- 行业: Mining
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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 dynamites of this class come in cartridges 4 in (10.2 cm) and up in diameter and in weight strengths from 20% to 70%. Their water resistance is considered good (the gelatin core being responsible for this), but their fume characteristics are rated as poor. Besides providing increased water resistance, these explosives tend to exhibit the higher velocities characteristic of gelatin explosives (10,500 ft/s, 15,000 ft/s, and 17,000 ft/s) (3,200 m/s, 4,600 m/s, and 5,200 m/s), rather than the low and medium velocities characteristic of other straight ammonia dynamite. In addition, the gelatin core assures propagation of detonation through the entire explosives column. Gelatin cored ammonia dynamites also are very useful when an operator wishes to practice alternate velocity loading to attain a more effective one-two punch in conjunction with the use of short period or millisecond delay, electric blasting caps.
Industry:Mining
The earlier part of Precambrian time, corresponding to Archean rocks. Also spelled: Archaeozoic.
Industry:Mining
The earliest view of subsidence in which it was supposed that the lines of break (limiting lines) were more or less vertical. Pillars left for support were accordingly formed immediately under the object to be protected, the question of dip being disregarded.
Industry:Mining
The earth formation that has been selected as the most suitable to support a given load.
Industry:Mining
The Earth motion produced by a natural (earthquake) or synthetic disturbance on the surface or underground; utilized in the seismic method of geophysical exploration and for investigating the Earth's interior. Three types of waves are produced: (1) longitudinal or P waves; (2) traverse or S waves; and (3) surface or Raleigh and L waves. The speed of propagation is characteristic for each type of rock, depending largely on its compactness. In sandy clay, the speed of the P wave is about 4,000 ft/s (1.22 km/s); in sandstone, 10,000 ft/s (3.05 km/s); and in igneous rock up to 22,000 ft/s (6.71 km/s).
Industry:Mining
The effect of surface friction between a particle and a liquid when the particle moves through the liquid. Compare: turbulent resistance
Industry:Mining
