Selective Recovery of Zn and Mn from Waste Zinc–Manganese Batteries by Autocatalytic Reduction Roasting Followed by Leaching Process

Waste Zn-Mn batteriesWaste Zn-Mn batteries were the largest producer of e-wasteWaste, which was not only typical hazardous materialsMaterials but also the high-grade secondary resource of Zn and Mn. Existing hydrometallurgyHydrometallurgy methods mainly used acids to leach the wasteWaste batteriesBatteries, and then purified the products by precipitating, extracting, etc. However, Mn-Zn spinelMn-Zn spinel was easily formed in spent batteriesBatteries, which were stubborn and only dissolved in strong acid systems. In this study, a novel processProcess for selective recoverySelective recovery of Zn and Mn from wasteWaste batteriesBatteries by reduction roastingReduction roasting followed by an acid leachingLeaching processProcess was developed, of which spent graphite electrodes were used as reducing agents. The effect of roasting and leachingLeaching parameters was studied, and the recoveryRecovery efficiency of Zn and Mn was about 98.5% and 99.5%, respectively. In addition, the phase transformationPhase transformations of Mn-Zn spinelMn-Zn spinel was declared by thermomechanical analysisThermomechanical analysis, XRDX-ray diffraction (XRD), ICP, etc.