continuous room-and-pillar mining

Continuous room-and-pillar mining is an underground mining method where parallel entries are driven into a coal seam. Wider rooms are cut at right angles to these entries, creating pillars of coal that support the overlying rock and earth.1

There are two main systems: conventional, which uses separate machines for cutting, drilling, blasting, and loading, and continuous. Continuous mining employs a single machine, the continuous miner, to break coal from the face and load it directly onto a hauling unit. This method is efficient for extracting coal from flat-lying deposits. Between 30% and 50% of the coal can be recovered during the initial development of the pillars. While removing pillars can increase recovery, it must be done carefully to manage stress on remaining pillars and ensure miner safety. This method becomes challenging at depths greater than 400 to 500 meters due to excessive roof pressure.123