- 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 controller is made up of three fixed electrodes consisting of groups of parallel plates of noncorroding alloy fixed at the bottom of curved troughs of insulating material of uniform width and varying depth. The trough is deep at the end, corresponding to full speed and minimum resistance; it is shallow at the maximum-resistance starting position. The moving electrodes, of similar construction, are joined to form the star point of the rotor and are moved toward or away from the fixed electrodes, giving a wide range of resistance.
Industry:Mining
This core may be 6 by 7, 7 by 7, 6 by 19, or 7 by 19 (number of strands laid together and ropes twisted together) construction, and the individual wires shall be of an appropriate grade of steel in accordance with the best practice and design, either bright (uncoated), galvanized, or drawn galvanized wire.
Industry:Mining
This cut is drilled with handheld equipment. The empty hole is drilled in two steps, the first as an ordinary hole and the second as an enlargement of this pilot hole. The cut is something between a four-section cut and a double-spiral cut. The Fagersta cut is drilled with light equipment, which makes it suitable for use in mines and in small drifts, where drilling with heavy machines is not profitable.
Industry:Mining
This cycle is comprised of the processes of weathering, soil formation, erosion, transportation, and sedimentation.
Industry:Mining
This device locks to rails to derail cars. Wedge construction eliminates spiking. It protects workers in railroads and mines against wild cars, switching cars, or sudden car movement. Some types are equipped with a warning flag.
Industry:Mining
This differs from the smoke helmet in that there is neither helmet nor bellows. Fresh air is passed to the wearer through a corrugated reinforced rubber tube by means of a rotary blower. A mouthpiece having an inhalation valve, an exhalation valve, and a noseclip takes the place of the helmet. It is held in position by straps attached to a head harness. The mouthpiece can be replaced by a full-face mask. This apparatus is fitted with an equalizing device that enables the wearer to continue breathing comfortably, even should the rotary blower stop.
Industry:Mining
This free-instrument-type device can be dropped over the side of a moving ship, where it will sink rapidly to the ocean floor, take a core of sediment, release ballast, and automatically return to the surface for retrieval.
Industry:Mining
This furnishes a measure of the capacity of a fan to produce useful depression (or positive pressure in the case of a forcing fan) and indicates the extent to which the total pressure produced by the fan is absorbed within the fan itself.
Industry:Mining
This gage consists essentially of a grid of fine wire cemented to a paper membrane, which can be attached to the surface under investigation. The ends of the wire grid are spot welded to a metal strip for the terminal connections. The use of these gages depends upon the fact that certain alloys show a linear relationship between applied strain and electrical resistance, so that if a wire constructed from one of these alloys is fixed to the 1062 surface of an object subject to variable strain, the change of resistance in the wire will be a measure of the change of strain in the object.
Industry:Mining
This has been the most commonly used magnetic instrument for prospecting on land. It consists of a magnet pivoted near but not at its center of mass, so that the magnetic field of the earth creates a torque around the pivot that is opposed by the torque of the gravitational pull upon the center. The angle at which equilibrium is reached depends on the strength of the field. Readings are taken through an eyepiece by comparing a scale reflected from a mirror on the magnetic element with a fixed scale. The balance may be either the horizontal or vertical type.
Industry:Mining
