- Industry: Mining
- Number of terms: 33118
- Number of blossaries: 0
- Company Profile:
The U.S. Bureau of Mines (USBM) was the primary United States Government agency conducting scientific research and disseminating information on the extraction, processing, use, and conservation of mineral resources.
Founded on May 16, 1910, through the Organic Act (Public Law 179), USBM's missions ...
A system of longwall working in which the faces advance from the shafts toward the boundary or other limit lines. In this method, all the roadways are in worked-out areas.
Industry:Mining
A system of measurement used in land surveying, having the surveyor's chain (one chain = 4 rods = 66 ft = 20.1 m = 100 links = 1/80 mile) as a unit. Compare: Gunter's chain
Industry:Mining
A system of mine development that is suitable for inclined, and perhaps faulted, coal seams. Main stone headings are driven, at predetermined levels, from the winding shaft to intersect and gain access to the seams to be developed. The stone headings, or horizons, are from 100 to 200 yd (91.44 to 182.88 m) vertically apart, depending on the seams available and their inclination. The life of each horizon ranges from 10 to 30 years. Connections between horizons at inby points are by staple shafts or drivages in the coal.
Industry:Mining
A system of mine development that is suitable for inclined, and perhaps faulted, coal seams. Main stone headings are driven, at predetermined levels, from the winding shaft to intersect and gain access to the seams to be developed. The stone headings, or horizons, are from 100 to 200 yd (91.44 to 182.88 m) vertically apart, depending on the seams available and their inclination. The life of each horizon ranges from 10 to 30 years. Connections between horizons at inby points are by staple shafts or drivages in the coal.
Industry:Mining
A system of mine development that is suitable for inclined, and perhaps faulted, coal seams. Main stone headings are driven, at predetermined levels, from the winding shaft to intersect and gain access to the seams to be developed. The stone headings, or horizons, are from 100 to 200 yd (91.44 to 182.88 m) vertically apart, depending on the seams available and their inclination. The life of each horizon ranges from 10 to 30 years. Connections between horizons at inby points are by staple shafts or drivages in the coal.
Industry:Mining
A system of mining established for many years in British coal mines. The longwall face is undercut, blasted, and loaded by hand to a face conveyor. The conveyor is then moved forward ready for the next day, the packs are built and the back props withdrawn. Such faces still produce about 60% of the total output and is known as conventional machine mining. It has the disadvantage that there are limits to production because it is cyclic mining, e.g., it involves separate operations as enumerated above.
Industry:Mining
A system of mining in which the distinguishing feature is the winning of less than 50% coal on the first working. It is more an extension of the development work than mining. The second working is similar in principle to top slicing. The remainder of the coal is won by a retreating system, the cover being caved after each unit has been worked. The term bord-and-pillar is not used to any great extent in American mining literature, but has a place in English literature. Various names have been applied to this method, such as checkerboard system, Brown panel system, following up the whole with the broken, Lancashire bord-and-pillar system, modified room-and-pillar working, narrow working, North Staffordshire method, rearer method of working inclined seams, rock-chute mining, room system, room system with caving, Warwickshire method of working contiguous seams, wide or square work, and pillar-and-breast.
Industry:Mining
A system of mining whereby solid blocks of coal are left on either side of miner's working places to support the roof until first-mining has been completed, when the pillar coal is then recovered.
Industry:Mining
A system of molding in which the molds are made of a mixture of silica sand and cement with water added.
Industry:Mining
A system of opening a mine by driving a single entry only, in place of a pair of entries. The air current returns along the face of the rooms, which must be kept open.
Industry:Mining
