RU2359050C1 - Method of selective extraction of indium from sulfuric solutions - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to hydrometallurgy of rare and scattered elements field and can be used in the method for extraction and concentration of indium from sulfuric solutions. Method includes indium extraction from sulfuric solutions and following its re-extraction. In the capacity of extractant it is used the mixture of two organophosphorous acids in diluting agent. One of it is di-2-ethylhexyl phosphoric acid (D2EHPA), and other is dioctylphenyl phosphoric acid (DIOPPA). Acids concentration in the mixture is equal to 10÷30 and 5÷10% vol. agreeably, the rest - diluting agent.

EFFECT: increasing of indium extraction ratio, expansion of acidity range of optimal extraction, rate and selectivity increasing of the extraction process.

5 tbl, 5 ex

Description

The invention relates to the field of technology of rare and trace elements and can be used for extraction extraction and concentration of indium from weakly acid sulfate solutions of complex composition. Such solutions can be obtained by hydrometallurgical processing of intermediates and concentrates of lead-zinc production. At present, an extraction method is used to extract indium from technological zinc production, which allows concentration of indium and its purification from many impurities. In this case, both individual extractants and their mixtures are used.

A known method of extracting indium from weakly acidic sulfate solutions of zinc production by extraction with a solution of di-2-ethylhexylphosphoric acid (D2EGFK) in kerosene (Kazanbaev LA, Kozlov PA, Kubasov VL, Travkin VF Indium. Technology receipt. M: Ores and metals, 2004, S. 179).

The disadvantage of this method is the use for hydroextraction of indium from the organic phase of solutions of hydrochloric acid, which leads to contamination of technological solutions with chloride ion and the need for subsequent purification from it.

There is a method of extracting indium from sulfate solutions with an extractant containing a mixture of D2EHPA and a quaternary ammonium salt of methyltrialkylammonium in kerosene (USSR Author's Certificate No. 261300, class C22B 58/00, 1985).

The disadvantage of this method of extraction of indium is the low selectivity of the process for certain impurities, for example antimony and arsenic, and the need to use a mixture of sulfuric and phosphoric acids of high concentration for indium extraction from the organic phase.

A known method of extracting indium from weakly acidic sulfate solutions with an extractant containing dialkylphosphinic acid in kerosene (RF Patent No. 218141, CL C22B 58/00, 3/38, 2001).

Closest to the proposed method in terms of technical nature and the achieved result is a method of extracting indium from acidic solutions using a mixture of D2EHPA and isododecylphosphetanoic acid (IDDFK) in an organic diluent as an extractant (RF Patent No. 2238994, CL C22B 58/00, 3/38 , 2003).

The disadvantage of this method is the relatively low extraction of indium from solutions containing more than 15 g / l of sulfuric acid, and low selectivity for some impurity metals present in the initial aqueous solution.

An object of the invention is to increase the degree of extraction into the organic phase, the acidity range of effective extraction, as well as the selectivity of the indium extraction process.

The technical result is achieved by the fact that in the proposed method for the extraction of indium from sulfate zinc-containing solutions, including the extraction of indium with an extractant containing, as main components, a mixture of organophosphorus acids and a diluent, extraction is carried out with a mixture of di-2-ethylhexylphosphoric and dioctylphenyl-phosphoric (DIOFPC) organic when the ratio of components (vol.%): D2EGFK 10 ÷ 30, DIOFFK 5 ÷ 10, the rest is an organic solvent; re-extraction of indium is carried out with solutions containing 250-450 g / l of sulfuric acid.

The proposed method allows to increase the degree of extraction of indium from the aqueous phase at a sulfuric acid concentration of more than 15 g / l, as well as the selectivity of its extraction by impurities from solutions of complex chemical composition.

The essence of the proposed method is visible from the following examples.

Example 1. The extraction of indium is carried out from zinc sulfate solutions with variable sulfuric acid content. As extractants used D2EGFK, DIOFK, as well as a mixture of D2EGFK with IDDFK (prototype) and D2EGFK with DIOFFK (the proposed method). The diluent is kerosene. The composition of the initial aqueous phase, g / l: indium 0.85-0.97; zinc 83-89; sulfuric acid 3-45. The ratio of the volumes of organic and aqueous phases O: B = 1: 1, temperature 20.5-21.2 ° C.

