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Mining
Mining is the extraction of value (economics)|valuable minerals or other geology|geological materials from the earth, usually (but not always) from an ore body, vein (geology)|vein or (coal) seam. Materials recovered by mining include bauxite, coal, copper, gold, silver, diamonds, iron, precious metals, lead, limestone, magnesite, nickel, phosphate, oil shale, Sodium chloride|rock salt, tin, uranium and molybdenum. Any material that cannot be grown from agriculture|agricultural processes, or created Chemical synthesis|artificially in a laboratory or factory, is usually mined. Mining in a wider sense comprises extraction of any non-renewable resource (e.g., petroleum, natural gas, or even fossil water|water).
History
Since the beginning of civilization people have used Rock (geology)|stone, ceramics and, later, metals found on or close to the Earth|Earth's surface. These were used to manufacture early tools and weapons. For example, high quality flint found in northern France and southern England were used to set fire and break rock.[Hartman, Howard L. ''SME Mining Engineering Handbook'', Society for Mining, Metallurgy, and Exploration Inc, 1992, p3.] Flint mines have been found in chalk areas where seams of the stone were followed underground by shafts and galleries. The mines at Grimes Graves are especially famous, and like most other flint mines, are Neolithic in origin (ca 4000 BC-ca 3000 BC). Other hard rocks mined or collected for axes included the greenstone of the Langdale axe industry based in the English Lake District.
The oldest known mine on archaeological record is the "Lion Cave" in Swaziland. At this site, which by radiocarbon dating proves the mine to be about 43,000 years old, paleolithic humans mined mineral hematite, which contained iron and was ground to produce the red pigment ochre.[Swaziland Natural Trust Commission, "Cultural Resources - Malolotja Archaeology, Lion Cavern," Retrieved Aug. 27, 2007, http://www.sntc.org.sz/cultural/malarch.asp.][Peace Parks Foundation, "Major Features: Cultural Importance." Republic of South Africa: Author. Retrieved Aug. 27, 2007, http://www.peaceparks.org/story.php?mid=168&pid=148.] 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.[Shaw, I. (2000). ''The Oxford History of Ancient Egypt''. New York: Oxford University Press, pp. 57-59.] 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."[Shaw, I. (2000). ''The Oxford History of Ancient Egypt''. New York: Oxford University Press, p. 108.] Quarries for turqoise and copper were also found at "Wadi Hamamat, Tura, Aswan and various other Nubian sites"[Shaw, I. (2000). ''The Oxford History of Ancient Egypt''. New York: Oxford University Press, p. 168.] on the Sinai Peninsula and at Timna. Mining in Egypt occurred in the earliest dynasties, and the gold mines of Nubia were among the largest and most extensive of any in Ancient Egypt, and are described by the Greek author Diodorus Siculus. He mentions that fire-setting was one method used to break down the hard rock holding the gold. One of the complexes is shown in one of earliest known maps. They crushed the ore and ground it to a fine powder before washing the powder for the gold dust.
Europe
Mining in Europe has a very long pedigree, examples including the silver mines of Laurium, which helped support the Greek city state of Athens. However, it is the Ancient Rome|Romans who developed large scale mining methods, especially the use of large volumes of water brought to the minehead by numerous aqueducts. The water was used for a variety of purposes, and included using it to remove overburden and rock debris, as well as washing comminuted or crushed ores, and driving simple machinery. Spain was one of the most important mining regions, but all regions of the Roman Empire were exploited. They used reverse overshot water-wheels for dewatering their deep mines such as those at Rio Tinto.
The Celts, for example, who were native to Great Britain|Britain, had Mining in Roman Britain|mined minerals for centuries,[The Independent, 20 Jan. 2007: ''The end of a Celtic tradition: the last gold miner in Wales''] but when the Roman Empire|Romans came, the scale of the operations changed dramatically. The Romans needed what Britain possessed, especially gold, silver, tin and lead.
