Thermogravimetric and infrared spectral analysis of candle coal pyrolysis under low-oxygen concentration
2021
Chen, Liangzhou | Qi, Xuyao | Yang, Jian | Xin, Haihui
For further understanding spontaneous combustion of coal in fire suspectable zone, this paper analyzed coal pyrolysis in low-oxygen conditions by thermogravimetric analysis and online FTIR. The results indicate that the oxidation and pyrolyzation of candle coal occur simultaneously at 3 %∼5 % oxygen concentration, the intensity of oxidation reaction can still promote the coal self-heating. With the decrease of oxygen concentration and temperature, the CC on benzene ring decreases while the oxygen-containing groups increase. With oxygen concentration decreasing continuously, the oxygen-containing groups begin to appear surplus. When the temperature rises to 500 °C, the content of −COOH and −OH still remains 0.3 % under 3 % oxygen concentration, but disappears at 5 % oxygen concentration. It indicates that 3 % oxygen supply cannot provide necessary oxidation conditions for candle coal. Consequently, in order to fully suppress the development and re-burning of underground coal fire, the oxygen concentration should be controlled below 3 %.
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