RU2157421C2 - Method of gallium recovery from aluminate solutions - Google Patents

Abstract

FIELD: nonferrous metallurgy; applicable in recovery of gallium from wastes of aluminum production, tailing solutions with low content of gallium from intermediate products, and wastes of various production processes of chemical industry and metallurgy. SUBSTANCE: method includes adding to aluminate solution containing gallium of reagent in form of copolymer of vinyl chloride and maleic anhydride applied to silicon dioxide from solution in dioxane; cooling to temperature of minus 4 to minus 8 and stirring at this temperature for 25- 30 min. Then, solution is decanted, filtered out, and gallium is separated from solid phase by washing with distilled water. EFFECT: higher degree of gallium recovery from solution and reduced process duration. 2 tbl, 3 ex

Description

The invention relates to the field of non-ferrous metallurgy and can be used to extract gallium from aluminum waste, tailings with a low gallium content and from industrial products and waste from various industries of the chemical industry and metallurgy. Currently, approximately 90% of gallium is obtained in the production of alumina, the rest is extracted from the dust of zinc plants, in the processing of phosphate ores, from coal ash. The proximity of the ionic radii of gallium and aluminum (0.62 and 0.57 Nm) and close pH values of the deposition of hydroxides of these elements (pH _{Ga (OH) 3} from 3.4 to 9.7; pH _{Al (OH) 3} from 4.1 up to 10.6) makes it possible to replace aluminum with gallium in a large number of rocks and minerals.

 For the processing of aluminum ores using Bayer and sintering methods, as well as their combined options. In the process of decomposition of aluminate solutions (decomposition or carbonization), aluminum hydroxide initially precipitates, and most of the gallium remains in the circulating solutions. When bauxite is processed by the Bayer method, gallium is transferred to an aluminate solution by 55-70% and accumulates to a concentration of about 0.2 g / l, then an equilibrium occurs between the gallium content in alumina and the aluminate solution. About 30-40% of gallium remains in dump red mud [1].

 In foreign practice, extraction methods have been widely used that make it possible to extract, concentrate and separate gallium from a number of related elements. The most widely extraction methods for the extraction of gallium have been studied for aluminum products. Extraction is mainly used for the extraction of gallium from primary gallium concentrates (for example, precipitation of the last stages of carbonization of reverse aluminate solutions, etc.).

 Practically, the extraction is carried out as follows: the gallium concentrate is dissolved in hydrochloric acid and the acidity is adjusted to the optimal values for extraction (4-6 N). Then the solution is intensively mixed with an extractant (most often ether or ketone): gallium in the form of tetrachlorogallic acid passes into the organic phase. After that, the organic layer is separated and either water stripping (or a solution of acids or salts) is carried out, or the solvent is distilled off, and the gallium chloride contained in it is dissolved in water. The aqueous solution is adjusted to the alkalinity necessary for the electrolysis or cementation process [1]. At low gallium concentrations (less than 30 mg / l), extraction may be economically unjustified due to significant loss of extractant.

 An example of the use of ion exchange in the production of gallium is the method described in [2] for the sorption extraction of gallium from hydrochloric acid solutions obtained in the process of leaching of anode alloys. Anion exchangers AMP, VP, AN-2F, EDE-10P were used as ion exchangers. The total exchange capacity (POE) of these gallium ion exchangers is almost the same (2 mEq / g), and all of them provide complete separation of gallium from aluminum. In accordance with this method, the crushed anode alloy is dissolved in HCl so that the acidity is not less than 3.7 N. HCl. The solution is treated with iron chips to restore iron to ferrous and passed through anion exchange resin, which is then washed with 5 N. HCl. Gallium is stripped with 0.5 n. HCl, treated with NaOH and electrolysis from an alkaline solution.

 In the table. 1 (the compositions of the initial solution and the eluate are given after ion-exchange separation of gallium from impurities (see the end of the description).

