RU2275438C1 - Extractant for extraction of indium - Google Patents

Abstract

FIELD: hydrometallurgy, chemical technology.

SUBSTANCE: invention proposes octanoic acid-base extractant in organic solvent that comprises additionally nitrogen-containing oligomeric para-tert.-butylphenol in the molar ratio of reagents octanoic acid : oligomeric para-tert.-butylphenol = (1.5-2.5):(2.5-1.5). Using this extractant allows enhancing the distribution coefficient for indium and separation of indium and zinc, to carry out extraction from the parent solutions with pH = 2.4-2.8 and to re-extract indium with sulfuric acid in the concentration 0.5 mole/l with effectiveness of extraction ~99%. Invention can be used for extraction, purification and concentrating indium in processing leaching indium-containing waste solutions and concentrates, for example, from zinc sulfate solutions.

EFFECT: improved and valuable properties of extractant.

1 tbl, 8 ex

Description

The invention relates to hydrometallurgy of rare and non-ferrous metals and can be used in the technology of extraction, purification and concentration of indium.

In the technology of producing indium in the processing of leach solutions of Waelz oxides, dusts and sublimates from zinc and zinc-lead industries, copper wastes, as well as products from the processing of primary indium concentrates, for example jarosite or cementation sediments, it becomes necessary to extract and concentrate indium and separate it from a number of related elements, including zinc.

It is known to extract indium from zinc sulfate solutions by liquid extraction of D2EHPA (di-2-ethylhexylphosphoric acid) followed by reextraction with a solution of sulfuric acid [Patent 2048563, Russia, MKI ⁶ C 22 V 58/00. Publ. 11/20/95. Bull. No. 32], as well as the extraction of indium by extraction with mixtures of D2EHPA with aliphatic alcohols, in this case, reextraction is carried out with a mixture of H ₂ SO ₄ and HCl in a ratio of 4-5: 1 g · equiv / l [A.s. 1308559, USSR, MKI C 01 G 15/00, B 01 D 11/04. Publ. in B.I., 1987, No. 17] (in contrast to the classical reextraction of 4–9 mol / L with hydrochloric acid solutions [Giganov G.P., Maltsev V.K., Pavlov Yu.I. // In the book: Extraction and sorption in the metallurgy of non-ferrous metals. Collection of scientific works of VNIItsvetmeta, Moscow, 1968, No. 12, S.35-38]), the extraction of indium in re-extract from the initial solution is E _total = 96-98%.

The main disadvantages of using D2EGFK are the difficulty of purifying the extractant from strong complexes of iron and tin, which are extracted together with indium and accumulate in the organic phase, as well as the accompanying D2EGFK impurities M2EGFK (mono-2-ethylhexylphosphoric acid), which pollute the aqueous phase in suspension and the formation.

Common disadvantages of extraction systems with D2EHPA are the high concentrations of sulfuric acid at the stage of re-extraction, the difficulty of preparing the extractant for reuse (removal of inorganic acid from the extractant, its purification from hard-to-extract iron and adjusting the composition of the extractant), as well as low selectivity with respect to indium in the pH range 2-3.6 (the degree of zinc extraction in the re-extract is 50-99% of the original).

Closest to the proposed extractant is octanoic acid and an organic diluent [RU 2186139 C2, IPC C 22 B 58/00, publ. July 27, 2002]. When indium is extracted with a 0.1 mol / L solution of octanoic acid in chloroform from a zinc solution with an initial concentration of the element C ⁰ _In = 10 ^-7 mol / L, the concentration of sodium perchlorate is 0.1 mol / L with a phase contact time of 24 hours and pH = 3.50-3.60 logarithm of the indium distribution coefficient logD _In = 1.03-1.17 (degree of extraction of indium E _In = (y _In / C ⁰ _In ) · 100% = 91-94%); at C ⁰ _Zn = 10 ^-3 ÷ 10 ^-7 mol / L under the same conditions, logD _Zn ~ - 5.5 ÷ -7 (E _Zn ~ 10 ^-3.5 ÷ 10 ^-5 %), the theoretical separation coefficient of indium and zinc β _{In / Zn} ~ 10 ^6.5 ÷ 10 ⁸ . At a raffinate pH of 2, logD _In <-1 (E _In <10%). The disadvantages of the use of monocarboxylic acids and, in particular, octanoic acid are: extraction of indium in a narrow pH range from solutions strongly diluted with acid (pH = 3.5-5.0); in real conditions, at such pH the risk of precipitation of basic salts or indium hydroxide increases, extraction from such solutions is practically difficult; extraction of indium from solutions with an initial pH of 2.4 is possible, but pH adjustment during the process or extraction with the sodium form of octanoic acid is required, which complicates the use of carboxylic acids. In addition, higher monocarboxylic acids and their concentrated solutions have a high viscosity, and when using them, there is a slight deterioration in the extraction of indium and a decrease in the separation coefficient of indium and zinc (β _{In / Zn} ) when passing to low-polar diluents and with an increase in the concentration of zinc sulfate in the initial solution.

