Effects of Chemical Solution Components on Pore Structure Development and Permeability Characteristics of Coal

Using chemical methods to improve the pore structure of coal and increase its permeability is an effective measure for preventing mining gas disasters. To study the effects of chemical solution components on the pore structure and permeability of coal samples, this paper used diethylene glycol butyl ether, citric acid, and sodium dodecyl benzene sulfonate to soak the coal samples. The methods used included mass analysis, scanning electron microscopy/energy dispersive spectroscopy, low-field nuclear magnetic resonance, and permeability testing to analyze the coal sample’s mass loss, microstructure, pore structure, and permeability. The results showed that the multicomponent composite solution had the strongest erosive effect on the coal. After soaking, the coal sample’s mass loss rate was 4.95%, the coal matrix became loose and surface rough, the pore structure was fully developed with many new pores appearing, porosity increased by 5.25%, and permeability improved by 3.19 mD. Diethylene glycol butyl ether primarily promotes the development of micropores and mesopores, while citric acid mainly promotes the development of macropores or fractures. Surfactants can enhance the penetration and wetting capabilities of the solution, promoting the dissolution of soluble components in the coal and increasing the development and connectivity of pores. The synergistic effect of the multiple components has achieved significant results in modifying the pore structure and increasing the permeability of the coal.