A known method of ion-exchange separation of gallium and aluminum on anion exchange resin L-150, based on the use of their different propensities to form rhodanide complexes [3]. In a slightly acidic medium, at a concentration of potassium thiocyanate 2M, the Ga (SCN) ₄ ^- complex is formed, which is absorbed by the sorbent. Aluminum in the form of a cation passes into the filtrate.

 Under static conditions, the sorption properties of a number of ion exchangers (see Table 2) with respect to gallate and aluminate ions were studied [4]. The greatest adsorbability in gallium is possessed by anion exchangers AB-16, AN-31. For the separation of gallium and aluminum, ion-exchange resin AB-16 was used.

 The sorbability of gallium in the presence of aluminum under dynamic conditions was 40 mg / g.

 Closest to the claimed method is a method for extracting hydrolyzed gallium ions by cation exchangers [5], which is adopted as a prototype.

Sorption was carried out from 0.1 N. stoichiometrically neutral solutions of gallium nitrate with a pH of 2.7. Through columns with a cross section of 1 cm ² , 1.00 g of H-form cation exchangers were passed at a rate of 0.1 - 0.2 ml / min of a 1-3 liter solution. The difference in pH and gallium concentration in the initial solution and in the filtrate was established within 10-50 days. It was shown that the sorbability of gallium at pH 2.0–2.3 with KU-2x8, KB-2x7P and KFP 6-8 cation exchanges exceeds the total exchange capacity of these resins, which is explained by the sorption of gallium hydroxocomplexes [5].

 The disadvantages of the prototype are a very long duration and low productivity of the process.

 The objectives of the invention are to increase the degree of extraction of gallium from solutions and reduce the time of the process.

The technical result is achieved by the fact that gallium is removed from the aluminate solution by ion exchange, while the solution is poured into a container with a reagent (a copolymer of vinyl chloride and maleic anhydride deposited from a solution in dioxane on silicon oxide as a base), cooled to (-4) - ( -8) ^o C and stirred at this temperature for 25-30 minutes, then the solution is decanted, filtered off, the solid phase is isolated - the precipitated gallium precipitate in the composition with a copolymer of vinyl chloride and maleic anhydride (SP) on SiO ₂ (SP / SiO ₂ ) and secrete gallium from solid distillirorannoy phase by washing with water.

 A copolymer of vinyl chloride and maleic anhydride is obtained according to the method [6].

The essence of the technical solution lies in the fact that gallium is practically separated from aluminum for 25-30 minutes at a low temperature from -4 to -8 ^o C with SP / SiO ₂ reagent, as a result of which, after phase separation, gallium is captured and held by a SP / SiO reagent ₂ , and aluminum remains in solution.

 The extraction of gallium from solutions of aluminum production by the proposed method reaches a value of 86.4% in one stage of the process.

Such a combination of features, as in the claimed method, namely:
- the use of a solution containing Ga ³⁺ and Al ³⁺ with the reagent SP / SiO ₂ ;
- cooling the mixture to (-4) - (-8) ^o C with stirring for 25 to 30 minutes;
- phase separation by filtration and subsequent isolation of pure gallium (without aluminum) in the form of nitrate is not in the known solutions.

 Example 1

Dry fine powder of silicon oxide SiO ₂ (with a grain diameter of not higher than 0.25 mm), and weighing m = 3.2379 g, is filled with a homogeneous 10% solution of DP in dioxane in a volume of 8 ml (the content of DP is 0.8888 g) . Then, after thoroughly mixing and holding for 24 hours at room temperature, the solvent (dioxane) is removed by drying at 35-40 ^° C and atmospheric pressure, and subsequently, in order to completely get rid of the solvent, at 35 ^° C and increased pressure. The amount of SP in the mixture is 21.54% of the total mass or 27.45% of the mass of SiO ₂ .

 In this form, it is used to isolate gallium from aqueous solutions with aluminum.

