Control technology for the avoidance of the simultaneous occurrence of a methane explosion and spontaneous coal combustion in a coal mine: A case study

Methane gas explosions and spontaneous combustion of coal severely threaten mining production safety and efficiency. Methane drainage can reduce the risk of a methane explosion while it may intensify the self-ignition of coal. To understand the relationship between these two issues, a working face of the Xinji No.2 Coal Mine in China was studied. A model of high drill holes extraction (HDHE) is established and the methane concentration distribution and air leakage under four different drainage pressures (below atmospheric) were determined. The simulation results show that drainage pressures can control the methane concentration in the air, so as not to exceed a threshold value. However, these drainage pressures enlarged the size of the zone where spontaneous combustion could occur due to the increase in air leakage. The possibility of the coexistence of a methane explosion and spontaneous coal combustion was proposed. This is an important index for the selection of a reasonable methane drainage pressure. The monitoring data from the mine were used to validate the model.