Mining

Mining is the extraction of valuable minerals or other geological materials from the earth, usually (but not always) from an ore body, vein, or (coal) seam. Materials recovered by mining include bauxite, coal, copper, gold, silver, diamonds, iron, precious metals, lead, limestone, nickel, phosphate, oil shale, rock salt, tin, uranium, and molybdenum. Any material that cannot be grown from agricultural processes, or created artificially in a laboratory or factory, is usually mined. Mining in a wider sense can also include extraction of petroleum, natural gas, and even water.
History
The oldest known mine on archaeological record is the "Lion Cave" in Swaziland. At this site, which by radiocarbon dating the mine dates between 4,100 BC, paleolithic humans mined mineral hematite, which contained iron and was ground to produce the red pigment ochre. Mines of a similar age in Hungary and are believed to be sites where Neanderthals may have mined flint for weapons and tools.
Ancient Egyptians mined malachite at Maadi. At first, Egyptians used the bright green malachite stones for ornamentations and pottery. Later, between 2,613 and 2,494 BC, large building projects required expeditions abroad to the area of Wadi Maghara in order "to secure minerals and other resources not available in Egypt itself." Quarries for turqoise and copper were also found at "Wadi Hamamat, Tura, Aswan, and various other Nubian sites" [5] on the Sinai Peninsula and at Timna.
In North America there are ancient, prehistoric copper mines along Lake Superior that formed from volcanic activity 1280 million years ago. "Indians availed themselves of this copper starting at least 5000 years ago," and copper tools, arrowheads, and other artifacts that were part of an extensive native trade network have been discovered. In addition, obsidian, flint, and other minerals were mined, worked, and traded. Fraudulant artifacts often claim to be genuinely native. While the early French explorers that encountered the sites made no use of the metals due to the difficulties in transporting it, Procedurethe copper was eventually traded throughout the continent along major river routes. In Manitoba, Canada, there also are ancient quartz mines near Waddy Lake and surrounding regions.
In the early colonial history of the Americas, "native gold and silver was quickly expropriated and sent back to Spain in fleets of gold- and silver-laden galleons." Turquoise dated at 700 A.D. was mined in pre-Columbian America. In the Cerillos Mining District in New Mexico, estimates are that "about 15,000 tons of rock had been removed from Mt Chalchihuitl using stone tools before 1700." Duly noted, black gun powder in mining was first used in a mineshaft in Banská Štiavnica, Slovakia in 1627. In 1762, the world's first mining academy was established in the same town.
Mining in the United States became prevalent in the 19th century. As with the California Gold Rush in the mid 1800s, mining for minerals and precious metals alongside ranching and exploration for oil and gas fields was very important in the Westward Expansion to the Pacific coast. With the exploration of the West, mining camps were established and "expressed a distinctive spirit, an enduring legacy to the new nation;" Gold Rushers would experience the same problems as the Land Rushers of the transient West that preceded them. Aided by railroads, many traveled west for work opportunities in mining. Western cities such as Denver and Sacramento originated as mining towns.
Procedure
Steps of process
Prospecting or Exploration to find and then define the extent and value of ore where it is located ("ore body")
Conduct resource estimation to mathematically estimate the size and grade of the deposit
Conduct a pre-feasibility study to determine the theoretical economics of the ore deposit. This identifies, early on, whether further investment in estimation and engineering studies is warranted and identifies key risks and areas for further work.
Conduct a feasibility study to evaluate the financial viability, technical and financial risks and robustness of the project and make a decision as whether to develop or walk away from a proposed mine project. This includes mine planning to evaluate the economically recoverable portion of the deposit, the metallurgy and ore recoverability, marketability and payability of the ore concentrates, engineering, milling and infrastructure costs, finance and equity requirements and a cradle to grave analysis of the possible mine, from the initial excavation all the way through to reclamation.
