Infiltration characteristics of surfactant solution in non gas-bearing coal and its influence mechanism

Coal dust is a major killer that restricts coal mine safety production and endangers the lives and health of miners. Increasing the water content in coal can reduce the amount of dust produced. Surfactant solution can improve the wetting effect. The infiltration characteristics of surfactant solution inside coal, including the filling degree in pores, water saturation in pores and infiltration distance, are the key to evaluating the wetting effect. However, the infiltration characteristics of surfactant solution are not clear, which leads to insufficient understanding of the mechanism of surfactant solution wetting coal. To obtain the infiltration characteristics of surfactant solution and reveal its influence mechanism, molecular dynamics simulation, nuclear magnetic resonance threedimensional imaging and Fourier transform infrared spectroscopy testing technology are used. The results show that the wetting heat of sulfonated aliphatic polyester solution on coal is more than that of water on coal. Filling degree with regard to micropore is the biggest, and the micropore plays a controlling role in the water infiltration. The water saturation in the macropore is the biggest, and the macropore and mesopore function importantly to in transmit water. Helmholtz free energy from the system decreases with increasing infiltration time. When the infiltration process reaches an equilibrium state, the system reaches the most stable state. A dimensionless method is used to treat the infiltration time and infiltration distance, and the infiltration rate of sulfonated aliphatic polyester solution in coal is faster than that water. Infiltration process of surfactant solution cannot change the pore structure of coal. However, it can change the proportion of hydroxyl functional groups and oxygen-containing functional groups. The current research results lay a theoretical foundation for revealing the wetting mechanism of surfactant solution and the application of coal seam surfactant solution injection.