RU2264481C1 - Method of production of gallium from alkali-aluminate solutions of aluminous production - Google Patents

Abstract

FIELD: methods of production of gallium.

SUBSTANCE: the invention is pertaining to the method of electrochemical extraction of gallium from the alkali-aluminate solutions of aluminous production. The electrolysis is conducted on the solid cathode at presence of zinc previously introduced into the source solution with production zinc-gallium alloy as a cathode deposit. The source solution is prepared by mixture of the recirculated alkali-aluminate solution with the solution produced at causticization by lime of recirculated soda, either with water, or with the solution of the electrolyte after realization of an electrolysis. The cathode deposit dissolve in the circulating solution of a sodium hydroxide containing 0.3 kg/m³ Na₂O_caustic of not-containing in the composition of sodium salts of gallium, aluminum and zinc. The solution circulation is conducted up to the concentration in it of no less than 10 kg/m³ of gallium and no more 85 kg/m³ of sodium carbonate. From the solution remove zinc by injection in it of 90 % from computational quantity of sodium hydrocarbonate, from which 65-75 % are injected at once, and the rest is introduced under control, that the contents of zinc in the solution kept within the limits of 0.4 - 0.7 kg/m³. Then they add sodium hydroxide in the solution bringing the concentration of Na₂O_caustic upto 70-80 kg/m³ and evaporate it by 16 - 20 volumetric %. The metallic gallium is extracted from the solution by aluminum gallama carburization. The invention ensures an increased productivity of the process, improved purity of commercial gallium, a decreased power input and consumption of reactants.

EFFECT: the invention ensures an increased productivity of the process, improved purity of commercial gallium, a decreased power input and consumption of reactants.

3 cl, 2 tbl, 5 ex

Description

The invention relates to methods for producing rare and dispersed elements, and in particular to methods for electrochemical isolation of gallium from alkaline aluminate solutions of alumina production.

Closest to the claimed invention is a method for producing gallium from alkaline aluminate solutions of alumina production, which includes electrolysis in the presence of zinc previously introduced into the initial solution to obtain a zinc-gallium precipitate (alloy) on a solid (steel) water-cooled cathode, its dissolution when off current transducer and closed electrodes in sodium hydroxide solution, multiple circulation of the initial solution for the accumulation of gallium, removal of zinc from the circulating solution sodium oxide concentration of 40 ÷ 160 kg / m ³ by neutralization with sodium carbonate to give a precipitate of zinc oxide and gallium-rich soda solution, to bring a solution to a concentration of 90-100 kg / m ³ Na ₂ O _caustic sodium hydroxide and subsequent removal of metallic gallium carburizing gallamoy aluminum (gallium-aluminum alloy) or electrolysis (RF Patent No. 2127328, C 22 V 58/00, 1999).

The known method allows to obtain sufficiently pure gallium - 99.9990-99.9996% with a high degree of extraction, but cannot satisfy the production for the following reasons:

- low productivity of the process of extracting gallium;

- high consumption of reagents - sodium bicarbonate, sodium hydroxide and granular aluminum, as well as electric current;

- insufficiently high purity of commodity gallium.

The objective of the present invention is to increase the productivity of the process of extracting gallium, increasing the purity of commodity gallium, as well as reducing the consumption of reagents and electrical energy.

The problem is solved in the proposed method, including electrolysis on a solid cathode in the presence of zinc previously introduced into the initial solution to obtain a cathode precipitate of a zinc-gallium alloy, dissolving the cathode precipitate in a sodium hydroxide solution using multiple circulation of the solution to concentrate gallium in it, removing it from the solution zinc by adding sodium bicarbonate, introducing sodium hydroxide into it and the subsequent allocation of metallic gallium by cementation with aluminum gallama, in which a single solution for electrolysis is obtained by mixing a reverse alkaline aluminate solution with a solution obtained by causticizing lime with soda, taken in the ratio 2: (0.8 ÷ 1.2), or with water, taken in the ratio 3: (1.0 ÷ 1,2), or with an electrolyte solution after electrolysis, moreover, the circulating solution is pre-sedimented at a temperature of 70-80 ° C for at least a day, and the resulting stock solution is cooled to 30-40 ° C and kept without stirring for 8-12 for days, in the case of using an electrolyte solution, the initial solution held for 2-3 days after administration of zinc into it, when conducting electrolysis every 20 ÷ 50 operations in the electrolytic cell is supplied with reverse current bulk density of 5.4 kA / m ³ for 0.5-1.0 hours, removal of the cathode deposit is carried out with a solution containing 0.3-10.5 kg / m ³ Na _{2 Caustic} , which is not part of the sodium salts of gallium, aluminum and zinc, the volume of which is equal to the volume of the electrolyte in one series of electrolyzers, sequentially used in two or more series, while the necessary concentration of Na ₂ O _{caustic is} maintained by the introduction of sodium bicarbonate, and the solution is circulated to a concentration of not less than 10 kg / m ³ gallium and not more than 85 kg / m ³ sodium carbonate, and when removing zinc from the solution, sodium bicarbonate is introduced in an amount of 90-95% of the calculated amount, of which 65-75% is introduced immediately, and the rest is introduced, controlling the zinc content in the solution in the range of 0.4-0.7 kg / m ³ , after which sodium hydroxide is added to the solution, bringing the concentration of Na ₂ O _caustic to 70-80 kg / m ³ and evaporated at 16-20 vol.%.

