Microbial acclimatization and inhibition of coal spontaneous combustion in coal mine goaf

The occurrence of coal spontaneous combustion (CSC) is related to the chemical structure and characteristics of coal,while microorganisms can act on its structure. The idea of using specific microorganisms to dissolve the surface structure of coal and inhibit CSC was proposed. Two coal-derived microorganisms from goaf, Aureobasidium pullulans (DA. pu) and Staphylococcus pettenkoferi (DS. pe), were separated, purified and domesticated from lignite. After processing the coal, the influence characteristics of coal-derived microorganisms on the microstructure and oxidation performance of coal during low-temperature oxidation were explored. The results show that different microorganisms have varing effects on functional groups of coal. DA. pu reduces the hydroxyl content in coal, but DS. pe significantly increases the hydroxyl content.The contents of aliphatic hydrocarbons and oxygen-containing functional groups in coal decreased to varying degrees. DS. pe has the strongest destructive ability to aliphatic hydrocarbons in coal and can completely dissolve —CH₃. It also has a strong dissolving ability for aromatic ether bonds, with a reduction rate of up to 66.37%. DS. pe reduces the peak area of tetrasubstituted hydrocarbons in the aromatic hydrocarbons in coal to 0, and the reduction rate of monosubstituted hydrocarbons reached 58.52%. The peak areas of γ and 002 peaks, stacking height and number of aromatic flakes of treated coals were reduced.Based on the changing characteristics of the microstructure, DA.pu has a more significant impact on the structural parameters of coal than DS.pe. The microbial action delays the characteristic temperature T₁ of the coal, and DA. pu increases the activation energy of the combustion stage by 4 428.41 J/mol, delaying the development of CSC.The microstructure and oxidation performance are consistent, indicating that DA. pu has stronger inhibition ability. This is because microorganisms can effectively dissolve the molecular structure of coal and reduce the reactivity of coal molecules, which increases the reaction activation energy of coal and reduces its oxidation performance. The research results provide a theoretical basis for exploring the concept of microbial domestication in coal mine goafs and inhibiting CSC.