The technical task of the invention is to increase the degree of extraction of indium during its extraction from zinc sulfate solutions.

The technical result is achieved by the fact that the extractant for the extraction of indium from zinc sulfate solutions contains octanoic acid (OK), an organic diluent and additionally nitrogen-containing oligomeric para-tert-butylphenol (OBF) at a molar ratio of octanoic acid: nitrogen-containing oligomeric para-tert-butylphenol, equal to 1.5: 2.5-2.5: 1.5.

The effect of increasing the degree of indium extraction can be explained by the formation and extraction of mixed hydrophobic complexes of indium with OK and OBF. As a result, a synergistic effect is observed in this system. At pH 3.4–3.6, a sharper than expected increase in the indium distribution coefficients to 10 ^{–3–10 4} occurs, apparently due to the polymerization of indium complexes with reagents in the organic phase and a change in the thermodynamic activities of organic components (decrease activities of indium complexes and / or increased activity of OBF and OK).

An increase in the equilibrium (final) pH (> 3.6) is impractical, since zinc extraction is improved, and basic indium compounds may precipitate, which disrupts the extraction process.

With a decrease in the OBF: OK ratio from 1.5: 2.5 to 1: 3 or with an increase to 3: 1, and also with a decrease in pH (<3.48), the indium distribution coefficients decrease (to logD _In ≤2.0) and indium-zinc separation coefficients (up to β _{In / Zn} ≤580).

With a decrease in the total molar concentration of OK and OBF, the distribution coefficient of indium D _In decreases, and with an increase to 0.6 mol / L, the degree of zinc extraction increases (to Е _Zn = 17%), which reduces the efficiency of separation of In from Zn.

When processing indium-containing primary concentrates and wastes, solutions containing 0.5-1.5 g / l indium are weakly concentrated in sulfuric acid (up to 0.12 mol / l). Extraction of indium by the proposed mixture is accompanied by extraction of sulfuric acid, therefore, taking into account the optimal extraction conditions, in the presence of a background electrolyte (0.1 ÷ 0.2 mol / L ZnSO ₄ ), the pH of the initial solutions can vary in the range of 2-3 (at V _O : V _B = 0.5 ÷ 2), which corresponds to a concentration of H ₂ SO ₄ 0.0012 ÷ 0.0125 mol / L. This distinguishes the extractant from the prototype.

The extractant was tested in laboratory conditions. Used toluene solutions of nitrogen-containing oligomeric para-tert.butylphenol brand "Yarrezin B" (with an average molecular weight of 477 and a nitrogen content of 1.28-1.29%), obtained by polycondensation of para-tert.butylphenol with formaldehyde in the presence of ammonia and octanoic acid qualifications "h". Extraction was carried out at a volume ratio of organic and aqueous phases V _O : V _B = 1: 1.

Examples illustrating the invention.

Example 1. From a solution containing 1.011 g / l In and 0.121 mol / l ZnSO ₄ (7.912 g / l Zn), indium is extracted by contacting the solution with an organic phase containing 0.4 mol / l octanoic acid (OK) in toluene, with a phase volume ratio of V _O : V _B ~ 1: 1 for three hours. After phase separation, pH = 3.60, the degree of indium extraction into the organic solution E _In = 87.83% (indium concentration in the organic phase y _In = 0.888 g / l, indium concentration in the aqueous phase x _In = 0.122 g / l, coefficient indium distribution D _In = 7.28), the degree of zinc extraction E _Zn = 8.33 · 10 ^-2 % (the concentration of zinc in the organic phase y _Zn ~ 1 · 10 ^-4 mol / l, the concentration of zinc in the aqueous phase x _Zn ~ 0.121 mol / L, zinc distribution coefficient D _Zn = 8.33 · 10 ^-4 ). 0.5 mol / L H ₂ SO ₄ indium is re-extracted from the extract with a phase volume ratio V _O : V _B = 1: 1 for 50 minutes. The degrees of extraction of indium and zinc in the re-extract are R _In = 99.9% and R _Zn = 99.99%. The separation coefficient of indium and zinc β _{In / Zn} = 8738.