At the same time, to obtain the initial solution, to the mixture of the circulating solution and the solution obtained after caustification with lime of circulating soda or water, the solution obtained after electrolysis can be added in an amount of 15-20% of the total volume of the initial solution.

In this case, when using a mixture of a reverse alkaline-aluminate solution with a solution obtained during caustification with lime soda, or with an electrolyte solution after electrolysis, the gallium metal obtained by cementation is settled for at least 2 days, and the slag is removed and treated with vigorous stirring with running distilled water at a temperature of 40-50 ° C.

The essence of the claimed method is as follows.

In the process of research, it was found that in the case of an increased concentration of organic substances in an alkaline aluminate solution, the extraction of gallium into the cathode precipitate during electrolysis is largely determined by their content, and the most harmful effects are humic and aliphatic carboxylic acids. Being surfactants, they accumulate during electrolysis in the hydration shell of the cathode and block the recovery of the hydrophilic anion of the gallate Ga (OH) ₄ · nH ₂ O ^- . As a result, after the accumulation of harmful impurities in the hydration shell of the cathode, the recovery process of the gallate anion slows down and then stops. Moreover, if electrolysis continues in this case, gallium losses are possible due to mechanical wear of the cathode deposit.

The content of organic substances in solutions of alumina production used in the proposed method is 1.5-2 times higher than in the prototype. Therefore, in spite of the higher concentration of gallium in solutions for electrolysis, for example, -0.37 kg / m ³ instead of 0.29 kg / m ³ , isolation by electrolysis encounters great difficulties. However, in the proposed method, it is technologically possible to purify solutions of organic substances, which allows to achieve a higher daily productivity than the prototype method, for example, 0.577 kg gallium / day versus 0.545 kg gallium / day (in terms of an electrolyzer with a volume of 1 m ³ )

The content of organic substances in solutions mainly depends on the composition of bauxite processed into alumina. It is great for their surface occurrence and significantly lower for deep occurrence. The alumina processing technology has a great influence. For example, during thermal caustification of circulating soda, the organic substances contained in it are burned, while in the case of the classical Bayer process, circulating soda is causticized with lime and some of the organic substances remain in the pro-causticized solution (Table 1, p. 3) used to dilute the circulating solution in the proposed a method for improving electrolysis parameters. Moreover, a decrease in the proportion of pro-causticized solution in the declared ratio of less than unity leads to a decrease in electrical conductivity and an increase in the viscosity and foaming of the electrolyte, which negatively affects the electrolysis indices. With an increase in the proportion of pro-causticized solution over 1.2, the concentration of gallium in the electrolyte solution decreases, which also negatively affects the performance of electrolysis.

When diluting the circulating solution with water, gallium recovery, despite a decrease in the concentration of organic substances in the initial solution, remains at about the same level that can be associated with different properties of water - simply added to the circulating solution and included in the solutions after various operations. Moreover, similar to the above, a decrease in the proportion of water in the claimed ratio of less than 3: 1 negatively affects the electrolysis, and an increase in the proportion of water more than 3: 1.2 reduces the concentration of gallium in the electrolyte solution.

In the proposed method, the content of organic substances is significantly reduced already at the stage of preparation of the initial solution. So, when standing for at least 1 day at 70-75 ° C, part of the soda drops together with a certain amount of organic substances (mainly humic and carboxylic acids) from the circulating solution. In the process of aging for 8-12 days, cooled to 30-35 ° C, the initial solution precipitates an average of 27% of organic substances from it. This process is significantly intensified by rapidly cooling a solution heated to 70-75 ° to 30-40 ° in a heat exchanger, in which local supersaturations occur in the solution and the solid phase precipitates, which is subsequently the center of crystallization of impurities, as well as in the presence of suspended particles in the solution, for example zinc sulfide, on which part of the impurities is deposited.

