Urban biomining: lithium recovery from spent batteries through multi-step bioprocesses

Abstract

Multi-step design to evaluate the bio-recovery of lithium from spent batteries was studied. The first step consisted of lithium extraction from spent batteries, using bacterial and fungal acid extrolites. The second step explored lithium recovery in the form of carbonate salts by using MICP (Microbial Induced Carbonate Precipitation) bacteria from Sporosarcina species. For lithium extraction (Step 1) sulfuric acid produced by sulphur oxidizing bacteria Acidithiobacillus thiooxidans was evaluated for its capacity to leach lithium. Extraction with biogenic sulfuric acid and with fungal bio- produ-cts (from Aspergillus sp. and Simplicillum sp. isolated at our facilities) were compared with commercial sulfuric acid. For biorecovery processes (Step 2), two type strains of Sporosarcina sp. were tested due to their capacity to precipitate lithium carbonate. Results showed fungal bioextracts gave a lithium leaching yield close to 60% and a global recovery yield of 27%. These observations are reported for the first time and lay the foundations for continuing the study and scaling up of this combined process for lithium recovery.