact tractor FELs, the traditional dogleg designed style and the curved arm style.

John Deere Tractor manufactures a semi-curved loader design that does not feature the one piece curved arm, but also is not of the traditional two piece design. New Holland Ag introduced a compact loader with a one piece curved arm on its compact utility tractors, similar one piece curved arm loaders are now available on compact tractors on many brands including Case/Farmall, and some Montana and Kioti tractors. Kubota markets traditional loader designs on most of its compact tractors but now features a semi-curved loader design similar to the John Deere loader design on several of its small tractors.

While the Front End Loaders on CUT size tractors are capable of many tasks, given their relatively small size and low capacities when compared to commercial loaders, the compact loaders can be made more useful with some simple options. A Toothbar is commonly added to the front edge of a loader bucket to aid with digging. Some loaders are equipped with a Quick Attach (QA) system, the QA system allows the bucket to be removed easily and other tools to be added in its place. Common additions would include a set of Pallet Forks for lifting pallets of goods or a Bale Spear for lifting hay bales.

Skid loaders & track loaders

A skid loader is a small loader utilizing four wheels with hydraulic drive that directs power to either, or both, sides of the vehicle. Very similar in appearance and design is the track loader, which utilizes a continuous track on either side of the vehicle instead of the wheels. Since the expiration of Bobcat's patent on its quick-connect system, newer tractor models are standardizing on that popular format for front end attachments.

Unconventional use

Front loaders were sometimes used in ways they weren't ment to, mostly by criminals, but not always.

In 1998 Tom Leask killed one person in city of Alma, Colorado, then used a front loader to demolish several buildings, such as post office, school, water and fire departments. Eventually, he stopped the machine and was arrested by police.

During 2004 bulldozer rampage in Granby, Colorado concrete plant's owner, Code Docheff, used a front loader as weapon against his neighbor, Marvin Heemeyer, who went on rampage for closing the only way to his workshop. Despite attempts to stop bulldozer (trying to rip his tracks off, then ram into engine), Docheff eventually ran from the place after Heemeyer shot several warning shots into loader's scoop.

Front loader was also used in Horsens, Denmark when it was rammed into country's oldest prison's wall. Several prisoners escaped through the hole, but were eventually caught later.

The most infamous use of front loader were two rampages on July 2 and July 22, 2008 in Jerusalem. In the first attack 4 people were killed (including loader's driver), in the second - only the terrorist was killed. On March 5, 2009 another attack occured, with one casualty (loader's driver).

Loaders in popular culture

* In James Bond's fifteenth movie, The Living Daylights, Kamran Shah, leader of the Mujahideen group uses the front loader to demolish Soviet air base.
* Front loaders were almost always the vehicle mode for Constructicon's leader, Scrapper. The only exception is his Transformers Animated incarnation, in which he turns into excavator.

From http://en.wikipedia.org/

Excavator

2009-09-01T05:29:00.000-07:00

An excavator is an engineering vehicle consisting of an articulated arm (boom, stick), bucket and cab mounted on a pivot (a rotating platform, like a Lazy Susan) atop an undercarriage with tracks or wheels. Their design is a natural progression from the steam shovel.

Usage

Excavators are used in many ways:

* Digging of trenches, holes, foundations
* Material handling
* Brush cutting with hydraulic attachments
* Forestry work
* Demolition
* General grading/landscaping
* Heavy lift, e.g. lifting and placing of pipes
* Mining, especially, but not only open-pit mining
* River dredging
* Driving piles, in conjunction with a Pile Driver

Configurations

Excavators come in a wide variety of sizes. The smaller ones are called a mini-excavator or compact excavator. One manufacturer's largest model weighs 84,980 kg (187,360 lb) and has a maximum bucket size of 4.5 m³ (5.9 yd³). The same manufacturer's smallest mini-excavator weighs 1470 kg (3240 lb), has a maximum bucket size of 0.036 m³ (0.048 yd³) and the width of its tracks can be adjusted to 89 cm (35 inches). Another company makes a mini excavator that will fit through a doorway with tracks that can be adjusted to only 70 cm (28 inches) wide.

To identify the basic pieces, the cab attaches by way of a pin to the deck which holds the final drives which have a gear that drives the tracks. The Boom attaches to the cab by way of a large pin. Attached to the Boom is the Stick. Attached to the stick is the bucket and optionally, the thumb. Usually 2 large hydraulic cylinders create the lift of the boom. Some booms have a swivel capability so the boom can swing independent of the cab. The stick provides the reach along with the boom. Usually a model of excavator has optional lengths of stick that enhance either reach (longer stick) or break-out power (shorter stick). Bucket sizes and configurations are used for varying purposes. A wide "clean-up" bucket is used in situations where too much dig force would make the surfaces uneven. It "cleans-up" a site smooting and filling the ground. A "dig bucket" is much smaller. It usually has teeth on it to aggressively break into the ground. Buckets have numerous shapes and sizes for various applications. A "V-shaped" bucket can even penetrate ground that is frozen!

Excavator attachments

In recent years, hydraulic excavator capabilities have expanded far beyond excavation tasks with buckets. With the advent of hydraulic powered attachments such as a breaker, a grapple or an auger, the excavator is frequently used in many applications other than excavation. Many excavators feature quick-attach mounting systems for simplified attachment mounting, increasing the machine's utilization on the jobsite. Excavators are usually employed together with loaders and bulldozers. Most wheeled versions, and smaller, compact excavators have a small backfill (or dozer-) blade. This is a horizontal bulldozer-like blade attached to the undercarriage and is used for pushing removed material back into a hole. Prior to the 1990s, all excavators had a hang over, or "conventional" counterweight that hung off the rear of the machine to provide more digging force and lifting capacity. This became a nuisance in tight turn areas - the machine could not swing the second half of its cycle due to restricted turn radius. In the early 1990s The Komatsu Engineering Company launched a new concept excavator line that did away with the "conventional" counterweight design, and so started building the world's first tight tail swing excavators (PC128.PC138,PC228,PC308). These machines are now widely used though out the world.

From http://en.wikipedia.org/

Domestic Canary

2009-09-01T05:25:00.000-07:00

The Domestic Canary (Serinus canaria domestica) is a domesticated form of the Wild Canary, a small songbird in the finch family originating from Madeira, the Azores and the Canary Islands.

Canaries were first bred in captivity in the 1600s. They were brought over by Spanish sailors to Europe. Monks started breeding them and only sold the males (which sing). This kept the birds in short supply and drove the price up. Eventually Italians obtained hens and were able to breed the birds themselves. This made them very popular and resulted in many breeds arising and the birds being bred all over Europe.

The same occurred in England. First the birds were only owned by the rich but eventually the local citizens started to breed them and, again, they became very popular. Many breeds arose through selective breeding, and they are still very popular today for their voice.

They come in many colours such as; yellow, orange, brown, black, white, and red. 1 in 65 wild canaries are naturally red.

Varieties

Canaries are generally divided into three main groups: Colorbred Canaries (bred for their many color mutations - Ino, Eumo, Satinette, Bronze, Ivory, Onyx, Mosaic, Brown, etc.), Type Canaries (bred for their shape and conformation - Border, Fife, Gloster, Gibber Italicus, Raza Española, Berner, Lancashire, Yorkshire, Norwich, Australian Plainhead, etc.), and Song Canaries (bred for their unique and specific song patterns - Spanish Timbrado, German Roller, Waterslager (also known as "Malinois"), American Singer, Russian Singer, Persian Singer).

Competitions

In the Northern hemisphere, Canaries are judged in competitions every fall. Shows generally begin in October and November after the breeding season ends. Birds can only be shown by the person who raised them. They all have unique bands on their legs that indicate the year of birth, the unique band number, the club to which the breeder belongs. Some song-breed canaries are judged later in the year (January).

There are many canary bird shows all over the world. The world show (C.O.M.) is held in Europe each year and attracts thousands of breeders. As many as 20,000 birds are brought together for competition.

Miner's canary

Canaries were once regularly used in coal mining as an early warning system. Toxic gases such as carbon monoxide and methane in the mine would kill the bird before affecting the miners. Because canaries tend to sing much of the time, they provided both a visual and audible cue in this respect. The use of so called miner's canaries in British mines was phased out as recently as 1987.

Hence, the phrase "canary in a coal mine" is frequently used to refer to a person or thing which serves as an early warning of a coming crisis. By analogy, the term climate canary is used to refer to a species that is affected by an environmental danger prior to other species, thus serving as an early warning system for the other species with regard to the danger.

Use in research

Canaries have been extensively used in research to study neurogenesis, or the birth of new neurons in the adult brain, and also for basic research in order to understand how songbirds encode and produce song. Thus, canaries have served as model species for discovering how the vertebrate brain learns, consolidates memories, and recalls produces coordinated motor movements. Fernando Nottebohm, a professor at The Rockefeller University detailed the brain structures and pathways that are involved in the production of bird song.

Trivia

* Canaries have been depicted in cartoons from the middle 20th century as being harassed by domestic cats; the most famous cartoon canary is Warner Brothers' "Tweety Bird".

* Norwich City, an English football team is nicknamed 'The Canaries' due to the city once being a famous centre for breeding and export of the birds. The club adopted the colours of yellow and green in homage.

Breeding

Inexperienced breeders find it difficult to determine the sex of canaries by appearance, intensity of colour, or demeanor. Most males sing and most females do not. As spring approaches physical changes are observed in the vent area. The abdomen of the hen becomes more rounded and that of the cock becomes larger and protudes downward in the same direction as the legs.

Canaries are only fertile when the length of the day increases to about 12 hours. This occurs naturally in the spring but can be induced earlier through artificial lighting and heating. Good nutrition is essential. Cuttlefish bone is often used to provide calcium for the formation of egg shells. Liquid vitamin drops help guard against deficiencies. Greens are a staple, such as chickweed, seedy (lawn type) grass heads, dandelion, carrot, broccoli, sprouts, and apple. There are many different recipes for soft food that include ingredients such as hard boiled egg, gelatin, and bread or biscuit crumbs. A protein-rich soft food, together with sprouted seed, is the fundamental diet of canary chicks.

Canaries are best suited to breeding in a controlled environment with one pair per cage. This is essential for any pedigree show varieties. They can also be bred successfully in an avaiary situation if there is sufficient room, excess nesting sites, and a plentiful supply of nesting material.

Males will often be ready to breed before the females. A cock may pursue a hen relentlessly or fight with her. In these situations the pair is separated until the female has most of the nest built and is more likely to accept to the male. Many breeders use a "double breeder" cage with two compartments separated by a removable wire partition. The partition is removed when the pair is observed "kissing" (the male trying to feed the female) through the bars.

An open (uncovered) 4" nest cup is previously installed in an accesible position above the height of the perches. Nesting material such as hessian, plumber's hemp, cotton wool, burlap, and tissue paper is provided.

The hen lays a total of four or five eggs, on successive days. She rarely leaves the nest during the two weeks of incubation and relys on the cock to bring food. Some breeders remove the first two or three eggs and replace them with dummy eggs. They then return the real eggs when the clutch is completed. This causes the eggs to hatch over fewer days and gives a higher survival rate due to less disparity in the size of the chicks. Fresh soft food and sprouted seed is provided regularly until the chicks are weaned to hard seed.

The chicks leave the nest at about 18 days and are fed by the parents for another week or so. The hen then commences a second round and may attack the first one. At this point the partition is returned in a "double breeder" cage so that the fledglings can be housed in one side. Their parents in the other side feed them through the wire while also proceeding with further breeding.

From http://en.wikipedia.org/

Drilling rig

2009-08-30T18:47:00.000-07:00

A drilling rig is a machine which creates holes (usually called boreholes) and/or shafts in the ground. Drilling rigs can be massive structures housing equipment used to drill water wells, oil wells, or natural gas extraction wells or they can be small enough to be moved manually by one person. They sample sub-surface mineral deposits, test rock, soil and groundwater physical properties, and also can be used to install sub-surface fabrications, such as underground utilities, instrumentation, tunnels or wells. Drilling rigs can be mobile equipment mounted on trucks, tracks or trailers, or more permanent land or marine-based structures (such as oil platforms, commonly called 'offshore oil rigs' even if they don't contain a drilling rig). The term "rig" therefore generally refers to the complex of equipment that is used to penetrate the surface of the earth's crust.

Drilling rigs can be:

* Small and portable, such as those used in mineral exploration drilling, water wells and environmental investigations.
* Huge, capable of drilling through thousands of meters of the Earth's crust. Large "mud pumps" circulate drilling mud (slurry) through the drill bit and up the casing annulus, for cooling and removing the "cuttings" while a well is drilled. Hoists in the rig can lift hundreds of tons of pipe. Other equipment can force acid or sand into reservoirs to facilitate extraction of the oil or natural gas; and in remote locations there can be permanent living accommodation and catering for crews (which may be more than a hundred). Marine rigs may operate many hundreds of miles or kilometres distant from the supply base with infrequent crew rotation.

From http://en.wikipedia.org/

Mountaintop removal mining

2009-08-28T07:38:00.000-07:00

Mountaintop removal mining (MTR), often referred to as mountaintop mining (MTM), is a form of surface mining that involves the mining of the summit or summit ridge of a mountain. It is most closely associated with coal mining in the Appalachian Mountains, located in the eastern United States, the most biologically diverse temperate hardwood forests in the world. The process involves blasting with explosives to remove up to 1,000 vertical feet (300 m) of mountain to expose underlying coal seams. Waste form mining in the form of excess rock and soil are often dumped into what are called a "holler fills" or "valley fills." After active mining has been completed all disturbed areas of the mining operation are required by Federal law contained in the Surface Mining Control and Reclamation Act of 1977 (SMCRA) to be reclaimed as one of several post-mining land use options.

History

Increased demand for coal in the United States, sparked by the 1973 and 1979 petroleum crises, created incentives for a more economical form of coal mining than the traditional underground mining methods involving hundreds of workers, triggering the first widespread use of MTR. Its prevalence expanded further in the 1990s to retrieve relatively low-sulfur coal, a cleaner-burning form, which became desirable as a result of amendments to the U.S. Clean Air Act that tightened emissions limits on high-sulfur coal processing. With an increasing call for energy independence in the U.S., as well as a growing call for Coal-To-Liquids and "clean coal technologies", MTR has continued to expand into the 2000s.

Occurrence

MTR in the United States is most often associated with the extraction of coal in the Appalachian Mountains, where the United States Environmental Protection Agency (EPA) estimates that 2,200 square miles (5,700 km2) of Appalachian forests will be cleared for MTR sites by the year 2012. It occurs most commonly in West Virginia and Eastern Kentucky, the top two coal producing states in Appalachia, with each state using approximately 1000 metric tons of explosives per day for the purposes of surface mining. At current rates, MTR in the U.S. will mine over 1.4 million acres (5,700 km²) by 2010, an amount of land area that exceeds that of the state of Delaware.

