Hydrometallurgy leaching of manganese from electrolytic manganese anode slime using hydrogen peroxide as reducing agent

Manganese is one of the important strategic resources in China, and there is a saying that “no manganese, no steel”. In 2020, China’s output of electrolytic metal manganese was 1501300 tons, accounting for 96.5% of the global output. At present, manganese metal is mainly obtained using the electrodeposition process. Electrolytic manganese anode slime (EMAS) is a kind of solid waste generated during the production of electrolytic metal manganese, which contains a significant amount of manganese, lead, and other resources. Every year, 60000−180000 tons of EMAS will be discharged in China, and direct discharge will cause severe environmental pollution. Cleaning and efficiently leaching Mn from EMAS is the key to realizing its resource utilization. A large number of studies have achieved efficient leaching of manganese from EMAS. Still, there are a number of issues, such as complicated processes, high leaching cost, a large amount of reducing agent, and residual organic matter in the leaching solution. Therefore, it is urgent to find a new method for efficient clean leaching of manganese from EMAS. This study proposed a new method of enhancing manganese leaching from EMAS with an H₂SO₄–H₂O₂ leaching system. The effects of the dosage of H₂SO₄ and H₂O₂, reaction temperature, reaction time, and solid–liquid ratio on the leaching efficiency of manganese from EMAS were studied. The results show that the leaching efficiency of manganese was 97.23%, and the content of Pb in the leaching residue was 53.71%, when the mass ratio of EMAS to H₂O₂ was 1∶0.8, the mass ratio of EMAS to H₂SO₄ was 1∶0.9, the leaching temperature was 45 ℃, the solid–liquid mass ratio was 1∶10 and the leaching time was 15 min. Leaching mechanism analysis showed that manganese oxide leaching in EMAS was reduced by H₂O₂ under acidic conditions, and Mn mainly exists in the leaching solution as MnSO₄, as well as Pb in leaching residue is mainly enriched with PbSO₄. This study offers a new idea for resource utilization of EMAS.