Improvement of the electrical disintegration of coal sample with different concentrations of NaCl solution

The application of high-voltage electrical pulse (HVEP) technology to the improvement of pore structure of coal has achieved encouraging results. However, the very high breakdown voltage of some kinds of coal seriously affects the application of HVEP technology. In this study, the relationship between the concentration of NaCl solution and the breakdown voltage of coal sample was studied by improving the electrical breakdown effects of Linhua anthracite coal and Hongliu bituminous coal with different concentrations of NaCl solution, and a negative exponential relationship was established. The results indicate that the breakdown voltages of coal samples decrease with the increase of the concentration of NaCl solution, but there is a limit to the magnitude of the decrease. Additionally, nuclear magnetic resonance (NMR) and X-ray photoelectron spectrometer (XPS) were adopted in this study to investigate variations in pore structure and functional groups before and after the electrical breakdown. The NMR analysis demonstrates that the electrical breakdown mainly improves the number of mesopores and macropores and enhances the connectivity between them, thus providing a smoother channel for gas extraction. The XPS analysis reveals that a new oxidation reaction appears where the current flows through, which promotes gas desorption from surfaces of coal samples.