Process

Land is deforested prior to mining operations and the resultant lumber is either sold or burned. According to SMCRA, the topsoil is supposed to be removed and set aside for later reclamation. however, coal companies are often granted waivers and instead reclaim the mountain with "topsoil substitute." The waivers are granted if adequate amounts of topsoil are not naturally present on the rocky ridge top. Once the area is cleared, miners use explosives to blast away the overburden, the rock and subsoil, to expose coal seams beneath. The overburden is then moved by various mechanical means to areas of the ridge previously mined. These areas are the most economical area of storage as they are located close to the active pit of exposed coal. If the ridge topography is too steep to adequately handle the amount of spoil produced then additional storage is used in a nearby valley or hollow, creating what is known as a valley fill or “hollow fill.” A front-end loader or excavator then removes the coal, where it is transported to a processing plant. Once coal removal is completed, the mining operators back stack overburden from the next area to be mined into the now empty pit. After backstacking and grading of overburden has been completed topsoil (or a topsoil substitute) is layered over the overburden layer. Next grass seed is spread in a mixture of seed, fertilizer, and mulch made from recycled newspaper. Dependant on surface land owner wishes the land will then be further reclaimed by adding trees if the pre-approved post-mining land use is forest land or wildlife habitat. If the land owner has requested other post-mining land uses the land can reclaimed to be used as pasture land, economic development or other uses specified in SMCRA.

Because coal usually exists in multiple geologically stratified seams, miners can often repeat the blasting process to mine over a dozen seams on a single mountain, increasing the mine depth each time. This can result in a vertical descent of hundreds of extra feet into the earth. Many if not all of these seams mined in the MTR method are too thin to be mined using any other method of mining.

Economics

Just under half of the electricity generated in the United States is produced by coal-fired power plants. MTR accounted for less than 5% of U.S. coal production as of 2001. In some regions, however, the percentage is higher, for example MTR provided 30% of the coal mined in West Virginia in 2006.

Historically in the U.S. the prevalent method of coal acquisition was underground mining which is very labor-intensive. In MTR, through the use of explosives and large machinery, more than two and a half times as much coal can be extracted per worker per hour than in traditional underground mines, and thus greatly reducing the need for workers. The industry lost approximately 10,000 jobs from 1990 to 1997, as MTR and other more mechanized underground mining methods became more widely used. The coal industry asserts that surface mining techniques, such as mountaintop removal, are safer for miners than sending miners underground.

Proponents argue that in certain geologic areas, MTR and similar forms of surface mining allow the only access to thin seams of coal that traditional underground mining would not be able to mine. MTR is some times the most cost-effective method of extracting coal and provides high paying jobs. The counties that host MTR are often the poorest in Appalachia. For instance, in McDowell County, West Virginia, which produces the most coal in the state, over 37% of residents live below the poverty line. In Kentucky, counties with coal mining have economies no better than adjoining counties where no mining occurs.

Legislation in the United States

In the United States, MTR is allowed by section 515(c)(1) of SMCRA. Although most coal mining sites must be reclaimed to the land's pre-mining contour and use, regulatory agencies can issue waivers to allow MTR. In such cases, SMCRA dictates that reclamation must create "a level plateau or a gently rolling contour with no highwalls remaining."

Permits must be obtained to deposit valley fill into streams. On four occasions, federal courts have ruled that the US Army Corps of Engineers violated the Clean Water Act by issuing such permits. Massey Energy Company is currently appealing a 2007 ruling, but has been allowed to continue mining in the meantime because "most of the substantial harm has already occurred," according to the judge.

The Bush administration appealed one of these rulings in 2001 because the Act had not explicitly defined "fill material" that could legally be placed in a waterway. The EPA and Army Corps of Engineers changed a rule to include mining debris in the definition of fill material, and the ruling was overturned. However, if passed, the Clean Water Protection Act (H.R.1310), a bill in the House of Representatives, would revert this change by specifying that coal mining waste does not constitute fill material, in effect disallowing valley fills.

On December 2, 2008, the Bush Administration made a rule change to remove the Stream Buffer Zone protection provision from SMCRA allowing coal companies to place mining waste rock and dirt directly into headwater waterways.

A federal judge has also ruled that using settling ponds to remove mining waste from streams violates the Clean Water Act. He also declared that the Army Corps of Engineers has no authority to issue permits allowing discharge of pollutants into such in-stream settling ponds, which are often built just below valley fills.

On January 15, 2008, the environmental advocacy group Center for Biological Diversity petitioned the United States Fish and Wildlife Service to end a policy that waives detailed federal Endangered Species Act reviews for new mining permits. The current policy states that MTR can never damage endangered species or their habitat as long as mining operators comply with federal surface mining law, despite the complexities of species and ecosystems. Since 1996, this policy has exempted many strip mines from being subject to permit-specific reviews of impact on individual endangered species.

On May 25, 2008 North Carolina State Representative Pricey Harrison introduced a bill to ban the use of mountaintop removal coal from coal fired power plants within North Carolina. This proposed legislation would have been the only legislation of its kind in the United States, however the bill was defeated.

Criticism

Critics contend that MTR is a destructive and unsustainable practice that benefits a small number of corporations at the expense of local communities and the environment. Though the main issue has been over the physical alteration of the landscape, opponents to the practice have also criticized MTR for the damage done to the environment by massive transport trucks, and the environmental damage done by the burning of coal for power. Blasting at MTR sites can also expels fly-rock into the air, which can disturb or settle onto private property nearby.

Advocates of MTR claim that once the areas are reclaimed as mandated by law, the area provides flat land suitable for many uses in a region where flat land is at a premium. They also maintain that the new growth on reclaimed mountaintop mined areas is better suited to support populations of game animals. Many thin seams of coal can only be recovered by MTR mining as they are too small for man and machines to enter by underground mining methods. Critics are quick to show photographs of active mine sites but then rarely show the same area after mining and reclamation has been completed. They claim that because flat land is worth more than steep rocky mountain side, land value increases after completion of MTR for the local land owners. These mines employ many local residents and pay some of the highest wages in the region for equipment operators.

Some artists have been leaders in the fight against the process of mountaintop removal. Writers and musicians have been particularly active in Kentucky. In April 2005, respected writer and social critic Wendell Berry invited Kentucky writers on a tour of mountaintop removal sites that started a movement that continues to heat up. The attending writers have since contributed writing on the issue to national magazines and newspapers and even created a respected book called Missing Mountains, edited by Kristin Johnason, Bobbie Ann Mason, and Mary-Ann Taylor Hall. The book contains a foreword by Silas House and an afterword by Berry and is widely used in college courses.

2005 also saw the release of the album Songs For the Mountaintop, a collection of anti-MTR music. In 2007 the band Public Outcry (Silas House, Jason Howard, Jessie Lynne Keltner, Kate Larken, George Ella Lyon, and Anne Shelby) was formed to sing anti-MTR songs. They have performed at universities, festivals, and libraries throughout the region and in 2008 released their first, eponymous album.

Many personal interest stories of coalfield residents have been written; the first, Lost Mountain by Erik Reese,was released in 2005. In addition, Penny Loeb (Moving Mountains: How One Woman and Her Community Won Justice From Big Coal) and Michael Shnayerson (Coal River) have also contributed to the anti-mountaintop removal struggle with informative works. To date, Dr. Shirley Stewart Burns, a coalfield native, has written the only academic book on mountaintop removal, titled Bringing Down The Mountains (2007), which is loosely based on the 2005 Ph.D. dissertation of the same name. All of these books are critically acclaimed and their authors continue to make a collective effort to give voice to the people of the Appalachian coalfields.

In 2006, cultural historian, Jeff Biggers, published The United States of Appalachia, which chronicled the historical contributions of Appalachians and their impact on the nation, and examined the role of mountaintop removal in destroying Appalachia's history and cultural significance. Biggers continues to write extensively on the cultural and human costs of mountaintop removal, and the parallel connection between the devastation of the environment and the culture.

In 2006, Catherine Pancake released the first comprehensive feature-length documentary on mountaintop removal "Black Diamonds: Mountaintop Removal and the Search for Coalfield Justice." The film received critical acclaim and multiple awards including a selection in the Documentary Fortnight at Museum of Modern Art (MoMA.org.) The film features Julia Bonds who won the 2003 Goldman Prize.

In 2007 Ann Pancake released the novel Strange As This Weather Has Been, which has been hailed by critics and received several awards. The book is the first major fiction work about the subject of MTR and was highly critical of the mining practice.

In 2007, a feature documentary titled Mountain Top Removal was completed by Haw River Films. The film features Mountain Justice Summer activists, coal field residents, and coal industry officials. Included in the film are Former US President George W. Bush and West Virginia Governor Joe Manchin, among others. On April 18, 2008 the film received the Reel Current award selected and presented by Al Gore at the Nashville Film Festival.

In 2008, a second feature documentary titled Burning the Future: Coal in America was made by Director David Novack and produced by former Shooting Gallery executive, CJ Follini. The film examines the explosive conflict between the coal industry and residents of West Virginia. Confronted by emerging “clean coal” energy policies, local activists watch a world blind to the devastation caused by coal's extraction. The film was awarded The International Documentary Association's 2008 Pare Lorentz award for Best Documentary

Maria Gunnoe is a community organizer with the Ohio Valley Environmental Coalition who is concerned about the long-term effects of mountaintop removal coal mining. She is featured in the 2008 documentary film Burning the Future: Coal in America and the 2007 documentary film Mountain Top Removal. In 2006, Gunnoe received the Callaway Award for her organizing efforts in her southern West Virginia community.

Biodiversity

An EPA environmental impact statement finds that streams near valley fills from mountaintop removal contain high levels of minerals in the water and decreased aquatic biodiversity. The statement also estimates that 724 miles (1,165 km) of Appalachian streams were buried by valley fills between 1985 to 2001.

Although U.S. mountaintop removal sites by law must be reclaimed after mining is complete, reclamation has traditionally focused on stabilizing rock formations and controlling for erosion, and not on the reforestation of the affected area.Fast-growing, non-native grasses such as lespedeza sericea, planted to quickly provide vegetation on a site, compete with tree seedlings, and trees have difficulty establishing root systems in compacted backfill. Consequently, biodiversity suffers in a region of the United States with numerous endemic species. In addition, introduced species of elk on mountaintop removal sites in Kentucky are eating tree seedlings.

From http://en.wikipedia.org/

Mine reclamation

2009-08-28T07:37:00.001-07:00

Mine reclamation is the process of creating useful landscapes that meet a variety of goals, typically creating productive ecosystems (or sometimes industrial or municipal land) from mined land. It includes all aspects of this work, including material placement, stabilizing, capping, regrading, placing cover soils, revegetation, and maintenance.

In the USA, Mine reclamation is a regular part of modern mining practice.[1]

From http://en.wikipedia.org/

Longwall mining

2009-08-23T03:35:00.000-07:00

Longwall mining is a form of underground coal mining where a long wall (typically about 250-400 m long) of coal is mined in a single slice (typically 1-2 m thick). The longwall "panel" (the block of coal that is being mined) is typically 3-4 km long and 250-400 m wide.

History

The basic idea of longwall mining was developed in England in the late 17th century. Miners would undercut the coal along the width of the coal face, removing coal as it fell, and using wooden props to control the fall of the roof behind the face. this was known as the Shropshire method of mining. While the technology has changed considerably, the basic idea remains the same, to remove essentially all of the coal from a broad coal face and allow the roof and overlying rock to collapse into the void behind, while maintaining a safe working space along the face for the miners.

Starting around 1900, mechanization was applied to this method. By 1940, some referred to longwall mining as "the conveyor method" of mining, after the most prominent piece of machinery involved. Unlike earlier longwall mining, the use of a conveyor belt parallel to the coal face forced the face to be developed along a straight line. The only other machinery used were an electric cutter to undercut the coal face and electric drills for blasting to drop the face. Once dropped, manual labor was used to load coal onto the conveyor parallel to the face and to place wooden roof props to control the fall of the roof.

Such low-technology longwall mines continued in operation into the 1970's. The best known example of this was the New Gladstone Mine near Centerville, Iowa. This longwall mine did not even use a conveyor belt, but relied on ponies to haul coal tubs from the face to the slope where a hoist hauled the tubs to the surface.

Longwall mining has been extensively used as the final stage in mining old room and pillar mines. In this context, Longwall mining can be classified as a form of retreat mining.

Modern Methods

The gate road along one side of the block is called the maingate or headgate; the road on the other side is called the tailgate. Where the thickness of the coal allows, these gate roads have been previously developed by continuous miner units, as the longwall itself is not capable of the initial development. In thinner seams the advancing longwall mining method may be used. In this system the gate roads are formed as the coal face advances. Only the maingate road is formed in advance of the face. The tailgate road is formed behind the coal face by removing the stone above coal height to form a roadway that is high enough to travel in. The end of the block that includes the longwall equipment is called the face. The other end of the block is usually one of the main travel roads of the mine. The cavity behind the longwall is called the goaf, goff or gob.

Fresh air travels up the main gate, across the face, and then down the tail gate. Once past the face the air is no longer fresh air, but return air carrying away coal dust and mine gases such as methane, carbon dioxide, depending on the geology of the coal. Return air is extracted by ventilation fans mounted on the surface. A series of seals are erected as mining progresses to maintain goaf gas levels.

Typically to avoid coal in the goaf spontaneously combusting, goaf gases are allowed to build up so as to exclude oxygen from the goafed area. This means that there is an explosive goaf fringe between the face and the goaf at all times requiring constant monitoring.

The longwall equipment includes:

* A number of hydraulic jacks, called powered roof supports, chocks or shields, which are typically 1.75m wide and placed in a long line, side by side for up to 400 m in length in order to support the roof of the coalface. An individual chock can weigh 30-40 tonnes, extend to a maximum cutting height of up to 6 m and have yield rating of 1000-1250 tonnes each, and hydraulically advance itself 1m at a time.
* The coal is cut from the coalface by a machine called the shearer (power loader). This machine can weigh 75-120 tonnes typically and comprises a main body, housing the electrical functions, the tractive motive units to move the shearer along the coalface and pumping units (to power both hydraulic and water functions). At either end of the main body are fitted the ranging arms which can be ranged vertically up down by means of hydraulic rams, and onto which are mounted the shearer cutting drums which are fitted 40-60 cutting picks. Within the ranging arms are housed very powerful electric motors (typically up to 850 kW) which transfer their power through a series of lay gears within the body the arms to the drum mounting locations at the extreme ends of the ranging arms where the cutting drums are. The cutting drums are rotated at a speed of 20-50 revs/min to cut the mineral from coal seam.
* The shearer moves along the length of the face sat upon the AFC, driving through a chainless haulage system (which resembles a ruggedised rack and pinion system especially developed for mining),Previous to chainless haulage systems, a heavy duty chain was run the length of the coal face for the shearer to pull itself along the face. The shearer moves at a speed of 10-30m/min depending on cutting conditions. The AFC on which the shearer sits, is placed in front of the powered roof supports, and the shearing action of the rotating drums cutting into the coal seam, disintegrates the coal this being loaded onto the AFC. The coal is removed from the coal face by a scraper chain conveyor called the AFC to the main gate. Here it is loaded onto a conveyor belt and transported to the surface, usually via a network of conveyor belts.
* At the main gate the coal is usually reduced in size in a crusher, and loaded onto the first conveyor belt by the beam stage loader (BSL).

As the shearer removes the coal, the AFC is snaked over behind the shearer and the powered roof supports move forward into the newly created cavity. As mining progresses and the entire longwall progresses through the seam, the goaf increases. This goaf collapses under the weight of the overlying strata. The strata approximately 2.5 times the thickness of the coal seam removed collapses and the beds above settle onto the collapsed goaf. This collapsing can lower surface height considerably, causing serious problems like changing the course of rivers and severely damage building foundations.

