Discussion on prevention and control experience of coal spontaneous combustion in 8.8 m super large mining height working face

The monitoring data of coal spontaneous combustion in super large mining height working face includes gas concentration, temperature, etc. The research methods include experiments, numerical simulations, on site measurements, etc. Most of the existing studies have not considered the relationship between the indicators, and the research methods and data analysis methods are single. In order to solve this problem, taking the working face with a mining height of 8.8 m in Shangwan Coal Mine as an example, this paper analyzes the correlation between gas concentration and temperature in the process of coal spontaneous combustion and summarizes the law and characteristics of fire in the goaf area through a combination method of coal spontaneous combustion experiment, on-site "three zone" measurement and numerical simulation. A surface borehole nitrogen injection model is established, and the changes of O2 concentration field, CO concentration field, temperature field and "three zone" distribution before and after the nitrogen injection measures are inverted. For the high temperature abnormal area, the nitrogen injection location is selected according to the numerical simulation results. And the combined method of surface nitrogen injection and mine nitrogen injection is adopted to reduce the fire hazard. The research results show that CO can be used as an indicator gas for predicting coal spontaneous combustion, O2 and CH4 cannot be used as indicator gases, and C2H6, C2H4, C2H2 and H2 can be used as auxiliary indicator gases. After the nitrogen injection measures are taken, the width of the oxidation heating zone is greatly reduced, and the CO volume fraction is significantly reduced. The highest temperature drops rapidly and the inerting effect is significant. The CO volume fraction and temperature in the high temperature abnormal area show a gradual decrease trend, which verifies the rationality of the nitrogen injection location and the effectiveness of nitrogen injection measures.