Characteristics of kinetic of oxidation of low rank coal in typical mining area of Xinjiang

This paper presents a study on the kinetic of combustion of low rank coal in main coal seam of typical mining areas in Xinjiang by using different methods, such as the XRD, the FTIR, the TPO and the TGA, etc. XRD results show that the major minerals contained in coal matrix are quartz, kaolinite, dolomite, calcite, etc.The mineral composition content of coal samples in Dahuangshan mining area is the highest.FTIR results show that different coal samples have similar types of functional groups and different absorbance; the absorbance of functional groups of Sikeshu coal samples increases with the decrease of particle sizes; the contents of oxygen-containing functional groups decrease with the increase of temperature. TPO results show that the oxygen-consumption rate of Sikeshu coal samples is larger than those of the Wudong and Dahuangshan coal samples.TGA results show that the activation energy of heated coal samples of Sikeshu coal samples decreases with the increase of temperature at T₁-T₂ stage, and increases with the increase of temperature at T₃-T₅ stage; the activation energy of coal samples at T₁-T₂ stage is lower than that at T₃-T₅ stage. The coal quality and element mass fraction have a certain influence on the kinetic parameters of coal oxidation, and the activation energy and burning point temperature of coal samples show an overall trend of increasing with the decrease of moisture content (< 8%) at T₃-T₅ stage; the peak area of oxygen-containing functional groups increases with the decrease of volatile content from 27% to 31% of coal samples, decreases with the decrease of ash content from 4% to 7% of coal samples, and it shows a decreasing trend with the decrease of water content from 1.9% to 10.0%. Results also show that the temperature of burning point T₃ decreases with the reduction of oxygen content from 15.5% to 18.0% of coal samples; the activation energy at T₁-T₂ stage increases with the reduction of hydrogen content from 3.3% to 3.6% of coal samples, and increases with the decrease of nitrogen content from 0.65% to 0.80% of coal samples.