Sustainable Desulfurization of Fine High-Sulfur Coal via Flotation-Electrochemical Method

Coal remains a primary global energy source, however, the continued exploitation has positioned high-sulfur coal as a critical concern, with its desulfurization remaining a significant technical challenge worldwide. In this study, fine high-sulfur samples were selected for investigation, and a series of flotation and electrochemical methods were employed for desulfurization. The results indicate that both sulfur and ash contents of high-sulfur coal decrease with decreasing particle size. The desulfurization efficiencies for different methods are as follows: 31.04% for flotation, 32.15% for grinding-flotation, 41.08% for electrochemistry, 42.04% for ultrasonic-electrochemistry, 49.51% for electrochemical-flotation, and 51.23% for ultrasonic-electrochemistry-grinding-flotation. Flotation effectively removes most of the inorganic sulfur content, while electrolysis can remove both inorganic sulfur and a portion of organic sulfur content. Grinding facilitates the liberation of sulfur inclusions in coal, while ultrasonic treatment aids in detaching gangue minerals from the coal surface, thereby accelerating the electrochemical reactions. Simulation results show that the C-S bond in coal is more resistant to dissociation than the S-S bond. The oxidation efficacy varies across different crystal planes, with the {111} plane exhibiting the most optimal electrochemical oxidation performance. Furthermore, molecular dynamics simulations indicate that both the collector and electrolytic oxidation affect sulfur migration within the coal matrix.