Biological Leaching and Chemical Precipitation Methods for Recovery of Co and Li from Spent Lithium-Ion Batteries

Spent Li-ion batteries (LIBs) are highly rich in cobalt and lithium that need to be recovered to reduce shortages of these valuable metals and decrease their potential environmental risks. This study applied bioleaching using Aspergillus niger strains MM1 and SG1 and Acidithiobacillus thiooxidans 80191 for removal of Co and Li from spent LIB under type 1 and type 2 conditions. Moreover, metal recovery was attempted from the fungal leaching solution by sodium sulfide, sodium hydroxide, and sodium oxalate for Co and then for Li using sodium carbonate. The findings of this work show that metal removal in fungal bioleaching under type 2 system was highly comparable or even better than bacterial or acid leaching. A significant quantity of Co (82%) and Li (100%) dissolution was observed in strain MM1; however, metal solubilization was poor in strain 80191 because only 22% Co and 66% Li solubilized. A high amount of Co precipitated potentially as cobalt sulfide (100%), cobalt hydroxide (100%), or cobalt oxalate (88%), whereas Li precipitated as lithium carbonate (73.6%). Finally, results of this study suggest that fungal bioleaching could be an environmentally friendly approach for solubilization and recovery of considerable quantities of metals from spent LIBs.