Structural Features of Coals and Their Proneness to Spontaneous Combustion

Abstract

The paper presents the results of an assessment of the influence of coals’ structural features on their proneness to spontaneous combustion. Fifteen samples of hard coals and anthracite from different deposits of the Russian Federation were used as objects of study. Based on the deconvolution of coal vitrinite Raman spectra, a structural index characterizing the ratio between amorphous and crystallite forms of carbon compounds has been identified. It is noted that this index differs significantly for coals with a close stage of metamorphism. For the studied coals, the activity to ozone was determined for two types of sites that are differing in the rate of deactivation when interacting with it. It is shown that the activity of sites of the first type (with a higher deactivation rate when interacting with ozone) grows with an increase in the proportion of crystalline carbon in the coals’ vitrinite. Whereas, the activity of sites of the second type (with a low rate of deactivation) generally decreases. The kinetic parameters of coal combustion (ignition temperature and activation energy) were estimated according to their thermogravimetric analysis in the air environment. It is shown that with an increase in the proportion of amorphous carbon compounds in vitrinite of coals, both the ignition temperature and the activation energy of coal combustion decrease, which altogether leads to an increase of a risk of spontaneous combustion.