Experimental studies of spontaneous combustion and anaerobic cooling of coal

To study the spontaneous combustion and anaerobic cooling of coal, a 15-t experimental furnace was constructed, and large-scale spontaneous combustion tests were conducted. The coal sample came from No. 3 seam in Dongtan mine in Yanzhou coalfield, Shandong province, China. The variations in temperature, gas ratios, oxygen consumption rate, and heat intensity were studied. The experimental results show that for coal spontaneous combustion below 70 °C, the temperature increases slowly with time and the oxygen consumption rate and heat intensity increase slowly with temperature and accelerate when the temperature exceeds 100 °C. In anaerobic cooling, the cooling rate decreases with the decrease in temperature. When the coal temperature goes from 452.7 to 250.0 °C, the cooling rate decreases rapidly, whereas below 250.0 °C, the cooling rate decreases slowly. The variation trends of the CO2/CO, CH4/C2H6, C2H4/C2H6, and C3H8/C2H6 gas ratios in the spontaneous combustion and anaerobic cooling of coal in a certain range of temperature can be used to predict the temperature of coal.