The advantages of longwall mining include:

* better resource recovery (about 80% compared with about 60 percent for Room and pillar method)
* less roof support consumables needed
* higher volume coal clearance systems
* minimal manual handling
* subsidence is largely immediate, allowing for better planning and more accountability by the mining company.
* safety of the miners is enhanced by the fact that they are always under the hydraulic roof supports when they are extracting coal

The disadvantages of longwall mining include:

* surface subsidence, which may considerably alter the landscape above the mine which can damage natural or man-made structures or features.

From http://en.wikipedia.org/

Landfill mining

2009-08-23T03:32:00.000-07:00

Landfill mining and reclamation (LFMR) is a process whereby solid wastes which have previously been landfilled are excavated and processed. The function of landfill mining is to reduce the amount of landfill mass encapsulated within the closed landfill and/or temporarily remove hazardous material to allow protective measures to be taken before the landfill mass is replaced. In the process, mining recovers valuable recyclable materials, a combustible fraction, soil, and landfill space. The aeration of the landfill soil is a secondary benefit regrading the landfill's future use. The combustible fraction is useful for the generation of power. The overall appearance of the landfill mining procedure is a sequence of processing machines laid out in a functional conveyor system. The operating principle is to excavate, sieve and sort the landfill material.

The concept of landfill mining was introduced as early as 1953 at the Hiriya landfill operated by the Dan Region Authority next to the city of Tel Aviv, Israel. Waste contains many resources with high value, the most notable of which are non-ferrous metals such as aluminium cans and scrap metal. The concentration of aluminium in many landfills is higher than the concentration of aluminum in bauxite from which the metal is derived.

Practical applications

Landfill mining is also possible in countries where land is not available for new landfill sites. In this instance landfill space can be reclaimed by the extraction of biodegradable waste and other substances then refilled with wastes requiring disposal.

Mining construction landfill sites is the simplest form of landfill mining. Construction landfills contain three basic components, wood, scrap metal and gypsum, or drywall, along with a minimal amount of other construction materials. The wood collected can be used as fuel in coal burning power plants and the scrap metal reprocessed.

Mining of municipal landfills is more complicated and has to be based on the expected content of the landfill. Older landfills, in the United States before 1994, were often capped and closed, essentially entombing the waste. This can be beneficial for waste recovery. It can also create a higher risk for toxic waste and leachate exposure as the landfill has not fully processed the stewing wastes. Mining of bioreactor landfills and properly stabilized modern sanitary landfills provides its own benefits. The biodegradable wastes are more easily sieved out, leaving the non biodegradable materials readily accessible. The quality of these materials for recycling and reprocessing purposes is not as high as initially recycled materials, however materials such as aluminum and steel are usually excluded from this.

Landfill mining is most useful as a method to remediate hazardous landfills. Landfills that were established before landfill liner technology was well established often leak their unprocessed leachate into underlying aquifers. This is both an environmental hazard and also a legal liability. In the US, Environmental Protection Agency fines can tax the local economy up to 30 years after the site has closed. Mining the landfill simply to lay a safe liner is a last, but sometimes necessary resort.

Tools and machinery

The parts of the mining process are the different mining machines. Depending on the complexity of the process more or fewer machines can be used. Machinery is easily transported on trucks from site to site, mounted on trailers. The following machines are added in order in increase of mining complexity:

* Excavators
* Moving floor and elevator conveyor belts
* A coarse rotating trommel screen
* A fine rotating trommel screen
* A magnet
* Front end loader
* Odor control sprayer

The mechanics of mining

An excavator or front end loader uncovers the landfilled materials and places them on a moving floor conveyor belt to be taken to the sorting machinery. A trommel is used to separate materials by size. First, a large trommel separates materials like appliances and fabrics. A smaller trommel then allows the biodegraded soil fraction to pass through leaving non-biodegradable, recyclable materials on the screen to be collected.

An electromagnet is used to remove the ferrous material from the waste mass as it passes along the conveyor belt.

A front end loader is used to move sorted materials to trucks for further processing.

Odour control sprayers are wheeled tractors with a cab and movable spray arm mounted on a rotating platform. A large reservoir tank mounted behind the cab holds neutralising agents, usually in liquid form, to reduce the smell of exposed wastes.

Operational flow

Excavators dig up waste mass and transport it, with the help of front end loaders, onto elevator and moving floor conveyor belts. The conveyor belts empty into a coarse, rotating trommel. The large holes in the screen allow most wastes to pass through, leaving behind the over-sized, non-processable materials. The over-sized wastes are removed from inside the screen. The coarse trommel empties into the fine rotating trommel. The fine rotating trommel allows the soil fraction to pass through, leaving mid-sized, non-biodegradable, mostly recyclable materials. The materials are removed from the screen. These materials are put on a second conveyor belt where an electromagnet removes any metal debris. Depending on the level of resource recovery, material can be put through an air classifier which separates light organic material from heavy organic material. The separate streams are then loaded, by front end loaders, onto trucks either for further processing or for sale. Further manual processing can be done on site if processing facilities are too far away to justify the transportation costs.

From http://en.wikipedia.org/

In-situ leach

2009-08-14T17:42:00.000-07:00

In-situ leaching (ISL), also called in-situ recovery (ISR) or solution mining, is a process of recovering minerals such as copper and uranium through boreholes drilled into the deposit. The process initially involves drilling of holes into the ore deposit. Explosive or hydraulic fracturing may be used to create open pathways in the deposit for solution to penetrate. Leaching solution is pumped into the deposit where it makes contact with the ore. The solution bearing the dissolved ore content is then pumped to the surface and processed. This process allows the extraction of metals and salts from an ore body without the need for conventional mining involving drill-and-blast, open-cut or underground mining.

Process

In-situ leach mining involves pumping of a leachate solution into the ore body via a borehole, which circulates through the porous rock dissolving the ore and is extracted via a second borehole.

The leachate solution varies according to the ore deposit - for salt deposits the leachate can be fresh water into which salts can readily dissolve. For copper, acids are generally needed to enhance solubility of the ore minerals within the solution. For uranium ores, the leachate may be acid or sodium bicarbonate.

Soluble salts

In-situ leach is widely used to extract deposits of water-soluble salts such as sylvite (potash), halite (rock salt, sodium chloride), and sodium sulfate. It has been used in the US state of Colorado to extract nahcolite (sodium bicarbonate). In-situ leaching is often used when the deposits are too deep, or the beds too thin for conventional underground mining.

Uranium

Solutions used to dissolve uranium are either acid (sulfuric acid or less commonly nitric acid) or carbonate (sodium bicarbonate, ammonium carbonate, or dissolved carbon dioxide). Dissolved oxygen is sometimes added to the water to mobilize the uranium. ISL of uranium ores started in the United States and the Soviet Union in the early 1960s. The first uranium ISL in the US was in the Shirley Basin in the state of Wyoming, which operated from 1961-1970 using sulfuric acid. Since 1970, all commercial-scale ISL mines in the US have used carbonate solutions.

At the end of 2008 there were four in-situ leaching uranium mines operating in the United States, operated by Cameco, Mestena and Uranium Resources Company, all using sodium bicarbonate. ISL produces 90% of the uranium mined in the US. Two more ISL projects are in licensing and proposal stages in the US, and two in reclamation in 2006.

Significant ISL mines are operating in Kazakhstan and Australia. The Beverley uranium mine in Australia uses in-situ leaching. ISL mining produces around 21% of the world's uranium production.

Examples of in-situ uranium mines

* The Beverley Uranium Mine, South Australia, is an operating ISL uranium mine and Australia's first such mine.
* The Honeymoon Uranium Mine, South Australia, due 2008, will be Australia's second ISL uranium mine.
* Crow Butte (operating), Smith Ranch-Highland (operating), Christensen Ranch (reclamation), Irigaray (reclamation), Churchrock (proposed), Crownpoint (proposed), Alta Mesa (operating), Hobson (standby), La Palangana (development), Kingsville Dome (operating), Rosita (standby) and Vasquez (restoration) are ISL uranium operations in the United States. See Uranium mining in the United States

Copper

In-situ leaching of copper was done by the Chinese by 977 AD, and perhaps as early as 177 BC. Copper is usually leached using acid (sulfuric acid or hydrochloric acid), then recovered from solution by solvent extraction electrowinning (SX-EW) or by chemical precipitation.

Ores most amenable to leaching include the copper carbonates malachite and azurite, the oxide tenorite, and the silicate chrysocolla. Other copper minerals, such as the oxide cuprite and the sulfide chalcocite may require addition of oxidizing agents such as ferric sulfate and oxygen to the leachate before the minerals are dissolved. The ores with the highest sulfide contents, such as bornite and chalcopyrite will require more oxidants and will dissolve more slowly. Sometimes oxidation is speeded by the bacteria Thiobacillus ferrooxidans, which feeds on sulfide compounds.

Copper ISL is often done by stope leaching, in which broken low-grade ore is leached in a current or former conventional underground mine. The leaching may take place in backfilled stopes or caved areas. In 1994, stope leaching of copper was reported at 16 mines in the US. At the San Manuel mine in the US state of Arizona, ISL, underground mining, and open-pit mining were being done simultaneously in different parts of the same ore body.

Gold

In-situ leaching has not been used on a commercial scale for gold mining. A three-year pilot program was undertaken in the 1970s to in-situ leach gold ore at the Ajax mine in the Cripple Creek district in the US, using a chloride and iodide solution. After obtaining poor results, perhaps because of the complex telluride ore, the test was halted.

Controversies

In-situ leach techniques are often controversial, sometimes because of acid leachate solution.

The concerns of environmental groups and landholders centre around;

* Acidification of groundwaters
* Mobilisation of potentially hazardous heavy metals and, in the case of uranium, radioactive heavy metals.
* Disturbance of the groundwater table, mixing of groundwater aquifers and general disturbance of the land atop the ore body
* Destruction of habitat for stygofauna and other rock-inhabiting organisms, bacteria, et cetera.
* Potential spills of acidic and metal-bearing or salt-bearing leachates upon the surface

From http://en.wikipedia.org/

Hydraulic mining

2009-08-14T17:39:00.000-07:00

Hydraulic mining, or hydraulicking, is a form of mining that employs water to dislodge rock material or move sediment. Previously, the use of a large volume of water had been developed by the Romans to remove overburden and then gold-bearing debris as in Las Médulas of Spain, and Dolaucothi in Britain. The method was also used in Elizabethan Britain for developing lead, tin and copper mines, and became known as hushing.

The modern form of hydraulicking, using jets of water directed under very high pressure through hoses and nozzles at gold-bearing upland paleogravels, was first used by Edward Matteson near Nevada City, California in 1853. Matteson used canvas hose which was later replaced with crinoline hose by the 1860s. In California, hydraulic mining often brought water from higher locations for long distances to holding ponds several hundred feet above the area to be mined. Insofar as California hydraulic mining exploited primarily river gravels, it was one form of placer mining, that is, working of alluvium (river sediments).

Ancient development

Water was used on a large scale by Roman engineers in the first centuries BC and AD when the Roman empire was expanding rapidly in Europe. Using a process later known as hushing, the Romans stored a large volume of water in a reservoir immediately above the area to be mined; the water was then quickly released. The resulting wave of water removed overburden and exposed bedrock. Gold veins in the bedrock were then worked using a number of techniques, and water power was used again to remove debris. The remains at Las Medulas and in surrounding areas show badland scenery on a gigantic scale owing to hydraulicking of the rich alluvial gold deposits. Las Medulas is now a UNESCO World Heritage site. The site shows the remains of at least seven large aqueducts of up to 30 miles in length feeding large supplies of water into the site. The gold-mining operations were described in vivid terms by Pliny the Elder in his Naturalis Historia published in the first century AD. Pliny was a procurator in Hispania Terraconensis in the 70's and must have witnessed for himself the operations. The use of hushing has been confirmed by field survey and archaeology at Dolaucothi in South Wales, the only known Roman gold mine in Britain.

Modern process

Early placer miners in California discovered that the more gravel they could process, the more gold they were likely to find. Instead of working with pans, sluice boxes, long toms, and rockers, miners collaborated to find ways to process larger quantities of gravel more rapidly. Hydraulic mining became the largest-scale, and most devastating, form of placer mining. Water was redirected into an ever-narrowing channel, through a large canvas hose, and out a giant iron nozzle, called a "monitor." The extremely high pressure stream was used to wash entire hillsides through enormous sluices. By the early 1860s, while hydraulic mining was at its height, small-scale placer mining was a thing of the past. The vast majority of lone prospectors could not sustain themselves, and the mining industry was taken over by large companies, most of which found hard rock gold mining (or quartz mining) more profitable. By the mid-1880s, it is estimated that 11 million ounces of gold (worth approximately US$7.5 billion at mid-2006 prices) had been recovered by hydraulic mining in the California Gold Rush.

Environmental effects

While generating millions of dollars in tax revenues for the state and supporting a large population of miners in the mountains, hydraulic mining had a devastating effect on riparian environments and agricultural systems in California. Millions of tons of earth and water were delivered to mountain streams that fed rivers flowing into the Sacramento Valley. Once the rivers reached the relatively flat valley, the water slowed, the rivers widened, and the sediment was deposited in the floodplains and river beds causing them to rise, shift to new channels, and overflow their banks, causing major flooding, especially during the spring melt.

Cities and towns in the Sacramento Valley experienced an increasing number of devastating floods, while the rising riverbeds made navigation on the rivers increasingly difficult. Perhaps no other city experienced the boon and the bane of gold mining as much as Marysville. Situated at the confluence of the Yuba and Feather rivers, Marysville was the final "jumping off" point for miners heading to the northern foothills to seek their fortune. Steamboats from San Francisco, carrying miners and supplies, navigated up the Sacramento River, then the Feather River to Marysville where they would unload their passengers and cargo. Marysville eventually constructed a complex levee system to protect the city from floods and sediment. Hydraulic mining greatly excerbated the problem of flooding in Marysville and shoaled the waters of the Feather River so severely that few steamboats could navigate from Sacramento to the Marysville docks.

The spectacular eroded landscape left at the site of hydraulic mining can be viewed at Malakoff Diggins State Historic Park in Nevada County, California. A similar landscape can be seen at Las Médulas in northern Spain, where Roman engineers hydrauliced the rich gold alluvial deposits of the river Sil. Pliny the Elder mentions in his Naturalis Historia that Spain had encroached on the sea and local lakes as a result of hydraulic operations.

Legal ramifications

Vast areas of farmland in the Sacramento Valley were deeply buried by the mining sediment. Frequently devastated by flood waters, farmers demanded an end to hydraulic mining. In the most renowned legal fight of farmers against miners, the farmers sued the hydraulic mining operations and the landmark case of Edwards Woodruff v. North Bloomfield Mining and Gravel Company made its way to the United States District Court in San Francisco where Judge Lorenzo Sawyer decided in favor of the farmers in 1884, declaring that hydraulic mining was “a public and private nuisance” and enjoining its operation in areas tributary to navigable streams and rivers. Hydraulic mining was recommenced after 1893 when the United States Congress passed the Camminetti Act which allowed such mining if sediment detention structures were constructed. This led to a number of operations above brush dams and log crib dams. Most of the water-delivery infrastructure had been destroyed by an 1891 flood, so this later stage of mining was carried on at a much smaller scale in California.

