Study on Characteristics of Coal Spontaneous Combustion in Kerjian Mining Area, Xinjiang, China

The spontaneous combustion of coal is a disaster associated with coal mining. In this study, the authors investigated the characteristics of spontaneous combustion of coal at different temperatures (room temperature, 50–500 °C with 50 °C interval) using Fourier transform infrared spectroscopy (FTIR), high-resolution transmission electron microscopy (HRTEM), etc. The results showed the aromatic structure was mainly naphthalene. The aliphatic hydrocarbons were long chain. Oxygen, nitrogen, and sulphur existed as C-O, pyridine, pyrrole nitrogen, aliphatic sulphur, and sulfone. The molecular structural formula is C142H112N2O22. The stable 3D structural was obtained through optimization. Thermogravimetric analysis results showed the critical and dry-cracking temperatures of coal samples showed downward trends overall, whereas the acceleration and thermal-decomposition temperatures varied greatly with increase in oxidation temperature. The activation energy change pattern of 4 stages is not obvious. The FTIR results showed the contents of self-associated OH changed greatly. The aliphatic hydrocarbons changed greatly at 30–150 °C and 300–500 °C. The C-O showed increasing trends, whereas the C=O decreased consistently. The HRTEM results showed the aromatic fringes in coal samples were dominated by 1 × 1 and 2 × 2, the contents of which accounted for more than 80% of the total fringes