Unveiling the inhibitory mechanism of fungi on Dananhu low-rank coal spontaneous combustion: Multi-technique analysis of coal pyrolysis behavior and structural evolution

Green mine construction demands coal spontaneous combustion inhibitors to be eco-friendly and efficient. Fungi, with their efficient enzyme systems and excellent degradation ability for low-rank coal, are potential green inhibitors. Thus, this study systematically investigated the specific roles of the lignin-degrading fungi in inhibiting coal spontaneous combustion. Experimental results showed that all three fungi could effectively suppress spontaneous combustion of Dananhu low-rank coal. P. neostrigosus , M. verrucaria , and P. chrysosporium increased the ignition temperature of Dananhu coal by 10.98, 30.80 and 6.74 °C, respectively. M. verrucaria exhibited the optimal inhibitory effect, while P. neostrigosus and P. chrysosporium showed stronger effects on the earlier-stage characteristic temperatures. The coupled TG-FTIR and Py-GC/MS technique was employed to analyze the effects of fungal inhibition on the coal pyrolysis process and characterize the pyrolysis gas products. After fungal treatment, the release of aliphatic hydrocarbons declined at low temperatures, and the generation of aromatic hydrocarbons and heteroatom compounds was reduced at high temperatures. the release of CO and CH 4 from Dananhu coal were delayed, and the release of CO 2 was decreased. Combined with structure characterization methods such as FTIR and X-ray diffraction, the evolution characteristics of the molecular and crystal structures of Dananhu coal under fungal action were analyzed in depth. In addition, qualitative and quantitative analyses of liquid-phase dissociation products were performed using GC–MS. Multi scale combined technology reveals the full chain inhibition mechanism of coal pyrolysis-product distribution-structural evolution, and further elucidates the pathway of fungal inhibition of coal spontaneous combustion. Three types of fungi weaken the reactivity of active functional groups such as hydroxyl, carboxyl, and aliphatic side chains in coal, remove loose structures, and promote the enrichment of aromatic nuclei and ether crosslinking. This enhanced the thermal stability of coal molecules and suppresses the spontaneous combustion of Dananhu coal.