Beyond California

Although often associated with California due to its adoption and widespread use there, the technology was exported widely, to Oregon (Jacksonville in 1856), Colorado (Clear Creek, Central City and Breckenridge in 1860), Montana (Bannack in 1865), Arizona (Lynx Creek in 1868), Idaho (Idaho City in 1863), South Dakota (Deadwood in 1876), Alaska, British Columbia (Canada), and overseas. It was used extensively in Dahlonega, Georgia and continues to be used in developing nations, often with devastating environmental consequences. The devastation caused by this method of mining caused one miner Edwin Carter Log Cabin Naturalist to switch from mining to collecting wildlife specimens from 1875-1900 in Breckenridge . His unique 12 foot high ceiling log cabin exists today and has been recently renovated.

Hydraulic mining was used extensively in the Central Otago Gold Rush that took place in the 1860s in the South Island of New Zealand, where it was known as sluicing. In addition to its use in true mining, hydraulic mining can be used as an excavation technique, principally to demolish hills. For example, the Denny Regrade in Seattle was largely accomplished by hydraulic mining. Hydraulic mining is the principal way that kaolinite clay is mined in Cornwall, in South-West England.

Popular Culture

The battle between the old method of pan mining and hydraulic mining is the central theme of the 1985 western film Pale Rider.

From http://en.wikipedia.org/

Heap leaching

2009-08-12T20:09:00.002-07:00

Heap leaching is an industrial mining process to extract precious metals and copper compounds from ore.

Process

The mined ore is crushed into small chunks and heaped on an impermeable plastic and/or clay lined leach pad where it can be irrigated with a leach solution to dissolve the valuable metals. Either sprinklers, or often drip irrigation, are used to minimize evaporation. The solution then percolates through the heap and leaches out the precious metal. This can take several weeks. The leach solution containing the dissolved metals is then collected.

Precious metals method

The crushed ore is irrigated with a dilute cyanide solution. The solution percolates through the heap and leaches out the precious metal. This can take several weeks.

The solution containing the precious metals ("pregnant solution") continues percolating through the crushed ore until it reaches the liner at the bottom of the heap where it drains into a storage (pregnant solution) pond. After separating the precious metals from the pregnant solution, the dilute cyanide solution (now called "barren solution") is normally re-used in the heap-leach-process or occasionally sent to an industrial water treatment facility where the residual cyanide is treated and residual metals are removed. The water is then discharged to the environment, posing possible water pollution.

During the extraction phase, the gold ions form complex ions with the cyanide:

Recuperation of the gold is readily achieved with a redox-reaction:

Copper method

The method is similar to the cyanide method, above, except sulfuric acid is used to dissolve copper from its ores. The acid is recycled from the solvent extraction circuit (see solvent extraction-electrowinning, SX/EW) and reused on the leach pad. A byproduct is iron(II) sulfate, jarosite, which is produced as a byproduct of leaching pyrite, and sometimes even the same sulfuric acid that is needed for the process.

Although the heap leaching is a low cost-process, it normally has recovery rates of 60-70%, although there are exceptions. It is normally most profitable with low-grade ores. Higher-grade ores are usually put through more complex milling processes where higher recoveries justify the extra cost. The process chosen depends on the properties of the ore.

Sulfuric acid heap leaching of nickel

The method is an acid heap leaching method like that of the copper method in that it utilises sulfuric acid instead of cyanide solution to dissolve the target minerals from crushed ore. The method has been developed by European Nickel PLC for the rock laterite deposits of Turkey and the Balkans.

From http://en.wikipedia.org/

Glory hole (petroleum production)

2009-08-12T20:09:00.001-07:00

A glory hole in the context of the offshore petroleum industry is an excavation into the sea floor designed to protect the wellhead equipment installed at the surface of a petroleum well from icebergs or pack ice. An economically attractive alternative for exploiting offshore petroleum resources is a floating platform; however, ice can pose a serious hazard to this solution. While floating platforms can be built to withstand ice loading up to a design threshold, for the largest icebergs or the thickest pack ice the only sensible alternative is to move out of the way. Floating platforms can be disconnected from the wellheads in order to allow them to be moved away from threatening ice, but the wellhead equipment is fixed in place and hence vulnerable.

The keel of an iceberg or pack ice can extend far below the surface of the water. If this keel extends deep enough to make contact with the sea floor, it will scour the sea floor as the ice moves with the current. To protect the wellhead equipment from possible scouring, a glory hole is excavated into the sea floor. This excavation must be deep enough to allow adequate clearance between the top of the wellhead equipment and the surrounding sea floor. The resulting glory hole can be either open or cased. A cased glory hole utilizes steel casing as a retaining wall while an open glory hole is simply an excavation.

Due to the cost of excavating individual glory holes, typically each glory hole will contain several wellheads. Locating multiple wellheads within a single glory hole is made possible by the use of directional drilling.

Etymology

The usage of the term glory hole in this context almost certainly is taken from its historical usage in the mining industry to refer to excavations.

From http://en.wikipedia.org/

Fire-setting

2009-08-10T23:12:00.000-07:00

Drift mining

2009-08-10T23:11:00.000-07:00

Drift mining is a method of accessing valuable geological material, such as coal, by cutting into the side of the earth, rather than tunneling straight downwards (see shaft mine). Drift mines have horizontal entries, called adits, into the mineral deposit from a hillside. Drift mines are distinct from slope mines, which have an inclined entrance from the surface to the mineral deposit. If possible, though, drifts are driven at just a slight incline so that removal of material can be assisted by gravity.

Nome Alaska
Drift mining methods were used extensively during the gold rush, around the turn of the last century, in Nome, Alaska. The technique, slightly different than that described above, was ingeniously adapted to the challenges faced in the region. Gold was abundant around the turn of the century in Nome. During the warm summer months gold could be easily recovered using gravity separation techniques; these techniques required water.

It didn't take long for miners to discover and recover all of the "easy" gold. During the winter time, when the sun disappears for months and everything including the ocean freezes, miners found themselves sitting around in bars doing nothing, or drinking and getting in trouble. Most of the ground in Nome, called permafrost, has been frozen solid for centuries. By "drift mining" miners were able to recover much of the gold buried under the permafrost, as described below.

Gold is not everywhere, over time nature causes it to be concentrated in specific places. In Nome these places included three ancient beach lines, now inshore, above sea level, and buried under roughly fifty feet of permafrost with two feet of tundra (a mossy layer of vegetation that acts like a blanket to keep the permafrost frozen during the summer) on top of it. The miners that drifted these buried deposits got rich beyond your wildest dreams!

The first step in mining is, of course, finding the gold. This is called prospecting. Drift miners, knowing roughly where to look, still had to find exactly where the gold was deep under the frozen ground. This was done by building a fire on top of the permafrost and, each day as it melted, shoveling away the mud. The process would be continued until reaching either a "pay streak" or bedrock. Not all prospecting shafts paid off. Even the luckiest miners prospected many a barren hole before striking it rich. When the gold was found the true "drift mining" began.

Gold, when it was finally found in these places, occurred on top of either bedrock or "false bedrock" (a layer of clay that the gold was not able to sink through). Drift miners, once they had found a "pay streak," would tunnel horizontally from the bottom of their prospecting shaft and follow the gold across the surface of the bedrock. This was a very efficient mining method. The fifty feet or more of frozen dirt above them did not need to be removed. The tunnels, because the ground was frozen, would not cave in. Miners would discover old underground beaches and rivers rich with gold and follow the gold until it was depleted. One drift miner, on "Little Creek" in Nome, having sunk five unproductive holes, almost out of money, and working on his sixth, struck what turned out to be the richest pay dirt ever found on the face of the planet; two hundred ounces of gold per pan (a small shovel full of dirt). Around the year 1900 the population of Nome was more than twenty thousand; it's a bit less than four thousand today. Many of those people were drift miners. Nome's gold fields, appearing untouched from the surface, are honeycombed with tunnels left by the gold rush drift miners. Today's miners, as they prospect for gold using modern drilling equipment, almost expect as they follow promising underground signs of gold to find, right when they think they're going to strike it rich, that a gold rush era drift miner has beat them to it! Their drill, grinding through the permafrost, suddenly hits an air pocket... a drift miner's tunnel.

Today's miners use heavy equipment to remove all of the dirt, or "overburden" from on top of the pay streak. With all of the "easy" gold long gone, this takes a lot of digging. A personal friend, after spending two years digging a huge pit with excavators, was dismayed to find a drift miner had been there first; there was other gold, but the drift miner had gotten the best of it. This form of drift mining proved to be an efficient and safe way for turn of the century miners to recover gold from deep beneath the frozen ground in Nome Alaska. It could be done during the winter. A hot fire, some shovels, and a few hearty souls were all that was needed. To their credit, for their hard work and persistence, many a drift miner left Nome with pockets full of gold.

From http://en.wikipedia.org/

Dredging

2009-08-08T05:56:00.001-07:00

Dredging is an excavation activity or operation usually carried out at least partly underwater, in shallow seas or fresh water areas with the purpose of gathering up bottom sediments and disposing of them at a different location.

This technique is often used to keep waterways navigable. It is also used as a way to replenish sand on some public beaches, where too much sand has been lost because of coastal erosion. Dredging is also used as a technique for fishing for certain species of edible clams and crabs, see fishing dredge.

A dredge is a device for scraping or sucking the seabed, used for dredging. A dredger is a ship or boat equipped with a dredge (though in American usage, there is no added letter).

The process of dredging creates spoils (excess material), which are conveyed to a location different from the dredged area. Dredging can produce materials for land reclamation or other purposes (usually construction-related), and has also historically played a significant role in gold mining. Dredging can create disturbance in aquatic ecosystems, often with adverse impacts.

Uses

* Capital: dredging carried out to create a new harbour, berth or waterway, or to deepen existing facilities in order to allow larger ships access. Because capital works usually involve hard material or high-volume works, the work is usually done using a cutter suction dredge or large trailing suction hopper dredge, but for rock works drilling and blasting along with mechanical excavation may be used.

* Preparatory: work and excavation for future bridges, piers or docks/wharves, often connected with foundation work.

* Maintenance: dredging to deepen or maintain navigable waterways or channels which are threatened to become silted with the passage of time, due to sedimented sand and mud, possibly making them too shallow for navigation. This is often carried out with a trailing suction hopper dredge. Most dredging is for this purpose, and it may also be done to maintain the holding capacity of reservoirs or lakes.

* Land reclamation: dredging to mine sand, clay or rock from the seabed and using it to construct new land elsewhere. This is typically performed by a cutter-suction dredge or trailing suction hopper dredge. The material may also be used for flood or erosion control.

* Beach nourishment: mining sand offshore and placing on a beach to replace sand eroded by storms or wave action. This is done to enhance the recreational and protective function of the beaches, which can be eroded by human activity or by storms. This is typically performed by a cutter-suction dredge or trailing suction hopper dredge.

* Harvesting materials: dredging sediment for elements like gold or other valuable trace substances.

* Seabed mining: a possible future use, recovering natural metal ore nodules from the sea's abyssal plains.

* Construction materials: dredging sand and gravels from offshore licensed areas for use in construction industry, principally for use in concrete. Very specialist industry focused in NW Europe using specialized trailing suction hopper dredgers self discharging dry cargo ashore.

* Anti-eutrophication: Dredging is an expensive option for the remediation of eutrophied (or de-oxygenated) water bodies. However, as artificially elevated phosphorus levels in the sediment aggravate the eutrophication process, controlled sediment removal is occasionally the only option for the reclamation of still waters.

* Contaminant remediation: to reclaim areas affected by chemical spills, storm water surges (with urban runoff), and other soil contaminations. Disposal becomes a proportionally large factor in these operations.

* Removing trash and debris: often done in combination with maintenance dredging, this process removes non-natural matter from the bottoms of rivers and canals and harbors.

Relevance

Without the many and almost non-stop dredging operations world wide, much of the world's commerce would be impaired, often within a few months, since much of world's goods travel by ship, and need to access harbours or seas via channels. Recreational boating also would be constrained to the smallest vessels. The majority of marine dredging operations (and the disposal of the dredged material) will require that appropriate licences are obtained from the relevant regulatory authorities, and dredging is usually carried out by (or for) harbour companies or corresponding government agencies.

Types of dredging vessels

Suction

For suction-type excavation out of water, see Suction excavator.

These operate by sucking through a long tube, like some vacuum cleaners but on a big scale.

A plain suction dredger has no tool at the end of the suction pipe to disturb the material. This is often the most commonly used form of dredging.

Trailing suction

A trailing suction hopper dredger (TSHD) trails its suction pipe when working, and loads the dredge spoil into one or more hoppers in the vessel. When the hoppers are full, the TSHD sails to a disposal area and either dumps the material through doors in the hull or pumps the material out of the hoppers. Some dredges also self-offload using drag buckets and conveyors. The largest trailing suction hopper dredger in the world is currently Jan de Nul's Cristobal Colon (launched July 4, 2008 ); its sister ship Leiv Eriksson is under construction as of the end of 2008 (keel laid August 27, 2008, expected launch July 2009). Main design specs for the Cristobal Colon and the Leiv Eriksson are: 46,000 cubic meter hopper and a design dredging depth of 155 m. Next largest is HAM 318 (Van Oord) with its 37,293 cubic meter hopper and a maximum dredging depth of 101 m.

Cutter suction

A cutter-suction dredger's (CSD) suction tube has a cutter head at the suction inlet, to loosen the earth and transport it to the suction mouth. The cutter can also be used for hard surface materials like gravel or rock. The dredged soil is usually sucked up by a wear-resistant centrifugal pump and discharged through a pipe line or to a barge. In recent years, dredgers with more powerful cutters have been built in order to excavate harder rock without blasting.

The, at this moment, two largest cutter suction dredgers in the world are Deme's D'Artagnan (28,200 kW total installed power) and Jan De Nul's J.F.J. DeNul (27,240 kW). Jan de Nul has by far the most heavy cutters in the market.

Auger suction

This process functions like a cutter suction dredger, but the cutting tool is a rotating Archimedean screw set at right angles to the suction pipe. The first widely used auger dredges were designed by Mud Cat Dredges in the 1980s.

Jet-lift

These use the Venturi effect of a concentrated high-speed stream of water to pull the nearby water, together with bed material, into a pipe.

Air-lift

An airlift is a type of small suction dredge. It is sometimes used like other dredges. At other times, an airlift is used, handheld underwater by a diver. It works by blowing air into the pipe, and that air, being lighter than water, rises inside the pipe, dragging water with it.

Bucket

A bucket dredger is equipped with a bucket dredge, which is a device that picks up sediment by mechanical means, often with many circulating buckets attached to a wheel or chain. Some bucket dredgers and grab dredgers are powerful enough to rip out coral to make a shipping channel through coral reefs.

Grab

A grab dredger picks up seabed material with a clam shell grab, which hangs from an onboard crane or a crane ship, or is carried by a hydraulic arm, or is mounted like on a dragline. This technique is often used in excavation of bay mud. Most of these dredges are crane barges with spuds.

Backhoe/dipper

A backhoe/dipper dredge has a backhoe like on some excavators. A crude but usable backhoe dredger can be made by mounting a land-type backhoe excavator on a pontoon. The three largest backhoe dredgers in the world are Vitruvius and Mimar Sinan (Jan De Nul) and Goliath (Van Oord). They featured barge-mounted excavators. Small backhoe dredgers can be track-mounted and work from the bank of ditches. A backhoe dredger is equipped with a half-open shell. The shell is filled moving towards the machine. Usually dredges material is loaded in barges. This machine is mainly used in harbors and other shallow water.