Table 1 shows the experimental data on the effect of the acidity of the aqueous phase on the extraction of indium in the organic phase.

Table 1
The effect of the acidity of the aqueous phase on indium recovery Conc. H ₂ SO ₄ , g / l The degree of extraction of indium E,% The increase in the degree of extraction ΔE = E ₃ -E ₂ 20% vol. D2EGFK + 5% vol. IDDFK (prototype) E ₂ 20% vol. D2EGFK + 5% vol. DIOFF (proposed method) E ₃ one 2 3 four 3 96.4 99.6 3.2 5 95.8 99.3 3,5 10 93.1 99.5 6.4 fifteen 92.3 99.1 6.9 17 90.9 99,2 8.3 twenty 92.6 97.9 5.3 25 81.6 95.6 14.0 thirty 71.2 93.1 21.9 35 65,4 91.2 25.8 40 59.2 88.6 29.4

It can be seen from the above data that the use of the proposed mixture of D2EGFK with DIOPCF as an extractant provides a 3–30% increase in the degree of extraction of indium compared to a mixture of D2EGFK with IDDFK (prototype) in the entire studied acidity range. As a result, the range of acidity in which efficient extraction of indium (> 90%) takes place extends 2.7 times along the upper boundary and reaches 40 g / l of sulfuric acid (instead of 15 g / l of the prototype).

Example 2. Extraction is carried out from an aqueous solution containing, g / l: indium 0.91; zinc 89.7; sulfuric acid 26.9. The extractant is a mixture of D2EGFK with IDDFK (prototype) and DIOFF (proposed method) in kerosene with a variable ratio between its active components. The ratio of volumes of organic and aqueous phases O: B = 1: 3, temperature 20.9 ° C, mixing time 10 minutes Table 2 shows the experimental data on the effect of the composition (concentration of components) of the extractant on the extraction of indium in the organic phase.

table 2
The effect of extractant composition on indium recovery The composition of the extractant, vol.% The degree of extraction of indium Concentration D2EGFK DIOFFK one 2 four thirty 10 97.8 thirty 5 93.2 25 10 94.7 25 5 96.0 twenty 10 92.1 twenty 5 96.4 twenty 2.5 84.3 fifteen 10 95.4 10 5 93.2 5 5 18.6 D2EGFK IDDFK 81.3 (prototype)

From the above data it is seen that effective extraction (> 90%) in the proposed method is achieved with the following composition of the organic phase (vol.%): D2EGFK 10 ÷ 30; DOPFK 5 ÷ 10; kerosene rest.

Example 3. The completeness of indium reextraction, achieved using solutions of sulfuric acid of various concentrations, is demonstrated. Reextraction is carried out from an organic phase containing 1.95-2.08 g / l of indium, with a ratio of contacted volumes of phases O: B = 10: 1, temperature 21.2 ± 1.0 ° C. The experimental data are shown in table 3.

Table 3
Dependence of the degree of stripping on the concentration of sulfuric acid in the stripping agent The concentration of H ₂ SO ₄ in the stripping agent, g / l Extraction of indium from the organic phase,% The increase in the degree of stripping,% ΔЕ = E ₃ -E ₂ 20% vol. D2EGFK + 10% vol. IDDFK (prototype) E ₂ 20 vol.% D2EGFK + 10 vol.% DOPFK (proposed method) E ₃ 233 61.0 70.8 9.8 252 78,4 80.9 2.5 306 80.3 83.5 3.2 357 85.1 89.5 4.4 398 89.6 92.1 2.5 425 93.5 95.4 1.9 450 97.6 98.8 1,2 461 99.6 99.9 0.3

From the above data it follows that effective reextraction (≥80%) of indium from the organic phase in one step from a mixture of D2EHPA with DIOPPA in kerosene can be carried out with aqueous sulfuric acid solutions containing 250-450 g / l. From a mixture of D2EGFK with IDDFK (prototype) in kerosene, indium reextraction is 2-4% worse and slower.

