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Aiming at leaching solution of indium residue produced by zinc hydrometallurgy, rotating disk extraction tower was used to separate indium and iron from the solution. The extraction effects of indium and iron ions in the solution, the extraction sequence of metal ions, the separation effect and emulsification of light and heavy phases was studied. The influences of the rotating disk rotating speed, feed flow rate, concentration of P204, solution acidity, reaction temperature and the phase ratio on separation effects were examined. The results show that under the optimal conditions of reaction temperature of 25 °C, heavy phase volume flow rate of 7. 8 L/h, P204 concentration of 20%, rotating disk rotating speed of 360 r/min, initial acidity of 60 g/L, Vo/VA phase ratio of 1/1, the extraction rate of indium can reach 75%, the extraction rate of impurity element iron is less than 5%. The light and heavy phases are basically completely separated, and there is no emulsification. The result of extraction isotherms shows that complete extraction of indium can be achieved by three-stage countercurrent extraction under the condition of Vo/VA phase ratio of 1/1. The loaded organic phase is pre-washed with dilute sulfuric acid, and then stripping with 5 mol/L hydrochloric acid under the condition of Vo/VA = 1/1. And the extraction rate of indium is more than 98%. After the replacement treatment, the stripping solution can be directly returned to zinc hydrometallurgy, the organic phase can be recycled after scrubbing. [ABSTRACT FROM AUTHOR]

In this study, hydrometallurgical processes involving pressure acid leaching and solvent extraction were developed to aid recovery of indium from zinc slag, which is produced in the imperial smelting process. Four different acid leaching methods were studied, namely atmospheric leaching, atmospheric leaching with KMnO4, roasting-atmospheric leaching, and oxygen pressure leaching in a sulfuric acid medium. Oxygen pressure acid leaching is the most effective method for indium extraction, and 94.1% of indium was leached under the optimum conditions, i.e., 300 g/L H2SO4,oxygen pressure 0.4 MPa, liquid/solid ratio 10 mL/g, and temperature 100°C for 5 h. X-ray diffraction and scanning electron microscopy examination of the raw material and leaching residue samples indicated that the intermetallic compounds Cu5Zn8and Cu2Zn, metallic zinc, and iron in the raw material dissolved, leaving the insoluble components PbSO4 and Pb as the major compounds in the leaching residue. A 98.5% proportion of the indium in the leaching solution was selectively extracted with 30% bis(2-ethylhexyl) phosphate and 70% kerosene by three-stage counter-current extraction, and 99.5% of the indium in the loaded organic phase was stripped by 6 mol/L HCl through four-stage counter-current stripping. The overall recovery yield of indium through all processes was approximately 92%. [ABSTRACT FROM AUTHOR]

The separation and recovery of copper and indium from a solution arising from the reductive leaching of a zinc leaching residue was studied. Copper was enriched into a copper precipitate produced by iron powder precipitation; indium was hydrolyzed and enriched into a gypsum indium precipitate produced by limestone adjustment of pH. Separation and recovery of both copper and indium were achieved. The results showed that precipitation of copper(II) and arsenic(III) as Cu2O and Cu3As is thermodynamically feasible by adding iron powder to the reductive leach of a zinc leaching residue. Increasing the iron powder addition and reaction temperature promoted the formation of Cu2O and Cu3As. In the process of neutralizing and precipitating indium by adjusting the pH using limestone, indium was mainly concentrated in the precipitate by hydrolytic precipitation. The pH of the neutralization endpoint plays a decisive role in this hydrolytic enrichment. The extent of indium precipitation exceeded 98%, and the indium content of the precipitate reached 3.6 kg/t. Addition of limestone balances the acid across the entire production process. The main phase in the gypsum indium precipitate was CaSO4·2H2O, the stable properties of which create favorable conditions for the recovery of indium in subsequent steps. [ABSTRACT FROM AUTHOR]