Mining in the Medieval period is best known through the work De Re Metallica (1556) of Georg Agricola, who described many different mining methods then used in German or Saxon mines. Use of water power in the form of water mills was extensive, and were employed in crushing ore, raising ore from shafts and ventilating galleries by giant bellows.
gun powder|Black powder was first used in mining in Banská Štiavnica, Kingdom of Hungary present-day Slovakia in 1627.[Heiss, A.G. & Oeggl, K. (2008). Analysis of the fuel wood used in Late Bronze Age and Early Iron Age copper mining sites of the Schwaz and Brixlegg area (Tyrol, Austria). ''Vegetation History and Archaeobotany'' 17(2):211-221, Springer Berlin / Heidelberg, http://dx.doi.org/10.1007/s00334-007-0096-8.] In 1762, the world's first mining academy was established in the same town.
Britain
Britain's gold mines were located in Wales at Dolgellau and Dolaucothi Gold Mines|Dolaucothi. Romans discovered the Dolaucothi vein (geology)|vein after the Roman conquest of Britain|invasion, in about 74 AD, and a settlement was soon set up in the Cothi Valley protected by a fort. They used hydraulic mining methods on a large scale to prospect for the veins of ore, especially a now redundant form of mining known as hushing. It involved building numerous aqueducts to supply water to the minehead where it was stored in large reservoirs and tanks. When a full tank was opened, the wave of water sluiced away the overburden to expose the bedrock underneath and any gold veins. The rock was attacked by fire-setting to heat the rock, which would then be quenched with a stream of water. The thermal shock cracked the rock, enabling it to be removed, aided by further streams of water from the overhead tanks. They used similar methods to work cassiterite deposits in Cornwall and lead ore in the Pennines. The methods had been developed by the Romans in Spain in 25 AD to exploit large alluvial gold deposits, the largest site being at Las Medulas, where seven long aqueducts were built to tap local rivers and to sluice the deposits.
They followed the ore veins underground once opencast mining was no longer feasible. At Dolaucothi they stoped out the veins, and drove adits through barren rock to drain the stopes. Alternatively, the veins may have been trenched, keeping the upper part open to the air. At deeper levels, stoping will have been necessary. The same adits were also used to ventilate the workings, especially important when fire-setting was used. At other parts of the site, they penetrated the water table and dewatered the mines using several kinds of machine, especially reverse overshot water-wheels. They were used extensively in the copper mines at Rio Tinto in Spain, where one sequence comprised 16 such wheels arranged in pairs, and lifting water about . They were worked as treadmills with miners standing on the top slats. Many examples of such devices have been found in old Roman mines and some examples are now preserved in the British Museum and the National Museum of Wales.
Lead and silver were widely exploited during the Roman period, in Wales, the Mendips and Pennines. A lead-silver mine at Charterhouse, Somerset for example, was guarded by a small fort and was next to the mine workings and settlement for the miners. Lead pigs have been found at several localities in Britain, and mining was so successful, that the Spanish complained about over-production depressing the market. The silver was valuable bullion, while the lead found numerous applications, especially in roofing and plumbing.
