- Industry: 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 standard error of estimation computed for a kriged estimate. By definition, kriging is the weighted linear estimate with the particular set of weights that minimizes the computed estimation variance (standard error squared). The relationship of the kriging standard deviation to the actual error of estimation is very dependent on the variogram model used and the validity of the underlying assumptions; therefore, kriging standard deviations should be interpreted with caution.
Industry:Mining
The standard method used by the U.S. Bureau of Mines samplers is as follows: A space of 5 ft (1.52 m) in width should be cleared of dirt and powder from top to bottom of the seam being sampled. Down the center of this cleared space, a zone 1 ft (0.3 m) wide is cut to a depth of at least 1 in (2.54 cm) in order to get perfectly clean coal. A cut is then made up the center of this zone to a depth of 2 in (5.2 cm) and a width of 6 in (15.2 cm); or, if the coal is soft, to a depth of 3 in (7.6 cm) and a width of 4 in (10.2 cm). Approx. 5 to 6 lb (2.3 to 2.7 kg) of coal will be obtained for each foot (0.3 m) of thickness of the seam. This should include all bony coal included in the mining operation and exclude all slate or partings, which are thrown out during the operation. The sample obtained should be collected on a waterproof cloth 6 ft by 7 ft (1.83 m by 2.13 m) and then screened, the lumps being broken in a mortar, and all passed through a 1/2-in (12.7-mm) screen. Any 644 impurities, such as slate or pyrite, are crushed to 1/4 in (6.4 mm) or finer and thoroughly mixed with the coal. The coarser materials should be evenly distributed, the sample being then quartered, remixed, and requartered. When the mixing is complete, the sample should be placed in a can with the capacity of 3 lb (1.35 kg) and the top screwed on and sealed with adhesive tape. The can should be labeled with the name of the collector, the location, the date, and any other information necessary for the analysis.
Industry:Mining
The standard type of heading blast consists of a straight in or main drive, at right angles to the rock face, and a back drive at right angles to the main drive and parallel to the face. The main drive is normally driven at quarry floor level to a depth of 0.6 times the height of rock above the back drive. Apart from exceptional circumstances, the maximum depth of the main drive should be 50 ft (15 m), so that with faces over 85 ft (26 m) high the 0.6 ratio should not be used, but the main drive limited to 50 ft.
Industry:Mining
The standards prescribed by regulations to provide air underground of a certain degree of purity.
Industry:Mining
The starting and stopping of a pump by a mechanism actuated by the level of water in the suction well or pump, or by the level or pressure of water in a discharge tank.
Industry:Mining
The state of a tidal current when its velocity is near zero, the moment when a current reverses direction. Sometimes considered the intermediate period between ebb and flood currents during which the velocity of the currents is less than 0.1 knot (0.16 km/h).
Industry:Mining
The state of interlocking of grains of two different minerals as a result of their simultaneous crystallization. Compare: graphic granite
Industry:Mining
The state of stress theory as developed by Rankine in 1860 for application to earth pressures. He formulated that the pressure on a vertical retaining wall restraining earth with a horizontal surface is (1 - sinphi ) / (1 + sinphi ) multiplied by the soil density for each foot depth of soil retained, where phi is the angle of internal friction of the soil. The value (1 - sinphi ) / (1 + sin#2f) is the coefficient of active earth pressure.
Industry:Mining
The state of stress, either homogeneous or varying from point to point, in a given domain.
Industry:Mining
