Recovery of manganese and zinc via sequential precipitation from spent zinc–MnO2 dry cells after fusion with potassium hydrogenosulfate

Abstract This work describes a route for processing the electroactive components of spent zinc–MnO 2 dry cells via fusion with potassium hydrogenosulfate (KHSO 4 ). The fused mass was dissolved in water. Lead remained in the insoluble matter. Soluble zinc and manganese were isolated by a two-step precipitation procedure. Zinc was precipitated as oxalate after addition of aqueous H 2 C 2 O 4 at pH around 1. Manganese was isolated as MnO(OH) 2 after adjusting pH at 11 using aqueous KOH + H 2 O 2 . pH control is essential for a successful separation of the elements. Both were recovered in high yields (>92 wt.%). About 75 wt.% of potassium was recovered as K 2 SO 4 after treatment of the final effluent with sulfuric acid (pH 7) followed by slow evaporation.