There were many iron mines in Roman Britain. The index to the Ordnance Survey Map of Roman Britain lists 33 iron mines: 67% of these are in the Weald and 15% in the Forest of Dean. The majority of mine workers were Slavery in antiquity|slaves. The work conditions were poor, and up to 12% of miners died every year.[''The Romans in Britain: mining'']
North America
In North America there are ancient, prehistoric copper mines along Lake Superior.[Lankton, L. (1991). ''Cradle to Grave: Life, Work, and Death at the Lake Superior Copper Mines''. New York: Oxford University Press, p. 5-6.][West, G.A. (1970). ''Copper: its mining and use by the aborigines of the Lake Superior region''. Westport, Conn: Greenwood Press.] "Indians availed themselves of this copper starting at least 5000 years ago,"[Lankton, L. (1991). ''Cradle to Grave: Life, Work, and Death at the Lake Superior Copper Mines''. New York: Oxford University Press, p. 5-6.] and copper tools, arrowheads, and other Cultural artifact|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.[West, G.A. (1970). ''Copper: its mining and use by the aborigines of the Lake Superior region''. Westport, Conn: Greenwood Press, pp. 119-120.] While the early French explorers that encountered the sites made no use of the metals due to the difficulties in transporting it,[West, G.A. (1970). ''Copper: its mining and use by the aborigines of the Lake Superior region''. Westport, Conn: Greenwood Press, p. 51.] the 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.[Bruno, L. & Heaman, L.M. (2004). Structural controls on hypozonal oroganic gold mineralization in the La Rouge Domain, Trans-Hudson Orogen, Saskatchewan. ''The Canadian Journal of Earth Sciences'', Vol. 41, Issue 12, pp. 1453-1471.]
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."[Vaden, H.E. & Prevost. G. (2002). ''Politics of Latin America: The Power Game''. New York: Oxford University Press, p. 34.] 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."[Maynard, S.R., Lisenbee, A.L. & Rogers, J. (2002). Preliminary Geologic Map of the Picture Rock 7.5 - Minute Quadrangle Sante Fe County, Central New Mexico. New Mexico Bureau of Geology and Mineral Resources, Open-File Report DM-49. ][The Cerrillos Hills Park Coalition, (2000). Cerrillos Hills Historic Park Vision Statement. Public documents: Author. Retrieved Aug. 27, 2007, http://www.cerrilloshills.org/Coalition/document.html.]
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 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.[Boorstin, D.J. (1965). ''The Americans: The National Experience''. New York: Vintage Books, pp. 78-81.] Aided by railroads, many traveled West for work opportunities in mining. Western cities such as Denver, Colorado|Denver and Sacramento, California|Sacramento originated as mining towns.
According to the NAICS classification system, there are ten industries that are classified as belonging to the Mining division. Over 2008, the three riskiest industries within the Mining division are expected to be: Oil and Gas Extraction, Coal Mining and Other Metal Ore Mining. These three industries combined account for around 2.3% of America's gross domestic product. [ September 2007, Case Study: The Riskiest Industry in the US, ''IBISWorld'']
Procedure
Steps of process
- Prospecting or Mineral exploration|Exploration to find and then define the extent and value of ore where it is located ("ore body")
- Conduct mineral resource classification|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
- Land rehabilitation|Reclamation to make land where a mine had been suitable for future use
Techniques
Mining techniques can be divided into two basic Earthworks (engineering)|excavation types:
References
Citations
Bibliography
- Ali, Saleem H. (2003). Mining, the Environment and Indigenous Development Conflicts. Tucson AZ: University of Arizona Press.
- Bhattacharya Jayanta (2003) ''Principles of Mine Planning'', Allied Publishers, New Delhi, India. 454 pages
- Morrison, Tom (1992) ''Hardrock Gold: A Miner's Tale'' (ISBN 0-8061-2442-3)
- Even-Zohar, Chaim (2007) ''From Mine to Mistress: Corporate Strategies and Government Policies in the International Diamond Industry ''(ISBN 0953733610)
- Geobacter Project: Gold mines may owe their origins to bacteria (in Portable Document Format|PDF format)
- Garrett, Dennis ''Alaska Placer Mining''
External links
- Mining 101
- Glossary of terms
- Introduction to Mining
- What is mining?
- Mining
Category:History of mining
Category:Mining|*
Category:Occupational safety and health
Category:National Institute for Occupational Safety and Health
simple:Mining
Related Images- Agricola, author of ''De Re Metallica''
- Drainage wheel from Rio Tinto mines
- The Dolaucothi Golden Wheel
Sources: StartLearningNow, Wikipedia | Usage license: GNU FDL
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