coal mining

coal mining physical extraction of coal resources to yield coal; also, the business of exploring for, developing, mining, and transporting coal in any form. Strip mining is the process in which the overburden (earth and rock material overlying the coal) is removed to expose a coal seam or coal bed. Excavators either dispose of the overburden or store the waste material for replacement after the coal has been extracted. Once exposed, the coal is usually removed in a separate operation. Surface soil is often stripped separately and spread back onto the reclaimed surface. The environment can also be protected by seeding or planting grass or trees on the fertilized restored surface of a strip mine. The term strip mining is most often used in reference to coal mining, although the process may also be used to extract certain metallic ores as well. Sometimes the terms open-pit, open-cast, or surface mining are used in the same sense, although they usually refer to metalliferous mining or the mining of other minerals. Underground coal mining is the extraction of coal from below the surface of the earth. The coal is worked through tunnels, passages, and openings that are connected to the surface for the purpose of the removal of the coal. Mechanical equipment breaks the coal to a size suitable for haulage. Alternatively, the coal is drilled, and the resultant holes are loaded with explosives and blasted in order to break the coal to the desired size. In order to protect the miners and equipment in an underground coal mine, much attention is paid to maintaining and supporting a safe roof or overhead ceiling for the extraction openings. Long-wall mining is a method of underground mining believed to have been developed in Shropshire, England, near the end of the 17th cent. A long face, or working section, of coal, some 600 ft (180 m) in length, is operated at one time. The miners and machinery at the working face are usually protected by hydraulic jacks or mechanical props which are advanced as the coal is extracted. The excavated, or gob, area is either allowed to cave in, or is filled in by waste material called stowing. The Anderton shearer is a widely used coal cutter and loader for long-wall mining. It shears coal from the face as it moves in one direction and loads coal onto an armored conveyor as it travels back in the opposite direction. It is ordinarily used for coal seams greater than 3.5 ft (9.1 cm) in thickness.

coal mining in Ireland has never matched that of Great Britain. The various periods of folding and faulting during the geological formation of Ireland greatly denuded its original coal deposits. Also, Ireland's easy access to cheap supplies in Britain and the absence of concerted industrialization, outside the north‐east, greatly reduced the impetus towards mining. In 1900 Ireland produced only 125,000 tons, compared to Scotland's 30 million tons annually. Sporadic mining of anthracite deposits at Crataloe, west Clare, Kanturk, Co. Cork, Coalbrook and Castlecomer, Co. Kilkenny, Co. Carlow, and the Slieve Ardagh hills in Tipperary has now ceased. In Leitrim, Arigna's bituminous coal, originally mined for local iron furnaces, supplied the nearby power station, until closure in 1990. Mining was carried on at Coalisland, Co. Tyrone, from the 18th century. Between July 1924 and December 1926, 36,000 tons were raised, by Sir Samuel Kelly & Co., with heavy government subsidies and miners imported from Scotland and Cumberland. However, it proved an uneconomic proposition and was closed in 1926. Further unsuccessful mining was carried on in Coalisland in the 1950s. Poor quality ‘limestone coal’, found at Ballycastle, Co. Antrim, is no longer mined. Although the Second World War gave a boost to Irish mining, in peacetime competition from abroad and other power sources, as well as modern environmental pressures, have all but done away with Irish coal mining.

Peter Collins