- 行业: Mining
- Number of terms: 33118
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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 ...
A period of the Paleozoic, thought to have covered the span of time between 440 and 400 million years ago; also, the corresponding system of rocks. The Silurian follows the Ordovician and precedes the Devonian; in the older literature, it was sometimes considered to include the Ordovician. It is named after the Silures, a Celtic tribe.
Industry:Mining
A permanent main pump is one on which a mine depends for the final disposal of its drainage. As it is usually not moved during the life of the mine, its location, installation, and design require careful consideration. A permanent main pump may discharge on the surface, into an underground sump, or into some other part of a mine.
Industry:Mining
A permanent method of lining a circular shaft in which the tubbing (German type) is temporarily suspended from the next wedging curb above. Slurry is run in behind the tubbing by means of a funnel passing through the holes provided in the segments. No temporary supports are required.
Industry:Mining
A permanent stopping to seal off a large body or feeder of water. It consists usually of a block of concrete between two brick end walls and these are extended well into the surrounding ground. The contact points and all breaks in the strata are sealed by cement injection. The various pipes, pressure gages, etc., may be left through the stopping.
Industry:Mining
A permanent support for circular shafts. On reaching the rockhead, a firm ledge is prepared to receive the first bricking curb or ring. The curb is fixed correctly with reference to the centerline of the shaft. The bricks are then built upwards from the curb, the space behind being firmly packed to the rock sides with bricks and mortar. Concrete is replacing brickwork as a shaft lining.
Industry:Mining
A permanently frozen layer of soil or subsoil, or even bedrock, which occurs to variable depths below the Earth's surface in arctic or subarctic regions. It underlies about onefifth of the world's land area.
Industry:Mining
A permit, not including more than 2,560 acres (1,037 ha) in one State, is granted to prospect for chlorides, sulfates, carbonates, borates, silicates, or nitrates of sodium, and the royalty and rentals are similar to those for potash. Where necessary to secure the most economical mining, a person, association, or corporation may be permitted to hold up to 15,360 acres (6,221 ha) in one State.
Industry:Mining
A permitted device, used in some English coal mines, that resembles Cardox in that a steel cylinder with a thin shearing disk is used. However, the charge is not liquid carbon dioxide but rather a powder composed chiefly of ammonium chloride and sodium nitrate. It is proportioned to give water, nitrogen, and salt as the products of combustion. On being ignited, this powder is gasified and shears the steel disk, with the gas escaping into the hole.
Industry:Mining
A permitted explosive of medium strength, which can be used in wet boreholes provided its immersion time does not exceed 2 to 3 h. Can be used for coal and ripping shots in conjunction with short-delay detonators.
Industry:Mining
