Transformation and migration of key elements during the thermal reaction of coal spontaneous combustion

Abstract

As deep coal mining continues to expand, the problem of coal spontaneous combustion (CSC) becomes increasingly severe, posing a significant threat to the safe extraction of energy resources. For preventing CSC, it is of great significance to determine the relationship between the content changes of major elements in the constituent coals and CSC, and it is a necessary study to reveal the mechanism of CSC. By utilizing elemental analyzers, it was found the coal experienced dominant changes in O/C ratios up to 120 °C, H/C ratios between 120 and 270 °C, and O/C ratios beyond 270 °C; By employing a correlation approach, it was determined that the key elements influencing heat release during CSC, i.e., C, H, and O. Additionally, with the key elements as monomers, the migration and transformation process of its mutual composition and structure was investigated, and mastered the influence of elemental migration on the thermal reaction properties in the CSC, as well as uncovering migration and transformation pathways in the CSC. Meanwhile, both the critical groups and temperatures that promote CSC generation were obtained, i.e., –CH2, –CO, and 150 °C, It is expected that the study results may provide theoretical support for the development of fire extinguishing materials.