Study on Gas Control Technology and Protect Scope of Lower Protective Seam Mining

The gas content of Jinjia Mine mid-coal group was great, and there was outburst risk in the coal seam, gas control effect was worse and it was hard for a dvancing of the face while downward mining.ln order to smooth recovery the coal group, the paper carried out related research through theoretical analysis, numerical s imulation and field measurement methods on the choice of first coal group, gas control and investigation of the protective layer face.The study showed that it was best t 0 take No.22 coal seam as the protective layer, the protective effect to the main coal seam was well.The scope of protection angle in inclined direction 01 and 62 was 5 4° and 82°，protection angle in strike direction 85 was 53° .During protective seam mining process, the average gas drainage quantity was 72.9 m3/min, the gas drainag e rate of working face reached to 84.3%91 .6%，the average gas concentration of the return air lane was 0.25%，gas control effect was remarkable.