- 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 ...
When an area of a mine has been sealed off from the remainder of the workings by barriers or stoppings inserted at suitable points, it is important to prevent the circulation of air within the sealed area. This means that external air pressures must be equalized on all the seals. The object of equalizing the atmospheric pressures on the seals is attained by inserting or removing doors or brattice cloths at appropriate places. It is possible to make all the seals contiguous with a common airway by this means, so that, if they are not widely separated, they will be subjected to the same external atmospheric pressure.
Industry:Mining
When applied to valves and fittings, means suitable for a working pressure of 125 to 175 psi (860 to 1,200 kPa).
Industry:Mining
When calculating or plotting the distances, angles, or coordinates of a closed traverse or one connecting two accurately located points, the discrepancy between starting and finishing point. This error is adjusted in proportion to the magnitude of the angles and distances involved, if it is below a tolerable limit.
Industry:Mining
When conditioning is designed to perform only one or a limited number of functions, then it should be so designated. Air-conditioning processes include dust control, ventilation, dehumidification, cooling, heating, and many others.
Industry:Mining
When conducting a mine ventilation pressure survey, zero time is the time of the commencement of the survey from the base station, and the reading of the control barometer there is taken as the pressure datum to which subsequent pressures are referred.
Industry:Mining
When one speaks of the interest on a mining investment, the rate mentioned ordinarily consists of the normal rate plus a substantial additional rate that represents the profit that should accrue in proportion to the hazardous nature of the mining business. In this sense, the rate of interest in most forms of mining should be high; to be satisfied with less than 10% annually would show a lack of acumen.
Industry:Mining
When rock is subjected to increasing stresses there comes a time when it is on the point of failure. In some circumstances it may remain at that point for a considerable time. Any small external influence, such as a seismic wave, may then be sufficient to precipitate the failure. This is known as the trigger effect.
Industry:Mining
When shot firing in thick coal seams, two rows of holes may be necessary. These are usually staggered to a triangular pattern to distribute the burden. A similar pattern is often adopted in quarry wellhole blasting.
Industry:Mining
When the Pitot tube and static tube are combined, they form the Pitot-static tube, and as such they can be used as an anemometer. The tubes are usually arranged concentrically. When they are connected to the opposite sides of a manometer, the dynamic or velocity pressure will be measured directly.
Industry:Mining
When the results of a survey indicate a possible ore deposit, test holes may be drilled and a special adaptation of a scintillation counter, called a drill-hole counter, may be lowered in a hole in an attempt to locate, outline, and assay an orebody. The drill-hole counter can distinguish between formations by their radiation intensity.
Industry:Mining
