- 行业: Mining
- Number of terms: 33118
- Number of blossaries: 0
- Company Profile:
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 abrasive is the densest form of crystallized carbon, the hardest substance known. It occurs most commonly as well-developed crystals in volcanic pipes or in alluvial deposits. Bort (boart or borts) sometimes refers to all diamonds not suitable for gems, or it may refer to off-color, flawed, or impure diamonds not fit for use for gems or most other industrial applications, but suitable for the preparation of diamond grain and powder for use in lapping or the manufacture of most diamond grinding wheels. This type of bort is also called crushing bort or fragmented bort.
Industry:Mining
This butane combustible gases recorder has a small flame of burning butane gas, which is controlled to give constant heat output with varying ambient temperature and humidity, and with varying butane gas pressure. The heat output is measured by means of a group of thermocouples in a chimney above the flame. The presence of methane in the atmosphere, which has access to the flame via suitable gauzes, increases the voltage generated by the thermocouples. These changes are recorded on a rotating chart calibrated in percentage methane.
Industry:Mining
This clutch transmits power through friction shoes carried on the tube of cord and rubber construction. The pneumatic clutch is self-adjusting for wear owing to the natural resilience of the rubber tube. Disengagement is complete and automatic when the air under pressure is released. The clutch is controlled by finger pressure on a valve. The valve can be installed at the place most convenient for the operator.
Industry:Mining
This coal consists of more than 50% of small resin bodies embedded in gelito-collinite, fusinito-collinite, or in collinite of fusinitic nature. The resin bodies differ in shape and may be angular, spheroidal, or lenticular. Varying in size, they may be visible to the unaided eye in a hand specimen of coal or only distinguishable under the microscope. Resinite coal may also contain small quantities of microspores, fine fragments of fusinized tissue, and, not infrequently, broad streaks of vitrinite. Hand specimens of resinite coal are matt or semimatt and in coals of low rank are brown or brownish-black. On fractures perpendicular to the bedding, the resin bodies appear rounded, black, and lustrous; in the bedding planes themselves they frequently appear as matt rodlets. Resinite coals frequently are high in ash.
Industry:Mining
This coal washer uses a calcium chloride solution of a comparatively low density and depends on mechanically induced upward currents to obtain a separation at the desired specific gravity. It produces a clean, dustless, nonfreezing coal.
Industry:Mining
This compound, which approximates in composition to K<sub>2</sub>Ti<sub>6</sub>O <sub>13</sub>and melts at 1,370 degrees C, can be made into fibers for use as a heat-insulating material.
Industry:Mining
This consists of a head harness, mouthpiece, and noseclip, corrugated breathing tube, Briggs equalizing device, 120 ft (36.58 m) of reinforced air tubes, and a strainer and spike. It has neither bellows nor rotary blower but depends entirely on the action of the equalizer for comfortabIe respiration. The resistance to breathing is so low that reasonably hard work can be done by the wearer over a period of 2 h or more. The air supply tube is attached to the waist by a strong leather body belt.
Industry:Mining
This consists of a small box containing an iron disk thinly coated with the rare element selenium. When electromagnetic radiation in the form of light waves falls on this surface it sets up a potential difference between the iron and the selenium, which in turn causes a minute electric current to flow through the sensitive microammeter connected between them. The magnitude of this current is proportional to the intensity of the light, and it can be used as a measure. For use with miners' hand lamps the cell is mounted in a box, the microammeter being housed in the top or side. The lamp to be tested is placed in the box on a turntable, and the candlepower is read off directly since the instrument is already calibrated.
Industry:Mining
This consists of a thin steel wire stretched between knife edges, one being free to move longitudinally. The wire is maintained vibrating at its natural frequency by an electrical method. The knife edges are held firmly against the girder under test, a change of strain in the girder varying tension in the wire and hence its natural frequency. This gage is used in conjunction with a reference instrument of fixed frequency; electrical impulses from both instruments are superimposed to produce beats having a frequency equal to the difference between the frequencies of the two instruments. Changes in the frequency of the test gage caused by variations in strain result in identical changes in the beat frequency. The joint output from these two instruments is applied to the plates of a cathode-ray tube, leading to an oscillation of the electron beam with a frequency equal to that of the higher of the two applied frequencies, with an amplitude that increases and decreases with the same frequency as that of the beats.
Industry:Mining
This controller gives a high ratio of maximum to minimum resistance, 6,000:1. A high resistance is thus available for reverse-current braking, but the design ensures that there is an ample volume of electrolyte between the electrodes when starting at twice full-load torque. It is similar to the swinging-electrode controller.
Industry:Mining
