Appalachian mineral coal basin


APPALACHIAN MINERAL COAL BASIN (RU: Аппалачский каменноугольный бассейн) is one of the largest coal basins within the world. It is situated at the east of the USA, on the territory of the Alabama, Kentucky, Virginia, West Virginia, Ohio, Maryland, Pennsylvania states, stretching for more than 1,200 kilometres along the southern slopes of the Appalachians. The area is approximately 180 thousand square kilometres.

There are approximately 300 coal extracting regions in total within the basin; 10 of them provide annually more than 10 million tonnes of coal, and 30 of them provide more than 5 million tonnes (map). The reserves of mineral coal within the basin down to the depth of 900 metres are estimated at 1600 billion tonnes; proven reserves down to the depth of 305 metres within the seams with thickness of approximately 1 metre are approximately 102 billion tonnes, of which 14.3 billion tonnes are suitable for open pit development. The industrial development of coal within the basin has started in 1800 within the Ohio state.

Appalachian mineral coal basin is situated within the foredeep of the late Hercynides of the Southern Appalachians, has asymmetric structure with wide slightly inclined western side, and narrow steep eastern side. Within the western part of the basin, coal-bearing depositions are embedded with very gentle inclination (the angles of the dip are 2-3 degrees), the structure of embedment is simple; within the eastern part, which is adjacent to the folded belt of the Southern Appalachians, the structure of the coal-bearing strata is complicated on the account of the narrow, long folds, with local uplifts and disjunctive dislocations (the amplitude of elevations reaches up to 300 metres, the angles of dip reach up to 30 degrees). The coals are confined to the Carboniferous and Permian depositions. The major industrial coal-bearing capacity is associated with Pennsylvanian (Upper Carboniferous) depositions. Within the stratum of Pennsylvania (360-1670 metres), there are more than 75 coal seams with operational thickness in total. There is most saturated with coal the Allegheny formation, to which there are confined the Brookville (the thickness is 2-2.2 metres), Clarion (3.6-3.8 metres), Lower, Middle, and Upper Kittaning (1.2-1.3 metres) major operational seams, and also the Monongahela formation (the Pittsburgh seam with thickness of 1.2-3 metres). Within the Early Permian depositions (the thickness is up to 300 metres), there are known more than 10 seams of coal, of which the Washington seam (the thickness is 1.6-3.2 metres) has the greatest importance. The coals are predominantly bituminous, with middle and high content of volatile substances. The average ash content of the coals is approximately 8%, the average sulfur content (excluding the high-sulfurous coals of the Monongahela formation) is approximately 4%, the heat of combustion is 28.87-35.35 megajoules per kilogram. The coals from the seams of the Lower and Upper Kittaning and Pittsburgh can be coked well.

There is concentrated within the Appalachian mineral coal basin the overwhelming majority of the coal extracting enterprises of the country, namely, approximately 95% of underground mines, and approximately 85% of open pit mines, at which there are employed approximately 78% of all the personnel of the coal industry. Approximately 45% of the coal is extracted with the open pit method. There operated during 1978 within the basin 2575 underground mines and 3018 open pit mines; the greatest quantity of underground mines were concentrated within the Kentucky (1060) and West Virginia (740) states, the greatest quantity of open pit mines were within the Kentucky (979) and Pennsylvania (754) states. The overwhelming quantity of the mining fields have been unsealed with adits and inclined shafts. The depth of development at the mines of Appalachian mineral coal basin is 126.4 metres on average (the greatest depth is 335 metres). The emission of gases is approximately 5.9 cubic metres per tonne on average; at 49 underground mines (25% of underground extraction of the Appalachian mineral coal basin), this indicator is approximately 20 cubic metres per tonne on average (2.5 to 100 cubic metres per tonne). There are dangerous because of gas 13 seams, including the Pittsburgh seam (more than 50% of the total volume of the gas emissions throughout the whole Appalachian mineral coal basin). There are used at the mines of the basin various varieties of the chambered and chamber-and-pillar systems of development (there belong 3.5% of extraction to the comprehensively mechanized long wall stopes). There are widely used the short-stope combined cutter-loader machines (68% of extraction), the roof is supported with anchors. The mining workings are performed, as a rule, through the coal only, without accidental cutting through the rocks. There dominate at the underground transport the powerful contact electrical locomotives, heavy load trolleys and conveyors. The largest underground mines are the "Moss #3" (Virginia, has been commissioned in 1958, 3.7 million tonnes per year), "Robinson Run" (West Virginia, has been commissioned in 1968, 2.6 million tonnes), "Robin" (Pennsylvania, has been commissioned in the early 40s, 2.1 million tonnes), "Maple Creek" (Pennsylvania, has been commissioned in 1959, 2 million tonnes). There is universally adopted at the open pit mines the system of development without transport, with the help of draglines. The coal is extracted with power shovels or end loaders. The transport is powerful dump trucks.

The largest open pit mines are the "Muskingum" (Ohio state, has been commissioned in 1952, 2.1 million tonnes) and "Egypt Valley" (Ohio state, has been commissioned in 1967, 1.9 million tonnes). There is beneficiated approximately 50% of the extracted coal. There operate at the underground mines and open pit mines (less often) 236 coal preparation (beneficiation) plants. There dominate the wet methods of beneficiation, namely, jigging and heavy environments. The total extraction of the coal-extracting enterprises of the Appalachian mineral coal basin during 1980 was 406 million tonnes. The greatest total extraction is at the enterprises of the West Virginia (approximately 26%), Kentucky (approximately 24%), and Pennsylvania (approximately 21%) states. The largest coal-extracting companies are the "Peabody group" and "Consolidation Coal". The extracted coal is transported with the rail and river transport. Approximately 65% of the coal is consumed by electrical power plants, approximately 50 million tonnes of the coal (mainly of the coking one) is exported annually: 23% into Canada, 45% into Japan, and 26% into Europe. The export is performed through the Atlantic port of the Hampton Roads harbour (map).