Study on secondary oxidation characteristics of coal gangue at different pyrolysis rank

In order to further investigate the spontaneous combustion characteristics of coal gangue (CG) hills, this paper explored the potential connection between the spontaneous combustion characteristics of CG and its pyrolysis rank. Though the method of gas chromatography (GC) and mass spectrometry (MS), the temperature pro-grammed experiments of CG samples with different pyrolysis ranks were carried out. The variation of index gas emission behavior and the oxidation kinetics of CG after high-temperature pyrolysis were investigated under the condition of heating from 30 degrees C to 900 degrees C. The results showed that there is a certain connection between the rank of pyrolysis of CG and its emission behavior and the thermodynamic parameter. The energy required for the combustion of samples after pre-pyrolysis were significantly higher than the raw sample. With the increase of the rank of pyrolysis, due to the decomposition of oxygen-containing functional groups in the process of pyrolysis, a large amount of volatiles were released, the CG in the combustion process of the emission of index gas and its oxygen consumption rate gradually reduced, the rapid oxidation stage shifted to the high temperature direction, and the combustion interval was also greatly shortened. The increase of the rank of pyrolysis will greatly reduce the thermal value and spontaneous combustion risk of the CG. Therefore, the CG hill with low rank of pyrolysis is more likely to cause spontaneous combustion, with higher risk and greater pollution. The results of this paper have important guiding significance for exploring the spontaneous combustion characteristics and management of CG hills.