Multi-Scale Characteristics of Coal Secondary Spontaneous Combustion Under Different Pre-Heating Oxygen Concentrations by TG and FTIR Analysis

The study aimed to explore the influence of pre-oxidation oxygen concentration on the mass variation and microstructure of coal oxidation using TG and FTIR experiments. The objective was to comprehend the thermal effects and mechanisms of coal oxidation under distinct pre-oxidation conditions. Employing fuzzy mathematics and multiple linear regression equations, the study sought to elucidate the influence mechanism of pre-oxidation oxygen concentration on the thermal effect. The findings reveal that pre-oxidation did not alter the overall weight loss pattern during the spontaneous combustion process of coal, yet significantly accelerated the rate of weight loss. Furthermore, the dry cracking temperature experienced a notable advancement. Through FTIR experiments, it was observed that pre-oxidation activated the reactivity of C=O, -CH2-, and aromatic hydrocarbons, thus leading to more intense reactions. The key functional groups influencing the mass change were identified as aromatic hydrocarbons and hydrogen bonds. Notably, the pre-oxidation effect on the thermal impact was most pronounced when the pre-oxidation oxygen concentration reached 15%.