Kinetics and mechanism of enhanced high-temperature oxidation in water-immersed coal

To explore how water immersion affects the macroscopic properties of coal during high-temperature oxidation, coal samples soaked for different durations (30, 90, and 180 days) were prepared. Thermogravimetry-differential scanning calorimetry (TG-DSC) and in-situ Fourier transform infrared (FTIR) spectroscopy were employed to compare the raw coal with the soaked samples. The oxidation kinetics of coal in both oxygen adsorption and combustion phases were analyzed via the Achar differential approach and Coast-Redfern integral method, and the model validity was verified by comparing the experimental and predicted TG curves. It is found that the apparent activation energy of soaked coals is significantly lower than that of unprocessed coal, particularly for the 180-day soaked sample, indicating enhanced oxidation reactivity after immersion. Meanwhile, the soaking treatment exerts a significant influence on the exothermic behaviors of coal, which is manifested by the earlier initiation of coal oxidation and greater heat emission. The enhanced oxidation reactivity of soaked coal enables it to burn more completely at high temperatures, thereby increasing CO2 production. The findings of this study are expected to provide guidance for formulating targeted fire prevention and control strategies for soaked coal in mines.