Sequential Recovery of Critical Metals from Leached Liquor of Processed Spent Lithium-Ion Batteries

Abstract

The processing and extraction of critical metals from black mass is important to battery recycling. Separation and recovery of critical metals (Co, Ni, Li, and Mn) from other metal impurities must yield purified metal salts, while avoiding substantial losses of critical metals. Solvent extraction in batch experiments were conducted using mixed metal sulphates obtained from the leach liquor obtained from spent and shredded lithium-ion batteries. Selective extraction of Mn2+, Fe3+, Al3+ and Cu2+ from simulated and real leached mixed metals solution was carried out using di-2-ethylhexylphophoric acid (D2EPHA) and Cyanex-272 at varying pH. Further experiments with the preferred extractant (D2EPHA) were performed under different conditions: changing the concentration of extractant, organic to aqueous ratio, and varying the diluents. At optimum conditions (40% v/v D2EPHA in kerosene, pH 2.5, O:A = 1:1, 25 °C, and 20 min), 85% Mn2+, 98% Al3+, 100% Fe3+, and 43% Cu2+ were extracted with losses of only trace amounts (<5.0%) of Co2+, Ni2+, and Li+. The order of extraction efficiency for the diluents was found to be kerosene > Exxal-10 >>> dichloromethane (CH2Cl2) > toluene. Four stages of stripping of metals loaded on D2EPHA were performed as co-extracted metal impurities were selectively stripped, and a purified MnSO4 solution was produced. Spent extractant was regenerated after Fe3+ and Al3+ were completely stripped using 1.0 M oxalic acid (C2H2O4).