New bio-hydrometallurgical application to recover zinc and manganese from alkaline spent batteries

The consumption of batteries has continually accelerated trend. Disposal of spent batteries represent severe environmental problem due to the metallic content, being considered as hazardous waste. Reutilization and recycling of spent batteries are appearing in order to minimize the wastes as well as to preservation of raw materials. The present experimental work involves the new bio-hydrometallurgical application, considering the integration of physical-chemical and biological-chemical methods for Mn-Zn recovery from spent alkaline batteries. The main aims of the research were: - to develop the preliminary experimental work to recover selectively MnO2 and Zn from bioleaching solutions containing Mn and Zn by electrolysis, with the scope to apply electrochemical technologies for Zn and Mn recovery from spent batteries; - to verify the possibility of spent batteries processing by bioleaching with Acidithiobacillus ferrooxidans together with the molasses coming, as waste materials, from agro-food industry. Average content of Zn in alkaline batteries was about 22.00%. The average Mn content was similar (21.00%). Average content in K was 4.9%, while Ni 0.65% and Fe 0.6%. Experimental results have demonstrated the technical feasibility of the application of bio-hydrometallurgical processes - integrated by electrochemical technologies - for Zn and Mn recovery from exhaust batteries. On the basis of the experiments outlined, a preliminary flow-sheet for the recycling of alkaline batteries has been realized.