Study on the Structural Changes and Spontaneous Combustion Characteristics of Coal Oxygen Composite Reaction

The study of structural changes and spontaneous combustion characteristics of the coal oxygen composite reaction is the key to preventing coal spontaneous combustion. In this study, gas coal from the 12-2 coal seam of the Donghuantuo Coal Mine was selected for sampling. Various characterization methods were used to conduct elemental analysis on the raw coal and preoxidized coal samples at different degrees as well as surface and internal characteristic analysis on the raw coal and oxidized coal samples to explore the pore distribution of the coal samples and the conversion law of pores with different pore sizes. Simultaneously, the main functional groups and distribution characteristics of different coal samples during low-temperature oxidation were determined, and combined with the analysis of gas products produced by programmed heating, the gas production law and oxygen consumption rate changes were determined by combining the microstructural changes and macroscopic characteristics of coal. The research findings indicate that the pore structure and morphology in coal are greatly affected by temperature, exhibiting a transition from a small number of micropores and a large number of transition pores to medium to large pores in the range of 0-80 °C. The higher the degree of oxidation of coal samples, the lower the content of internal fatty hydrocarbons and the total content of oxygen-containing functional groups. Coal preoxidation shows an exponential rapid increase in CO and CO₂ with the continuous increase of temperature. This study provides scientific measures and a theoretical basis for the prevention and control of the coal spontaneous combustion process.