Two-step bioleaching of Li, Co and Mn from spent lithium-ion coin cells batteries using Acidithiobacillus ferrooxidans

Batteries can be hazardous to the environment and human health due to their toxic compounds. In this study, for detoxification and recovery of metals from spent coin batteries, a two-step bioleaching using Acidithiobacillus ferrooxidans was investigated.
A number of spent coin batteries were powdered. The powder was added to the bacterial culture medium and after 12 days the concentration of leached metals was determined. For investigating the effect of how to add the powder on metals recovery, the gradual addition of powder to the medium was carried out. For this purpose, the powder was added to the medium every 48 h at a rate of 20 g/L until the pulp density of 100 g/L. All experiments were run in triplicate and the standard deviation was shown as an error bar in the graphs.
With an increase in pulp density, the metals recovery rate reduced. The highest recovery rates for lithium, cobalt and manganese was 100%, 88% and 20%, in pulp density of 40 g/L after 12 days. Leaching of lithium, cobalt and manganese was 66%, 8% and 0%, if the powder was added gradually until pulp density of 100 g/L.
The two-step bioleaching using Acidithiobacillus ferrooxidans was an appropriate method for recovery of metals from spent coin batteries. Also, gradual powder addition to the medium did not have a positive effect on the metals recovery and on improvement of bacterial growth characteristics. The metals recovery in high pulp densities was mainly due to chemical leaching.