Comparative analysis of exothermic behaviour of fresh and weathered coal during low-temperature oxidation

摘要

Spontaneous combustion of weathered coal is the main hazard in coal-rich countries which needs to be addressed. The exothermic behaviour of weathered coal on low-temperature oxidation was investigated in fresh and weathered coal during spontaneous combustion. The variation law of thermal diffusivity, specific heat, and thermal conductivity of weathered coal on spontaneous combustion oxidation was analysed using the laser flash technique. Weathered coal thermal conduction characteristics were enhanced compared with fresh coal. On the basis of differential scanning calorimetry results, the characteristics of the thermal effect during the low temperature oxidation of weathered coal were studied by conducting C80 micro thermal. The exothermic onset temperature and total thermal energy of weathered coal were lower than those of fresh coal, as the thermal release showed distinct stage characteristics. The exothermic characteristics of various reaction stages were determined. The influence of the heating rate during the low-temperature reaction of weathered coal was evaluated. The heat flow obtained using the iso-conversion method indicated that the apparent activation energy of weathered coal varied with the reaction process. The results can provide a basis for the prevention and control of spontaneous combustion of weathered coal.