- 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 ...
There is a constant ratio between shock pressure loss and the velocity pressure corresponding to the mean velocity of flow. Shock pressure losses can be calculated from the following formula: P<sub>s</sub>=XP<sub>v</sub>, where P<sub>s</sub>equals the total shock pressure loss in 2880 inches of water, P <sub>v</sub>equals the velocity pressure, in inches of water corresponding to the mean velocity of flow (equals approx. (V/4,000)<sub>2</sub>at standard air density of 0.075 lb/ft<sub>3</sub>or 1.2 kg/m<sub>3</sub>), and X equals an empirical factor or shock factor found by experiment. P<sub>s</sub>and P <sub>v</sub>are expressed in the same units and are equally affected by density. X is therefore independent of both the density and the units used and is the number of velocity pressures equivalent to the shock pressure loss.
Industry:Mining
There is a minimal market price for each metal below which it cannot fall without putting the average producer out of business; this price has been called the base price.
Industry:Mining
Thermal energy absorbed or emitted in a process (as fusion or vaporization) other than change of temperature. Compare: sensible heat.
Industry:Mining
These are applied as a routine matter to slope, temperature, sag, standardization, gravity and sea level effect when measuring a length accurately with a tape.
Industry:Mining
These are pelagic deposits that contain a large percentage of siliceous skeletal materials produced by planktonic plants and animals. The siliceous oozes are subdivided into two types on the basis of the predominance of the forms represented, namely (1) diatom ooze, containing large amounts of diatom frustules, therefore, produced by plankton plants, and (2) radiolarian ooze, containing large porportions of radiolarian skeletons formed by these plankton animals.
Industry:Mining
These are properties only of solutions and include vapor pressure, freezing point, boiling point, and osmotic pressure changes that occur with changes in the characteristics of the solution. Seawater does not follow the general rules of solutions, but departures are proportional.
Industry:Mining
These are the weights used for precious metals. The equivalents are 24 grains = 1 pennyweight; 20 pennyweights = 1 oz; 12 oz = 1 lb. The troy grain is the same as the avoirdupois grain, but the ounce is larger on the troy scale; 1 tr oz = 31.103 g; 1 avoirdupois oz = 28.35 g.
Industry:Mining
These are used when the cable is removed from a machine or apparatus frequently. The most common type is the 100-amp British Standard plug and socket, and it is employed to connect the trailing cable to a coal cutter or face conveyor. The gland of the plug is arranged to grip the sheath of the cable and to make connection with the screen and earth core. Power and pilot conductors are connected to the appropriate contact tubes, which make connection with corresponding pins in the socket portion.
Industry:Mining
These complete the breaking out of the ground. The positioning and number of trimmer shots are governed by the size of the drift, the hardness of the ground, and the fragmentation required for the loading-out method to be adopted.
Industry:Mining
These consist of timber blocks, 8 to 12 in (20.3 to 30.5 cm) square, set in transverse rows in a sluicebox; they are arranged so that in contiguous rows the joints are staggered to prevent the development of longitudinal cracks. It is usual to separate adjacent rows by means of a strip of ordinary riffle scantling.
Industry:Mining
