- المجال: Mining
- Number of terms: 33118
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- 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 ...
An axial symmetry operation requiring three repetitions to complete 360 degrees or return to identity.
Industry:Mining
An axial symmetry operation requiring three repetitions to complete 360 degrees or return to identity.
Industry:Mining
An axial-flow fan mounted in, or intended for mounting in, a section of duct.
Industry:Mining
An axial-flow fan with a series of blades formed by cutting and bending flat sheets or plates. When rotated, the disk imparts to the air a motion along the axis of the fan shaft.
Industry:Mining
An earlier percussive boring method used largely in Europe for exploration, etc. The cutting tool is given a rapid but very short stroke, and the hole is flushed by water passing down through the hollow rods. No beam is used, but the rope to which the boring tools are suspended has an up-and-down motion imparted to it by an eccentric. The arrangement gives up to 250 strokes/min with a stroke length as low as 3-1/4 in (8.3 cm).
Industry:Mining
An earlier practice whereby miners paid a blacksmith for sharpening their picks.
Industry:Mining
An earlier system of working coal between two levels in an inclined coal seam. The top holes are driven to the full rise, and the face-line is usually stepped. Only the coal is worked, and no ripping is done in the top holes. The coal gravitates into trams in the lower level.
Industry:Mining
An earlier system of working thick seams in South Wales. Two narrow stalls are turned off the heading and after advancing some 8 to 12 yd (7.32 to 10.97 m) (so as to leave a pillar of coal next to the heading) are connected and the coal between them worked as a single face. Double stalls are intermediate between pillar-and-stall and longwall.
Industry:Mining
An earlier type of centrifugal fan. It had no external casing, but delivered directly to the atmosphere all around its periphery. The veins were curved backwards in the direction of rotation and the air was led into the fan by a curved inlet passage or throat. It was usually driven by steam at about 70 rpm; efficiency about 40%; external diameter of about 30 ft (9.1 m).
Industry:Mining
An earlier type of miners' flame safety lamp fitted with two or three conical gauzes, thus adding to the safety of the lamp when used in high air velocities. The Marsaut lamp is the basis of modern flame safety lamps.
Industry:Mining
