- 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 prepared outside membrane of the large intestine of cattle used for separating the leaves of metal in goldbeating and sometimes as the moisture-sensitive element in hygrometers.
Industry:Mining
The presence of a very large excess of coal dust in the air over that required for consumption of the oxygen.
Industry:Mining
The pressure arch theory in roof action suggests that, when a narrow heading is advanced, the layers of rock in the immediate roof deflect slightly and relieve themselves 2449 of the load of the overlying strata by transferring it to the sides of the opening by means of a pressure arch. The arch width just short of that which the higher strata cannot span and transfer the load to the sides of the opening is called the maximum-pressure arch. The depth mainly influences the minimum width of the pressure arch, although the type of overburden also plays a part. The following formula has been developed for approximating the minimum width of the maximum-pressure arch (W = minimum width of arch, in feet; D = depth of coal from surface, in feet): W = 3((D / 20) + 20). The equation does not apply for overburden less than 400 ft (122 m) or more than 2,000 ft (610 m) thick.
Industry:Mining
The pressure at which a liquid and its vapors are in equilibrium at a definite temperature. If the vapor pressure reaches the prevailing atmospheric pressure, the liquid boils. Symbol, p.
Industry:Mining
The pressure built up in the casing when closed at the top of the well. It is usually measured by placing a pressure gage on one of the side outlets on the casing head.
Industry:Mining
The pressure exerted per square centimeter by a column of mercury 1 mm high at a temperature of 0 degrees C where the acceleration of gravity is 980.665 cm/s<sub>2</sub>.
Industry:Mining
The pressure exerted per square centimeter by a column of sea water 1 m tall is approx. 1 decibar. The depth in meters and the pressure in decibars, therefore, are expressed by nearly the same numerical value.
Industry:Mining
The pressure lost or consumed in overcoming friction along an airway.
Industry:Mining
The pressure of a liquid on the surface of its container or on the surface of any body in the liquid is equal to the weight of a column of the liquid whose height equals the depth of the liquid at that certain point.
Industry:Mining
