Research on combined gas extraction technology of high andbottom extraction lane in high gas mine

In order to solve the problems of low extraction efficiency, low extraction concentration, poor permeability of coal seam and difficulty in drilling holes in the gas management of U-ventilated return working face of loose and low-permeability coal seams, the combined gas extraction technology of high and bottom roadway in high gas mine is proposed. The research object of this paper is 1307 fully mechanized mining face of Zhaozhuang Mine of Shanxi Jin Coal Group. The technology consists of a high extraction lane, a central bottom extraction lane and a side bottom extraction lane on the basis of the original U-shaped ventilation. The side bottom extraction lane covers the drilling of two heading faces, the central bottom extraction lane penetrates the strip of the seam area to pre-pump the gas of the coal seam, and the high extraction lane extracts the gas from the upper corner. This study proposes the position of the side bottom extraction lane and the central bottom extraction lane, and proposes the drilling arrangement and the reasonable layer arrangement of the high extraction lane. The practical application results show that the maximum gas volume fraction of the coal working face covered by the side bottom extraction lane is 0.48%, and the extraction through the layer drilling reduces the gas emission from the heading face effectively. After the central bottom extraction lane extracting the gas from this coal seam, the gas content decreases by 4.18 m3/t on average. As the negative pressure of the high extraction lane is 12-15 kPa, the pure extraction volume is stable at about 46.13 m3, which reduces the gas emission to the working face.