Electrolytic recovery of Mn3O4 and Zn from sulphuric acid leach liquors of spent zinc–carbon–MnO2 battery powder

• Values are recovered from spent battery leaching liquors with no environmental impact.
• By electrolysis Zn and Mn3O4 are obtained in a closed type anionic membrane cell.
• Electrolytes are recovered by combined electrode and membrane processes.

In the present study, manganese and zinc are recovered from spent Zn–C batteries through a closed-type hydrometallurgical route. After dismantling, spent batteries have been sorted by type, followed by mechanical and chemical treatments. The obtained spent battery active material has been leached with 1 M H2SO4, in order to extract the metal constituents from the solid to the liquid phase. In the development of a hydrometallurgical recovery process for spent batteries, it has been found that the acidic leaching liquor contains 6 g/L Mn2 +, 65 g/L Zn2 + and of 190 mg/L Fe2 + ions. Electrolysis tests have been carried out in an anionic exchange membrane reactor under galvanostatic control with different current densities with highest yield at 50 mA cm− 2 in our experimental conditions. Voltammetry studies have been completed to understand the electrochemical behaviour exhibited by the Pb–Ag anodic substrate in the current electrochemical setup. Also, an experimental study was undertaken to evaluate the feasibility of an electrochemical setup for spent Zn–C battery recycling by recovery of Mn3O4 and Zn at the anode and cathode, respectively, in a single divided cell setup. The spent electrolyte was suitable for high efficiency leaching of zinc and manganese from spent battery powder and the leach liquor has been recycled in the same electrochemical setup until ≥ 99% Zn2 + and Mn2 + has been recovered.The obtained anodic and cathodic deposits have been characterized by scanning electron microscopy, energy dispersive X-Ray spectroscopy, X-ray crystal diffraction.