Example 2. Of containing 1.020 g / l In and 0.11867 mole / liter ZnSO ₄ (7.760 g / l Zn) solution with pH = 2.74 is performed _ref indium extraction, contacting the solution with an organic phase containing 0.15 mol / L of oligomeric para-tert-butylphenol (OBF) and 0.25 mol / L of octanoic acid (OK) in toluene (molar ratio of OBF: OK 1.5: 2.5), with a phase volume ratio of V _O : V _B = 1: 1 for three hours. After phase separation, pH = 3.48, the degree of extraction of indium in the organic solution E _In = 99.90% (concentration of indium in the organic phase y _In = 1.019 g / l), the degree of extraction of zinc E _Zn = 7.22% (concentration of zinc in the organic phase, y _Zn = 0.00857 mol / L). 0.5 mol / L H ₂ SO ₄ indium is re-extracted from the extract with a phase volume ratio V _O : V _B = 1: 1 for 50 minutes. The degrees of extraction of indium and zinc in the re-extract are R _In = 99.3% and R _In = 99.99%. The separation coefficient of indium and zinc β _{In / Zn} = 13064.

Example 3. The extraction is carried out from a solution with a concentration of indium 1.001 g / l, zinc 0.12128 mol / l (7.930 g / l) and pH _Ref = 2.57 with a mixture of 0.2 mol / l OBF and 0.2 mol / l OK (OBF: OK ratio 1: 1) is the same as in Example 2. Final pH = 3.49, E _In = 99.92% (x _In = 0.0008 g / l, in _In = 1.000 g / l ), E _Zn = 9.31% (y _Zn = 0.0113 mol / L). The degree of re-extraction of indium with 0.5 mol / L sulfuric acid for 50 minutes and with a ratio of phase volumes V _O : V _B = 1: 1 is R _In = 98.7%. β _{In / Zn} = 12186.

Example 4. The extraction is carried out from a solution with concentrations of 1.041 g / l indium, 0.12393 mol / l (8.104 g / l) zinc and pH _Ref = 2.43 with a mixture of 0.25 mol / l OBF and 0.15 mol / l OK (OBF: OK ratio 2.5: 1.5) as in Example 2. Final pH = 3.58. E _In = 99.99% (x _In = 0.0001 g / l, y _In = 1.041 g / l), E _Zn = 12.85% (y _Zn = 0.0159 mol / l, which corresponds to y _Zn = 1.042 g / l). The degree of re-extraction of indium with 0.5 mol / L sulfuric acid for 50 minutes and with a phase ratio V _O : V _B = 1: 1 is R _In = 99.0%. β _{In / Zn} = 71119.

Example 5. The extraction is carried out from a solution containing 1,030 g / l In and 0.12135 mol / l (7.935 g / l) zinc, a mixture of 0.1 mol / l OBF and 0.3 mol / l OK (ratio OBF: OK 1: 3) the same as in example 2. Final pH = 3.59, E _In = 98.54% (y _In = 1.015 g / l), E _Zn = 10.4% (y _Zn = 0.0126 mol / L), β _{In / Zn} = 583.

Example 6. Extraction is carried out from a solution containing 1.032 g / l of indium and 0.12257 mol / l (8.015 g / l) of zinc, with a mixture of 0.3 mol / l of OBF and 0.1 mol / l of OK (ratio of OBF: OK 3: 1) as in Example 2. Final pH = 3.60. E _In = 96.51% (for _In = 0.996 g / L), E _Zn = 15.4% (y _Zn = 0.019 mol / L), β _{In / Zn} = 152.

Example 7. The same as in example 4, but after extraction to separate zinc, the extract is washed twice with a dilute solution of sulfuric acid at a final pH of 3.58 and with a phase volume ratio of V _O : V _B ~ 1: 10 for 30 minutes. After a double wash, the concentration of zinc in the organic phase is ~ 7 · 10 ^-6 mol / l, the loss of indium with wash solutions is ~ 3% (the concentration of indium in the aqueous solution after washing is 1-2 mg / l). Then, 0.85 mol / L sulfuric acid is back-extracted for 50 minutes and with a phase volume ratio of V _O : V _B = 10: 1. R _In = 91.1%. R _Zn = 99.9%. The concentration of indium in the reextract is 9.171 g / l, the concentration of zinc is ~ 4.6 mg / l. The total degree of indium extraction E _total = 88.1%. The residual acidity of the reextract ~ 0.41 mol / l H ₂ SO ₄ .

