Study of Gases and Thermal Behavior of Oxidized Coal during Spontaneous Combustion Process

Abstract

Coal spontaneous combustion is one of the most severe and constant hazards in the coal industry. Understanding the mechanisms is the basis for effective hazard control in the coal-producing process. This paper investigated two types of oxidized coal samples from the re-mining faces of an underground coal mine. Proximate analysis, elemental analysis, surface analysis, temperature-programmed experiments, and differential scanning calorimetry analysis were conducted to study the spontaneous combustion characteristics. Various reaction mechanism functions were adopted to calculate the kinetic parameters, and multiple linear regression was performed to simulate the reaction behavior. The results show that the thermal decomposition of the oxidized coal followed a two-stage reaction model. The first stage reaction occupied smaller apparent activation energy and promoted the second stage reaction, dominating the heat production. Therefore, significant prevention measures for coal spontaneous combustion should be conducted and emphasized appropriately in the first stage to break the continuous reaction. The findings of this study can serve as a reference for predicting and preventing spontaneous combustion of oxidated coal.