Example 4. Shows the selectivity of the proposed method. The extraction is carried out from an aqueous solution of the composition, g / l: In 0.81; Zn 90.2; Cd 0.94; Cu 1.21; As 1.08; Sb 0.08; Fe (III) 0.17; Fe (II) 5.1; H ₂ SO ₄ 19.8. The extractant is a mixture of 20% D2EGFK and 10% IDDFK (prototype), a mixture of 20% D2EGFK and 10% DIOFFK (the proposed method) in kerosene. The ratio of the contacted phases is O: B = 1: 1, the temperature is 20.8 ° C, and the mixing time is 10 minutes. The experimental data on the distribution coefficients of impurity elements are given in table 4.

Table 4
Selectivity of In extraction in the presence of impurities Extractant Partition coefficient, D In Zn Cd Cu As Sb Fe (II) Fe (III) 20% D2EGFK + 10% IDDFK (prototype) 18.3 0.02 0,03 0.01 0.006 0.15 0.008 12.6 20% D2EGFK + 10% DOFFK (the proposed method) 26.2 0.01 0.02 0.005 0.003 0.10 0.005 10.7

Impurity reduction
D _prot / D _pre - 2 1,5 2 2 1,5 1,6 1,2

From the above data it follows that the proposed method in comparison with the prototype provides 1.5-2 times less extraction of impurity elements. This allows you to get organic solutions (extracts) of indium, purer in the content of these elements, which in the future can significantly reduce the number of operations for cleaning them.

Example 5. Extraction is carried out from a sulfate solution containing, g / l: indium 0.54; zinc 91.2; sulfuric acid 35.8. The extraction is carried out in countercurrent mode at a temperature of 21.3 ° C and a stirring time of 10 minutes at each stage of the process. As the extractant used a mixture of D2EGFK with DIOFFK, as well as D2EGFK with IDDFK (prototype). Table 5 shows the modes of extraction and re-extraction of indium and the main indicators of the process.

Table 5
The main indicators of the countercurrent process of extraction of indium from sulfate solutions Indicator Prototype The proposed method The composition of the extractant (in kerosene) A mixture of 20% D2EGFK and 10% IDDFK A mixture of 20% D2EGFK and 10% DIOFFK Extraction Ratio O: B 1: 7 Number of countercurrent stages 2 The content of In raffinate, g / l 0,026 0.001 Extraction of In to extract,% 95.2 99.8 Reextraction Ratio O: B 1:10 Number of countercurrent stages 3 The content of In reextract, g / l 34.8 37.6 The content of In in the circulating extractant, g / l 0.02 0.01 The extraction of In re-extract,% 99,4 99.7 Total recovery In,% 94.6 99.5

A review of the data indicates that the extraction of indium by the claimed method is higher (99.5%) than by the previously known prototype method (99.6). In addition, the use of the proposed method allows to expand the range of concentrations of sulfuric acid to 40 g / l in an aqueous solution in which effective extraction (> 90%) occurs, in the prototype such extraction is achieved only if the concentration of sulfuric acid does not exceed 15-16 g / l Finally, it allows one to increase the selectivity of indium extraction by a factor of 1.5–2 and obtain reextracts that do not contain chloride ions and other impurity ions. High quality indium is obtained from such reextracts without additional purification.

Claims (1)

A method of extracting indium from sulfuric acid solutions, including extraction of indium using a mixture of two organophosphorus acids in an organic diluent as an extractant, one of which is di-2-ethylhexylphosphoric acid (D2EGFK), and reextraction with a solution of sulfuric acid with a concentration of 250-450 g / dm ³ , characterized in that as the second organophosphorus acid using dioctylphenylphosphoric acid (DIOFF) in the following ratios,%:
di-2-ethylhexylphosphoric acid (D2EGPA) 10 ÷ 30 dioctylphenylphosphoric acid (DIOFF) 5 ÷ 10 organic diluent rest