METHOD OF WEAKENING OF COAL SEAM (VERSIONS) Russian patent published in 1997 - IPC

FIELD: mining; preparation of coal mass for mining. SUBSTANCE: method includes drilling hole in coal seam into treated zone, supply of carbon dioxide at pressure not below the threshold value. Distinguishing feature of the technical solution of version one is the fact, that pressure in hole exceeds the threshold value, but is less than seam hydraulic fracturing pressure, by means of injection of water into holes up to full saturation of treated zone. Then water pressure is increased in holes up to hydraulic fracturing of seam, and water is injected until pressure in hole is less than threshold one. According to the other version, after complete water saturation of treated zone and increase of pressure in holes up to hydraulic fracturing of seam, injection of water is periodically discontinued, and injected again up to maximum attained pressure of hydraulic fracturing until it becomes below the threshold value. EFFECT: higher efficiency. 2 cl