Experimental Study on the Mechanism of Lignite Oxidation and Free Radical Activity Suppression by Oxygen-Consuming Microbial Communities from Mining Areas

To investigate the impact of microbial consortia on coal spontaneous combustion in mining areas, this study employed scanning electron microscopy, infrared spectroscopy, and temperature programmed oxidation tests to examine microbial inhibition effects from macro and micro perspectives. This work aimed to reveal the mechanism of coal matrix remodeling and oxidative pathway blocking caused by microbial metabolism. The results showed that polysaccharide-rich biofilms formed by microbial metabolism on lignite surface covered pores, reducing oxygen diffusion area, decreasing moisture and volatile matter in coal samples, and weakening the source of oxidizing fuel. Using oxygen kinetics, it was found that the bacterial flora mainly acted in the first two stages of the combustion process. The Crossover Point Temperature, CPT, increased by 26.0°C for D-2 treated coal and 35.8°C for D-3 treated coal, and the apparent activation energy increased across all three stages, while carbon monoxide release decreased, blocking the oxidation chain reaction. The relative contents of active functional groups in coal samples were compared to further analyze the microscopic mechanism of bacterial flora degradation affecting coal spontaneous combustion in mining areas. The content of key active groups, such as aliphatic and phenolic hydroxyl groups, is significantly reduced, and the active sites of free radicals are passivated. This approach offers a theoretical basis for green control of coal spontaneous combustion in goaf environments. Indigenous mine-derived microbial consortia enable in situ suppression of coal oxidation via coupled oxygen depletion and reactivity passivation.Coal oxidation is inhibited through a physical surface barrier and chemical passivation of reactive functional groups.Microbial treatment increases the crossover point temperature and raises the apparent activation energy across oxidation stages. Indigenous mine-derived microbial consortia enable in situ suppression of coal oxidation via coupled oxygen depletion and reactivity passivation. Coal oxidation is inhibited through a physical surface barrier and chemical passivation of reactive functional groups. Microbial treatment increases the crossover point temperature and raises the apparent activation energy across oxidation stages.