Method of stabilising the roof during the mining 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. Mineral oil is added to this transport liquid. The mineral oil is mixed with finely suspended substances capable of swelling in water. These substances have a certain adhesiveness in the swollen state and thereby close gaps and cracks in the roof.