Latest Advances in Hydrometallurgical Recycling Routes for Primary Alkaline Batteries: A Review

This review presents the advances regarding the recovery and purification of zinc (Zn) and manganese (Mn) from alkaline batteries via hydrometallurgical processes. The characteristics of alkaline batteries are defined, and a comparison among leaching processes of spent batteries is presented, including the reactions that take place during the leaching process and the most influential operating parameters. Hydrometallurgical processes for recycling batteries arise as an advantageous alternative for spent batteries management. Data reported from the literature shows that alkaline and complexation-assisted leaching are more focused on the selective extraction of Zn. To attain a high Mn dissolution, an acid-reductive leaching is necessary, but this technique is not selective and simultaneously dissolves both Mn and Zn. To finish, metal separation and purification processes to recover high-quality metals from the leachates are discussed. Precipitation, solvent extraction, ion exchange resins, and electrodeposition are the main operations presented in this work. It has been proven that more than one separation or purification techniques are required to obtain the separation of these metals with high purity.