• Extraction of In from from hydrochloric acid solution and the indium on the loaded organic phase was stripped by water was developed. • N503, P350 and TBP were used as the extractants for In, respectively. • The extracted complexes with N503 and P350 were determined to be [InCl 4 −[2S·H]+; the complex formed with TBP was [InCl 4 −[3S·H]+, where S represents the neutral extractant species. • It was found that 99% of In were extracted and 100% of the indium on the loaded organic phase was stripped by water. • Indium can be extracted from hydrochloric acid and enriched in a low-acidity strip solution. Solvent extraction of indium from hydrochloric acid solution using N,N-di(1-methyl-eptyl) acetamide (N503), di(l-methylheptyl)methyl phosphate (P350), and tributyl phosphate (TBP) diluted in sulfonated kerosene was investigated. Extraction was studied as a function of hydrochloric acid and chloride ion concentrations, organic-phase composition, initial indium concentration, phase contact time, and aqueous/organic (A/O) volumetric ratio. The extraction stoichiometry was determined by slope analysis and confirmed by Fourier-transform infrared spectroscopy. It was found that indium extraction efficiency decreased in the order: N503 > P350 > TBP. The extracted complexes with N503 and P350 were determined to be [InCl 4 −[2S·H]+; the complex formed with TBP was [InCl 4 −[3S·H]+, where S represents the neutral extractant species. N503 was found to be best extractant of the three with respect to extracting indium from solutions containing a high concentration of hydrochloric acid. Almost quantitative (99%) indium extraction was obtained using 0.5 mol·L−1 N503 in three extraction stages at an A/O ratio of 2/1; 100% of the indium on the loaded organic phase was stripped by water in two stages at an A/O ratio of 1/3. Indium can therefore be extracted from hydrochloric acid and enriched in a low-acidity strip solution. [ABSTRACT FROM AUTHOR]

• The separation and recovery of indium and germanium in the coexistence solution of indium and germanium were studied, rather than the recovery of a single element. • The element flow and mechanism of the whole process is clearly explained. • The recovery efficiency of indium and germanium both reached>99%. • A flowsheet can be applied to selectively recover germanium and indium from the investigated solution. Selective extraction of indium and germanium from natural resources due to their important role in high-tech fields is attracting more and more attention. In this paper, indium and germanium were recovered from In-Ge residue leaching solution by the selective solvent extraction of indium with D2EHPA and the precipitation of germanium using tannin. This process included two main stages: indium-selective solvent extraction and germanium-selective precipitation. In the first stage, indium was extracted by using an organic phase containing 15% D2EHPA and 85% kerosene. The indium-loaded organic phase was washed with 0.5 M H 2 SO 4 and then stripped by 4 M HCl solution to obtain an indium extraction ratio of 99% and a stripping ratio of 98.3%. In the second stage, the pH of the raffinate was adjusted to 3.5–4.0 with ZnO dust and then mixed with tannin. Germanium (99%) was selectively precipitated as a tannin-germanium complex. The washed tannin-germanium complex was baked at 500 °C for 3 h to produce a germanium concentrate. By studying the separation coefficients of indium, germanium, and zinc (1994 and 1093, respectively), and controlling the reaction conditions, the maximum separation of indium, germanium, and zinc was obtained. The extraction mechanism of indium from sulfuric acid solution by D2EHPA and element migration during the precipitation of germanium using tannin were also studied. This proposed process flow can be used to selectively recover germanium and indium from In-Ge residue leaching solutions. [ABSTRACT FROM AUTHOR]

Abstract: The leaching of a sphalerite concentrate with high indium and iron content in sulfuric acid–oxygen media has been studied in the present paper. The variables considered in the study were particle size, concentration of sulfuric acid, partial pressure of oxygen, leaching temperature, and leaching time. The experimental data indicated that under the conditions employed up to 99% zinc and 90% indium extraction were achieved. The mineralogical analysis of the residue showed that the main minerals are elemental sulphur, unreacted pyrite and quartz, the amount of sulphide sulphur oxidized to sulphate during leaching is 81%. [Copyright &y& Elsevier]