Selective separation and recovery of gallium and germanium from complex polymetallic sulfate solutions

Abstract

The composite sulfate solution generated during zinc hydrometallurgy is rich in Ga and Ge, Zn, Al, and other elements. However, existing single extraction systems exhibit poor efficiency for simultaneous Ga and Ge extraction. In addition, the high co-extraction rate of Al hinders the subsequent separation of Al from Ga. In this study, an innovative process—based on synergistic extraction with P507–YW100 and stepwise stripping—was proposed to realize efficient separation and recovery of Ga and Ge. An extraction system, composed of 15 vol% P507 and 4 vol% YW100, yielded Ga and Ge extraction efficiencies of 97.38 % and 99.23 %, respectively. Subsequently, a two-stage extraction process was applied, which increased the extraction efficiencies of Ga and Ge to > 99.5 %. Consequently, the concentrations of these elements in the raffinate were reduced to < 5 mg/L, and the extraction efficiency of Al reached 12.06 %. To minimize the impact of Al on the purities of the subsequent Ga and Ge products, an innovative selective stripping method, involving the use of 6 mol/L of HCl, was applied. The resulting stripping efficiency of Al reached 92.97 %, whereas those of both Ga and Ge were < 1 %. Subsequently, 2 mol/L of H₂SO₄ was used to preferentially strip Ga, and a 1.5 mol/L NH₄F solution was used to strip Ge. Ultimately, Ga and Ge stripping efficiencies of 97.07 % and 96.16 %, respectively, were achieved. This process establishes an efficient and environmentally friendly method for recovering gallium and germanium from complex sulfate systems, significantly promoting the clean separation and value-added utilization of rare metals in the zinc hydrometallurgical process.