Electrolysis has a great effect on the removal of organic substances. Their concentration is reduced due to oxidation and destruction of compounds. This fact explains the positive effect of adding part of the solution to the initial solution after electrolysis or using electrolyte as the initial solution after electrolysis.

A sufficiently high concentration of gallium in the initial solution - 0.37 kg / m ³ , taking into account its insufficiently high extraction during the first electrolysis and purification of the solution during electrolysis from organic substances and other impurities, makes it advisable to reuse the electrolyte. When using one portion of the initial working solution twice, the total gallium recovery is 69.9%, which is 11.2% higher than in the prototype - 58.7%. In this case, the average allocation of gallium from one portion of the initial solution exceeds the prototype data by 5.9%, the electrolyte consumption per 1 kg of commodity gallium is reduced by 26.4%, the need for equipment for settling the solution is reduced, and the material consumption is also reduced.

The electrolysis is carried out at a bulk current density of 7.0-7.5 kA / m ³ . When calculating the current strength to maintain a constant bulk current density of 7.0-7.5 kA / m ^3, the volume of electrolyte occupied by the foam, which is usually 7-9% and from which gallium is not released, is excluded from the electrolyte volume. Therefore, with the total volume of electrolyte in the electrolyzer, for example, 1.92 m ^{3, the} effective volume is 1.75-1.78 m ³ , and the current strength will be 13.35-12.60 kA at a constant current density of 7.0-7, 5 kA / m ³ .

To dissolve the cathode deposit, a slightly alkaline solution containing from 0.3 to 10.5 kg / m ³ Na ₂ O _{caustic is used} . The lower limit of Na ₂ O concentration is _caustic - 0.3 kg / m ^{3 is} formed directly in the bath when it is initially filled with hot water. Subsequently, due to the electrolyte residues in the bath and in the cathode deposit, the alkali concentration increases from 0.3 to 10.5 kg / m ³ for Na ₂ O _ku (that part of it that is not bound to chemical compounds).

At a higher concentration of Na ₂ O _ku , an accelerated transition of zinc to the circulating solution is observed, which is also undesirable. The accelerated transition of gallium is explained by the fact that it is in the cathode deposit in an active state and interacts vigorously with a weak alkaline solution, while the solubility of zinc under these conditions is significantly lower. A bath filled with an alkaline solution, when the current transducer is turned off, is a large galvanic battery in which, due to chemical reactions occurring during dissolution of the cathode deposit, a current arises that intensifies the processes of cathode deposit dissolution. The surface of the cathodes may be periodically contaminated with various impurities. To clean the cathode, a reverse current is periodically fed with a bulk density of 4-5 kA / m ³ for 0.5-1.0 hours, which ensures the transfer of impurities from the surface of the cathode back to the used electrolyte and restoration of the cathode's efficiency.

To improve the performance of gallium precipitation by cementation, the solution should be enriched in gallium, for this purpose the alkaline solution is circulated after gallium is transferred to it from the cathode deposit. In this case, it is possible to use the circulation of the solution in two or more series. To obtain rich solutions, multiple solutions are circulated, reaching up to 96 times. However, there is a need to neutralize the excess of free Na ₂ O _ku . For this purpose, sodium bicarbonate is introduced into the circulating solution, leaving 0.5-1.0 kg / m ^{3 of} free Na ₂ O _ku to prevent precipitation of aluminum hydroxide, on which some gallium can be adsorbed.

When zinc is removed from the solution, sodium bicarbonate is introduced in an amount of 90-95% of the calculated amount, of which 65-75% is introduced immediately and quickly, which makes it possible to obtain “seed” - a zinc oxide precipitate due to local supersaturations of the solution. Further neutralization of Na ₂ O _ku to 90-95% of the calculated value is carried out slowly, under the control of zinc content in the range of 0.4-0.7 kg / m ³ , while due to the combination of neutralization processes and hydrolytic decomposition of sodium zincate, 5-10 % sodium bicarbonate. To further increase the concentration of gallium, the soda circulating solution after the introduction of sodium hydroxide is evaporated by 16-20 vol.% To the optimal Na ₂ O _ku content equal to 90-100 kg / m ³ , necessary to create optimal conditions for further gallium isolation, while the content sodium carbonate should not exceed 105 kg / m ³ , since at higher concentrations it can fall out of the solution during cementation, worsening its performance.

