Correlation between oxygen concentration and reaction rate of low-temperature coal oxidation: A case study of long-flame coal

Coal spontaneous combustion (CSC) is one of the main disasters that plague coal mine safety production. It is of great significance to clarify the relationship between coal oxidation reaction rate and oxygen concentration for the prevention and control of CSC disasters. In the present study, an improved model of coal oxidation reaction order is established based on previous studies. Taking long flame coal as an example, the nonlinear relationship between coal oxidation reaction rate and oxygen concentration is obtained. In addition, the variation of oxidation kinetic parameters was studied, and the actual oxygen consumption rate of coal oxidation was calculated. The results show that oxidation reaction order of the experimental coal samples was generally <1, and a stage linear change with temperature (clear mutations occurred at 60, 90, and 160 °C), indicating a nonlinear relationship between oxidation reaction rate and oxygen concentration. The calculation results of two coal oxygen consumption rate models were compared. Under the first-order assumption, the error rate of the calculation results can reach 50.86%, and the slight change of reaction order has a great influence on the reaction rate. The results can provide a theoretical basis for accurate analysis of coal–oxygen composite reaction rates.