Investigation of the kinetics of spontaneous combustion of the major coal seam in Dahuangshan mining area of the Southern Junggar coalfield, Xinjiang, China

In the present paper, with using diverse methods (including the SEM, the XRD, the TPO, the FTIR, and the TGA), the authors analysed samples of the major coal seam in Dahuangshan Mining area with different particle sizes and with different heated temperatures (from 50 to 800 degrees C at regular intervals of 50 degrees C). The results from SEM and XRD showed that high temperature and high number of pores, fissures, and hierarchical structures in the coal samples could facilitate oxidation reactions and spontaneous combustion. A higher degree of graphitization and much greater number of aromatic microcrystalline structures facilitated spontaneous combustion. The results from TPO showed that the oxygen consumption rate of the coal samples increased exponentially with increasing temperature. The generation rates of different gases indicated that temperatures of 90 degrees C or 130 degrees C could accelerate coal oxidation. With increasing temperature, the coal oxidation rate increased, and the release of gaseous products was accelerated. The FTIR results showed that the amount of hydroxide radicals and oxygen-containing functional groups increased with the decline in particle size, indicating that a smaller particle size may facilitate the oxidation reaction and spontaneous combustion of coal. The absorbance and the functional group areas at different particle sizes were consistent with those of the heated coal samples, which decreased as the temperature rose. The results from TGA showed that the characteristic temperature T-3 declined with decreasing particle size. After the sample with 0.15-0.18 mm particle size was heated, its carbon content decreased, and its mineral content increased, inhibiting coal oxidation. This result also shows that the activation energy of the heated samples tended to increase at the stage of high-temperature combustion with increasing heating temperature.

Automated summary

In this paper, the authors analyzed the oxidation reaction and spontaneous combustion characteristics of samples from the major coal seam in the Dahuangshan Mining area using diverse methods such as SEM, XRD, TPO, FTIR, and TGA. The results showed that high temperature, high porosity, fissures, and hierarchical structures in coal samples facilitated oxidation reactions and spontaneous combustion, while a higher degree of graphitization and aromatic microcrystalline structures promoted spontaneous combustion.