Inhibition of Coal Spontaneous Combustion During Dynamic Mining in Adjacent Gob with Narrow Coal Pillars

The spontaneous combustion of residual coal in gobs due to air leakage in coal pillars during mining significantly impacts coal mine safety. However, current research predominantly focuses on gobs at the working face, with limited attention to the spontaneous combustion of residual coal in adjacent gobs caused by air leakage from narrow coal pillars influenced by mining activities. In this study, COMSOL Multiphysics software was employed to develop a dynamic extended "double" gob model separated by narrow coal pillars and the gob of the working face. The dynamic changes in the seepage, temperature, and concentration fields in the gob during mining were coupled and calculated. The results indicated that although small coal pillar mining is conducive to the prevention and control of impact ground pressure, the fire prevention work is under great pressure, and there is a risk and hidden danger of natural ignition in the small coal pillars and the adjacent gob. Dynamic mining affected the narrow coal pillar, increasing the air leakage channel and expanding the high-temperature area in the adjacent gob. Upon reaching the stopping mining line, a temperature anomaly area appeared on both sides of the narrow coal pillar near the stopping line. Additionally, the risk of spontaneous combustion near the goaf was positively correlated with the wind speed in the roadway. Sensitivity analysis of the primary inhibiting factors for coal spontaneous combustion in the adjacent gob revealed that reducing air intake speed and ensuring the working face advances no less than 6 m/day are critical. Strengthening gas and temperature monitoring in the adjacent gob and timely implementation of leak-proof measures on the narrow coal pillars are essential to prevent spontaneous combustion. These findings provide guidance for managing the narrow 2131 (3) coal pillar working face gob of the Xieqiao Mine.