Obtained by gallam aluminum cementation, zinc-containing gallium is purified by a known technology used in the production of metal of technical purity -99.99%. However, in the case of using a solution obtained by caustification of circulating soda with lime, the smallest carbon particles from coke residues get into the initial solution. During electrolysis and cementation, these particles pass in a small amount into filtered liquid gallium. To remove rough gallium, they are treated with vigorous stirring with running distilled water before cleaning. The purity of gallium obtained by the proposed method reaches 99.9997-99.9999%.

The proposed method can be implemented as follows.

As alkaline-aluminate solutions of alumina production use the solutions obtained by processing bauxite according to the Bayer method:

- reverse aluminate solution containing, on average, kg / m ³ : Na ₂ O _total -320; Na ₂ O _caustic - 306; _{Carbon dioxide} Na ₂ O -14; Al ₂ O ₃ -155; Ga 0.49; Zn - 0.01; S 0.70; V - 0.35; C (organic substances) - 5.6-5.8 (5.69 for calculations), while the content of organic substances is up to 2 times higher than in the initial solutions of the prototype method;

- a solution obtained by caustification of circulating soda with lime milk, containing, on average, kg / m ³ : _{total total} Na ₂ O — 120; Na ₂ O _caustic - 108; Na ₂ About _{carbon dioxide} - 12; A1 ₂ O ₃ - 35; Ga 0.13; Zn - 0.005; S 0.35; V is 0.02; C (organic matter) - 0.70.

As the initial solutions, a mixture of a working alkaline aluminate solution with a solution obtained by causticizing lime with soda, taken in the ratio 2: (0.8 ÷ 1.2), or with water, taken in the ratio 3: (1.0 ÷ 1,2), or by using an electrolyte solution after electrolysis and additional introduction of zinc into the solution. Moreover, the circulating solution is pre-sedimented at a temperature of 70-80 ° C for at least a day, and the resulting stock solution is quickly cooled to 30-40 ° C and kept without stirring for 8-12 days, in the case of using an electrolyte solution, it is kept for 2-3 days after the introduction of zinc into it. In order to improve the performance of the process, a solution obtained after electrolysis in the amount of 15-20% of the total volume of the initial solution can be added to the initial solution, which is a mixture of a circulating solution and a solution obtained after caustification with lime of circulating soda or water. Then, electrolysis is carried out at a volumetric current density of 7.0-7.5 kA / m ³ for 3-5 hours, while every 20 ÷ 50 operations, a reverse current with a bulk density of 4-5 kA / m in within 0.5-1.0 hours, the dissolution of the cathode deposit is carried out with a solution containing 0.3-10.5 kg / m ³ Na ₂ O _ku , which is not part of the sodium salts of gallium, aluminum and zinc, the volume of which is equal to the volume electrolyte in one series of electrolysis cells used sequentially in two or more lots, the required concentration of Na ₂ O _ku maintained by introducing sodium idrokarbonata and circulation of the solution is carried out to a concentration therein of not less than 10 kg / m ³ gallium and not more than 85 kg / m ³ of sodium carbonate, removing zinc from a solution of sodium hydrogen carbonate is introduced in an amount of 90-95% of the estimated amount, and the 65 -75% of this amount is administered immediately, and the rest is controlled by the content of zinc in the solution in the range of 0.4-0.7 kg / m ³ . The cathode precipitate is removed by circulating sodium hydroxide solution at a temperature of 70-80 ° C. At the same time, water is used at the beginning, into which electrolyte residues pass from the electrolyzer, due to which the concentration of free Na ₂ O _ku increases each time by 0.20-0.30 kg / m ³ . Accordingly, the concentration of Al ₂ O ₃ and other impurities increases. Then sodium hydroxide is added and the solution is evaporated by 16-20 vol.%. Then, cementation is carried out at a temperature of 65-70 ° C with gallam of aluminum in two stages: at the first stage, with gallam containing 1.0-1.5 wt.% Aluminum, to obtain a concentration of gallium in the solution of 2-3 kg / m ³ , and the second stage - gallam containing 1.0-0.6 wt.% aluminum, to obtain a gallium concentration in the solution of not more than 0.4 kg / m ³ . The gallium metal obtained by cementation is treated with hot distilled water.

In the case of using a mixture of a reverse alkaline-aluminate solution with a solution obtained by causticizing with lime soda, or with an electrolyte solution after electrolysis, the gallium metal obtained by cementation is settled for at least 2 days, the slag is removed and treated with vigorous stirring with running distilled water at a temperature of 40-50 ° C.

