Hydrothermal Leaching Behavior of Manganese from Waste Zn–Mn Dry Batteries

In this study, phosphoric acid and hydrogen peroxide systems were used to recover manganese from the positive electrode material of zinc–manganese dry batteries. Factors influencing leaching reaction were discussed. The results of response surface analysis showed that the degree of influence of each factor on the leaching reaction followed the trend reaction temperature > solid–liquid ratio > phosphoric acid concentration > reaction time > amount of hydrogen peroxide added. The best conditions for leaching reaction optimized through the curved surface method were as follows: 225 °C temperature, 2.28 mol/L phosphoric acid concentration, 80.9 min reaction time, 30.4 g/L solid to liquid ratio, and 3 vol % hydrogen peroxide. The average leaching efficiency of manganese under best condition was 97.3%, which was consistent with the theoretical value. This model can be used to predict the leaching efficiency of manganese. The apparent activation energy of the leaching reaction was 17.04 kJ/mol.