Separation of cobalt, nickel, and copper metal using the mixture of HCl in ethylene glycol and Aliquat 336 in kerosene

Abstract

The recovery of valuable metals such as Co, Cu, and Ni from spent lithium-ion batteries has attracted much attention due to environmental issues and economic values. Separation of these metals from the synthetic metallic mixtures was investigated by employing nonaqeous solvent. In this work, the mixture of HCl in ethylene glycol (EG) and Aliquat 336 in kerosene was employed as nonaqeous solvents and the leaching conditions were optimized. Under the optimum condition, Ni was completely leached and remained in the EG phase with 99.8% purity. Meanwhile, the leaching percentage of Co(II) and Cu(II) was 62.3% and 18.3% and most of the two dissolved metal ions were extracted into Aliquat 336 phase. After complete stripping of Co(II) and Cu(II) from the loaded Aliquat 336 phase with 2.0 mol L−1 H2SO4, Cu(II) was selectively extracted over Co(II) by 0.1 mol L−1 Cynanex301 and then stripped by 50% aqua regia solution with >99.9% purity. The purity of Co(II) in the raffinate was 99.6%. Besides, Co from the leaching residue was selectively dissolved over Cu by 5.0 mol L−1 H2SO4 with 99.6% purity. A process was proposed for the separation of Co, Cu and Ni from metallic mixtures. The process showed some advantages in terms of the high purity of the metal solutions recovered and a decrease in the number of steps for the metal recovery. Thus, the application of this process to real operation can be considered.

Keywords

• Non-aqueous leaching
• Cobalt
• Nickel
• Alloys
• Lithium-ion battery