Research on the influence law and its causes of inert gas injection port depth and air leakage sealing distance on the spontaneous combustion hazard zone in high-gas mines

Due to the fact that gas drainage carried out in high-gas mines to address gas issues may exacerbate the spontaneous combustion of coal in goaf areas, and fires may disrupt normal production, it is necessary to adopt appropriate fire prevention and suppression measures. This paper takes Yangquan No. 5 Mine as the background and investigates the influence of the inert gas injection port depth and air leakage sealing length on the spontaneous combustion hazard zone under gas drainage conditions by combining experiments and simulations. The reasons for the influence were explained from the perspectives of the flow field and concentration flux field. The results show that the best effect is achieved when inert gas is injected at the junction of the oxidation zone and the heat dissipation zone, as the inert gas coverage is most balanced at this point. The relationship between the distance of air leakage sealing and the area of the oxidation zone has been determined. Blindly increasing the distance of air leakage sealing will be counterproductive. Starting from the intake side, the optimal sealing length is the average of the horizontal distances from the low-level suction roadway and the high-level suction roadway to the intake airflow roadway, and the oxidation zone area can be reduced by up to 45%. This research outcome has guiding significance for the reasonable determination of on-site fire prevention process parameters.