Low Oxygen Comprehensive Treatment Technology of Fully Mechanized Mining Face in Very Close Coal Seams

In order to effectively control the problem that the oxygen concentration is not up to the standard in the upper corner of the working face and the return air roadway, by the technique of large diameter borehole of overburden layer and casing hole pretection drainage, air ejector and upper and lower ends plugging, the effect of controlling gas leakage from overburden goaf and instantaneous gas emission from roof caving was studied. The results show that drainage volume was increased by 40% under the drainage technology of large diameter borehole with casing hole protection drainage. The oxygen concentration in the upper corner was increased by 7.4% under the comprehensive application of large diameter borehole with casing hole protection drainage technology, air ejector and plugging method at the upper and lower ends.