Gas control technology and engineering practice for three-soft coal seam with low permeability in XuanGang region, China

Underground coal mining needs effective technical methods for the control of gas emissions in order to be able to work under safe conditions. Based on the coal seam geological conditions among the Xuan Gang region, a major part of theoretical research and technical development has been directed to this purpose. According to the roles of mining fractures development and relief gas flow, a novel method for the comprehensive gas drainage was proposed and engineering practiced in the mining field, which includes long drilling boreholes, oblique crossed boreholes and upper corner flexible drainage pipelines. Compared with previous gas control measurements, the total gas drainage ratio significantly enhanced from 30% to 67.33% (No.51109 working face) and 76.44% (No.51105 working face). The ventilation air methane concentration of working face greatly decreased down to about 0.3%. Field tests shows that it is an effective method for gas control, which ensured the safety production of underground coal mine. The proposed gas drainage technology provides a novel approach for the three-soft coal seam gas management in China.