al in shape, which may drop out of the roof of a mine without warning. The origin of this feature is thought to be the remains of the stump of a tree that has been replaced by sediments so that the original form has been rather well preserved.Kerf- The undercut of a coal face.
L
Lamp- The electric cap lamp worn for visibility. Also, the flame safety lamp used in coal mines to detect methane gas concentrations and oxygen deficiency.
Layout- The design or pattern of the main roadways and workings. The proper layout of mine workings is the responsibility of the manager aided by the planning department.
Lift- The amount of coal obtained from a continuous miner in one mining cycle.
Liquefaction�C The process of converting coal into a synthetic fuel, similar in nature to crude oil and/or refined products, such as gasoline.
Lithology- The character of a rock described in terms of its structure, color, mineral composition, grain size, and arrangement of its component parts; all those visible features that in the aggregate impart individuality of the rock. Lithology is the basis of correlation in coal mines and commonly is reliable over a distance of a few miles.
Load- To place explosives in a drill hole. Also, to transfer broken material into a haulage device.
Loading machine- Any device for transferring excavated coal into the haulage equipment.
Loading pocket- Transfer point at a shaft where bulk material is loaded by bin, hopper, and chute into a skip.
LongwallMining�C One of three major underground coal mining methods currently in use. Employs a steal plow, or rotation drum, which is pulled mechanically back and forth across a face of coal that is usually several hundred feet long. The loosened coal falls onto a conveyor for removal from the mine.
Loose coal- Coal fragments larger in size than coal dust.
Low voltage- Up to and including 660 volts by federal standards.
M
Main entry- A main haulage road. Where the coal has cleats, main entries are driven at right angles to the face cleats.
Main fan- A mechanical ventilator installed at the surface; operates by either exhausting or blowing to induce airflow through the mine roadways and workings.
Manhole- A safety hole constructed in the side of a gangway, tunnel, or slope in which miner can be safe from passing locomotives and car. Also called a refuge hole.
Man trip- A carrier of mine personnel, by rail or rubber tire, to and from the work area.
Manway- An entry used exclusively for personnel to travel form the shaft bottom or drift mouth to the working section; it is always on the intake air side in gassy mines. Also, a small passa
��һҳ[1][2][3][4][5][6]��һҳ
