Study on the oxidation and heating characteristics of residual coal in goafs under different air-leakage conditions

The spontaneous combustion of broken coal is one of the main causes for mine safety accidents in goafs. To determine the effect of different air-leakage conditions on the spontaneous combustion of leftover coal, the air-leakage passage of the goaf was designed based on the principle of Sudoku grid in an inflammable coal seam. The temperature rise during the auto-ignition oxidation of coal was studied using a self-built experimental platform. By changing the air-flow rate, the laws of the change in the oxygen consumption rate and the heat release intensity with the coal temperature were analyzed. Results show that the oxygen consumption rate had three obvious peaks at 48°C, 75°C, and 105°C, respectively. Above 80°C, spontaneously combustion of the experimental coal samples began. The exothermic intensity increased exponentially with the rise of temperature. Furthermore, an exponential relationship was observed between the air supply at the working face and the spontaneous combustion of broken coal in the goaf. In addition, the increase in air supply in the fully-mechanized mining face increased the width of the oxidation zone