Recovery of zinc and manganese from spent zinc-carbon and alkaline battery mixtures via selective leaching and crystallization processes

Andak B., Ozdugan E., Turdu S., Bulutcu A. N.

JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING, vol.7, no.5, 2019 (SCI-Expanded) identifier identifier


A hydrometallurgical process is proposed for zinc and manganese recycling from waste zinc-carbon and alkaline battery mixtures as sulfate salts. The collected scrap battery mixture is crushed, sieved, magnetically separated and ground using industrial scale equipment in order to represent realistic battery powder content. The obtained fine powder, which contains high iron (2% w/w), is subjected to three-stage washing at 25 degrees C to remove potassium. Then, the cake is transferred to a pH-controlled staged selective acid leaching step, which is optimized for maximum zinc and manganese and minimum iron extraction yields. Next, impurities like Cd, Co, Cu, Ni are removed by cementation using Zn powder, Sb2O3 and CuSO4 center dot 5H(2)O. Finally, utilizing the ternary phase diagram formed, the liquor leaving cementation is subjected to evaporative crystallization followed by cooling crystallization, where MnSO4 center dot H2O and ZnSO4 center dot 7H(2)O (> 99.9%) are obtained, respectively. Moreover, utilizing the whole data produced, a recovery process is proposed. The studies show that the developed process not only solves iron removal problem thanks to the unique pH-controlled staged selective leaching developed, but also makes it possible to recover manganese and zinc as sulfate salts having high-purity.