Development to create access to an ore body and building of mine plant and equipment
The operation of the mine in an active sense
Reclamation to make land where a mine had been suitable for future use
Techniques
Mining techniques can be divided into two basic excavation types:
1. Surface mining
· Open-pit mining
· Quarrying
· Strip mining
· Placer mining
· Mountaintop removal
2. Sub-surface mining
· Drift mining
· Slope mining
· Shaft mining
· Hard rock mining
· Borehole mining
· Drift and Fill mining
· Long Hole Stope mining
· Sublevel Caving
· Block Caving
· Shrinkage Stope mining
· Room and pillar
· Longwall mining
· Retreat mining
In-situ leach is a particular mining technique that is used to mine minerals (potash, potassium chloride, sodium chloride, sodium sulphate and uranium oxide) which dissolve in water.

Extractive metallurgy
The science of extractive metallurgy is a specialized area in the science of metallurgy that studies the extraction of valuable metals and minerals from their ores, especially through chemical or mechanical means. Mineral processing (or mineral dressing) is a specialized area in the science of metallurgy that studies the mechanical means of crushing, grinding, and washing that enable the separation (extractive metallurgy) of valuable metals or minerals from their gangue (waste material).
Environmental effects
Environmental issues can include erosion, formation of sinkholes, loss of biodiversity, and contamination of groundwaters and surface water by chemicals from the mining process and products.
Modern mining companies in some countries are required to follow environmental and rehabilitation codes, ensuring the area mined is returned to close to its original state. In some countries with pristine environments, such as large parts of Australia, this is impossible despite the best intentions. Some mining methods have devastating environmental and public health effects.
Mining can have adverse effects on surrounding surface and ground water if protection measures are not exercised. The result can be unnaturally high concentrations of some chemical elements, notably arsenic and sulfuric acid, over a significantly large area of surface or subsurface. Coal mining releases approximately twenty toxic chemicals, of which 85% is said to be managed on site. Combined with the effects of water and the new 'channels' created for water to travel through, collect in, and contact with these chemicals, a situation is created in which massive contamination can occur. In well-regulated mines, hydrologists and geologists take careful measures to mitigate any type of water contamination that could be caused by mines. In modern American mining, operations must, under federal and state law, meet standards for protecting surface and ground waters from contamination, including acid mine drainage (AMD). To mitigate these problems water is continuously monitored at coal mines. The five principal technologies used to control water flow at mine sites are: diversion systems, containment ponds, groundwater pumping systems, subsurface drainage systems, and subsurface barriers. In the case of AMD, contaminated water is generally pumped to a treatment facility that neutralizes the contaminants.
Some examples of environmental problems associated with mining operations are:
Ashio Copper Mine, Ashio, Japan was the site of substantial pollution at end of the nineteenth century
Acid mine drainage, exemplified by the cases of the Berkeley Lake Mine, and the Wheal Jane Mine
Dissolution and transport of dissolved metals and heavy metals by run-off and ground waters, an example being the Britannia Mine, a former copper mine near Vancouver, British Columbia. Tar Creek, an abandoned mining area in Picher, Oklahoma that is now an Environmental Protection Agency superfund site. Water in the mine has leaked through into local groundwater, contaminating it with metals such as lead and cadmium.[17]
Long-term storage of tailings and dust, which can be easily blown off site by wind, an example being Scouriotissa, an abandoned copper mine in Cyprus.
Erosion of exposed hillsides, mine dumps, tailings dams and resultant siltation of drainages, creeks and rivers, the prime example being the giant Ok Tedi Mine in Papua New Guinea.
In areas of wilderness mining may cause habitat destruction and destruction or disturbance of ecosystems, and in areas of farming it may disturb or destroy productive grazing and cropping lands. In urbanised environments mining may produce noise pollution, dust pollution and visual pollution.
Although such issues have been associated with some mining operations in the past, modern mining practices have improved significantly and are subject to close environmental scrutiny. Modern mining practises aim to lessen environmental impacts from mining, and the ultimate aim is to return the local environment to as close to pristine as is possible. In many cases, the most significant environmental impact longer-term is visual, with pits and mine dumps prominent landscape features.
To ensure completion of reclamation (restoring mine land) most governments and regulatory authorities around the world require that mining companies post a bond to be held in escrow until productivity of reclaimed land has been convincingly demonstrated. Since 1978 the mining industry has reclaimed more than 2 million acres (8,000 km²) of land in the United States alone. This reclaimed land has renewed vegetation and wildlife in previous mining lands and can even be used for farming and ranching.
For further reading on reclamation of former mining sites, see Restoration ecology.