Effects of igneous rock erosion on spontaneous combustion properties and structure of coal

In order to explore the influence law of igneous rock erosion on coal spontaneous combustion characteristics and structure, taking primary coal and igneous rock eroded coal in the same coal face of Shanxi Mine and Liaoning Mine as the samples, the oxidation characteristics, the limit parameters of the spontaneous combustion, the content of the active functional group and pore structure characteristics of coal were analyzed from macro and micro perspectives by temperature programmed test, FT-IR experiment, low temperature nitrogen adsorption experiment and mercury injection experiment respectively. The results of temperature programmed test showed that igneous rock erosion increased the spontaneous combustion risk of coal, igneous rock erosion could enhance the gas circulation inside the coal body, which is conducive to the oxidation reaction between oxygen and active groups inside the coal body, and the coal body of the igneous erosion had higher oxidizing activity. In addition, igneous rock erosion altered the occurrence conditions of coal seams, increased the difficulty of coal seams mining and the intensity of wind leakage in the mining airspace, prolonged the oxidation time of the residual coal in the “oxidized heating zone” in goaf, thus increasing the risk of spontaneous combustion of coal from the level of external influencing factors. The erosion of igneous rock changes the structure of coal itself and the external environmental factors of coal spontaneous combustion, which intensifies the spontaneous combustion risk of the eroded coal seam.