Study on the mechanism of coal oxidation under stress disturbance

Abstract Coal oxidation experiments under the three stages of loading-unloading-secondary loading were conducted, and three oxidized coal samples were scanned using atomic force microscopy. The oxidation capacity of the coal sample subjected to unloading was higher than those of the coal samples subjected to loading and secondary loading, and that of the coal sample subjected to secondary loading was slightly higher than that of the coal sample subjected to loading. In the loading-unloading-secondary loading stages, the number of micropores first increases and then decreases. The number and depth of mesopores in the coal subjected to unloading are larger than those in the coal subjected to loading and secondary loading. The micropore variation rule is verified by fractal dimension calculations. A pore structure change analysis indicated that the number of micropores directly affects the coal oxidation characteristics and pore-to-pore channels are formed between mesopores and macropores under loading, and these changes explain the oxidation differences between the three coal samples. Based on the stress distribution and the oxidation characteristics of the three coal samples, the dangerous areas of coal spontaneous combustion in single coal seam mining and protective layer mining are distinguished and predicted.