Mining the Coal. Coal miners use giant machines to remove coal from the ground. They use two methods: surface or underground mining. Many U.S. coal beds are very near the ground's surface, and about two-thirds of coal production comes from surface mines.
Mining is the process by which commercially valuable mineral resources are extracted (removed) from Earth's surface. These resources include ores (minerals usually containing metal elements), precious stones (such as diamonds), building stones (such as granite), and solid fuels (such as coal).
LONGWALL MINING Overview. In the method of secondary extraction known as longwall mining a relatively long mining face (typically in the range 100 to 300m but may be longer) is created by driving a roadway at right angles between two roadways that form the sides of the longwall block, with one rib of this new roadway forming the longwall face.
Carlson Underground Mining -- For Precise Design, Scheduling, and Mapping Create complete mine projections and ventilations in minutes vs. hours with all the tools needed for precise design and scheduling The Carlson Underground Mining module enables users to individualize their design with:
Water. Large quantities of water are used in mining operations for cooling machinery, dust suppression, cleaning, fire-fighting and drinking. Water supplies are normally carried in steel pipes from surface to points close to the work places, with flexible hoses used for the final connections.
Underground hard rock mining refers to various underground mining techniques used to excavate hard minerals, usually those containing metals such as ore containing gold, silver, iron, copper, zinc, nickel, tin and lead, but also involves using the same techniques for excavating ores of gems such as diamonds or rubies.
A. Abutment - In coal mining, (1) the weight of the rocks above a narrow roadway is transferred to the solid coal along the sides, which act as abutments of the arch of strata spanning the roadway; and (2) the weight of the rocks over a longwall face is transferred to the front abutment, that is, the solid coal ahead of the face and the back abutment, that is, the settled packs behind the face.
Underground coal gasification (UCG) is an industrial process which converts coal into product gas. UCG is an in-situ gasification process carried out in non-mined coal seams using injection of oxidants, and bringing the product gas to surface through production wells drilled from the surface.