- Industry: 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 test utilizes a special grindability mill of the ring-and-ball type, in which a 50-gm portion of closely sized coal is ground for 60 revolutions. This method is of the constantwork type; i.e., a fixed amount of work is expended on each coal, and a grindability value is determined from the size composition of the ground material.
Industry:Mining
This timber is used where the coal seam is separated by a rock band and one bench is loaded out before the other. If the top bench is worked off first, the jack posts are set between the bottom bench of the coal and the roof. If the bottom bench is cleaned up 1664 first, the jack posts are set between the bottom and the top bench. At least two jack posts should be used and as many more as is necessary to keep the top bench of coal or the roof from coming down while the coal is being loaded out.
Industry:Mining
This type of blasting is virtually benching on a large scale. The depth and burden of the holes are much greater, and in consequence, the hole diameter must also be increased to ensure sufficient concentration of the explosive charge. Wellhole blasting is used in limestones esp. if the beds are horizontal and well-defined. It is not often used in highly abrasive igneous rocks because of the cost of drilling.
Industry:Mining
This type of centrifugal pump is the most commonly used. The impellers may be open, closed or semienclosed, single suction, double suction, or nonclogging. They discharge into casings that are progressively expanding spiral designs of one or more stages (multistage). The casings housing the rotating elements may be vertically or horizontally split, and a few designs have casings divided on an angle from the horizontal. Pumps in this class usually have a specific speed below 4,000 rpm with single-suction impellers and a specific speed of 5,000 rpm with double-suction impellers.
Industry:Mining
This type of coal consists of more than 50% of cuticle, the fragments of which occur embedded in gelito-collinite, fusinito-collinite, and collinite of fusinitic nature. In addition to cuticle, spores, resin bodies, and fragments of finely fusinized and gelified tissue are present. Leaf parenchyme and stem tissue, bordered by cuticle, may also be seen. Hand specimens of this type of coal are grayish-black, matt or semimatt, finely striated, or sometimes even banded. The coal breaks angularly and generally has high ash. Cutinite coal occurs as thin bands in seams of different geological age, and its use is largely determined by the other forms of coal with which it is associated.
Industry:Mining
This type of coal consists of more than 50% of spores (microspores and megaspores). Other structured components uniformly distributed through the coal are cuticles, resin bodies, and gelified and fusinized tissues. Hand specimens of low rank sporinite coal are brownish, with matt or granular surfaces. The coal may have high or low ash and occurs in seams of different geological, age but is particularly common as bands of limited thickness in seams of the Lower Carboniferous. Sporinite coal naturally admixed with medium rank gelitocollinite coals is used for coking.
Industry:Mining
This type of collector is designed to remove very large dust particles. It is often used ahead of other collectors to reduce the dust load, and to remove the particles most likely to cause abrasion. The velocity reducing collector has no moving parts and, in most instances, can be installed in front of the induced draft fan, reducing the abrasion of the fan blades. This type of collector also can be used under many high-temperature conditions.
Industry:Mining
This type of excavator operates in general the same as a slackline cableway, except that it uses a bottomless scraper bucket that must convey its load over the ground instead of through the air. Like the slackline cableway, this machine is operated by a two-drum hoist that controls a track cable that spans the working area and a haulage cable that leads to the front of the bucket. Both cables are reeved through sheave blocks attached to a high guyed mast or tower at the head end of the installation. When the bucket comes in with a load and reaches the desired dumping point, a few rotations of the rear drum of the hoist serve to tighten the track cable and lift the bucket off its load; then the brake is 3346 released on the front drum that controls the haulage cable, permitting the empty bucket and carrier to glide back down the inclined track cable.
Industry:Mining
This type of motor has a stator similar to a squirrel cage motor, but the rotor has a directcurrent field winding with salient poles equal in number to the stator poles. The direct current is supplied to the field winding through slip rings. In addition to the direct3213 current field windings, the rotor normally has a squirrel cage (amortisseur) winding that is used for starting.
Industry:Mining
This type of pump consists essentially of three single-acting ram pumps side by side, either vertical or horizontal, and driven from a triple crankshaft with cranks set at angles of 120 degrees . The three-throw pump can deal with heads up to 1,000 yd (900 m) in a single lift.
Industry:Mining
