Rare metals have become indispensable for the production of parts such as batteries, motors, and semiconductors, which are important for achieving high functionality in products in advanced industries in the decarbonized society such as xEV (electric vehicles) and AI / IoT. As the spread of xEV is promoted toward a decarbonized society, the demand for in-vehicle lithium-ion batteries is expected to increase significantly. Therefore, cobalt used as a positive electrode material such as nickel, cobalt, lithium and manganese, etc. In the future, competition for resources is expected to intensify with developed and emerging countries, and it will become even more important to build a supply chain to secure a stable supply. In building a supply chain, it is important to improve the recovery rate of cobalt and nickel by recovering cobalt and nickel from unused resources and used products and improving the smelting process.

In the present study, the solvent extraction and separation of cobalt and nickel from the sulfuric acid leach liquor of zinc smelting residue with acidic extractants, such as APT 6500, Cyanex 272 and D2EHPA was examined. It was possible to separate Cd, Cu, Mn and Zn from Co and Ni by simultaneously extracting Cd, Cu, Mn and Zn with D2EHPA. And also, as a result of comparing the separation efficiency of Co and Ni with APT 6500 and Cyanex 272, it was found that the separation efficiency of Co and Ni using APT 6500 in which part of H⁺ was replaced with Na⁺ was best.

Typical high-temperature recycling processes for precious metals use molten metal as a collector to concentrate the precious metals. The purpose of this study is to compare the performance of the collector metals and to investigate the feasibility of selective recovery of precious metals. Using the two liquid phases separation of the ternary alloy system, Rh, Pd, Pt, and Au were added to the Fe-Cu-C, Fe-Pb-C, or Fe-Ag-C systems at 1500 K and to the Ni-Ag-C system at 1700 K under carbon saturation, and the distribution ratios of precious metals between the two liquid phases of each system were determined. In all conditions, the molten metal was separated into two liquids. Rh was mainly concentrated in the Fe-C or Ni-C phases, Au in the Cu, Pb, or Ag phases, and Pd and Pt in the intermediate distribution.