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

Abstract

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, 0.75 M malic + 0.75 M citric acid was found to be better than either 1.5 M citric acid or 1.5 M malic acid for 20 g L−1 pulp density at 90 °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 10 g L−1 pulp density. When 9 g L−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 100 g L−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 100 g L−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.