Controlled blasting technique to improve gas pre-drainage effect in a coal mine

Gas pre-drainage is the main solution to solve gas disaster problems. The efficiency of gas pre-drainage, however, is low by far. The method of controlled blasting was investigated to improve the effect of gas pre-drainage. Such problems as safe ignition in high-gas coal bed, charging technique in a long horizontal borehole, and selection of explosives were solved. After the blasting, the amount of gas selfdrainage is more than 5 times that in the non-blasting area, the efficiency of gas pre-drainage is improved, and pre-drainage time is less than 2/3 of the original time.