The inhibitory effect of microbes on coal spontaneous combustion

Initial prevention and control of coal spontaneous combustion has been a hot issue for scientists. The unique advantages of microbes, such as green and low cost, are used to make up for the defects of the traditional coal spontaneous combustion (CSC) control technology. Different microbes within the coal mine environment were isolated, purified, and identified. Different time groups of microbes were cultured in a mixture with coal and structural differences between coal samples were compared. The composition, appearance, and key properties of the coal were characterized through proximate analysis, scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric-mass-infrared spectrometry (TGMS-FTIR). The results show that all five isolated microbes obviously influence the pore fissures of the coal, and can seal and cover the pores. The moisture and volatile components of the coal with different microbes and time groups are less than those of the raw coal. Microstructural analysis reveals that the degree of coalification and the aromaticity gradually increased with time. The microbes lead to the aliphatic structure to be cleaved. Infrared structural parameters indicate microbes are also influencing oxygen-containing groups. Thermal analysis shows that by using CO2 as an index gas to determine the oxidation stage, it was possible to determine the partial temperature of the microbial inhibition in CSC. The temperature of coal oxidation is delayed by all microbes, with filamentous fungi being the most effective in delaying the temperature. Rhizopus arrhizus can significantly enhance the activation energy. It effectively inhibits the oxidation process of coal, providing a theoretical foundation for microbes to prevent coal spontaneous combustion fires in large-scale mining areas.