PROCESSING OF SPENT ZINC-MnO2 DRY CELLS IN VARIOUS ACIDIC MEDIA

Vinício Ibiapina, Ulysses Florentino, Júlio Carlos Afonso, Valdir Gante, Cláudio Vianna, José Luiz Mantovano
2017 Química Nova  
publicado na web em 04/12/2017 This paper describes a route for recovering manganese and zinc from spent zinc-MnO 2 dry cells via acid leaching. Sulfuric, hydrofluoric and formic acids were used as leachants. Hydrogen peroxide was added as reductant, except for formic acid since it is itself a reductant. Experiments were run at 25-40 o C for 1-3 h. Under the best optimal conditions, over 95 wt.% of zinc and manganese were leached irrespective of the leachant. Leaching of contaminants was
more » ... aminants was strongly dependent on the leachant due to the insolubility of salts or complexing reactions. Zn(II) was best extracted with D2EHPA diluted in n-heptane at pH > 1, particularly from the leachates of weak acids. Mn(II) was much more co-extracted from sulfuric leachates, but was easily scrubbed with dilute leachant (~2 mol L -1 ). Zn(II) striping was possible using 5 mol L -1 H 2 SO 4 . Manganese was isolated as MnO 2 carrying the leached contaminants. High-purity sodium salts of the anions of the leachants were recovered after slow evaporation of the final solution.
doi:10.21577/0100-4042.20170162 fatcat:ood3bvd5ybgllio6gkwdojejve