Comparison of Hydro- and Biohydrometallurgical Extraction of Metals from Waste Li-Ion Batteries of Cell Phone

In the present study, the black residual powders of waste Li-ion batteries were treated with citric, malic, and a combination of these acids for chemical extraction of multimetals. Among the treatments, 0.75M malic+0.75M citric acid was found to be better than either 1.5M citric acid or 1.5M malic acid for 20gL(-1) pulp density at 90 degrees C. Bioleaching studies were carried out by Leptospirillum ferriphilum-dominated consortium using the two-step process, which resulted in 1.2-1.8-fold higher metal extractions compared to a one-step process. At optimal pH 2.0, Cu-Zn-Ni solubilization was 85 +/- 2%, while Co and Li extractions were 97.2% and 33.96%, respectively, after 2-6 days with 10gL(-1) pulp density. When 9gL(-1) initial ferrous iron concentration was used, Cu-Zn-Ni-Co extractions were 92 +/- 7%, whereas Li solubilization attained 37.74% within 2-8 days. Optimization of the bioleaching process resulted in 1.7-2.7-fold increase in metal extractions. Studies at 10, 50, and 100gL(-1) pulp densities showed that metal extraction operational time increased as the pulp density was increased, and the obtained extractions ranged between 83 and 40% for Cu, 93 and 54% for Zn, 91 and 27% in the case of Ni, 99 and 17% Co and Li extractions were 44 and 13%. For the spent medium at 10, 50, and 100gL(-1) pulp densities, Cu extraction ranged between 52 and 33%, Zn extractions between 78 and 39%, Ni extractions between 73 and 25%, Co extractions between 58 and 16%, and Li extractions between 22 and 5% within 4-6 days of reaction time. Presence of the consortium had a beneficial influence on the extraction of all the metals studied.