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3725292 
Journal Article 
Production of potassium manganate and barium manganate from spent zinc-MnO2 dry cells via fusion with potassium hydroxide 
da Rocha, RA; Quintanilha, CL; Lanxin, TV; Afonso, JC; Vianna, CA; Gante, V; Mantovano, JL 
2014 
Yes 
Journal of Power Sources
ISSN: 0378-7753 
268 
831-840 
WOS:000340311800107 
This work describes a route for extracting manganese and zinc from spent zinc-manganese dioxide dry cells via fusion of the electroactive components with potassium hydroxide to form potassium manganate (K2MnO4) and soluble zincates. The fused mass was dissolved in aqueous KOH and the insoluble matter was separated. Under the best optimal conditions, 70-78 wt% of manganese was solubilized as K2MnO4 whereas 30-44 wt% of zinc was solubilized as [Zn(OH)(4)](2-) ions. Lead was the only minor component dissolved in detectable amounts. Manganese was isolated by a one-step precipitation procedure as barium manganate (BaMnO4) or via crystallization of K2MnO4. Lead and excess barium were isolated as sulfate by adding K2SO4. Zinc was precipitated as hydroxide after neutralizing the alkaline solution with H2SO4. pH control is essential to avoid decomposition of manganate ions and for the sequential precipitation of leached elements. K2SO4 was partially recovered as by-product after partial evaporation of the neutralized solution. (C) 2014 Elsevier B.V. All rights reserved. 
Potassium manganate; Alkaline fusion; Spent Zn-MnO2 dry cells; Barium manganate