Area strip-mining of horizontal deposits relatively near the surface (Fig. 2.1D). Historically, moving materials out of xcritical surface mines was accomplished through manual labor, horse-drawn vehicles, and/or mining railways. The United Mine Workers of America have also voiced dissent on the use of human sewage sludge to reclaim surface mining sites in Appalachia. The group launched their campaign back in 1999 after eight workers took ill after exposure to Class B sludge near their workplace.
Contour mining entails making cuts on the slant/angle where the coal seam is traced, to take away the overburden first and then the coal itself. Overburden of adjacent cuts is used to fill earlier cuts, just as area-mining. In most forms of strip mining, heavyweight apparatus, like earthmovers, first eliminate the overburden. Then, huge machines, for instance dragline excavators or bucket wheel excavators, remove the mineral. Statistics show that strip mining accounts for about 40% of the world’s coal mining, while open pit mines make up 80% of total coal production. 1.Reclamation – Reclamation is the process of restoring the land after mining activities have ended.
Alternative Mining Methods – Alternative mining methods such as underground mining and in-situ mining can be used to reduce the impact of mining on the environment. These methods are often more expensive than strip mining but are less damaging to the environment. In strip mining, a thin layer of material known as an overburden is removed so that access is made to the minerals buried underneath. This kind of mining is particularly useful when the minerals are located very close to the surface as it’s more feasible and much easier and quicker to remove the overburden in order to get them. After loading, waste rock is transported to special dumps, while ore is generally hauled to a mineral-processing plant for further treatment.
Contour Mining
As the dragline or continuous excavator moves the overburden to the adjacent empty pit where the coal has been removed, the rock swells in volume. Earth or rock increases in volume, called the swell factor, when the material is removed from its in situ or in-ground state and placed into a pit or on the surface. The range diagram allows the mine planner to identify the equipment dump height required to keep the displaced overburden (spoil) from crowding the machinery and mining operations. In certain cases of mining multiple coal seams from one pit, a coal seam can provide the boundary between the prestrip and strip elevations.
Environmental Impacts
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- In large mines rotary drills are used to drill holes with diameters ranging from 150 to 450 mm (about 6 to 18 inches).
- It is safer than underground mining Given that strip mining just covers the surface, workers aren’t exposed to risks like the collapse of a tunnel – a risk that is inherent in underground mining.
- Open-pit mining is a type of strip mining that involves the excavation of a large, open pit in the ground.
Strip mining is only applicable when the ore body to be dug is somewhat close to the surface. This kind of mining requires some of the biggest machines on earth, including bucket-wheel excavators which can dig as much as 12,000 cubic meters of earth per hour. Open-pit mining gained traction through the 20th century, with surface mines today turning out majority of the coal mined in the United States. Contour mining, on the contrary, progresses in a narrower and custom shaped zone where the overburden is removed, following the contours of outcrops and hilly terrain rather than long strips. Trough-type subsidence resulting from mining low and medium thickness, horizontal or slightly inclined seams; appear like natural depressions.
Once inland waters are contaminated by mine water, their remediation can take long and may involve large financial burdens (ERMITE Consortium et al., 2004). In the past, strip-mined mineral deposits that became exhausted or uneconomical to mine often were simply abandoned. The result was a barren sawtooth, lunarlike landscape of spoil piles hostile to natural vegetation and generally unsuitable for any immediate land use. Such spoil areas are now routinely reclaimed and permanent vegetation reestablished as an integral part of surface-mining operations. The common strip-mining techniques are classified as area mining or contour mining on the basis of the deposit geometry and type.
Area strip mining can also lead to soil erosion, which can negatively impact nearby water sources and cause water pollution. One of the primary environmental impacts of open-pit mining is the destruction of natural habitats. The creation of the open pit can also alter the topography and drainage patterns of the area, leading to soil erosion and water pollution. Minerals are typically excavated by underground mining, strip mining, or open-pit mining. The selection of the mine design is dictated by the physical structure and value of the ore body and by the characteristics of the adjacent geological materials. Although open-pit mines and underground mines are the two most common mining strategies, placer mining and solution mining also have been used for mineral extraction.
The Strip Mining Method
Mine plan alternatives are evaluated to minimize the distance that spoil volumes are moved from the beginning centroid of mass to the ending centroid of mass. Spoil handling design goals for strip mining surface methods that utilize draglines and continuous excavators also include the minimization of spoil haulage distance. For the dragline, the average swing angle is identified by evaluating alternative mine plan layouts. Open-pit mining refers to a method of extracting rock or minerals from the earth through their removal from an open pit or borrow. This process is done on the ground surface of the earth 6 It is best suited for accessing mostly vertical deposits of minerals. Although open-pit mining is sometimes mistakenly referred to as “strip mining”, the two methods are different (see above).
When the operator gets to the last cut, the only spoil left to fill this cut is the overburden from the original or box cut. In America, strip mining is also used for mining phosphate fertilizer in areas such as Florida, North Carolina, Idaho, and for obtaining gypsum in western United States. Bowl or cirque-type subsidence caused by the working of medium or thick seams dipping up to 27°.
Solutions to Strip Mining:
The operating sequence for each pit includes drilling and blasting, followed by overburden casting, then coal removal. Draglines and continuous excavators move or displace the overburden from the active pit to the previous pit that has had the coal removed. ] contend that mountaintop removal is a disastrous practice that benefits a small number of corporations at the expense of local communities and the environment.
While strip mining provides substantial economic benefits, it is essential to balance these advantages with responsible environmental and social practices. Sustainable mining practices ensure that the economic benefits of strip mining can be enjoyed without compromising the health of the environment and local communities. On the flip side, with proper management, the mined land can be restored once the strip-mining activities are over. The tailings (including ground vegetation and soil) can be put back to cover up the site and resemble the landscape before the mining operation. The empty mining site can also be filled with water to create an artificial lake. Strip mining has a long history that dates back to the early 20th century.
Geographic Distribution of Strip Mining
Meanwhile, vast quantities of loose topsoil can be washed away by rain and enter streams and waterways, which could cause blockage and lead to flooding. Strip mining, also known as open-pit mining, surface mining, or strip-cut mining, is a method of extracting valuable minerals or other geological materials from the Earth’s surface. This mining technique involves the removal of layers of soil, rock, and vegetation to xcritical access buried resources.
Strip mining implicates the stripping away of soil and rocks to access the coal beneath. If a mountain is standing in the way of a coal seam within, it will be exploded or demolished – successfully leaving a damaged landscape and distressing ecosystems and wildlife habitat. Other types of mining methods include mountaintop removal, dredging and highwall mining (an adapted form of auger mining done from the surface). Mining operations that treat or leach ores and/or store acid chemicals for the extraction of metals can generate large volumes of acidic metal-containing wastewaters and/or leachates.