Water injection

A water injection dredger uses a small jet to inject water under low pressure (to prevent the sediment from exploding into the surrounding waters) into the seabed to bring the sediment in suspension, which then becomes a turbidity current, which flows away down slope, is moved by a second burst of water from the WID or is carried away in natural currents. Water injection results in a lot of sediment in the water which makes measurement with most hydrographic equipment (for instance: singlebeam echosounders) difficult.

Pneumatic

These dredgers use a chamber with inlets, out of which the water is pumped with the inlets closed. It is usually suspended from a crane on land or from a small pontoon or barge. Its effectiveness depends on depth pressure.

Bed leveler

This is a bar or blade which is pulled over the seabed behind any suitable ship or boat. It has an effect similar to that of a bulldozer on land.

Krabbelaar

This is an early type of dredger which was formerly used in shallow water in the Netherlands. It was a flat-bottomed boat with spikes sticking out of its bottom. As tide current pulled the boat, the spikes scraped seabed material loose, and the tide current washed the material away, hopefully to deeper water. Krabbelaar is Dutch for "scratcher".

Snagboat

A snagboat is designed to remove big debris such as dead trees and parts of trees from rivers and canals.

Amphibious

Some of these are any of the above types of dredger, which can operate normally, or by extending legs, also known as spuds, so it stands on the seabed with its hull out of the water. Some forms can go on land.

Some of these are land-type backhoe excavators whose wheels are on long hinged legs so it can drive into shallow water and keep its cab out of water. Some of these may not have a floatable hull and, if so, cannot work in deep water.

* Oliver Evans (1755-1819) in 1804 invented an amphibious dredger which was America's first steam-powered road vehicle.

Submersible

These are usually used to recover useful materials from the seabed. Many of them travel on caterpillar tracks. A unique variant is intended to walk on legs on the seabed.

Fishing

Fishing dredges are used to collect various species of clams scallops, oysters or crabs from the seabed. These dredges have the form of a scoop made of chain mesh, and are towed by a fishing boat. Careless dredging can be destructive to the seabed. Nowadays some scallop dredging is replaced by collecting via scuba diving.

Police drag

In some police departments a small dredge (sometimes called a drag) is used to find and recover objects and bodies from underwater. The bodies may be murder victims, or people who committed suicide by drowning, or victims of accidents. It is sometimes pulled by men walking on the bank.

Disposal of materials

In a "hopper dredger", the dredged materials end up in a large onboard hold called a "hopper." A suction hopper dredger is usually used for maintenance dredging. A hopper dredge usually has doors in its bottom to empty the dredged materials, but some dredges empty their hoppers by splitting the two halves of their hulls on giant hinges. Either way, as the vessel dredges, excess water in the dredged materials is spilled off as the heavier solids settle to the bottom of the hopper. This excess water is returned to the sea to reduce weight and increase the amount of solid material (or slurry) that can be carried in one load. When the hopper is filled with slurry, the dredger stops dredging and goes to a dump site and empties its hopper.

Some hopper dredges are designed so they can also be emptied from above using pumps if dump sites are unavailable or if the dredge material is contaminated. Sometimes the slurry of dredgings and water is pumped straight into pipes which deposit it on nearby land. Other times, it is pumped into barges (also called scows), which deposit it elsewhere while the dredge continues its work.

When contaminated (toxic) sediments are to be removed, or large volume inland disposal sites are unavailable, dredge slurries are reduced to dry solids via a process known as dewatering. Current dewatering techniques employ either centrifuges, large textile based filters or polymer flocculant/congealant based apparatus.

In many projects, slurry dewatering is performed in large inland settling pits, although this is becoming less and less common as mechanical dewatering techniques continue to improve.

Similarly, many groups (most notable in east Asia) are performing research towards utilizing dewatered sediments for the production of concretes and construction block, although the high organic content (in many cases) of this material is a hindrance toward such ends.

Environmental impacts

Dredging can create disturbance to aquatic ecosystems, often with adverse impacts. In addition, dredge spoils may contain toxic chemicals that may have an adverse effect on the disposal area; furthermore, the process of dredging often dislodges chemicals residing in benthic substrates and injects them into the water column.

The activity of dredging can create the following principal impacts to the environment:

* Release of toxic chemicals (including heavy metals and PCB) from bottom sediments into the water column.
* Short term increases in turbidity, which can affect aquatic species metabolism and interfere with spawning.
* Secondary effects from water column contamination of uptake of heavy metals, DDT and other persistent organic toxins, via food chain uptake and subsequent concentrations of these toxins in higher organisms including humans.
* Secondary impacts to marsh productivity from sedimentation
* Tertiary impacts to avifauna which may prey upon contaminated aquatic organisms
* Secondary impacts to aquatic and benthic organisms' metabolism and mortality
* Possible contamination of dredge spoils sites

Major dredging companies

* Inai Kiara Sdn Bhd (Malaysia)
* Weeks Marine (United States)
* Great Lakes Dredging (United States)
* Cashman Dredging and Marine Contracting (United States)
* Ellicott Dredges (United States)
* Royal Boskalis Westminster (Netherlands)
* Jan De Nul (Belgium)
* DEME (Belgium)
* Van Oord Dredging and Marine Contractors (Netherlands)
* IHC Merwede (Netherlands)
* IHC Systems BV (Netherlands)
* Burnham Associates, Inc.(Massachusetts)

Dredging in nature

Some animals have evolved adaptations to find their food by dredging:

* Ducks
* Grey whales: they filter seabed sand with their baleen

From http://en.wikipedia.org/

Dragline excavator

2009-08-08T05:53:00.000-07:00

Dragline excavation systems are heavy equipment used in civil engineering and surface mining. In civil engineering the smaller types are used for road and port construction. The larger types are used in strip-mining operations to move overburden above coal, and for tar-sand mining. Draglines are amongst the largest mobile equipment (not water-borne), and weigh in the vicinity of 2000 metric tonnes, though specimens weighing up to 13,000 metric tonnes have also been constructed.

A dragline bucket system consists of a large bucket which is suspended from a boom (a large truss-like structure) with wire ropes. The bucket is manoeuvred by means of a number of ropes and chains. The hoist rope, powered by large diesel or electric motors, supports the bucket and hoist-coupler assembly from the boom. The dragrope is used to draw the bucket assembly horizontally. By skillful manoeuvre of the hoist and the dragropes the bucket is controlled for various operations. A schematic of a large dragline bucket system is shown below.

History

The dragline was invented in 1904 by John W. Page of Page Schnable Contracting for use digging the Chicago Canal. In 1912 it became the Page Engineering Company, and a walking mechanism was developed a few years later, providing draglines with mobility. Page also invented the arched dragline bucket, a design still commonly used today by draglines from many other manufacturers, and in the 1960s pioneered an archless bucket design.

In 1910 Bucyrus International entered the dragline market with the purchase of manufacturing rights for the Heyworth-Newman dragline excavator. Their "Class 14" dragline was introduced in 1911 as the first crawler mounted dragline. In 1912 Bucyrus helped pioneer the use of electricity as a power source for large stripping shovels and draglines used in mining.

In 1914 Harnischfeger Corporation, (established as P&H Mining in 1884 by Alonzo Pawling and Henry Harnischfeger), introduced the world's first gasoline engine-powered dragline. An Italian company, Fiorentini, produced dragline excavators from 1919 licensed by Bucyrus.

In 1939 the Marion Steam Shovel Dredge Company (established in 1880) built its first walking dragline. The company changed its name to the Marion Power Shovel Company in 1946 and was acquired by Bucyrus in 1997. In 1988 Page was acquired by the Harnischfeger Corp., makers of the P&H line of shovels, draglines, and cranes.

Operation

In a typical cycle of excavation, the bucket is positioned above the material to be excavated. The bucket is then lowered and the dragrope is then drawn so that the bucket is dragged along the surface of the material. The bucket is then lifted by using the hoist rope. A swing operation is then performed to move the bucket to the place where the material is to be dumped. The dragrope is then released causing the bucket to tilt and empty. This is called a dump operation.

The bucket can also be 'thrown' by winding up to the jib and then releasing a clutch on the drag cable. This would then swing the bucket like a pendulum. Once the bucket had passed the vertical, the hoist cable would be released thus throwing the bucket. On smaller draglines, a skilled operator could make the bucket land about one-half the length of the jib further away than if it had just been dropped. On larger draglines, only a few extra metres may be reached.

Draglines have different cutting sequences. The first is the side cast method using offset benches; this involves throwing the overburden sideways onto blasted material to make a bench. The second is a key pass. This pass cuts a key at the toe of the new highwall and also shifts the bench further towards the low-wall. This may also require a chop pass if the wall is blocky. A chop pass involves the bucket being dropped down onto an angled highwall to scale the surface. The next sequence is the slowest operation, the blocks pass. However, this pass moves most of the material. It involves using the key to access to bottom of the material to lift it up to spoil or to an elevated bench level. The final cut if required is a pull back, pulling material back further to the low-wall side.

Draglines in mining

A large dragline system used in the open pit mining industry costs approximately US$50-100 million. A typical bucket has a volume ranging from 30 to 60 cubic metres, though extremely large buckets have ranged up to 168 cubic metres. The length of the boom ranges from 45 to 100 metres. In a single cycle it can move up to 450 metric tonnes of material.

Most mining draglines are not diesel-powered like most other mining equipment. Their power consumption is so great that they have a direct connection to the high-voltage grid at voltages of between 6.6 to 22 kV. A typical dragline, with a 55 cubic metre bucket, can use up to 6 megawatts during normal digging operations. Because of this, many (possibly apocryphal) stories have been told about the blackout-causing effects of mining draglines. For instance, there is a long-lived story that, back in the 1970s, if all seven of the Peak Downs (a very large coal mine in central Queensland, Australia) draglines turned simultaneously, they would black out all of North Queensland.

In all but the smallest of draglines, movement is accomplished by "walking" using feet or pontoons, as caterpillar tracks place too much pressure on the ground, and have great difficulty under the immense weight of the dragline. Maximum speed is only at most a few metres per minute since the feet must be repositioned for each step. If travelling medium distances, (about 30-100 km), a special dragline carrier can be brought in to transport the dragline. Above this distance, disassembly is generally required. But mining draglines due to their reach can work a large area from one position and do not need to constantly move along the face like smaller machines.

Limitations

The primary limitations of draglines are their boom height and boom length, which limits where the dragline can dump the waste material. Another primary limitation is their dig depth, which is limited by the length of rope the dragline can utilize. Inherent with their construction, a dragline is most efficient excavating material below the level of their base. While a dragline can dig above itself, it does so inefficiently and is not suitable to load piled up material (as a rope shovel can).

Despite their limitations, and their extremely high capital cost, draglines remain popular with many mines, due to their reliability, and extremely low waste removal cost.

Examples

The coal mining dragline known as Big Muskie, owned by the Central Ohio Coal Company (a division of American Electric Power), was the world's largest mobile earth-moving machine, weighing nearly 13,000 metric tons and standing nearly 22 stories tall. It operated in Guernsey County, in the U.S. state of Ohio from 1969 to 1991, and was powered by 13,800 volts of electricity. It was scrapped in 1999.

The British firm of Ransomes & Rapier produced a few large (1400-1800 ton) excavators, the largest in Europe at the time (1960s). Power was from internal combustion engines driving electric generators. One, named SUNDEW, was used in a quarry from 1957 to 1974. After its working life at the first site in Rutland was finished it walked 13 miles to a new life at Corby; the walk took 9 weeks.

Smaller draglines were also commonly used before hydraulic excavators came into common use, the smaller draglines are now rarely used other than on river and gravel pit works. The small machines were of a mechanical drive with clutches. Firms such as Ruston and Bucyrus made models such as the RB10 which were popular for small building works and drainage work. Several of these can still be seen in the English Fens of Cambridgeshire, Lincolnshire and parts of Norfolk. Ruston's are a company also associated with drainage pumping engines. Electric drive systems were only used on the larger mining machines, most modern machines use a diesel-hydraulic drive, as machines are seldom in one location long enough to justify the cost cost of installing a substation and supply cables.

Technological Advances

Draglines, unlike most equipment used in earth-moving, have remained relatively unchanged in design and control systems for almost 100 years. Over the last few years, some advances in dragline systems and methodologies have occurred.

Automation

Researchers at CSIRO in Australia have a long-term research project into automating draglines and have moved over 250,000 tonnes of overburden under computer control.

Simulation software

Since draglines are typically large, complicated and very expensive, training new operators can be a tricky process. In the same way that flight simulators have developed to train pilots, mining simulator software has been developed to assist new operators in learning how to control the machines.

UDD

UDD stands for Universal-Dig-Dump. It represents the first fundamental change to draglines for almost a century, since the invention of the 'miracle hitch'. Instead of using two ropes (the hoist rope and the drag rope) to manipulate the bucket, a UDD machine uses three ropes, two hoist and one drag. This allows the dragline operator to have much greater selectivity in when to pick up the bucket, and in how the bucket may be dumped. UDD machines generally have higher productivity than a standard dragline, but often have greater mechanical issues. Within the mining industry, there is still much debate as to whether UDD improvements justify their costs.

From http://en.wikipedia.org/

Bucket-wheel excavator

2009-08-06T03:41:00.000-07:00

Bucket-wheel excavators are heavy equipment used in surface mining and civil engineering. They are among the largest vehicles ever constructed, and the biggest bucket-wheel excavator ever built, the MAN Takraf RB293, is the largest terrestrial vehicle in human history.

Operation

The excavation component itself is a large rotating wheel mounted on an arm or boom. On the outer edge of the wheel is a series of scoops or buckets. As the wheel turns, the buckets remove soil or rock from the target area and carry it around to the backside of the wheel, where it falls onto a conveyor, which carries it up the arm toward the main body of the excavator. Additional conveyors then may carry it further; in some cases, several long conveyors are placed end-to-end, each supported by a large vehicular base, usually with caterpillar tracks.

Size

The largest bucket-wheel excavators in the world are used in German strip-mining operations. These tremendous earth-movers can cost over $100 million, take 5 years to assemble, require 5 people to operate, weigh more than 13,000 short tons (12,000 t), and have a daily capacity of 240,000 short tons (220,000 t) of brown coal or m³ overburden. One of them, Bagger 288, is working in stripmine Garzweiler (Tagebau Garzweiler), and five others in stripmine Hambach (among them Bagger 293). Bagger 288 (the oldest, assembly completed in 1978) is 240 metres (790 ft) long and 96 metres (310 ft) high. Until 2001 it worked in Hambach, and then drove as a giant caterpillar vehicle to Garzweiler, a distance of 22 kilometres (14 mi) through the fields, crossing a few roads, a railroad, and a river. Bagger 293 (formerly RB293, manufactured by Tenova Takraf), the heaviest among these 240,000ers, was recognised by the Guinness Book of Records (2001–2009) as the largest and heaviest land vehicle.

RB293 was the name given by former brown coal company Rheinbraun to their biggest excavator; Rheinbraun's successor RWE calls it simply Bagger 293; and manufacturer Tenova Takraf generally refers to it as an excavator of the type SRs 8000.

