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More modern room and pillar mines use a more "continuous" method, that uses machinery to simultaneously grind off rock and move it to the surface. [12] Other processes, such as backfill, where discarded tailings are unloaded into mined-out areas, [9] can be used, but are not required. Retreat mining (below) is an example of a process like this.
Longwall mining is a form of underground coal mining where a long wall of coal is mined in a single slice (typically 0.6–6.0 m (2 ft 0 in – 19 ft 8 in) thick). The section of rock that is being mined, known as the longwall panel, is typically 3–4 km (1.9–2.5 mi) long, but can be up to 7.5 km (4.7 mi) long and 250–400 m (820–1,310 ft) wide.
During servicing, the "continuous" miner moves to another face. Some continuous miners can bolt and rock dust the face, two major components of servicing, while cutting coal, while a trained crew may be able to advance ventilation, to truly earn the "continuous" label. However, very few mines are able to achieve it. Most continuous mining ...
Shortwall mining – A coal mining method that accounts for less than 1% of deep coal production, shortwall involves the use of a continuous mining machine with moveable roof supports, similar to longwall. The continuous miner shears coal panels 150–200 feet wide and more than a half-mile long, depending on other things like the strata of the ...
The continuous-line bucket system (CLB) is an older approach. It operates like a conveyor-belt, running from the bottom to the surface where a ship or mining platform extracts the minerals, and returns the tailings to the ocean. [75] Hydraulic suction mining instead lowers a pipe to the seafloor and pumps nodules up to the ship.
In addition, water to wash the gold from the placers was not available in the winter. Many miners tunneled into deep placer deposits, bringing out the high-grade gravels to be washed at the spring thaw. Most of the ground in Nome is permafrost. By drift mining, miners were able to recover much of the gold buried under the permafrost. [citation ...
The Siilinjärvi carbonatite complex, [1] an open-pit mine owned by Yara International, in Siilinjärvi, Finland Coal strip mine in Wyoming. Surface mining, including strip mining, open-pit mining and mountaintop removal mining, is a broad category of mining in which soil and rock overlying the mineral deposit (the overburden) are removed, in contrast to underground mining, in which the ...
a solid solution mixes with others to form a new solution The phase diagram in the above diagram displays an alloy of two metals which forms a solid solution at all relative concentrations of the two species. In this case, the pure phase of each element is of the same crystal structure, and the similar properties of the two elements allow for ...