Example 1

The initial working solution of the composition specified in paragraph 1 of the table. 1, maintained at 70-75 ° C day. The settled part with a volume of 599 m ^{3 is} mixed with 300 m ^{3 of the} solution of item 3 of Table 1 (volume ratio 2: 1) and with 23 m ^{3 of a} zincate solution of item 4 of Table 1 (for the purpose of introducing zinc), an electrolyte solution containing 0.35 kg / m ^{3 of} zinc. A mixture with a volume of 922 m ^{3 is} stirred for 3 hours at 70-80 ° C and cooled in 6 hours in a heat exchanger to 30 ° C. Then, after exposure without stirring in air for 8 days, a solution of the composition of clause 5 of Table 1 is fed to electrolysis. In the process of preparing the solution, the content of organic substances in it is reduced by 27%. The duration of electrolysis is 3 hours. The electrolyte volume in the bath is 1.92 m ³ , the temperature is 28-32 ° C, the bulk current density is 7.5 kA / m ³ . The current strength when the volume of the liquid phase of the electrolyte is 1.78 m ³ (0.14 m ^{3 of} electrolyte is in the electrolysis in the form of foam, from which almost no gallium is released), support equal to 13.35 kA. The cathode alloy is dissolved at a temperature of 70-80 ° C with a circulating solution. The volume of the circulating solution - 10.5 m ³ support constant due to washing water. The concentration of gallium is carried out in two series of 5 electrolysers in each, using one portion of the circulating solution to remove the cathode deposit. After carrying out 48 cycles of gallium concentration in 10 days, a circulating solution of the composition is obtained, kg / m ³ : Na ₂ O _total - 23.6; _Caustic Na ₂ O — 22.5 (of which 10.7 is free); _{Carbon dioxide} Na ₂ O - 1.1; Al ₂ O ₃ -11.2; Zn - 2.5; S is 0.4; V is 0.03; C 0.17; Ga - 5.8 (60.93 kg). Na ₂ O free _ku neutralized by introducing a solution of 290 kg of sodium hydrogencarbonate, whereby changing the composition of alkalis, kg / m ^3: Na ₂ O _of - 33.3; Na ₂ O _ku - 12.3 (of which 0.5 free); Na ₂ O _y -21.0. Then, another 48 cycles of gallium concentration are carried out using the same portion of the circulating solution, in which only 398 kg of sodium bicarbonate is introduced to remove zinc, which is 90% of the calculated, with 260.7 kg (65%) immediately, and the remaining 137, 3 kg is added in portions, controlling the residual concentration of zinc in the circulating solution of 0.5 kg / m ³ . After 59 kg of zinc oxide precipitate is separated from the solution, 746 kg of sodium hydroxide are added to the solution and evaporated from 11.0 to 8.8 m ³ (20%). The cementation solution obtained in 20 days has a composition, kg / m ³ : _total Na ₂ O — 150.9; Na ₂ O _caustic - 90.0; Na ₂ O _{carbon dioxide} - 60.9; (104.1 Na ₂ CO ₃ ); Al ₂ O ₃ - 26.8; Zn - 0.06; S is 0.1; V is 0.07; C 0.38; Ga - 13.5 (118.8 kg). Cementation is carried out at a temperature of 65 ° in two stages: at the first stage, with gallam of aluminum containing 1.0 wt.% Aluminum, to a concentration of gallium in the solution of 2 kg / m ³ ; at the 2nd stage - gallam of aluminum, containing 0.6 wt.% aluminum, to a concentration of gallium in the solution of 0.4 kg / m ³ . After 2 days of settling and slag removal, the gallium is treated with water at 50 ° C and vigorous stirring, first with non-flowing, and then running distilled water - under visual observation - until the black carbon particles are stopped. After purification of gallium by a known technology (filtering through sintered ceramic or glass plates, acid and vacuum thermal treatment), marketable gallium was obtained 104.05 kg (11.25 kg of gallium remained in the sludge).

The purity of marketable gallium is 99.9998%, the carbon content in the metal with additional water purification decreases from 2 10 ^-5 to 0.2 10 ^-5 %.

The performance reduced to the volume of the electrolyzer 1 m ³ is 0.648 kg / day.

