Optimised Reductive Bioleaching Strategies for Sustainable Critical Metal Recovery from a Mixed Black Mass

This study focuses on optimising the bioleaching of critical minerals from black mass derived from spent lithium-ion batteries using a statistical design of experiments approach. The results clearly indicated that the dosage of ascorbic acid was the most influential parameter, particularly for lithium and manganese recovery. For nickel and cobalt, both ascorbic acid concentration and leaching temperature exerted significant effects on extraction efficiency, whereas the leaching time was shown to have no notable impact on the recovery of any of the targeted elements. Temperature was identified as a critical variable, especially in relation to nickel and cobalt dissolution. In contrast, the dissolution of lithium and manganese was not significantly influenced by temperature variations. <br/>Under optimized experimental conditions, the bioleaching system achieved extraction efficiencies of approximately 90% for lithium and manganese and around 60% for cobalt and nickel. These findings confirm the high potential of ascorbic acid-assisted bioleaching as an efficient, selective, and environmentally sustainable strategy for the recovery of critical metals from black mass. Furthermore, the results provide valuable insights into the interplay of key operating parameters, offering a basis for scaling up and developing greener recycling technologies for spent lithium-ion batteries.