Background (Encyclopedia of Global Resources)
Strip mining is the process of removing the overlying earth material to reach an economically useful mineral below. This process is frequently called “surface mining.” In its most elementary form, strip mining has been used by humans since they first dug into the ground to extract mineral resources. In terms of having an effect on the Earth’s surface, strip mining has had a more profound impact since the development of large-scale machinery for earth-moving purposes. By the late 1800’s, steam power had been harnessed to large-scale machinery that could move large amounts of earth material with ease. With changes in technology came changes in energy sources for mining. Steam power gave way to internal combustion engines; electric power is also often used in mining operations.
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Overburden Removal (Encyclopedia of Global Resources)
In strip mining, the removal of the overburden is usually carried out using site-preparation equipment such as bulldozers followed by draglines with a bucket capacity of many cubic meters. Draglines can excavate below the surface on which they sit, allowing them to move along the ground exposing the mineralized layers below. As draglines also have long booms, the excavated material can be deposited a considerable distance from the active mining area. Once the overburden has been removed to expose the mineral beneath, the mineral can be broken up with drills and explosives. The valuable mineral is then removed using power shovels and front-end loaders to put the material into trucks or railcars for shipment.
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Transportation of Material (Encyclopedia of Global Resources)
Transportation at the mine site can take several forms. In most cases, large trucks are used to haul the mined mineral to a sorting and grading area. These first trucks are often too large and heavy for regular highway use, so after sorting and grading, the commodity may be shipped by smaller trucks or by rail to market. Conveyor belts may be used to transport commodities short distances. This is often done to move materials from truck to railcar or, if water transport is available, from truck to barge. Some strip-mined minerals have been moved by pipeline after being mixed with water.
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Coal Strip Mining (Encyclopedia of Global Resources)
Strip mining is used in the mining of a variety of minerals worldwide. In the United States, it is often associated with the mining of coal. In the eastern United States this procedure is widely used in the coal-producing states of Pennsylvania, West Virginia, Kentucky, Ohio, Indiana, Illinois, and Tennessee. West of the Mississippi, strip mining is used for coal extraction in Wyoming and Kansas. Other countries in which surface or strip-mining techniques are used for coal removal include Germany, Great Britain, Poland, Canada, Australia, and China.
In areas where the landscape is hilly or mountainous, contour strip mining is used. In this instance, the coal seam is located and the mine follows the seam along the outer edge, or contour, of the hill. Excavation extends into the hillside, with the removed materials cast behind the machinery on the downslope side. This procedure continues into the hill until the cost of removing the overburden meets or exceeds the value of the coal being removed. In some cases, once the mine has extended into the hillside as far as economically practical, the exposed coal seam is further removed through the use of augers. The auger machinery sits on the flat surface left by the removal of the coal. The auger itself then bores into the coal seam to remove coal not economically obtainable by strip mining alone. Without reclamation, this practice of contour strip mining leaves a ridge of...
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Environmental Problems (Encyclopedia of Global Resources)
Strip mining has the potential for causing serious environmental damage. Degradation of the land’s aesthetic qualities is a part of the mine operation. Existing landscapes are disrupted, regional water supplies may become polluted from mining debris and acid drainage, and air quality is diminished from dust and equipment exhaust gases. The local social fabric also may be disrupted through the changes in road patterns, disruption of existing land uses, and encroachment of the mining activities on settlements.
Because strip mining for coal began as early as World War I, large areas in the coal-bearing regions of the United States were disrupted, and environmental damage followed. In numerous cases strip-mined lands were inadequately reclaimed or simply abandoned. Different coal-mining states had different requirements for the reclamation of mined land, and technology made it possible for ever-larger areas to be strip-mined more rapidly. Concern over the scope and severity of the environmental effects led to public demand for national legislation to deal with the environmental consequences of strip mining. The Surface Mining Control and Reclamation Act of 1977 was passed by Congress specifically to give the federal government a role in dealing with the environmental problems brought on through surface mining for coal.
Prior to the passage of this act, the regulation of coal surface mining was a matter for...
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Non-Coal Strip Mining (Encyclopedia of Global Resources)
Strip mining is used to obtain a large number of non-coal mineral resources. These minerals make up two categories of mine operations: widely distributed and relatively small mining operations associated with construction materials such as sand and gravel, and large-scale, more localized metallic mineral mines. In both of these cases, the mineral of value is usually obtained after the removal of some overlying earth material. Sand and gravel operations are usually designed to meet local material needs for construction, road building, and other structural requirements. Mining in these cases may be on dry land, in which case the overburden is removed in ways similar to coal strip mining except that the machinery is usually smaller and the use of explosives not as common. Sand and gravel surface mining may also be done on floodplains using dredges.
Reclamation of this type of sand and gravel mining is not covered by any national law in the United States, and reclamation requirements that may be in place are the result of state or local government actions. Problems resulting from such mining are usually not as serious as those resulting from coal mining. Problems include surface disruption, displacement of existing land uses, water quality decline, and disruption of groundwater flows. Large-scale metallic mineral mines such as those for iron ore or copper are also often of the strip-mining or surface-mining variety. This...
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Further Reading (Encyclopedia of Global Resources)
Bell, Fred J., and Laurance J. Donnelly. “Quarrying and Surface Mining.” In Mining and Its Impact on the Environment. New York: Taylor & Francis, 2006.
Beynon, Huw, Andrew Cox, and Ray Hudson. Digging up Trouble: The Environment, Protest, and Opencast Mining. New York: Rivers Oram, 2000.
Burns, Shirley Stewart. Bringing down the Mountains: The Impact of Mountaintop Removal Surface Coal Mining on Southern West Virginia Communities, 1970-2004. Morgantown: West Virginia University Press, 2007.
Hartman, Howard L., and Jan M. Mutmansky. Introductory Mining Engineering. 2d ed. Hoboken, N.J.: J. Wiley, 2002.
Reece, Erik. Lost Mountain—A Year in the Vanishing Wilderness: Radical Strip Mining and the Devastation of Appalachia. Photographs by John J. Cox. New York: Riverhead Books, 2006.
Tatiya, Ratan Raj. “Open Cast Mining/Strip Mining.” In Surface and Underground Excavations: Methods, Techniques, and Equipment. London: A. A. Balkema, 2005.
U.S. Senate Committee on Energy and Natural Resources. Surface Mining Act: Hearing Before the Committee on Energy and Natural Resources, United States Senate, One Hundred Tenth Congress, First Session, to Receive Testimony on the Surface Mining Control and Reclamation Act of 1977—Policy Issues Thirty Years Later, November 13, 2007. Washington, D.C.: U.S. Government Printing Office,...
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