Molecular simulation and experimentation studies on the low-temperature oxidation of water-containing coal in the goaf atmosphere

The moisture content of coal tends to have a significant impact on the occurrence of spontaneous combustion. In the present study, both molecular simulation and experimental investigation are performed to examine the interaction among water-containing coal and O2 in the goaf atmosphere, with the following conclusions drawn. Firstly, the presence of water and methane impedes the physical adsorption of coal and oxygen at a temperature of 298K. Methane mainly hinders the contact between coal and oxygen through the reduced concentration of oxygen and competitive adsorption. The increase in water content reduces the adsorption density of each gas but makes no difference to their relative proportions in the amounts of adsorption. At the initial stage of coal oxidation (30 degrees C-80 degrees C), the rate of oxygen consumption declines with a rise in water content. However, it is observed immediately after entry into the rapid oxidation stage (80 degrees C-230 degrees C) that the coal sample with a water content of 9.05% is the highest in the intensity of reaction. A higher concentration of methane in the initial atmosphere produces an inhibitory effect on both oxygen adsorption and chemical reaction, which is effective in reducing spontaneous combustion.