From http://en.wikipedia.org/

Beam engine

2009-08-06T03:39:00.000-07:00

A beam engine is a design of engine based on the principles of a first-class lever. A force is applied to one end of a beam, which is pivoted in the middle, and the lever action transfers the force to create work at the other end of the beam.

The most familiar example is the type of stationary steam engine used for pumping water from mines. Here the piston of a vertically-mounted cylinder is attached to one end of the beam, to apply the force through upward and/or downward motion. The other end of the beam is connected to a vertically-acting pump. A downward pull on the piston causes the other end of the beam to lift whatever is attached to it, thereby doing 'work'.

The most common engine was the stationary steam-driven type, but water, wind or other forms of propulsion could be used.

Beam engines need not be 'stationary'. The steamboat Eureka is still powered by its rotative beam engine.

History

The first beam engines were water-powered, and used to pump water from mines. A 'preserved' example may be seen at Wanlockhead, in Scotland.

Beam engines were extensively used to power pumps on the English canal system when it was expanded by means of locks early in the Industrial Revolution, and also to drain water from mines in the same period, and as winding engines.

The first steam-powered beam engine was developed by Thomas Newcomen. The Newcomen steam engine was adopted by many mines in Cornwall and elsewhere, but it was relatively inefficient and consumed a large quantity of fuel. James Watt resolved the main inefficiencies of the Newcomen engine in his Watt steam engine, and these beam engines were used commercially in much larger numbers.

Watt held patents on key aspects of his engine's design, and it was not until these patents expired that others could develop modifications to improve it. The beam engine was considerably improved and enlarged in the tin- and copper-rich areas of south west England, which enabled the draining of the deep mines that existed there. Consequently the Cornish beam engines became world famous, as they remain the most massive beam engines ever constructed.

Rotative beam engines

In a rotative beam engine, the piston is mounted vertically, and the piston rod does not connect directly to the connecting rod, but instead to a rocker or beam above both the piston and flywheel. The beam is pivoted in the middle, with the cylinder on one side and the flywheel, which incorporates the crank, on the other. The connecting rod connects to the opposite end of the beam to the piston rod, and then to the flywheel.

Early Watt engines used Watt's patent sun and planet gear, rather than a simple crank, as use of the latter was protected by a patent owned by someone else. Once the patent had expired, the simple crank was employed universally.

Compounding

Compounding involves two or more cylinders; waste low-pressure steam from the first, high-pressure, cylinder is passed to the second cylinder where it expands further and provides more drive. This is the compound effect; the waste steam from this can produce further work if it is then passed into a condenser in the normal way. The first experiment with compounding was conducted by Jonathan Hornblower, who took out a patent in 1781. His first engine was installed at Tincroft Mine, Cornwall. It had two cylinders – one 21-inch (0.53 m) diameter with 6-foot (1.8 m) stroke and one 27-inch (0.69 m) diameter with 8-foot (2.4 m) stroke – placed alongside each other at one end of the beam. The early engines showed little performance gain: the steam pressure was too low, interconnecting pipes were of small diameter and the condenser ineffective.

At this time the laws of thermodynamics were not adequately understood, particularly the concept of absolute zero. Engineers such as Arthur Woolf were trying to tackle an engineering problem with an imperfect understanding of the physics. In particular, their valve gear was cutting-in at the wrong position in the stroke, not allowing for expansive working in the cylinder. Successful Woolf compound engines were produced in 1814, for the Wheal Abraham copper mine and the Wheal Vor tin mine.Here, the cut-off problem had been solved but the engines were compromised by being single-acting: both cylinders driving the same shaft. This action was improved by Galloways of Manchester, whose horizontal side-by-side compound arrangement was patented in 1873.

McNaught engines

William McNaught of Glasgow, not to be confused with William McNaught of Rochdale (Petrie and McNaught), patented a compound beam engine in 1845. On a beam engine of the standard Boulton & Watt design he placed a high-pressure cylinder, on the opposite side of the beam to the existing single cylinder, where the water pump was normally fitted. This had two important effects: it massively reduced the pressure on the beam, and the connecting steam pipe, being long, acted as an expansive receiver – the element missing in the Woolf design. This modification could be made retrospectively, and engines so modified were said to be "McNaughted". The advantages of a compound engine were not significant at pressures under 60psi, but showed at over 100psi.

From http://en.wikipedia.org/

Air classifier

2009-08-04T09:06:00.000-07:00

An air classifier is an industrial machine which sorts materials by a combination of size, shape, and density. It works by injecting the material stream to be sorted into a chamber which contains a column of rising air. Inside the separation chamber, air drag on the objects supplies an upward force which counteracts the force of gravity and lifts the material to be sorted up into the air. Due to the dependence of air drag on object size and shape, the objects in the moving air column are sorted vertically and can be separated in this manner.

Air classifiers are commonly employed in industrial processes where a large volume of mixed materials with differing physical characteristics need to be sorted quickly and efficiently. One such example is in recycling centers, where various types of metal, paper, and plastics arrive mixed together and need to be sorted before further processing can take place.

From http://en.wikipedia.org/

Archimedes' screw

2009-08-04T09:03:00.000-07:00

Archimedes' screw, the Archimedes screw, the Archimedean screw or the screwpump is a machine historically used for transferring water from a low-lying body of water into irrigation ditches. It was one of several inventions and discoveries traditionally attributed to Archimedes in the 3rd century BC.

The Archimedes' Screw consists of a screw inside a hollow pipe. The screw is turned usually by a windmill or by manual labor. As the bottom end of the tube turns, it scoops up a volume of water. This amount of water will slide up in the spiral tube as the shaft is turned, until it finally pours out from the top of the tube and feeds the irrigation systems.

The contact surface between the screw and the pipe does not need to be perfectly water-tight because of the relatively large amount of water being scooped at each turn with respect to the angular frequency and angular speed of the screw. Also, water leaking from the top section of the screw leaks into the previous one and so on, so a sort of mechanical equilibrium is achieved while using the machine, thus preventing a decrease in mechanical efficiency.

The invention of the water-screw is credited to Archimedes of Syracuse in the 3rd century BC. Its tentative attribution to the 6th century BC Babylonian king Nebuchadnezzar II by the assyriologist Dalley has been refuted on the grounds of "the total lack of any literary and archaeological evidence for the existence of the water-screw before ca. 250 BC". A screw can be thought of as an inclined plane wrapped around a cylinder.

The "screw" does not necessarily need to turn inside the casing, but can be allowed to turn with it in one piece. In ancient times people ran on the screw to turn them. A screw could be sealed with Pitch resin or some other adhesive to its casing, or, cast as a single piece in bronze, as some researchers have postulated as being the devices used to irrigate Nebuchadnezzar II's Hanging Gardens of Babylon, one of the Seven Wonders of the Ancient World. Depictions of Greek and Roman water screws show the screws being powered by a human treading on the outer casing to turn the entire apparatus as one piece, which would require that the casing be rigidly attached to the screw.

The design of the everyday Greek and Roman water screw, in contrast to the heavy bronze device of Sennacherib, with its problematic drive chains, has a powerful simplicity. A double or triple helix was built of wood strips (or occasionally bronze sheeting) around a heavy wooden pole. A cylinder was built around the helices using long, narrow boards fastened to their periphery and waterproofed with pitch

Along with transferring water to irrigation ditches, this device was also used for "stealing" land from under sea level in the Netherlands and other places in the creation of polders. A part of the sea would be enclosed and the water would be pushed up out of the enclosed area, starting the process of draining the land for use in farming. Depending on the length and diameter of the screws, more than one machine could be used to successively lift the same water.

Archimedes screws are used in sewage treatment plants because they cope well with varying rates of flow and with suspended solids. An auger in a snow blower or grain elevator is essentially an Archimedes screw.

The principle is also found in pescalators, which are Archimedes screws designed to lift fish safely from ponds and transport them to another location. This technology is primarily used at fish hatcheries, where it is desirable to minimize the physical handling of fish.

Types

Screw conveyor

A screw conveyor is an Archimedean screw contained within a tube and turned by a motor so as to deliver material from one end of the conveyor to the other. It is particularly suitable for transport of granular materials such as plastic granules used in injection moulding, and cereal grains. It may also be used to transport liquids. In industrial control applications the conveyor may be used as a rotary feeder or variable rate feeder to deliver a measured rate or quantity of material into a process.

From http://en.wikipedia.org/

Uranium

2009-08-02T05:45:00.000-07:00

Uranium (pronounced /jʊˈreɪniəm/) is a silvery-white metallic chemical element in the actinide series of the periodic table that has the symbol U and atomic number 92. Besides its 92 protons, a uranium nucleus can have between 141 and 146 neutrons, with 146 (U-238) and 143 (U-235) in its most common isotopes. The number of electrons in a uranium atom is 92, 6 of them valence electrons. Uranium has the highest atomic weight of the naturally occurring elements. Uranium is approximately 70% denser than lead, but not as dense as gold or tungsten. It is weakly radioactive. It occurs naturally in low concentrations (a few parts per million) in soil, rock and water, and is commercially extracted from uranium-bearing minerals such as uraninite (see uranium mining).

In nature, uranium atoms exist as uranium-238 (99.284%), uranium-235 (0.711%),and a very small amount of uranium-234 (0.0058%). Uranium decays slowly by emitting an alpha particle. The half-life of uranium-238 is about 4.47 billion years and that of uranium-235 is 704 million years, making them useful in dating the age of the Earth (see uranium-thorium dating, uranium-lead dating and uranium-uranium dating).

Many contemporary uses of uranium exploit its unique nuclear properties. Uranium-235 has the distinction of being the only naturally occurring fissile isotope. Uranium-238 is both fissionable by fast neutrons, and fertile (capable of being transmuted to fissile plutonium-239 in a nuclear reactor). An artificial fissile isotope, uranium-233, can be produced from natural thorium and is also important in nuclear technology. While uranium-238 has a small probability to fission spontaneously or when bombarded with fast neutrons, the much higher probability of uranium-235 and to a lesser degree uranium-233 to fission when bombarded with slow neutrons generates the heat in nuclear reactors used as a source of power, and provides the fissile material for nuclear weapons. Both uses rely on the ability of uranium to produce a sustained nuclear chain reaction. Depleted uranium (uranium-238) is used in kinetic energy penetrators and armor plating.

Uranium is used as a colorant in uranium glass, producing orange-red to lemon yellow hues. It was also used for tinting and shading in early photography. The 1789 discovery of uranium in the mineral pitchblende is credited to Martin Heinrich Klaproth, who named the new element after the planet Uranus. Eugène-Melchior Péligot was the first person to isolate the metal, and its radioactive properties were uncovered in 1896 by Antoine Becquerel. Research by Enrico Fermi and others starting in 1934 led to its use as a fuel in the nuclear power industry and in Little Boy, the first nuclear weapon used in war. An ensuing arms race during the Cold War between the United States and the Soviet Union produced tens of thousands of nuclear weapons that used enriched uranium and uranium-derived plutonium. The security of those weapons and their fissile material following the breakup of the Soviet Union in 1991 is an ongoing concern for public health and safety.

From http://en.wikipedia.org/

Tin

2009-08-02T05:43:00.000-07:00

Tin is a chemical element with the symbol Sn (Latin: Stannum) and atomic number 50. It is a main group metal in group 14 of the periodic table. Tin shows chemical similarity to both neighboring group 14 elements, germanium and lead, like the two possible oxidation states +2 and +4. Tin is the 49th most abundant element and has, with 10 isotopes, the largest number of stable isotopes in the periodic table. Tin is obtained chiefly from the mineral cassiterite, where it occurs as tin dioxide, SnO2.

This silvery, malleable poor metal is not easily oxidized in air, and is used to coat other metals to prevent corrosion. The first alloy used in large scale since 3000 BC was bronze, an alloy of tin and copper. After 600 BC pure metallic tin was produced. Pewter, which is an alloy of 85 % to 90 % tin with the remainder commonly consisting of copper, antimony and lead, was used for flatware from the Bronze Age until the 20th century. In modern times tin is used in many alloys, most notably tin/lead soft solders, typically containing 60% or more of tin. Another large application for tin is corrosion-resistant tin plating of steel. Due to its low toxicity, tin-plated metal is also used for food packaging, giving the name to tin cans, which are made mostly out of aluminium or tin-plated steel.

Characteristics

Physical and allotropes

Tin is a malleable, ductile, and highly crystalline silvery-white metal. It is malleable at ordinary temperatures but is brittle when it is cooled, due to the properties of its two major allotropes, α- and β-tin. When a bar of tin is bent, a crackling sound known as the tin cry can be heard due to the twinning of the crystals. The two allotropes that are encountered at normal pressure and temperature, α-tin and β-tin, are more commonly known as gray tin, and respectively white tin. Two more allotropes, γ and σ, exist at temperatures above 161 °C and pressures above several GPa. White tin, or the β-form, is metallic, and is the stable one at room conditions or at higher temperatures. Below 13.2 °C, tin exists in the gray α-form, which has a diamond cubic crystal structure, similar to diamond, silicon or germanium. Gray tin has no metallic properties at all, is a dull-gray powdery material, and has few uses, other than a few specialized semiconductor applications.

Although the α-β transformation temperature is nominally 13.2 °C, impurities (e.g. Al, Zn, etc.) lower the transition temperature well below 0 °C, and upon addition of Sb or Bi the transformation may not occur at all. This conversion is known as tin disease or tin pest. Tin pest was a particular problem in northern Europe in the 18th century as organ pipes made of tin alloy would sometimes be affected during long cold winters. Some sources also say that during Napoleon's Russian campaign of 1812, the temperatures became so cold that the tin buttons on the soldiers' uniforms disintegrated, contributing to the defeat of the Grande Armée. The veracity of this story is debatable, because the transformation to gray tin often takes a reasonably long time.

Commercial grades of tin (99.8%) resist transformation because of the inhibiting effect of the small amounts of bismuth, antimony, lead, and silver present as impurities. Alloying elements such as copper, antimony, bismuth, cadmium, and silver increase its hardness. Tin tends rather easily to form hard, brittle intermetallic phases, which are often undesirable. It does not form wide solid solution ranges in other metals in general, and there are few elements that have appreciable solid solubility in tin. Simple eutectic systems, however, occur with bismuth, gallium, lead, thallium, and zinc.

Chemistry and compounds

Tin is classified as a semimetal, as its chemical properties fall between those of metals and non-metals, just as the semiconductors silicon and germanium do. It resists corrosion from distilled, sea and soft tap water, but can be attacked by strong acids, alkalis, and acid salts. Tin can be highly polished and is used as a protective coat for other metals in order to prevent corrosion or other chemical action. Tin acts as a catalyst when oxygen is in solution and helps accelerate chemical attack.

Tin forms the dioxide SnO2 (cassiterite) when it is heated in the presence of air. SnO2, in turn, is feebly acidic and forms stannate (SnO32−) salts with basic oxides. There are also stannates with the structure [Sn(OH)6]2−, like K2[Sn(OH)6], although the free stannic acid H2[Sn(OH)6] is unknown.

Tin combines directly with chlorine forming tin(IV) chloride, while reacting tin with hydrochloric acid in water gives tin(II) chloride and hydrogen. Several other compounds of tin exist in the +2 and +4 oxidation states, such as tin(II) sulfide and tin(IV) sulfide (Mosaic gold). There is only one stable hydride, however: stannane (SnH4), where tin is in the +4 oxidation state.

