Interventions in lignite oxidation: Microbial effects on reactivity and stability

Lignite coal is prone to oxidative spontaneous combustion due to its low degree of metamorphism, high moisture content and abundance of oxygen-containing functional groups. This presents a significant hazard to coal mine safety and environmental protection, underscoring the necessity for green and efficient technologies to inhibit spontaneous coal combustion. In this study, two coal-derived microorganisms, Schizophyllum commune and Bjerkandera adusta, were isolated and domesticated from lignite in Inner Mongolia. Their effects on the coal's microstructure and oxidation process were analyzed using SEM-EDS, FTIR, and TG-DSC. The results showed that microbial treatment altered the coal's surface morphology, elemental distribution, and microcrystalline structure. The treated coal displayed deeper surface layers, increased pore and fissure formation, and a reduction in oxygenated functional groups, with decreases of 7.71 % and 4.68 %. TG-DSC experiments revealed that the microorganisms increased the critical temperature of the coal by 37.89 °Cand 27.97 °C. The mass loss in Bjerkandera adusta-treated coal was reduced to 0.163 times that of untreated coal, with a 41.31 % decrease in the maximum weight loss rate. The research results demonstrate that the microorganisms significantly inhibit the oxidative combustion of lignite, providing valuable insights for the development of green coal combustion retardants.