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

Publication date: Available online 17 August 2019Source: Journal of Environmental Chemical EngineeringAuthor(s): Bayram Andak, Erhan Özduğan, Selçuk Türdü, A. Nusret BulutcuAbstractA 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 °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 CuSO4.5H2O. Finally, utilizing the ternary phase diagram formed, the liquor leaving cementation is subjected to evaporative crystallization followed by cooling crystallization, where MnSO4.H2O and ZnSO4.7H2O (>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.Graphical abstract
Source: Journal of Environmental Chemical Engineering - Category: Chemistry Source Type: research