The most important salt is stannous chloride, which has found use as a reducing agent and as a mordant in the calico printing process. Electrically conductive coatings are produced when tin salts are sprayed onto glass. These coatings have been used in panel lighting and in the production of frost-free windshields.

Tin is added to some dental care products as stannous fluoride (SnF2). Stannous fluoride can be mixed with calcium abrasives while the more common sodium fluoride gradually becomes biologically inactive combined with calcium. It has also been shown to be more effective than sodium fluoride in controlling gingivitis.

Organotin compounds or stannanes are chemical compounds based on tin with hydrocarbon substituents. Organotin compounds usually have high toxicity and have been used as biocides, but their use is slowly being phased out. The first organotin compound was diethyltin diiodide (Sn(C2H5)2I2), discovered by Edward Frankland in 1849. Organotin compounds differ from their lighter analogues of germanium and silicon in that there is a greater occurrence of the +2 oxidation state due to the "inert pair effect"; it also has a greater range of coordination numbers, and the common presence of halide bridges between polynuclear compounds. Most organotin compounds are colorless liquids or solids that are usually stable to air and water. The tetraalkyl stannates (R4Sn) always have a tetrahedral geometry at the tin atom. The halide derivatives R3SnX often form chained structures with Sn-X-Sn bridges. Alkyltin compounds are usually prepared via Grignard reagent reactions such as in:

SnCl4 + 4 RMgBr → R4Sn + 4 MgBrCl.

Isotopes

Tin is the element with the greatest number of stable isotopes, ten; these include all those with atomic masses between 112 and 124, with the exception of 113, 121 and 123. Of these, the most abundant ones are 120Sn (at almost a third of all tin), 118Sn, and 116Sn, while the least abundant one is 115Sn. The isotopes possessing even atomic numbers have no nuclear spin while the odd ones have a spin of +1/2. Tin, with its three common isotopes 115Sn, 117Sn and 119Sn, is among the easiest elements to detect and analyze by NMR spectroscopy, and its chemical shifts are referenced against SnMe4.

This large number of stable isotopes is thought to be a direct result of tin possessing an atomic number of 50, which is a "magic number" in nuclear physics. There are 28 additional unstable isotopes that are known, encompassing all the remaining ones with atomic masses between 99 and 137. Aside from 126Sn, which has a half-life of 230,000 years, all the radioactive isotopes have a half-life of less than a year. The radioactive 100Sn is one of the few nuclides possessing a "doubly magic" nucleus and was discovered relatively recently, in 1994. Another 30 metastable isomers have been characterized for isotopes between 111 and 131, the most stable of which being 121mSn, with a half-life of 43.9 years.

Etymology

The Latin name Stannum is connected to "stagnum" and "stag" (Indo-European) for dripping because tin melts easily. The former "stagnum" was the word for a stale pool or puddle, with a cognate in the English word "stagnant." The English word "tin" has cognates in many Germanic and Celtic languages. The American Heritage Dictionary speculates that the word was borrowed from a pre-Indo-European language. The later name "stannum" and its Romance derivatives come from the lead-silver alloy of the same name for the finding of the silver in ores. The word definitely assumed its present meaning in the 4th century (H. Kopp).

According to Meyers Konversationslexikon Stannum is derived from Cornish stean (present orthography sten), and is proof that Cornwall in the first centuries AD was the main source of tin. Other sources, however, see the Cornish stean merely as a back-derivation from the Latin stannum. The Latin Stannum became the source for most European words. According to SMI the English word for the metal is named after an Etruscan god, Tinia. (variants include Old English: tin, Old Latin: plumbum candidum ("white lead"), Old German: tsin, Late Latin: stannum)

From http://en.wikipedia.org/

Sodium chloride

2009-07-31T18:31:00.000-07:00

Sodium chloride, also known as common salt, table salt, or halite, is an ionic compound with the formula NaCl. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms. As the major ingredient in edible salt, it is commonly used as a condiment and food preservative.

Production and use

Salt is currently mass-produced by evaporation of seawater or brine from other sources, such as brine wells and salt lakes, and by mining rock salt, called halite. In 2002, world production was estimated at 210 million metric tonnes, the top five producers (in million tonnes) being the United States (40.3), China (32.9), Germany (17.7), India (14.5) and Canada (12.3).

As well as the familiar uses of salt in cooking, salt is used in many applications, from manufacturing pulp and paper, to setting dyes in textiles and fabric, to producing soaps, detergents, and other bath products. It is the major source of industrial chlorine and sodium hydroxide, and used in almost every industry.

Sodium chloride is sometimes used as a cheap and safe desiccant because it appears to have hygroscopic properties, making salting an effective method of food preservation historically. Even though more effective desiccants are available, few are safe for humans to ingest.

From http://en.wikipedia.org/

Slate

2009-07-31T18:27:00.000-07:00

Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low grade regional metamorphism. The result is a foliated rock in which the foliation may not correspond to the original sedimentary layering. Slate is frequently grey in colour especially when seen en masse covering roofs. However, slate occurs in a variety of colours even from a single locality. For example slate from North Wales can be found in many shades of grey from pale to dark and may also be purple, green or cyan. Slate is not to be confused with shale, from which it may be formed, or schist.

Chemical composition

Slate is mainly composed of quartz and muscovite or illite, often along with biotite, chlorite, hematite, and pyrite and, less frequently, apatite, graphite, kaolin, magnetite, tourmaline, or zircon as well as feldspar. Occasionally, as in the purple slates of North Wales, ferrous reduction spheres form around iron nuclei, leaving a light green spotted texture. These spheres are sometimes deformed by a subsequent applied stress field to ovoids, which appear as ellipses when viewed on a cleavage plane of the specimen.

Uses

Slate in buildings

Slate can be made into roofing slates, also called roofing shingles, installed by a slater. Slate has two lines of breakability: cleavage and grain. This makes it possible to split slate into thin sheets. When broken, slate produces a natural appearance while remaining relatively flat and can be easily stacked. Silicone glue adheres to slate.

Slate tiles are often used for interior and exterior flooring, stairs, walkways, and wall cladding. Tiles are installed and set on mortar and grouted along the edges. Chemical sealants are often used on tiles to improve durability and appearance, increase stain resistance, reduce efflorescence, and increase or reduce surface smoothness. Tiles are often sold gauged, meaning that the back surface is ground for ease of installation. Slate flooring can however be slippery when used in external locations subject to rain. Slate tiles were used in 19th century UK building construction (apart from roofs) and in slate quarrying areas such as Bethesda there are still many buildings wholly constructed of slate. Slates can also be set into walls to provide a rudimentary damp-proof membrane. Small offcuts are used as shims to level floor joists. In areas where slate is plentiful it is also used in pieces of various sizes for building walls and hedges, sometimes combined with other kinds of stone.

Other uses

Because it is a good electrical insulator and fireproof, it was used to construct early 20th century electric switchboards and relay controls for large electric motors. Fine slate can also be used as a whetstone to hone knives.

Due to its thermal stability and chemical inertness, slate has been used for laboratory bench tops and for billiard table tops. In 18th and 19th century schools, slate was extensively used for blackboards and individual writing slates for which slate or chalk pencils were used. They were largely used in the 20th century, though writing slates were largely replaced by lined paper and notebooks, and slates still continue wide usage, though they are sometimes replaced with whiteboards.

Where slate of fine quality is available it is used for gravestones and commemorative tablets and by artists in various genres. British sculptor Stephen Kettle is notable for his use of slate to create statues housed in the Science Museum in London.

Slate is often used as a decor in freshwater aquariums. Slate will not alter the chemistry of water (except in the slate containing feldspar which may leach silicates into the water resulting in excess diatom growth in marine aquaria). Traditional Japanese Go equipment uses slate for the black pieces.

Slate extraction

In Eurasia

Slate-producing regions in Europe include Wales (see slate industry in Wales), Cornwall (famously the village of Delabole), and Cumbria (see Burlington Slate Quarries, Honister Slate Mine and Skiddaw Slate) in the United Kingdom; parts of France (Anjou, Ardennes, Bretagne, Savoie); Belgium (Ardenne); Liguria in northern Italy especially between the town of Lavagna (which means chalkboard in Italian) and Fontanabuona valley; Portugal especially around Valongo in the north of the country; Germany's (Moselle River-region, Hunsrück, Eifel, Westerwald, Thuringia and north-Bavaria); Alta, Norway (actually schist not a true slate) and Galicia. Some of the slate from Wales and Cumbria is colored slate (non-blue): (purple and formerly green in Wales) and (green in Cumbria). China has vast slate deposits; in recent years its export of finished and unfinished slate has increased: it has slate in various colors.

In the Americas

Slate is abundant in Brazil (the second biggest producer of slate) around Papagaio in Minas Gerais (responsible for 95% of the extraction of slate in Brazil), the east coast of Newfoundland, the Slate Belt of Eastern Pennsylvania, and the Slate Valley of Vermont and New York. The area around Granville, NY, is one place where colored slate (non-blue) is mined.

There was also a major slating operation in Monson, Maine during the late 19th and early 20th centuries. The slate found in Monson is usually a dark purple to blackish color, and many local structures are still roofed with slate tiles. The roof of St. Patrick's Cathedral was made of roofing slate from Monson, as was the headstone of John F. Kennedy.

Slate is also found in the Arctic and was used by the Inuit to make the blades for ulus.

From http://en.wikipedia.org/

Sand mining

2009-07-29T15:54:00.000-07:00

Sand mining is a practice that is becoming an ecological problem as the demand for sand increases in industry and construction. Sand is mined from beaches and inland dunes and dredged from ocean beds and river beds. It is often used in manufacturing as an abrasive, for example, and it is used to make concrete. As communities grow, construction requires less wood and more concrete, leading to a demand for low-cost sand. Sand is also used to replace eroded coastline.

A related process is the mining of mineral sands, such as mineral deposits, grain, wheat, diamond which contain industrial useful minerals, mainly gold and silver. These minerals typically occur combined with ordinary sand. The sand is dug up, the valuable minerals are separated in water by using their different density, and the remaining ordinary sand is re-deposited.

Sand mining is a direct and obvious cause of erosion, and also impacts the local wildlife. For example, sea turtles depend on sandy beaches for their nesting, and sand mining has led to the near extinction of ghariyals (a species of crocodiles) in India. Disturbance of underwater and coastal sand causes turbidity in the water, which is harmful for such organisms as corals that need sunlight. It also destroys fisheries, causing problems for people who rely on fishing for their livelihoods.

Removal of physical coastal barriers such as dunes leads to flooding of beachside communities, and the destruction of picturesque beaches causes tourism to dissipate. Sand mining is regulated by law in many places, but is still often done illegally.

Sand mining by country

Australia

New South Wales

In the 1930s mining operations began on the Kurnell Peninsula (Captain Cook's landing place in Australia) to supply the expanding Sydney building market. It continued until 1990 with an estimate of over 70 million tonnes of sand having been removed. The sand has been valued for many decades by the building industry, mainly because of its high crushed shell content and lack of organic matter, it has provided a cheap source of sand for most of Sydney since sand mining operations began. The site has now been reduced to a few remnant dunes and deep water-filled pits which are now being filled with demolition waste from Sydney's building sites. Removal of the sand has significantly weakened the peninsula's capacity to resist storms. Ocean waves pounding against the reduced Kurnell dune system have threatened to break through to Botany Bay, especially during the storms of May and June back in 1974 and of August 1998.

Queensland

A large and long running sandmine in Queensland, Australia (on North Stradbroke Island) provides a case study in the (disastrous) environmental consequences on a fragile sandy-soil based ecosystem, justified by the provision of low wage casual labor on an island with few other work options.[

Sand mining contributes to the construction of buildings and development. However, the negative effects of sand mining include the permanent loss of sand in areas, as well as major habitat destruction.

From http://en.wikipedia.org/

Oil shale

2009-07-29T15:51:00.000-07:00

Oil shale, an organic-rich fine-grained sedimentary rock, contains significant amounts of kerogen (a solid mixture of organic chemical compounds) from which technology can extract liquid hydrocarbons. The name oil shale represents a double misnomer, as geologists would not necessarily classify the rock as a shale, and its kerogen differs from crude oil. Kerogen requires more processing to use than crude oil, which increases its cost as a crude-oil substitute both financially and in terms of its environmental impact. Deposits of oil shale occur around the world, including major deposits in the United States of America. Estimates of global deposits range from 2.8 trillion to 3.3 trillion barrels (450 × 109 to 520 × 109 m3) of recoverable oil.

The chemical process of pyrolysis can convert the kerogen in oil shale into synthetic crude oil. Heating oil shale to a sufficiently high temperature will drive off a vapor which processing can distill (retort) to yield a petroleum-like shale oil—a form of unconventional oil—and combustible oil-shale gas (the term shale gas can also refer to gas occurring naturally in shales). Industry can also burn oil shale directly as a low-grade fuel for power generation and heating purposes and can use it as a raw material in chemical and construction-materials processing.

Oil shale has gained attention as an energy resource as the price of conventional sources of petroleum has risen and as a way for some areas to secure independence from external suppliers of energy. At the same time, oil-shale mining and processing involve a number of environmental issues, such as land use, waste disposal, water use, waste-water management, greenhouse-gas emissions and air pollution. Estonia and China have well-established oil shale industries, and Brazil, Germany, Israel and Russia also utilize oil shale.

Geology

Oil shale, an organic-rich sedimentary rock, belongs to the group of sapropel fuels. It does not have a definite geological definition nor a specific chemical formula, and its seams do not always have discrete boundaries. Oil shales vary considerably in their mineral content, chemical composition, age, type of kerogen, and depositional history. Oil shale differs from bitumen-impregnated rocks (oil sands and petroleum reservoir rocks), humic coals and carbonaceous shale. While oil sands originate from the biodegradation of oil, heat and pressure have not (yet) transformed the kerogen in oil shale into petroleum.

Oil shale contains a lower percentage of organic matter than coal. In commercial grades of oil shale the ratio of organic matter to mineral matter lies approximately between 0.75:5 and 1.5:5. At the same time, the organic matter in oil shale has an atomic ratio of hydrogen to carbon (H/C) approximately 1.2 to 1.8 times lower than for crude oil and about 1.5 to 3 times higher than for coals. The organic components of oil shale derive from a variety of organisms, such as the remains of algae, spores, pollen, plant cuticles and corky fragments of herbaceous and woody plants, and cellular debris from other aquatic and land plants. Some deposits contain significant fossils; Germany's Messel Pit has the status of a Unesco World Heritage Site. The mineral matter in oil shale includes various fine-grained silicates and carbonates.

Geologists can classify oil shales on the basis of their composition as carbonate-rich shales, siliceous shales, or cannel shales. Another classification, known as the van Krevelen diagram, assigns kerogen types, depending on the hydrogen, carbon, and oxygen content of oil shales' original organic matter. The most commonly used classification of oil shales, developed between 1987 and 1991 by Adrian C. Hutton of the University of Wollongong, adapts petrographic terms from coal terminology. This classification designates oil shales as terrestrial, lacustrine (lake-bottom-deposited), or marine (ocean bottom-deposited), based on the environment of the initial biomass deposit. Hutton's classification scheme has proven useful in estimating the yield and composition of the extracted oil.