Example 2

The initial solution is obtained by adding an electrolyte solution to 905 m ³ after electrolysis of the composition indicated in clause 5 of Table 1, 23 m ^{3 of a} zincate solution (clause 4 of Table 1). After 2 hours of stirring and 2 days of exposure, the solution is subjected to electrolysis lasting 4 hours. The electrolyte volume in the bath is 1.92 m ³ , the temperature is 28-32 ° C, the bulk current density is 7.0 kA / m ³ . The current strength when the volume of the liquid phase of the electrolyte is 1.78 m ³ (0.14 m ^{3 of} electrolyte is found in the electrolysis in the form of a foam, from which practically no gallium is released) is maintained at 12.5 kA. Dissolution of the cathode deposit is carried out with a solution containing initially 0.3 kg / m ³ Na ₂ O _caustic . After 12 days of 48 cycles of concentration, 10.5 m ^{3 of a} circulating solution of the composition are obtained, kg / m ³ : _total Na ₂ O — 22.8; _Caustic Na ₂ O — 21.7 (of which 10.4 is free); Na ₂ O _{carbon dioxide} - 1.1; Al ₂ O ₃ - 10.8; Zn - 2.3; S is 0.3; V is 0.02; C is 0.11; Ga - 5.714 (60.0 kg).

Subsequently, to reduce the concentration of free Na ₂ O _ku to 1 kg / m ^3, 282 kg of sodium bicarbonate is introduced, due to which the composition of alkalis changes, kg / m ³ : Na ₂ O _total 32.7; Na ₂ O _caustic 11.8; (of which 1.0 is free); Na ₂ O _carbonate 20.9. Then for 12 days spend another 48 cycles of concentration of gallium. Extraction of gallium into the cathode precipitate for 4 hours of electrolysis is 53.1%. The final electrolyte is sent to alumina production.

378 kg of sodium bicarbonate is introduced into the circulating solution - 90% of the calculated amount, of which 284.5 kg (75%) - immediately, the remaining 93.5 kg - in portions under the control of zinc concentration up to 0.5 kg / m ³ . After 54 kg of zinc oxide are separated from the solution, 748 kg of sodium hydroxide are added to the solution and evaporated from 11.0 to 8.8 m ³ , which is 20%. A solution of the composition, kg / m ^3, is sent to cement gallium by cementation: Na ₂ O _about - 148.0; Na ₂ About _ku - 90; Na ₂ O _angle - 58.0 (99.2 Na ₂ CO ₃ ); Al ₂ O ₃ - 25.8; Zn 0.6; S is 0.6; V is 0.05; C - 0.075; Ga - 13.36 (117.6 kg). Cementation is carried out at a temperature of 70 ° in two stages: at the first stage, with gallam of aluminum containing 1.5 wt.% Aluminum, to a concentration of gallium in the solution of 3 kg / m ³ ; at the second stage, by gallam of aluminum containing 0.6 wt.% aluminum, to a concentration of gallium in the solution of 0.4 kg / m. After purification of gallium by a known technology (filtering through sintered ceramic or glass plates, acid and vacuum thermal treatment), marketable gallium was obtained 106.15 kg (7.90 kg of gallium remains in the sludge).

The purity of marketable gallium is 99.9998%.

Productivity, kg / day, reduced to a cell volume of 1 m ³ , is 0.55 kg / day.