The process is as follows: 20 ml of an aqueous solution of gallium nitrate Ga (NO ₃ ) _{3 at a} concentration of 0.004 g-eq / L 0 and aluminum nitrate Al (NO ₃ ) _{3 at a} concentration of 0.004 g-eq / L are poured into a flask prepared according to the procedure described above reagent (m _SiO2 = 3.2379 g; m _SP = 0.8888 g) and placed in a cryostat with a temperature of -8 ^o C. The mixture was kept at this temperature, stirring for 25 minutes, and the solution was filtered. The bulk of gallium remains in the solid phase, while aluminum remains in solution. After washing out the gallium nitrate salt from the solid phase with distilled water, its amount was 86.4% of the concentration in the initial solution. Thus, it is possible to obtain gallium containing small amounts of aluminum (the aluminum content in the aqueous eluate does not exceed 2% when the content of elements in the initial solution is 1: 1).

 Example 2

10 ml of an aqueous solution of gallium nitrate Ga (NO ₃ ) _{3 at a} concentration of 0.008 g-eq / L and aluminum nitrate Al (NO ₃ ) _{3 at a} concentration of 0.006 g-eq / l are poured into a flask with a reagent prepared according to the method described above, weighing m = 2 g (m _SiO2 ) = 1.5692 g; m _SP = 0.4308 g) and placed in a cryostat with a temperature of -4 ^o C. The mixture is kept at this temperature with stirring for 30 minutes and the solution is filtered. Extraction from the solid phase is carried out in a similar manner with distilled water. After washing, the amount of gallium nitrate salt was 50.6% of the salt concentration in the initial solution. The aluminum content in the aqueous eluate does not exceed 4%.

 Example 3

20 ml of an aqueous solution of gallium nitrate Ga (NO ₃ ) ₃ concentrations of 0.0032 g-eq / L and aluminum nitrate Al (NO ₃ ) ₃ concentrations of 0.0032 g-eq / l are poured into a flask prepared according to the procedure described in the example 1, reagent mass m = 5 g m _SiO2 = 3.9230 g; m _SP = 1.0770 g) and placed in a cryostat with a temperature of -7 ^o C. The mixture is kept at this temperature with stirring for 25 minutes and the solution is filtered. All subsequent operations are carried out as in the previous examples 1 and 2. The amount of gallium nitrate recovered was 83.1% of the salt concentration in the initial solution. The aluminum content in the aqueous eluate does not exceed 3% when the content of elements in the initial solution is 1: 1.

 The inventive method has several advantages, namely: the availability of the material used as the basis for the separation of gallium and aluminum, the short duration of the process (up to 86.4% gallium is extracted in one stage), simplicity and ease of implementation, which creates certain conveniences in the process .

List of references
1. Reznik A.M., Ponomareva E.N., Silaev Yu.N., Abisheva Z.S., Bukin V.N .; open editor S.S. Korovin. Extraction and sorption processes in the chemical technology of gallium. - Alma-Ata: Science, 1985, - 184 p.

 2. Laskorin B.N., Yuzhin A.N. Sorption and extraction methods for the separation of aluminum and gallium. - Color Metals, 1961, N 11, p. 44-47.

 3. Kocheva L. L., Draganova R. Ion exchange is divided into gallium and aluminum - Godishn. Sofiysk. University, Chem. Fak., 1970, T. 2 p. 129-133.

 4. Kazantsev EV, Smirnov AL, et al. Sorption of gallium and aluminum from alkaline solutions - Izv. universities. Non-ferrous metallurgy, 1974, N 4 p. 55-59.

 5. Kudryavsky Yu. P., Kazantsev E.N., Spiridonov E.N. On the behavior of hydrolyzed gallium ions on cation exchangers. - Izv. universities. Chemistry and Chemical Technology, 1973, Vol. 1, no. 11 sec 1660-1663.

 6. Filimoshkin A.G., Terentieva G.A., Berezina E.M. and Pavlova T.V., J. Polim. Sci., Part A: Polim. Chem., 1993, vol. 31, p. 1991.

Claims (1)

The method of extraction of gallium from aluminate solutions by ion exchange method, characterized in that the process is carried out using a copolymer of vinyl chloride and maleic anhydride deposited on silicon oxide at -4 - -8 ^o C and stirring for 25-30 minutes, followed by separation of gallium from solid phase by washing with distilled water.

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