- 行业: Mining
- Number of terms: 33118
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- 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 theory of mineral-deposit formation involving the separation and sinking of ore minerals below a silicate shell during the cooling of the Earth from a liquid stage, followed by their transport to and deposition in the crust as it was fractured (Shand, 1947). Modern thought ascribes more complex origins to mineral deposits.
Industry:Mining
A theory of ore genesis formulated in the 18th century and passing in and out of use since. It postulates the formation of ore deposits by the leaching of adjacent wall rock. In current usage, convectively driven fluids associated with cooling plutons are thought to have abstracted metals from adjacent host rocks and transported them to new sites of deposition, as in the formation of certain porphyry base-metal deposits.
Industry:Mining
A theory proposed by Van Bemmelen (1933) that explains the structural and tectonic features of the Earth's crust by vertical upward and downward movements caused by waves that are generated by deep-seated magma.
Industry:Mining
A theory that strata movements caused by underground excavations were limited by a kind of dome that had for its base the area of excavation, and that the movements diminished as they extended upward from the center of the area.
Industry:Mining
A thermal drying, batch-type process, in which the action of high-pressure steam on a lump of lignite produces the following effects. The lump is heated inside and out to an approx. uniform temperature by its envelope of condensing steam. As the temperature rises and the pressure increases part of the colloidal water is expelled from the lump as a liquid. The lump shrinks as water leaves and the cells collapse, and when the pressure is lowered, more water leaves by evaporation caused by the sensible heat stored in the lump. When the pressure is lowered further by vacuum, additional moisture is evaporated, which cools the lump.
Industry:Mining
A thermal process for drying fine coal. An example of this type is the Conreur dryer. Coal entering the top of the drying tower is carried down by a series of rollers, being permeated by an ascending stream of hot air. Fixed baffles direct the air to facilitate mingling. The very finest particles may have to be recovered by dry filters or wet scrubbers. The dryer treats coal with a top size ranging from 1/4 to 2 in (0.64 to 5.08 cm).
Industry:Mining
A thermal property of matter with the dimensions of area per unit time; it corresponds to the thermal conductivity divided by the product of density and heat capacity.
Industry:Mining
A thermometer in a hollow spherical black globe, the readings from which show a higher value, due to radiation, than those from a conventional thermometer so that the globe device measures the effectual radiation temperature.
Industry:Mining
A thick bed of limestone, of Eocene age, composed mainly of the remains of the foraminifer Nummulites. The formation stretches from the Alps through Iran to China. It is the stone of which the Great Pyramid is built.
Industry:Mining
A thick layer of reinforced concrete placed in the bottom of a shaft after it has been sunk to the desired depth and permanently lined. The plug resists floor lifting and provides a clean, smooth sump.
Industry:Mining
