Underground Mining

There are two main methods of extracting coal by underground mining: room-and-pillar (or, bord-and-pillar) and longwall mining.

Room-and-pillar mining involves cutting a network of ‘rooms’ or panels into the coal seam and leaving behind ‘pillars’ of coal to support the roof of the mine. Initially, recoveries are reduced (to 50–60 %) because of the coal left in the pillars—however, this coal can sometimes be recovered at a later stage of mine life.

Longwall mining involves the use of mechanised shearers to cut and remove the coal at the face, which can vary in length from 100 to 250 metres.

Self-advancing, hydraulic-powered supports temporarily hold up the roof while the coal is extracted. The roof over the area behind the face, from which the coal has been removed, is then allowed to collapse. Over 75% of the coal in the deposit can be extracted using this method.