bank

In underground coal mining, the bank is the exposed surface of the coal seam that miners are actively working against. It is the vertical or near-vertical face where the coal is being cut, undercut, or otherwise detached from the surrounding strata. The bank advances as extraction proceeds, moving deeper into the seam. This is the primary working surface where picks, cutting machines, or explosives are applied.

The condition of the bank directly affects productivity and safety. A clean bank with good roof control allows faster advance and safer work; a friable or unstable bank sheds coal dust and loose material, creating hazards and slowing extraction. Miners assess bank angles, coal quality, and structural stability before beginning a shift. The thickness of the coal at the bank, which varies seam by seam and even location to location, determines how much material must be removed and influences the choice of mining method.

Bank geometry and working depth

The bank height, or the vertical distance being worked, varies with pit design and equipment capability. Longwall operations may maintain banks 3 to 4 meters high; older pillar and stall methods often worked smaller bank heights. The term bank is sometimes applied to the main coal face in any seam workings, whether it is a single vertical edge or a sloping surface where gravity assists material handling.

The bank is distinct from the face in that face can refer to the entire working area, whereas bank refers specifically to the coal surface being cut or mined at that moment. As the bank advances, old working areas become part of the gob (waste or worked-out ground). Safety depends on keeping the bank properly supported and free of unstable overburden.