Example 3

Analogously to example 1, 922 m ^{3 of} solution is prepared, but with a ratio of volumes of the circulating solution and the solution after causticization with lime of circulating soda, equal to 2: 1.2, with the content, kg / m ³ : Na ₂ O _about - 241; Ga - 0.355; Zn — 0.36; C - 3.77 (after mixing) and 2.76 (after sedimentation), carry out electrolysis with the same parameters, but with a duration of electrolysis of 4.5 hours, and every 20 operations, a reverse current with a bulk density of 5 kA is supplied to the electrolyzer / m ³ for 0.5 hours. Extraction of gallium into the circulating solution is 45%. After conducting 48 cycles of concentration of gallium, 10.5 m ^{3 of a} circulating solution of the composition are obtained, kg / m ³ : Na ₂ O _, 23.6; Na ₂ O _ku , 22.5, of which (10.2 free); Na ₂ O _angle 1.1; Al ₂ O ₃ 11.2; Zn 2.5; S 0.04; V 0.03; C 0.16; Ga 7.07 (74.25 kg), into which 276 kg of sodium bicarbonate is introduced to neutralize 95% of free Na ₂ O _ku . Next, another 48 cycles of concentration are carried out, after which 369 kg of sodium hydrogen carbonate is introduced into the circulating solution to remove zinc up to 0.5 kg / m ³ , which is 90% of the calculated amount of 410 kg, of which 307.5 kg (75% ) is administered immediately, and the remaining 102.5 kg is added in portions under the control of zinc concentration. After separation of the zinc oxide precipitate, 769 kg of sodium hydroxide are added to the solution, and after evaporation from 11.0 to 8.8 m ³ (by 20%), a solution for cementing gallium composition is obtained, kg / m ³ : Na ₂ O _about - 151.0 ; Na ₂ About _ku - 90.0; Na ₂ O _angle - 61.0 (104.3 Na ₂ Co ₃ ); Al ₂ O ₃ - 26.7; Zn 0.6; S is 0.1; V is 0.07; C 0.38; Ga - 16.53 (145.5 kg). Cementation is carried out at a temperature of 65 ° in two stages: at the first stage, gallam of aluminum containing 1.0 wt.% Aluminum, to a concentration of gallium in the solution of 2 kg / m ³ ; at the 2nd stage, gallam of aluminum containing 1.0 wt.% aluminum, to a concentration of gallium in the solution of 0.4 kg / m ³ . After 2 days of settling and slag removal, the rough gallium is treated at 50 ° C and intensively stirring first with non-flowing and then running distilled water under visual observation until the black carbon particles are stopped. After purification of gallium by a known technology (filtering through sintered ceramic or glass plates, acid and vacuum thermal treatment), commodity gallium 129.2 kg was obtained (12.7 kg of gallium passes into the sludge).

The purity of marketable gallium is 99.9997%, the carbon content in the metal with additional water purification decreases from 2 · 10 ^-5 to 0.2 · 10 ^-5 %.

Productivity, kg / day, reduced to the volume of the electrolyzer 1 m ³ is 0.594 kg / day.

Example 4

A 922 m ³ solution is prepared containing 16% of the electrolyte from the previous electrolysis and with a ratio of the circulating solution and the solution after causticization of soda equal to 2: 0.8 (according to claim 7 of Table 1). The volume of solutions, m ³ : 537 recycled, 215 after causticization of soda, 22 zinc, 148 from the previous electrolysis. During the preparation of the electrolyte, the carbon content of organic substances is reduced by 25%.

The conditions of electrolysis, processing of the circulating solution and cementation are similar to those described in example 1, the duration of 4.5 hours.

Received 127 kg of commodity gallium.

The purity of marketable gallium is 99.9998%.

Productivity, kg / day, reduced to a cell volume of 1 m ³ , is 0.600 kg / day.

Example 5

Prepare 922 m ^{3 of the} solution (item 5 of Table 1) by mixing 675 m ^{3 of a} working solution (item 2 of Table 1), 23 m ^{3 of a} zincate solution and 224 m ^{3 of} water, and a stock solution is obtained in which the ratio of the working solution and water is 3: 1. The gallium content in the solution is 0.37 kg / m ³ , zinc - 0.35 kg / m ³ , and Na ₂ O - 236 kg / m ³ . The decrease in organic matter after sludge is 27%. The process is carried out as described in example 1 and the duration of 4.5 hours. For intermediate neutralization after 48 concentration operations, 262 kg of sodium bicarbonate are introduced into the circulating solution to a content of 0.5 kg / m ³ Na ₂ O _ku free. After another 48 concentration operations, zinc is removed by introducing 345 kg of sodium bicarbonate (90% of the calculated amount), of which 310 kg (90%) immediately, and the remaining amount (35 kg) - in portions under the control of a residual zinc concentration of 0, 5 kg / m ³ . When preparing the grout, 607 kg of sodium hydroxide are added.

Received 122.4 kg of commodity gallium.

The purity of marketable gallium is 99.9998%.

Productivity, kg / day, reduced to a cell volume of 1 m ³ , is 0.579 kg / day.

Thus, the proposed method allows to increase the productivity of the process of extracting gallium from alkaline aluminate solutions of alumina production while maintaining a sufficiently high percentage of extraction. In addition, the method can significantly reduce the consumption of reagents used, as well as energy consumption and improve the purity of gallium.

Na ₂ O _o - the total concentration of sodium in solution;

Na ₂ O _y - concentration of caustic alkali;

Na ₂ O _y — concentration of carbonate alkali;

S - sulfur compounds in the lowest degree of valency (in terms of elemental sulfur);

C - organic compounds in terms of carbon, (*) - the same immediately after mixing the solutions.

