Drift mine�C An underground coal mine in which the entry or access is above water level and generally on the slope of a hill, driven horizontally into a coal seam.

Drill- A machine utilizing rotation, percussion (hammering), or a combination of both to make holes. If the hole is much over 0.4m in diameter, the machine is called a borer.

Drilling- The use of such a machine to create holes for exploration or for loading with explosives.

Dummy- A bag filled with sand, clay, etc., used for stemming a charged hole.

Dump- To unload; specifically, a load of coal or waste; the mechanism for unloading, e.g. a car dump (sometimes called tipple); or, the pile created by such unloading, e.g. a waste dump (also called heap, pile, tip, spoil pike, etc.).

E

Electrical grounding- To connect with the ground to make the earth part of the circuit.

Entry- An underground horizontal or near-horizontal passage used for haulage, ventilation, or as a mainway; a coal heading; a working place where the coal is extracted from the seam in the initial mining; same as "gate" and "roadway," both British terms.

Evaluation- The work involved in gaining a knowledge of the size, shape, position and value of coal.

Exploration- The search for mineral deposits and the work done to prove or establish the extent of a mineral deposit. Alt: Prospecting and subsequent evaluation.

Explosive- Any rapidly combustive or expanding substance. The energy released during this rapid combustion or expansion can be used to break rock.

Extraction- The process of mining and removal of cal or ore from a mine.

F

Face�C The exposed area of a coal bed from which coal is being extracted.

Face cleat- The principal cleavage plane or joint at right angles to the stratification of the coal seam.

Face conveyor- Any conveyor used parallel to a working face which delivers coal into another conveyor or into a car.

Factor of safety- The ratio of the ultimate breaking strength of the material to the force exerted against it. If a rope will break under a load of 6000 lbs ., and it is carrying a load of 2000 lbs ., its factor of safety is 6000 divided by 2000 which equals 3.

Fall- A mass of roof rock or coal which has fallen in any part of a mine.

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