Study on Stereo Gas Extraction Laws and Effect in Extremely Thick Anthracite Coal Seam

According to the characteristics of high gas content and high gas emission in extremely thick coal seam of Baijigou Mine, the technology of floor through beds hole combined with long directional hole and drilling holes along seam at work face was proposed in order to solve gas exceeding the limit in mining period, and the gas extraction law was analyzed in field practice. The result showed that gas flow and gas concentration were stable after being decreased with the change of time, and the gas flow and gas concentration presented the laws of first increase and then decrease with the advancing of working face; after the pre-drainage of 0102¹02 first layering working face, the maximum gas content that could be desorbed reached 5.354 8 m³/t, the residual gas content was 2.82 m³/t, the result reached the standard; the maximum gas concentration of return air was 0.58%, the gas concentration of upper corner was 0.66% in mining period, the length of safe mining was 1 100 m without gas exceeding the limit. The high gas emission was controlled perfectly.