Coal Mining

Drift mining can be possible where the coal seam intersects the surface the mine enters the seam in a horizontal direction following the coal. Shaft mining is a common method accessing a coal seam in which elevator provide access to mines. These mines in WV commonly go deeper than 1000ft below surface. Room & planing mining, nearly half the coal is left behind to support the mine roof. Pillars can squeeze, putting pressure on adjacent pillars leading to roof collapse (very dangerous) Continuous mining is these machines can be used with draft or room & pillar mines. One miner can operate a continuous miner to a rotating steel drum with carbon teeth to mine 5 tons of coal per minute. These types of machines have been used since 1940's. Long wall Mining, long wall or retreat mining is highly efficient. Huge mining machines support the roof with hydraulics as it removes coal. Once coal is removed, the machine retreats allowing the roof to fall behind it. Long wall mines extract much more of the coal than room & pillar mines. Strip mining is used when coal is near the surface or when the overburden is unstable. As mining progresses, the overburden is placed in the previous mine cavity. Contour mining is a type of strip mining follows the contour of the hill of mountain leaving terraces in the mountainside. Mountain top removal is when tops of the hills are removed to access horizontal coal seams. Overburden is pushed to areas between high elevations. Following reclamation, the original contour is not restored. This is the most controversial mining method.

Coal

Types of coal 

The dicovery of coal is quite interesting. The first documented use of coal in the US was in 1748. Coal was used to produce "coal gas" to light up the gas lights in the cities. John Peter Sally descovered coal near Boone County.Coal was formed from the remains of swamp plants 300 to 400 years ago.
Types of coal:
Peat (coal precurser) slowly decay plant matter found in bogs, moors, and muskegs.










Lignite (Brown coal) Found in Alaska and western states, and used for electric power.

Bituminous coal ( black coal) a relatively soft coal containing a tarlike substance called bitumen.

Anthracite (Hard coal) Anthracite is the most metamorphosed type of coal. Coke ( coal product) is a fuel with few impurities and a high carbon.

http://www.fossil.energy.gov/education/energylessons/coal/gen_coal.html