From http://en.wikipedia.org/

Precious metal

2009-07-28T05:02:00.001-07:00

A precious metal is a rare metallic chemical element of high economic value, which is classically not radioactive (to exclude natural Polonium, Radium, Actinium and Protactinium). Chemically, the precious metals are less reactive than most elements, have high lustre, are softer or more ductile, and have higher melting points than other metals. Historically, precious metals were important as currency, but are now regarded mainly as investment and industrial commodities. Gold, silver, platinum, and palladium each have an ISO 4217 currency code.

The best-known precious metals are gold and silver. While both have industrial uses, they are better known for their uses in art, jewellery and coinage. Other precious metals include the platinum group metals: ruthenium, rhodium, palladium, osmium, iridium, and platinum, of which platinum is the most widely traded.

The demand for precious metals is driven not only by their practical use, but also by their role as investments and a store of value. Historically, precious metals have commanded much higher prices than common industrial metals. In January 2009, gold was about $840/troy ounce and silver was about $11/troy ounce, compared to copper at $1.50/pound and nickel at $5/pound.

In the early part of the 21st century, precious metal prices rose significantly and recycling precious metals became more and more attractive. Although some companies have been doing recycling for many years, such as Sabin Metal Corporation since 1945.

From http://en.wikipedia.org/

Phosphate

2009-07-28T05:00:00.000-07:00

A phosphate, an inorganic chemical, is a salt of phosphoric acid. Inorganic phosphates are mined to obtain phosphorus for use in agriculture and industry. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Organic phosphates are important in biochemistry.

Chemical properties

The phosphate ion is a polyatomic ion with the empirical formula PO43− and a molar mass of 94.973 g/mol. It consists of one central phosphorus atom surrounded by four identical oxygen atoms in a tetrahedral arrangement. The phosphate ion carries a negative three formal charge and is the conjugate base of the hydrogen phosphate ion, HPO42−, which is the conjugate base of H2PO4−, the dihydrogen phosphate ion, which in turn is the conjugate base of H3PO4, phosphoric acid. It is a hypervalent molecule (the phosphorus atom has 10 electrons in its valence shell). Phosphate is also an organophosphorus compound with the formula OP(OR)3. A phosphate salt forms when a positively-charged ion attaches to the negatively-charged oxygen atoms of the ion, forming an ionic compound. Many phosphates are not soluble in water at standard temperature and pressure. The sodium, potassium, rubidium, caesium and ammonium phosphates are all water soluble. Most other phosphates are only slightly soluble or are insoluble in water. As a rule, the hydrogenphosphates and the dihydrogenphosphates are slightly more soluble than the corresponding phosphates. The pyrophosphates are mostly water soluble.

In dilute aqueous solution, phosphate exists in four forms. In strongly-basic conditions, the phosphate ion (PO43−) predominates, whereas in weakly-basic conditions, the hydrogen phosphate ion (HPO42−) is prevalent. In weakly-acid conditions, the dihydrogen phosphate ion (H2PO4−) is most common. In strongly-acid conditions, aqueous phosphoric acid (H3PO4) is the main form.

From http://en.wikipedia.org/

Nickel

2009-07-25T09:44:00.000-07:00

Nickel (pronounced /ˈnɪkəl/) is a chemical element, with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. It is one of the four ferromagnetic elements at about room temperature. Its use has been traced as far back as 3500 BC, but it was first isolated and classified as a chemical element in 1751 by Axel Fredrik Cronstedt, who initially mistook its ore for a copper mineral. Its most important ore minerals are laterites, including limonite and garnierite, and pentlandite. Major production sites include Sudbury region in Canada, New Caledonia and Russia. The metal is corrosion-resistant, finding many uses in alloys, as a plating, in the manufacture of coins, magnets and common household utensils, as a catalyst for hydrogenation, and in a variety of other applications. Enzymes of certain life-forms contain nickel as an active center making the metal essential for them.

Characteristics

Nickel is a silvery-white metal with a slight golden tinge that takes a high polish. It is one of only four elements that are magnetic at or near room temperature. It belongs to the transition metals and is hard and ductile. It occurs most often in combination with sulfur and iron in pentlandite, with sulfur in millerite, with arsenic in the mineral nickeline, and with arsenic and sulfur in nickel galena. Nickel is commonly found in iron meteorites as the alloys kamacite and taenite. Similar to the elements chromium, aluminium and titanium, nickel is a very reactive element, but is slow to react in air at normal temperatures and pressures due to the formation of a protective oxide surface. Due to its permanence in air and its slow rate of oxidation, it is used in coins, for plating metals such as iron and brass, for chemical apparatus, and in certain alloys such as German silver.

Nickel is chiefly valuable for the alloys it forms, especially many superalloys, and particularly stainless steel. Nickel is also a naturally magnetostrictive material, meaning that in the presence of a magnetic field, the material undergoes a small change in length. In the case of nickel, this change in length is negative (contraction of the material), which is known as negative magnetostriction and is on the order of 50 ppm.

The most common oxidation state of nickel is +2 with several Ni complexes known. It is also thought that a +6 oxidation state may exist, however, this has not been demonstrated conclusively. The unit cell of nickel is a face centered cube with a lattice parameter of 0.352 nm giving a radius of the atom of 0.125 nm.

History

Because the ores of nickel are easily mistaken for ores of silver, understanding of this metal and its use dates to relatively recent times. However, the unintentional use of nickel is ancient, and can be traced back as far as 3500 BC. Bronzes from what is now Syria had contained up to 2% nickel. Further, there are Chinese manuscripts suggesting that "white copper" (cupronickel, known as baitung) was used there between 1700 and 1400 BC. This Paktong white copper was exported to Britain as early as the 17th century, but the nickel content of this alloy was not discovered until 1822.

In medieval Germany, a red mineral was found in the Erzgebirge (Ore Mountains) which resembled copper ore. However, when miners were unable to extract any copper from it they blamed a mischievous sprite of German mythology, Nickel (similar to Old Nick) for besetting the copper. They called this ore Kupfernickel from the German Kupfer for copper. This ore is now known to be nickeline or niccolite, a nickel arsenide. In 1751, Baron Axel Fredrik Cronstedt was attempting to extract copper from kupfernickel and obtained instead a white metal that he named after the spirit which had given its name to the mineral, nickel. In modern German, Kupfernickel or Kupfer-Nickel designates the alloy cupronickel.

In the United States, the term "nickel" or "nick" was originally applied to the copper-nickel Indian cent coin introduced in 1859. Later, the name designated the three-cent coin introduced in 1865, and the following year the five-cent shield nickel appropriated the designation, which has remained ever since. Coins of pure nickel were first used in 1881 in Switzerland.

After its discovery the only source for nickel was the rare Kupfernickel, but from 1824 on the nickel was obtained as byproduct of cobalt blue production. The first large scale producer of nickel was Norway, which exploited nickel rich pyrrhotite from 1848 on. The introduction of nickel in steel production in 1889 increased the demand for nickel and the nickel deposits of New Caledonia, which were discovered in 1865, provided most of the world's supply between 1875 and 1915. The discovery of the large deposits in the Sudbury Basin, Canada in 1883, in Norilsk-Talnakh , Russia in 1920 and in the Merensky Reef, South Africa in 1924 made large-scale production of nickel possible.

From http://en.wikipedia.org/

Molybdenum

2009-07-25T09:43:00.000-07:00

Molybdenum (pronounced /məˈlɪbdənəm/, from the Greek word for the metal "lead"), is a Group 6 chemical element with the symbol Mo and atomic number 42. The free element, which is a silvery metal, has the sixth-highest melting point of any element. It readily forms hard, stable carbides, and for this reason it is often used in high-strength steel alloys. Molybdenum does not occur as the free metal in nature, but rather in a variety of oxidation states in minerals. Industrially molybdenum compounds are used in high-pressure and temperature resistant greases between metals, as pigments, and catalysts.

Molybdenum minerals have long been known, but the element was "discovered" (in the sense of differentiating it as a new entity from minerals salts of other metals) in 1778 by Carl Wilhelm Scheele. The metal was first isolated in 1781 by Peter Jacob Hjelm.

Most of molybdenum's compounds have poor water-solubility, but the molybdate ion MoO2−4 is soluble, and will form if molybdenum-containing minerals are in contact with free oxygen and water. Recent theories suggest that the release of free oxygen by early life was important in removing molybdenum from minerals into a soluble form in the early oceans, where it was available to be used as a catalyst by single-celled organisms. This sequence may have been important in the history of life, because molybdenum-containing enzymes then became the most important catalysts used by some bacteria to break the bond in atmospheric molecular nitrogen, allowing biological nitrogen fixation. This, in turn allowed biologically driven nitrogen-fertilization of the oceans, and thus the development of more complex organisms. Aside from bacterial enzymes involved with nitrogen fixation, about 20 different molybdenum-containing enzymes are known today in animals. Molybdenum is a required element for life in these higher organisms, though not in all bacteria.

From http://en.wikipedia.org/

Marble

2009-07-19T02:35:00.000-07:00

Marble is a nonfoliated metamorphic rock resulting from the metamorphism of limestone, composed mostly of calcite (a crystalline form of calcium carbonate, CaCO3). It is extensively used for sculpture, as a building material, and in many other applications. The word "marble" is colloquially used to refer to many other stones that are capable of taking a high polish.

Etymology
Venus de Milo, front.

The word "marble" derives from the Ancient Greek μάρμαρον (mármaron) or μάρμαρος (mármaros), "crystalline rock", "shining stone", from the verb μαρμαίρω (marmaírō), "to flash, sparkle, gleam". This stem is also the basis for the English word marmoreal, meaning "marble-like."

Origins

Marble is a metamorphic rock resulting from regional or rarely contact metamorphism of sedimentary carbonate rocks, either limestone or dolomite rock, or metamorphism of older marble. This metamorphic process causes a complete recrystallization of the original rock into an interlocking mosaic of calcite, aragonite and/or dolomite crystals. The temperatures and pressures necessary to form marble usually destroy any fossils and sedimentary textures present in the original rock.

Pure white marble is the result of metamorphism of very pure limestones. The characteristic swirls and veins of many colored marble varieties are usually due to various mineral impurities such as clay, silt, sand, iron oxides, or chert which were originally present as grains or layers in the limestone. Green coloration is often due to serpentine resulting from originally high magnesium limestone or dolostone with silica impurities. These various impurities have been mobilized and recrystallized by the intense pressure and heat of the metamorphism.

Construction marble

n the construction, specifically the dimension stone trade, the term "marble" is used for any crystalline calcitic rock (and some non-calcitic rocks) useful as building stone. For example, "Tennessee marble" is really a dense granular fossiliferous gray to pink to maroon Ordovician limestone that geologists call the Holston Formation.

Industrial use

Colorless or light-colored marbles are a very pure source of calcium carbonate, which is used in a wide variety of industries. Finely ground marble or calcium carbonate powder is a component in paper, and in consumer products such as toothpaste, plastics, and paints. Ground calcium carbonate can be made from limestone, chalk, and marble; about three-quarters of the ground calcium carbonate worldwide is made from marble. Ground calcium carbonate is used as a coating pigment for paper because of its high brightness and as a paper filler because it strengthens the sheet and imparts high brightness. Ground calcium carbonate is used in consumer products such as a food additive, in toothpaste, and as an inert filler in pills. It is used in plastics because it imparts stiffness, impact strength, dimensional stability, and thermal conductivity. It is used in paints because it is a good filler and extender, has high brightness, and is weather resistant. However, the growth in demand for ground calcium carbonate in the last decade has mostly been for a coating pigment in paper.

Calcium carbonate can also be reduced under high heat to calcium oxide (also known as "lime"), which has many applications including being a primary component of many forms of cement.

Production

According to the United States Geological Survey, U.S. dimension marble production in 2006 was 46,400 tons valued at $18.1 million, compared to 72,300 tons valued at $18.9 million in 2005. Crushed marble production (for aggregate and industrial uses) in 2006 was 11.8 million tons valued at $116 million, of which 6.5 million tons was finely ground calcium carbonate and the rest was construction aggregate. For comparison, 2005 crushed marble production was 7.76 million tons valued at $58.7 million, of which 4.8 million tons was finely ground calcium carbonate and the rest was construction aggregate. U.S. dimension marble demand is about 1.3 million tons. The DSAN World Demand for (finished) Marble Index has shown a growth of 12% annually for the 2000-2006 period, compared to 10.5% annually for the 2000–2005 period. The largest dimension marble application is tile.

Artificial marble

Faux marble or faux marbling is a wall painting technique that imitates the color patterns of real marble (not to be confused with paper marbling). Marble dust can be combined with cement or synthetic resins to make reconstituted or cultured marble.

Cultural associations

As the favorite medium for Greek and Roman sculptors and architects (see classical sculpture), marble has become a cultural symbol of tradition and refined taste. Its extremely varied and colorful patterns make it a favorite decorative material, and it is often imitated in background patterns for computer displays, etc.

Places named after the stone include Marblehead, Ohio; Marble Arch, London; the Sea of Marmara; India's Marble Rocks; and the towns of Marble, Minnesota; Marble, Colorado; and Marble Hill, Manhattan, New York. The Elgin Marbles are marble sculptures from the Parthenon that are on display in the British Museum. They were brought to Britain by the Earl of Elgin.

From http://en.wikipedia.org/

Magnesite

2009-07-19T02:33:00.000-07:00

Magnesite is magnesium carbonate, MgCO3. Iron (as Fe2+) substitutes for magnesium (Mg) with a complete solution series with siderite, FeCO3. Calcium, manganese, cobalt, and nickel may also occur in small amounts. Dolomite, (Mg,Ca)CO3, is almost indistinguishable from magnesite.

Occurrence

Magnesite occurs as veins in and an alteration product of ultramafic rocks, serpentinite and other magnesium rich rock types in both contact and regional metamorphic terranes. These magnesites often are cryptocrystalline and contain silica as opal or chert.

Magnesite is also present within the regolith above ultramafic rocks as a secondary carbonate within soil and subsoil, where it is deposited as a consequence of dissolution of magnesium-bearing minerals by carbon dioxide within groundwaters.

Formation

Magnesite can be formed via talc carbonate metasomatism of peridotite and other ultrabasic rocks. Magnesite is formed via carbonation of olivine in the presence of water and carbon dioxide, and is favored at moderate temperatures and pressures typical of greenschist facies;

Magnesite can also be formed via the carbonation of magnesian serpentine (lizardite) via the following reaction:
Serpentine + carbon dioxide → Talc + magnesite + Water

2Mg3Si2O5(OH)4 + 3CO2 → Mg3Si4O10(OH)2 + 3MgCO3 + H2O

Forsterite magnesia-rich olivine compositions favor production of magnesite from peridotite. Fayalitic (iron-rich) olivine favors production of magnetite-magnesite-silica compositions.

Magnesite can also be formed from metasomatism in skarn deposits, in dolomitic limestones, associated with wollastonite, periclase, and talc.

Uses

Magnesite can be used as a slag former in steelmaking furnaces, in conjunction with lime, in order to protect the magnesium oxide lining. It can also be used as a catalyst and filler in the production of synthetic rubber and in the preparation of magnesium chemicals and fertilizers.

Similar to the production of lime, magnesite can be burned in the presence of charcoal to produce MgO, otherwise known as periclase. Such periclase is an important product in refractory materials.

Magnesite can also be used as a binder in flooring material.

In fire assay, Magnesite cupels can be used for cupellation as the Magnesite cupel will resist the high temperatures involved.

From http://en.wikipedia.org/