- 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 ...
This machine has been specially developed for boring in all types of ground, and incorporates a very important feature, that of controlling the water immediately if it is tapped. In boring, the hole is first prepared for the reception of a special rubber ring, two iron plates, and two wedges. When these are properly adjusted, the rubber washer is compressed and powerfully gripped on the sides of the borehole to effect a sound and reliable joint. If during boring operations water should rush out and the bore rods cannot be withdrawn, the two handwheels are screwed in; this presses india-rubber plugs onto the bore rods and effects a watertight joint.
Industry:Mining
This magnetometer is available in two models, one for airborne surveys and the other for use on the ground. Both measure the total magnetic field of the Earth rather than its components.
Industry:Mining
This may be a drophammer, a steam hammer, or a diesel hammer of which the last two are completely automatic. Steam hammers are also able to operate on compressed air.
Industry:Mining
This mechanism is designed to prevent accidents in mine cages caused by overspeeding in hoisting and lowering. It also prevents hoisting or lowering beyond the limits for which the controller is set. On electric hoists, it can apply a brake in case of power failure and may regulate brake speed in the event of an emergency stop.
Industry:Mining
This methane indicator is one in which the sample is made to flow continuously over the filaments while the determination is being made. In this case, two matched filaments form the adjacent arms of the bridge. One of these is specially activated in order to burn the methane while the other filament is inactive and operates at a somewhat lower temperature. This arrangement is designed to compensate for changes in barometric pressure, temperature, humidity, and the presence of carbon dioxide. Facilities for adjustment are provided to compensate for zero drift and change in battery voltage. The meter is provided with two shunts so that two ranges are provided on the scale: 0% to 5% by 0.1% divisions and 0% to 2% by 0.02% divisions.
Industry:Mining
This methane recorder is a combination of the principles used in the Ringrose and McLuckie detectors. Two combustion chambers are used, each of which operates every 6 min, the operation being staggered so that 20 determinations are made per hour. Samples are drawn into the instrument by means of an electrically driven pump, the operation of the pump and the combustion filaments being controlled by cams on a shaft driven by the motor. Pressures are measured by an aneroid cell and recorded on a clockwork driven drum.
Industry:Mining
This method consists in soaking the ore thoroughly in water and then heating to 180 degrees C under a pressure of 150 psi (1.03 MPa). The pressure is then suddenly released, and the absorbed water is converted to steam, which shatters and liberates mineral particles without harmful overgrinding of the ore.
Industry:Mining
This method employs two neutron logging tools with different spacings between the source and the detector or two detectors in the same tool at different spacings. The spacings usually differ by 6 to 10 in (15.24 to 25.4 cm). The long-spaced log is run slowly and with a large time constant so that its statistical variation is not excessive, for the counting rate is much lower than that of the regular-spaced log. This technique has proved to be a potent technique for discriminating gas sands from oil sands in Venezuela.
Industry:Mining
This method involves two essential features: (1) the circulation in the jig of a middling of approx. 3/16 in (4.8 mm) or smaller in size, with sp gr, 1.7 to 2.0--which fills the interstices of the jig bed and in effect converts the jig into a float-and-sink machine; and (2) the use of a suction stroke to hold the medium in the bed and prevent its washing over with the coal.
Industry:Mining
This method of excavation is used in loose or wet soils--unconsolidated formations-- where the banks must be supported by shoring or sheathing. The material must, out of necessity, be lifted out vertically.
Industry:Mining
