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| the federal coal min health and safety act of 1969 |
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| a nearly horizontal passage from the surface by which a mine is entered and dewatered. a blind horizontal opening into a mountain, with only one entrance |
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| exploitation in the same direction, or order of sequence, as development is known as mining in advance |
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| any passage through which air is carried. (also known as aircourse) |
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| allubial deposit; placer deposit |
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Definition
| earth, sand, gravel, or other rock or mineral materials transported by and laid down by flowing water. alluvial deposits generally take the form of (1) surface deposits, (2) river deposits, (3) deep leads, and (4) shore deposits. |
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| in coal mine subsidence, this angle is assumed to bisect the angle between the vertical and the angle of repose of the material and is .3 rad for flat seams. for dipping seams, the angle of break increases, being .6 rad from the vertical and .7 rad dip. the main break occurs over the seam at an angle from the vertical equal to half the dip |
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| any deviation from uniformity. a distinctive local feature in a geophysical or a geochemical survey over a larger area. an area or a restricted portion of a geophysical survey, such as a magnetic survey or a gravity survey, that differs from the rest of the survey in general. the anomaly might be associated with petroleum, natural gas, or mineral deposits, or provide a key to interpreting the underlying geologic structure. drilling for economic mineral deposits might be conducted in the area of a geophysical anomaly. in seismic usage, anomaly is generally synonymous with structure, but it is also used for spurious or unexplainable seismic events or for local deviations of potential functions which cannot be exclusively attributed to a unique cause |
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| coals with a volatile-carbon ratio equal to 0.12 or less |
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| a water-bearing bed of porous rock, often sandstone |
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| a rotary drill for soft materials that uses a screw device to penetrate, break, and then transport the drilled material. auger-type devices are popular in soft coal. to aid penetration and decrease wear on the auger rods, a hard-faced bit is used at the contact between drill and fresh material |
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| all activites supportive of but not contributing directly to the winning of ore, coal, or stone. |
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| Btu (British thermal units) |
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Definition
| the quantity of heat required to raise the temperature of one pound of distilled water 1F at it's point of maximum density |
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| the roof or upper part in any underground mining cavity |
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Definition
| said of rock or vein material containing no minerals of value, and of strata without coal, or containing coal in seams too thin to be workable |
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