- 行业: Mining
- Number of terms: 33118
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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 ...
When a block of ground is stoped in such a way that at some time its remainder is surrounded on all sides by stoped ground, that remainder is termed a remnant.
Industry:Mining
When a cut is so made by a mining machine or a shot is so placed by a miner that the cut or shot enters the coal beyond the proper line of the rib, it is said to grip the rib.
Industry:Mining
When a lode or vein is discovered in a tunnel, the tunnel owner is called upon to locate the area containing the vein or lode on the surface and thus create a mining claim.
Industry:Mining
When a new mine is projected or a new seam is to be worked from an existing mine, plans are prepared to show the proposed ventilating system, including the quantities of air and pressures and the principal appliances to control and distribute the air. Investigations and calculations are made to select a fan of the necessary type and size for the ventilation required. All of this important work comes within the general term ventilation planning.
Industry:Mining
When a particularly fine grinding of ore is needed, two and even three ball mills may be used in a series to attain the degree of fineness. The successive stages are referred to as primary, secondary, and tertiary grinding.
Industry:Mining
When a pocket of rock in the periphery of an excavation is weaker than the remainder, it may fail under the ring stress. Fragments split away or fall out until all the weak rock is removed, forming an artificial vugh. This is called vugh-arching.
Industry:Mining
When a shaft is sunk through a thick, dry deposit of shale, the absorption of water may cause the shale to swell and damage the shaft lining. Again, when shale is exposed to weathering, the lamina tends to separate and the material swells. When wet, the disintegrated mass still further swells and eventually becomes a plastic clayey deposit.
Industry:Mining
When a translucent crystal is viewed under microscope, light travels through the mineral at a speed which corresponds with its refractive index, as this is affected by the crystal 2180 planes. A uniaxial crystal has a negative optical sign when the velocity of its extraordinary ray exceeds that of the ordinary ray and vice versa. Calcite is negative; quartz positive. For biaxial crystals, the three principal directions of vibration are mutually at right angles.
Industry:Mining
When a winding rope, from the effects of wear and tear, has become less in diameter or in thickness from that cause, it is said to be "drawing small."
Industry:Mining
When airways are arranged in parallel and a prescribed quantity of air is made to flow through each branch. Compare: natural splitting.
Industry:Mining