Table 2.
Comparison of the main indicators of methods for producing gallium No. The composition of the initial solution The concentration of components in the electrolyte, kg / m ³ Duration of electrolysis, hour Productivity of electrolysis (in terms of the volume of the cell 1 m ³ ) Electricity consumption (in terms of electrolyzer volume 1 m ³ ) Electrolyte consumption per 1 kg of marketable Ga, m ³ / kg Consumption of materials per 1 kg of commodity gallium, kg / kg Sodium bicarbonate Sodium hydroxide Granules of aluminum Na ₂ O _ku Ga kg / day gallium in% kA-hour / kg Ga in% 1. Prototype 207 0.29 5.5 0.545 100 105 100 5.87 33.0 26.2 2.0 2. A mixture of a circulating solution, a solution after causticization of soda at a ratio of 2: 1 and zincate solution 240 0.37 3.0 0.634 116.3 52.9 50,4 8.86 6.6 7.2 1,5 3. The solution after electrolysis (electrolyte) + zincate solution 240 0.243 4.0 0.577 111.1 68.7 65,4 4.29 6.33 7.16 1.35 after successive electrolysis of solutions according to claims 2, 3 4. A mixture of a circulating solution, a solution after causticization of soda at a ratio of 2: 1.2 and zincate solution 241 0.355 4,5 0.594 109.1 84.9 90,4 6.21 5.11 6.09 1.48 5. A mixture of a circulating solution, a solution after causticization of soda (2: 0.8), a 16% solution after electrolysis (electrolyte) and zincate solution 247 0.36 4,5 0,600 110.1 84.0 80.0 6.15 5.06 6.12 1.45 6. A mixture of a circulating solution and water at a ratio of 3: 1 and a zincate solution 227 0.37 4,5 0.579 106.0 86.2 77.5 5.99 4.96 6.37 1,50

Claims (3)

1. A method of producing gallium from alkaline-aluminate solutions of alumina production, comprising electrolysis on a solid cathode in the presence of zinc previously introduced into the initial solution to obtain a zinc-gallium alloy as a cathode precipitate, dissolving the cathode precipitate in a sodium hydroxide solution using multiple circulation for concentrating gallium in it, removing zinc from a solution by adding sodium bicarbonate, introducing sodium hydroxide into it, and then isolating gallium metal by gallamation of aluminum, characterized in that the initial solution is obtained by mixing a reverse alkaline-aluminate solution with a solution obtained by causticizing lime with soda, taken in the ratio 2: (0.8 ÷ 1.2), or with water, taken in the ratio 3: (1.0 ÷ 1.2), or with an electrolyte solution after electrolysis, moreover, the circulating solution is pre-sedimented at a temperature of 70-80 ° C for at least a day, and the resulting stock solution is cooled to 30-40 ° C and kept without mixing for 8-12 days, in case of use electrolyte thieves, the initial solution is kept for 2-3 days after zinc is introduced into it, during electrolysis every 20 ÷ 50 operations, a reverse current with a bulk density of 4-5 kA / m ³ is applied to the electrolyzer for 0.5-1, 0 h, dissolution of the cathode deposit is carried out with a solution containing 0.3-10.5 kg / m ³ Na ₂ O _caustic , which is not part of the sodium salts of gallium, aluminum and zinc, the volume of which is equal to the volume of the electrolyte in one series of electrolyzers, sequentially is used in two or more lots, the required concentration of Na ₂ O _austichesky maintained by administration of sodium hydrogencarbonate, the solution circulation is carried out to a concentration therein of not less than 10 kg / m ³ gallium and not more than 85 kg / m ³ of sodium carbonate, the removal of zinc with sodium hydrogen carbonate solution is introduced in an amount of 90-95% of the calculated the amount of which 65-75% is administered immediately, and the rest is administered by controlling the zinc content in the solution in the range of 0.4-0.7 kg / m ³ , after which sodium hydroxide is added to the solution, bringing the concentration of Na ₂ O _caustic to 70 -80 kg / m ³ and evaporate it by 16-20 vol.%. 2. The method according to claim 1, characterized in that to obtain the initial solution to the mixture of the circulating alkaline-aluminate solution and the solution obtained after causticizing with lime, circulating soda or water, add the solution obtained after electrolysis in an amount of 15-20% of the total volume of the initial solution. 3. The method according to claim 1, characterized in that when using a mixture of a reverse alkaline aluminate solution with a solution obtained by causticizing with lime soda, or with an electrolyte solution after electrolysis, gallium metal obtained by cementation from a solution, defend for at least 2 days, remove the slag and process with vigorous stirring with distilled running water.