A novel solvent extraction system to recover germanium from H2SO4 leaching liquor of secondary zinc oxide: Extraction behavior and mechanism

Owning to the lack of commercial independent germanium deposit and the ever-growing germanium demand of high-tech field, the recovery of germanium from various resources shows strategic significance. In this study, a novel solvent extraction system based on primary amine (N1923) and hydroxycitric acid (HCA) was developed to recover germanium from leaching liquors of secondary zinc oxide and some typical resources. The results indicated that the solvent system showed high extraction efficiency and germanium selectivity ; equilibrium pH and the dosage of HCA were the key parameters for germanium recovery, the germanium extraction capacity of an organic phase with 0.24 mol/L N1923 was 7.97 g/L; germanium could be separated from zinc, arsenic, iron, and cadmium at an equilibrium pH of 1.0, and the separation factors of germanium to those elements were up to 1778, 232, 67074, and 14706, respectively; the system was also with well separation performance of germanium from typical germanium containing leachates of copper cake and coal fly ash. Stoichiometry analysis and FT-IR, NMR, and ESI-MS spectra demonstrated that the extraction of germanium followed a coordination anion extraction mechanism, the germanium extraction complexes was RNH 3 ⋅GeO 2 C 6 H 4 O 7 . 0.5 mol/L NaOH can be selected for the stripping of germanium. 2