A Novel Procedure for Comprehensive Recovery of Zinc Fluoride, Manganese Fluorides, Manganese Dioxide, and Carbon Powder from the Electrode Powder of Spent Alkaline Batteries

In this paper, a novel procedure is proposed for comprehensively recovering zinc fluoride (ZnF 2 ), manganese fluorides [MnF x(x = 2, 3) ], manganese dioxide (MnO 2 ), and carbon powder from the electrode powder of spent alkaline batteries. Firstly, hydrofluoric acid (HF) leaching is conducted on the electrode powder of spent alkaline batteries. Secondly, potassium permanganate (KMnO 4 ) is introduced into the leachate to selectively precipitate manganese (Mn) ions to recover MnO 2 . Subsequently, the water content in the leachate is evaporated to recover ZnF 2 . Finally, the leaching residue is leached again by using HF, after which the water content in the leachate is evaporated to recover MnF x . The results indicated that under optimal conditions of a HF concentration of 4 M, a leaching time of 15 min, and a liquid–solid ratio of 5 mL/g, the optimal leaching selectivity for Zn and Mn was achieved and the leaching efficiencies of Zn and Mn were 97.83% and 39.94%, respectively. When KMnO 4 with a dosage (KMnO 4 /Mn ion molar ratio) of 0.5:1 was added to the leachate, MnO 2 with a grade of 91.68% and a Mn recovery of 39.07% was obtained. In addition, ZnF 2 with a grade of 97.98% and a Zn recovery of 96.15% was also obtained after removing the water content from the leachate via evaporation. Under the optimal conditions of a HF concentration of 2 M, a leaching time of 15 min, and a liquid–solid ratio of 10 mL/g for the leaching residue, followed by removing the water content in the leachate via evaporation, MnF x with a grade of 94.20% and a Mn recovery of 59.46%, was obtained. The residue of the releaching process was carbon powder. The effectiveness of the proposed recovery procedure was confirmed.