In order to better explore the spontaneous combustion characteristics of lignite, a low-temperature heating experimental device was used to study the changes in the physical and chemical structure of lignite in an air atmosphere of 50–350°C. Through FTIR, XRD and SEM, the coal sample's chemical structure and surface microstructure change at low temperature are correlated and analysed, and the physical and chemical fabric change law of the coal sample at low temperature is obtained. The results show that in the water loss stage, the hydroxyl content in the coal sample increases, and the surface pores of the coal sample become larger. As the oxidation temperature increases, the pores further expand, secondary cracks appear, and gas escapes. In the decarboxylation stage, the coal sample is further coked, the methyl group increases, the oxygen-containing functional group increases, and the coal sample crystallisation degree increases, which accelerates the spontaneous combustion of the coal sample. The result of our study offers useful guide for early coal spontaneous combustion prediction on site.

为了更好地探索褐煤的自燃特性，采用低温加热实验装置，在50~350℃的空气气氛中研究褐煤的理化结构变化。通过FTIR、XRD和SEM，对煤样在低温下的化学结构和表面微观结构变化进行关联分析，得到煤样在低温下的理化结构变化规律。结果表明，在失水阶段，煤样中羟基含量增加，煤样表面孔隙变大。随着氧化温度升高，气孔进一步扩大，出现二次裂纹，气体逸出。在脱羧阶段，煤样进一步焦化，甲基增加，含氧官能团增多，煤样结晶度增加，加速煤样自燃。我们的研究结果为现场早期煤自燃预测提供了有益的指导。