A selective recovery of zinc and manganese from the spent primary battery black mass as zinc hydroxide and manganese carbonate

Abstract

The major challenge in zinc-carbon battery recycling lies in achieving selective separation of zinc and manganese while producing high-purity materials suitable for advanced applications. This study aims to develop a selective hydrometallurgical approach for recovering high-purity zinc and manganese from spent primary zinc-carbon battery black mass (BM), addressing environmental concerns from improper battery disposal. A three-stage sequential leaching process was employed, consisting of water leaching for impurity removal, alkaline leaching for selective zinc extraction as zincate ions, and glucose-assisted reductive acid leaching for manganese recovery. The BM composition was characterized using scanning electron microscope (SEM)-energy-dispersive X-ray (EDX) analysis, while recovered products were precipitated as Zn(OH)2 and MnCO3 and characterized using X-Ray diffraction (XRD), Fourier transform-infra red (FTIR), SEM-EDX, and elemental mapping techniques. SEM-EDX analysis revealed that BM contains high concentrations of Zn, Mn, C, Na, and K. The sequential leaching achieved excellent metal recovery with 98.2% zinc extraction efficiency and 91.2% manganese recovery, demonstrating high selectivity with minimal cross-contamination. XRD analysis confirmed the formation of crystalline ZnO/Zn3(OH)4(NO3)2 and pure rhodochrosite MnCO3. SEM analysis revealed spherical morphologies for both products, with high purity confirmed by FTIR and EDX mapping. This work presents the first comprehensive study combining glucose-assisted reductive leaching with alkaline selective extraction for simultaneous zinc and manganese recovery from Zn-C batteries, achieving superior separation efficiency compared to conventional single-stage approaches. The as-obtained high-purity products show promising potential for advanced applications in catalysts, Li-ion batteries, and supercapacitors.