- 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 ...
The number that expresses a material's resistance to elastic changes in volume; e.g., the number of pounds per square inch necessary to cause a specified change in volume.
Industry:Mining
The number, position, depth, and angle of the shot holes forming the complete round in the face of a tunnel or sinking pit. A good drill-hole pattern will ensure the maximum 995 possible pull and the fragmentation for easy loading without excessive scatter of material.
Industry:Mining
The numerical designation that indicates the surface flammability of materials as specified by the ASTM E-162 test method "Surface Flammability of Materials Using a Radiant Heat Energy Source." U.S. Federal regulations require a flame spread index of 25 or less for flame-retardant coatings and sealants used in underground mines.
Industry:Mining
The numerical expressions of the resistance to the passage of an electric current between two charged poles. It is the ratio of the attraction of two oppositely charged poles as measured in a vacuum to their attraction in a substance. The dielectric constant, which corresponds to permeability in magnetic materials, is a measure of the polarizability of a material in an electric field. This property determines the effective capacitance of a rock material and consequently its static response to any applied electric field, either direct or alternating. The dielectric constant of a vacuum is unity.
Industry:Mining
The object of nonselective mining is to secure a low cost, generally by using a cheap stoping method combined with large-scale operations. This method can be used in deposits where the individual stringers, bands, or lenses of high-grade ore are so numerous and so irregular in occurrence and separated by such thin lenses of waste that a selective method cannot be employed. Nonselective methods of stoping include caving, top slicing, some forms of open stoping, and shrinkage stoping under most conditions.
Industry:Mining
The occurrence of fracturing of the upper roof, with consequent rapid increase of the weight carried on the timber and packs supporting the roof; distinct from the fracturing of the nether roof.
Industry:Mining
The official at a mine who periodically surveys the mine workings and prepares plans for the manager. Formerly, the mine surveyor carried out many of the duties now performed by the planning department. See: surveyor; mine.
Industry:Mining
The offset of a side auxiliary telescope requires a correction to observed horizontal angles, and the offset of a top auxiliary telescope requires a correction to observed vertical angles. The process of computing the correct angle from the observed angle is called reduction to center.
Industry:Mining
