Kinetics of oxidation and spontaneous combustion of major super-thick coal seam in Eastern Junggar Coalfield, Xinjiang, China

Abstract In this study, the kinetics of a major coal seam oxidation which was collected from the Eastern Junggar coalfield of China, were investigated by programmed heating experiments and the thermo-gravimetric analysis (TGA) as well as the chemical thermodynamic tool FACTSage. Results show that the change of O 2 consumption rate, CO and CO 2 generation rate in process of coal oxidation are coincident with the content changes of fixed carbon, volatile, and sulfur but differ from those of ash and moisture contents. From results of TGA, the characteristic temperatures, i.e., the dehydration-oxygen-adsorption temperature T 1 , the pyrolysis temperature T 2 , the ignition temperature T 3 , the maximum combustion-rate temperature T 4 , and the burnout temperature T 5 , were calculated. The T 3 , T 4 , and T 5 exhibit a similar variation tendency. It was found that the pyrolysis temperature T 2 was easier reached by the coal sample collected from Xiheishan Mining area compared to those from other two mining areas. It also shows that the effect of particle size on characteristic temperatures are lightly different: T 1 remained almost unchanged, T 2 and T 3 decreased, while T 4 and T 5 demonstrated an initial growth followed by a drop and a further rise. At the T 2 -T 4 stage, the sample size is positively correlates with its reaction activation energy. Meanwhile, results also show the CO 2 and CO are the major gaseous products in coal oxidation process, and some trace elements compounds are also produced at different stages of temperature. Therefore, these compounds prosed the possibility to indicate consequent stage of coal oxidation stages.