Effect of Igneous Intrusions on Low-temperature Oxidation Characteristics of Coal in Daxing Mine, China

Abstract

ABSTRACT In order to investigate the effect of igneous intrusions on low-temperature oxidation characteristics of coal, metamorphic coal samples affected by igneous intrusions and normal coal samples were collected from Daxing Mine. The thermal effect of coal at a low temperature was studied by Thermogravimetric analysis and Differential scanning calorimetry (TG-DSC). The oxidation kinetics experiment was used to analyze the oxygen consumption, the index gas, the crossing point temperature (CPT) and apparent activation energy of coal. Compared with normal coal, the metamorphic coal had lower weight loss rate and higher oxygen absorption rate due to igneous intrusions. At the same time, the metamorphic coal absorbed less heat at low-temperature stage and entered the exothermic stage first, and the total heat release in the whole stage was larger. The author also found that the initial exothermic temperature of coal decreased obviously due to igneous intrusions. In addition, metamorphic coal had lower apparent activation energy because of igneous intrusions, which indicated that the molecular structure of coal became easy to be activated, and the energy needed for activation became lower. Fourier transform infrared spectroscopy (FTIR) analysis suggested igneous intrusions changed the chemical structure of coal and increased the branching degree and short aliphatic chains. Moreover, metamorphic coal consumed more oxygen and produced more carbon monoxide, ethylene and ethane, with lower crossing point temperatures, which concluded that the igneous intrusions accelerated the oxidation reaction of coal at low-temperature stage and increased the spontaneous combustion risk of Daxing coal.