Method of supporting the roof during the winning of deep-seated coal

摘要

Coal in very deep-seated seams is extracted from one or more boreholes by blasting or milling or shearing and is conveyed to the surface by means of a liquid flowing through the borehole and the extraction cavern. Hydrophobic material is added to the transport liquid. The hydrophobic material is not soluble in the transport liquid and is specifically lighter and thereby floats so that a barrier layer is built up between the transport liquid and the roof in the extraction cavern.