Example 8. The extraction is carried out from a solution with a concentration of indium 1.021 g / l, zinc 0.12387 mol / l (8.100 g / l) and pH _Ref = 2.26 with a mixture of 0.3 mol / l OBF and 0.3 mol / l OK (molar ratio OBF: OK 1: 1) is the same as in example 2. Final pH = 3.54. E _In = 99.97% (y _In = 1.0207 g / L), E _Zn = 17.4% (y _Zn = 0.0216 mol / L), β _{In / Zn} = 15791.

The results described in the examples are summarized in table.

No. p / p The ratio of OK: OBF, mol / l The degree of extraction of indium, E _In ,% The separation coefficient of indium and zinc, β _{In / Zn} one 0.4: 0 (prototype) 87.83 8738 2 0.25: 0.15 99.90 13064 3 0.2: 0.2 99.92 12186 four 0.15: 0.25 99,99 71119 5 0.3: 0.1 98.54 583 6 0.1: 0.3 96.51 152

Thus, a comparison of the known and proposed extractants shows that the use of a mixture of OBF and OK allows extraction from relatively acidic solutions (pH = 2.4-2.8), to increase the degree of extraction of indium (at pH≥3.48 and the total concentration OK and OBF 0.4 mol / l E _In ≥99.9% (logD _In ≥3.0) compared with E _In = 87.83% (logD _In = 0.86) for the prototype) and achieve an acceptable degree of separation In and (lgD _In = 0.86) for the prototype) and achieve an acceptable degree of separation of In and Zn: β _{In / Zn} = 12186 ÷ 71119 in contrast to β _{In / Zn} = 8738 for the prototype, and also reextract indium 0.5 mol / l H ₂ SO ₄ with R _In = 9 8.7-99.3%.

Using the proposed extractant, it is possible to concentrate indium by stripping 0.85 mol / L sulfuric acid with a phase volume ratio of V _O : V _B = 10: 1, with R _In = 91.1%, the concentration of indium in the reextract ~ 9.2 g / l

Instead of toluene, a mixture of kerosene and 25 vol.% Octanol can be used as a diluent; instead of OK, synthetic fatty acid fractions.

The use of a nitrogen-containing oligomeric para-tert-butylphenol can reduce the pollution of the aqueous phase with organic reagents (the solubility of the oligomeric alkyl phenol in the aqueous phase is ~ 1 · 10 ^-4 g / l). The complex of iron with OBF and OK is easily destroyed upon reextraction; accumulation of impurities in the extractant does not occur. However, during the extraction, stable emulsions and interfacial suspensions are not formed. The phase separation time during extraction and re-extraction is from 10 seconds to 1 minute.

In contrast to the prototype, when using the proposed extractant, practically quantitative extraction of indium is achieved when its concentration in the solution is ~ 1.0 g / l (8.7 · 10 ^-3 mol / l), V _O : V _B = 1: 1 and the initial value pH 2.4-2.8.

The positive effect is that due to the introduction of OBF additives into the system with octanoic acid, the obtained extractant extracts indium with significant indium and zinc separation coefficients (β _{In / Zn} = 12186 ÷ 71119) compared to β _{In / Zn} = 8738 for the prototype and almost quantitative extraction and re-extraction of indium in one step becomes possible: E _In ≥99.9%, R _In = 91.1-99%. The total degree of indium extraction into the reextract from the initial solution is ≥88.1-98.99%, and at V _O : V _B = 1: 1 98.60-99.29% (which is 10.87-11.56% more effective than for the prototype) with a residual indium concentration in the raffinate of ≤1 mg / L.

Claims (1)

An extractant for extracting indium from zinc sulfate solutions containing octanoic acid and an organic diluent, characterized in that it further comprises a nitrogen-containing oligomeric para-tert-butylphenol in a molar ratio of octanoic acid and a nitrogen-containing oligomeric para-tert-butylphenol equal to 1.5: 2 5 ÷ 2.5: 1.5.