Pyrometallurgical eco-recycling for Zn and MnO recovery from spent alkaline and Zn–C batteries

Most studies on the pyrometallurgical recovery of Zn from spent batteries have focused on assessing the recovery of Zn. However, the separation behavior of Zn from the produced black powder remains unknown. In this study, a pyrometallurgical process for recycling Zn and MnO from the black powder obtained by shredding spent alkaline and Zn–C batteries was developed. The black powder was washed with deionized water to remove KCl and subsequently used for recovering Zn and MnO. Preliminary thermodynamic calculations were performed using Factsage 8.2 and HSC 6.0 to set temperature conditions for the experiment. The washed black powder was placed in an electric vertical resistance furnace and heated to 800 ~ 1300 °C. The ZnO present in the black powder was reduced to Zn_(g) through carbothermal reduction, and then, Zn_(g) was rapidly condensed in a capture cup to recover Zn powder. After heat treatment at 1300 °C for 1 h, 99.39% of the Zn powder was recovered with 98.16% purity. Furthermore, MnO of 99.05% Mn purity remained as a residue from the black powder in the crucible. The results of this study present a crucial step in improving the resource recovery process while minimizing environmental impact, contributing to the advancement of environmentally friendly recycling technologies.