Research on the purification mechanism and high-value utilization of manganese leaching solution from electrolytic manganese anode slime

Manganese resources have become crucial for the burgeoning development of global industrialization and new energy sectors. The electrolytic manganese metal (EMM) process generates substantial amounts of electrolytic manganese anode slime (EMAS) as solid waste. During the smelting of waste printed circuit boards (WPCBs), large quantities of hazardous waste, specifically bromine-rich saline wastewater (BRSW), are produced. This study developed a novel synergistic treatment method to achieve efficient manganese leaching and purify the leachate to prepare manganese sulfate for battery. The kinetics of the Mn leaching process were elucidated, and the process was optimized using orthogonal experiments, achieving a manganese leaching rate of 98.53 %. The fluorine precipitation process was optimized using the response surface methodology (RSM), achieving removal rates of 99.62 %, 99.03 %, and 97.85 % for Ca2+, Mg2+, and Pb2+, respectively. The mechanism of the fluorine precipitation process was thoroughly studied using thermodynamics, E-pH diagrams, and Density Functional Theory (DFT) calculations, with the removal sequence being Ca > Mg > Pb. Finally, manganese sulfate for battery (99.84 %) was prepared through extraction-stripping and evaporation-crystallization methods. This study embodies the synergistic disposal of solid waste, recovering valuable components from waste and providing new approaches for the recovery and treatment of EMAS and BRSW, thereby reducing environmental impact.