Basically, scorch is exploitd by three methods. Underground mines are entered by a vertical or inclined shaft leading from the surface; the shaft intersects a coal hunch over of minable thickness and quality, and at that point lateral pass openings are driven into it and extraction begins. Coal mining at once required much human labor. Holes were drilled into the face of the coal seam and loaded with black powder or dynamite, and the explosions spewed up broken coal which was then loaded by hand-shovel into a small car. When full, this was pushed by men or pulled by a mule along a track to a incumbrance pocket adjacent to the shaft. The coal was then loaded into separate cars or buckets and hoisted to the surface. New technology has changed this picture. The continuous mining machines are powered by voltaicity, and they cut out the coal quite of blasting, break it, and convey it continuously into waiting cars for transport to the hoisting shaft. such(prenominal)(prenominal) mines are rarely three g-force feet deep; they cheat on from a few tons of daily production to disco biscuit thousand tons; and they employ one to two thousand men in individual mines.
Another form of mine is the strip mine, created by stripping the overlaying material, called burden, from a minable coal
The third method formulates very little coal in the United States -- auger mining, which is carried out by centre of large horizontal augers that bore into a coal bed exposed on the side of a hill; the auger pushes out the coal as it rotates.
seam. Draglines or large galvanising shovels are used for this purpose; in either case, the overburden is stacked behind the current operations on the latterly mined-out area of the pit so that it can be leveled or landscaped again. The coal bed is blasted to break it for shoveling. drill holes are now made a foot in diameter and the explosive material, ammonium nitrate, is chemically and physically more like fertilizer than dynamite. A shovel or front-loader is used to place the broken coal on trucks.
Most such mines are less than two hundred feet deep, and they may produce as much as fifteen thousand tons of coal a day, employing as many as septette hundred men in a single mine. more than than half the coal produced in the United States is produced from strip mines.
bituminous coal is the most abundant and widespread coal in the United States, and it is the coal most commonly used for industrial, electric power, and heating purposes. Coal is shew in beds ranging from those less than an pass on thick to those many feet deep. Many beds may be found in a single sedimentary sequence or depositional basin. In West Virginia there are 117 coal beds chief(prenominal) enough to be named and there are also hundreds of small beds. The lower boundaries of coal seams are sharp contacts with the underclay, while the swiftness boundary may be either well define or gradational to sandstone or shale. Certain geological periods engender been more conducive to the production of coal than others. The late Paleozoic age has coal beds as a distinctive feature, and this geologic time scale is called the Carboniferous. Coal beds are also important among rocks of Cretaceous and early Tertiary beds in some separate of the world. Coal beds can be buried deeply
Order your essay at Orderessay and get a 100% original and high-quality custom paper within the required time frame.
No comments:
Post a Comment