World of Metallurgy ERZMETALL 68 2015 No 3184 Kaixi Jiang et al The Process Improvement Researches for Zinc Hydrometallurgy range was 80 to 95 C and the retention time was 0 5 h The resultant In rich residue could be successively treated by acid leaching solvent extraction and finally electrorefined into pure indium Indium recovery was as high as 91 Removal rate of iron exceeded 90 and the concentration of iron in solution decreased from 20 to 25 g L to below 2 0 g L Iron enriched in the residue and its content was more than 60 meanwhile little zinc 1 0 was lost in the residue Zinc recovery was above 96 The main parameters and results are shown in Table 4 The flowsheet of the process for indium recovery is shown in Figure 2 4 Recovery of gallium and germanium BGRIMM developed a selective leaching process facili tated by controlling potential to treat Ga Ge containing zinc concentrate 9 10 Ga Ge and Zn were effectively leached into the solution Then Ga and Ge were precipi tated as Ga Ge concentrates and separated from the solution Ga and Ge in the concentrates were acid leached and separately extracted by G3815 at different acid con centration The solution was sent for zinc extraction after iron removal using goethite process It is worth mentioning that G3815 is a ether hydroxamic acid extractant synthe sized by BGRIMM 11 12 According to the laboratory and pilot tests leaching rates of Ga Ge and Zn were 93 2 93 8 and 98 respec tively at the conditions of temperature of 105 C retention time of 1 h and final potential of 350 to 370 mV Almost all Fe existed as Fe2 in solution and thus Ga and Ge could be easily precipitated with less iron entrainment through the neutralization displacement method The precipitation rates of Ga and Ge reached more than 98 and 97 respectively resulting in Ga Ge concentrates containing about 0 2 Ga and 0 08 Ge The Ga Ge concentrates were dissolved with dilute sulphuric acid at 60 C and the Fig 2 The proposed principle flowsheet of the process for indium recovery Table 5 The main conditions and results of recovery of gallium and germa nium Leaching conditions Results Zinc concentrate Ga 230 g t Ge 205 g t Zn 55 50 Fe 5 27 S 31 5 Particle size P98 0 044 mm MH2SO4 MZn 0 7 Pulping L S 5 1 L kg temperature 105 C Retention time 1 h total pressure 350 400 kPa Oxygen partial pressure PO2 250 kPa Agitator speed 1 73 m s Final potential 350 to 370 mV Leaching rate Ga 93 2 Ge 93 8 Zn 98 Solution Zn 150 to 170 g L Fe 6 to 9 g L Fe3 1 0 g L Ga Ge precipitation conditions Results Neutralizing agent CaCO3 Amount of neutralizing agent 13 4 kg m3 Temperature 80 C retention time 1 5 h Final pH 4 5 to 5 2 displacing agent zinc powder Amount of displacing agent 1 kg m3 Precipitation Ga 98 Ge 97 Residue Ga 0 17 Ge 0 082 Solution Ga 0 0006 g L Ge 0 001 g L Solvent extraction conditions Results Ge extraction Organic phase 5 G3815 2 5 isooctanol kerosene Phase ratio O A 1 5 E 4 1 S 4 1 W Stages 4 E 3 S 3 W temperature 15 to 45 C Stripping agent 60 g L NH4F Washing agent 6 mol L HCl Ga extraction Feed solution after Ge extraction pH 1 8 2 2 Organic phase 10 G3815 5 P2O4 2 5 isooctanol kerosene Phase ratio O A 1 3 E 3 1 S 2 1 W Stages 4 E 3 S 3 W temperature 15 to 45 C Stripping agent 2 0 to 2 5 mol L HCl Washing agent 6 mol L HCl Extraction Ge 96 1 Ga 96 6 E extraction W washing S stripping

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