Auxiliary ventilation- Portion of main ventilating current directed to face of dead end entry by means of an auxiliary fan and tubing.

Azimuth- A surveying term that references the angle measured clockwise from any meridian (the established line of reference). The bearing is used to designate direction. The bearing of a line is the acute horizontal angle between the meridian and the line.

B

Back- The roof or upper part in any underground mining cavity.

Backfill�C Mine waste or rock used to support the roof after coal removal.

Barren- 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.

Barricading- Enclosing part of a mine to prevent inflow of noxious gasses from a mine fire or an explosion.

Barrier- Something that bars or keeps out. Barrier pillars are solid blocks of coal left between two mines or sections of a mine to prevent accidents due to inrushes of water, gas, or from explosions or a mine fire.

Beam- A bar or straight girder used to support a span of roof between two support props or walls.

Beam building- The creation of a strong, inflexible beam by bolting or otherwise fastening together several weaker layers. In coal mining this is the intended basis for roof bolting.

Bearing�C A surveying term used to designate direction. The bearing of a line is the acute horizontal angle between the meridian and the line. The meridian is an established line of reference. Azimuths are angles measured clockwise from any meridian.

Bearing plate- A plate used to distribute a given load. In roof bolting, the plate used between the bolt head and the roof.

Bed- A stratum of coal or other sedimentary deposit.

Belt conveyor- A looped belt on which coal or other materials can be carried and which is generally constructed of flame-resistant material or of reinforced rubber or rubber-like substance.

Belt idler- A roller, usually of cylindrical shape, which is supported on a frame and which, in turn, supports or guides a conveyor belt. Idlers are not powered but turn by contact with the moving belt.

Belt take-up- A belt pulley, generally under a conveyor belt and inby the drive pulley, kept under strong tension parallel to the belt line. Its purpose is to automatically compensate for any slack in the belting created by start-up, etc.

Bench- One of to or more divisions of a coal seam separated by slate or formed by the process of cutting the coal.

Beneficiation- The treatment of mined material, making it more concentrated or richer.

Berm- A pile or mound of material capable of restraining a vehicle.

Binder- A streak of imp

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