The widespread occurrence and abundance of coal makes it the world's principal source of energy for a wide variety of end uses. Coal is a sedimentary rock of organic composition consisting of carbon, hydrogen, oxygen and minor proportions of nitrogen and sulphur.
Two dominant methods account for the vast majority of underground coal mining: "room and pillar" and "longwall" mining.. In room and pillar mining, seams of coal are partially mined, leaving large pillars of coal intact to support the overlying layers of rock.
What is coal? Coal is a combustible black or brownish-black sedimentary rock composed mostly of carbon and hydrocarbons. Coal is made of the remains of ancient trees and plants that grew in great swampy jungles in warm, moist climates hundreds of millions of years ago.
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 ...
COAL is a solid, combustible, sedimentary, organic rocks. Coal formed when lush vegetation from warm swampy areas died and was buried to later be consolidated between other rock layers and was altered by the combined effects of pressure and heat over millions of years.
Sedimentary rock - Siliceous rocks: Those siliceous rocks composed of an exceptionally high amount of crystalline siliceous material, mainly the mineral quartz (especially microcrystalline quartz and fibrous chalcedony) and amorphous opal, are most commonly known as chert.
Back — The roof or upper part in any underground mining cavity. Backfill — Mine waste or rock used to support the roof after coal removal. Barren — Said of rock or vein material containing no minerals of value, and of strata without coal, or containing coal in seams too thin to be workable.