Recovery of Germanium via H₂SO₄/MnO₂ Leaching–NaAc Leaching/Na₂CO₃ Precipitation–Tri(octyl-decyl) Amine Stepwise Solvent Extraction

Abstract

Zinc and germanium are typically recovered by sulfuric acid leaching−tannin precipitation from germaniumbearing secondary zinc oxide (SZO). However, low recovery rate of Ge and large consumption of tannin are the obvious limitations. Herein, we propose a novel recovery process involving three main steps: (1) SZO is leached by H 2 SO 4 solution (pH 2.0 ± 0.5), and MnO 2 oxidation leaching is conducted for the residue (H 2 SO 4 : 10−40 g/L); (2) the oxidation leaching residue is treated with NaAc solution and, subsequently, Na 2 CO 3 (or CO 2 ) to precipitate lead and obtain PbCO 3 ; the resulting solution is reused for the leaching process (step 2); (3) a tri(octyl-decyl) amine(N235)/ tributyl phosphate/sulfonated kerosene system (no preacidification) is used to recover germanium from the oxidation leachate; the loaded organic phase is employed as an extractant to recover germanium from the leachate obtained in step 1. The raffinate could be sent to a zinc plant, and the loaded organic phase could be reused after stripping and washing. Up to 98% zinc and germanium leaching efficiencies, 98% germanium extraction efficiency, >90% lead recovery, and 97.87% purity PbCO 3 product were achieved. Therefore, a relatively sustainable treatment involving closed-circuit circulation of leaching agents and extractants for SZO was proposed.

The Extraction and Separation of Scarce Critical Metals: A Review of Gallium, Indium and Germanium Extraction and Separation from Solid Wastes

“…Ge(IV) exists in electroneutral form in both acidic and neutral sulfate solutions. In order to extract Ge(IV), relevant studies have investigated the N235/TOP/tartaric acid system [85], the N235/tri-n-butyl phosphate/sulfonated coal oil system (non-reacidified) [3] (Figure 10b), and the tertiary amine (N235/TOP)/tartaric acid system [86]. In these three acidic systems, the hydroxide of Ge is converted into the anionic complex by adding tartaric acid (H 4 T), and the complexation reaction is shown in Equations ( 20) and (21).…”

“…Gallium (Ga), indium (In), and germanium (Ge), as rare metals, are the key materials for contemporary high-tech new materials, and they play an important role in the development of high technology and future energy. Ga, In, and Ge have a wide range of applications in the computer, communication, aerospace, energy, medicine, and health industries (Figure 1a) [1][2][3]. According to USGS statistics, shown in Figure 1b-d, the global Ga, In, and Ge products are mainly manufactured in China, Russia, Korea, and Japan, and among these countries, China accounts for the majority of the production of these three metals.…”

Mechanism of Germanium Adsorption by Iron Hydroxide Colloids during the Leaching Process of Secondary Zinc Oxide

“…During the process of leaching germanium from germanium-containing resources, various phenomena occur such as germanium adsorption by silica gel, germanium encapsulation by lead sulfate, and self-hydrolysis of germanium forming colloidal precipitates. , In terms of solutions, controlling the acidity of leaching and applying ultrasound have shown significant effects. Acid control can inhibit the formation of silica gel and self-hydrolysis of germanium, while ultrasound application can disrupt formed colloids or encapsulation layers to prevent their aggregation and sedimentation, thus avoiding loss of germanium. − However, these measures require a clear understanding of the influencing mechanisms by many scholars in order to be targeted and achieve significant results.…”