Study on coupling control of gas drainage and gas control with nitrogen injection and fire prevention in goaf by long roof borehole replacing high drainage roadway
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Abstract
High gas mine is easy to spontaneous combustion coal seam, working face is threatened by gas exceeding limit in upper corner and spontaneous combustion of residual coal in goaf.In order to solve the contradiction between gas drainage in high gas extraction roadway and enlargement of oxidation zone area in goaf and increase the risk of spontaneous combustion of residual coal.The roof long borehole is used to replace the high extraction roadway, and the side injection of nitrogen into the air intake roadway is used.Through optimizing the parameters of long borehole and nitrogen injection, the coupling control of fire prevention and gas control is studied.Based on the measured data of 1401 working face of Zhongxing Coal Industry and ANSYS numerical simulation, the influence of the number and location of long boreholes on the gas in the upper corner of working face is studied.The optimum scheme of replacing high extraction roadway with 5 roof long boreholes of 300 mm in diameter, 10 m away from return air roadway and 15 m away from the floor plate of coal seam is obtained.On this basis, in order to ensure effective control of spontaneous combustion of residual coal in goaf, the effects of nitrogen injection amount and location on distribution of oxidation zone in goaf are studied.The optimal results are obtained by injecting 5.5 m3/min nitrogen into the boundary of oxidation zone and heat dissipation zone on the side of air inlet roadway and reducing the oxidation zone width of goaf to 25 m.Through the comprehensive control of gas in upper corner and spontaneous combustion of residual coal in goaf, the safe production of working face is guaranteed.
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