Coupling study of gas extraction and coal spontaneous combustion in goaf adjacent to extra-thick spontaneous combustion coal seam in Yanbei Coal Mine

The slicing method is applied to the extra-thick spontaneous combustion coal seam in Yanbei Coal Mine. In the process of advancing the working face, the gas in the corner of the working face instantaneously exceeds the limit due to periodic weighting. At present, the problem is mainly solved by gas extraction, but gas extraction near the goaf is easy to cause air leakage in goaf, which may leads to spontaneous combustion of residual coal and coal in the lower layer. In order to analyze the influence of gas extraction in goaf on spontaneous combustion of left coal and optimize the extraction parameters, the coupled script file of gas extraction, air leakage and oxidation temperature rise was compiled. The numerical calculation model of coupled oxidation temperature rise of gas extraction in adjacent goaf was established, and the distribution law of gas concentration, temperature and oxygen concentration in adjacent goaf under different extraction conditions was simulated by this model, considering the extraction efficiency and the prevention of coal oxidation spontaneous combustion. The results show that the best extraction effect is obtained when the height of the hole is 35 m and the negative pressure is 7 kPa. The research results can provide technical reference for gas control in corner of working face and gas extraction design in adjacent goaf of extra-thick spontaneous combustion coal seam.