WO1987002075A1

WO1987002075A1 - Process for producing gallium

Info

Publication number: WO1987002075A1
Application number: PCT/JP1985/000554
Authority: WO
Inventors: Kotaro Hirayanagi; Akira Sakamoto
Original assignee: Showa Denko Kabushiki Kaisha
Priority date: 1985-10-04
Filing date: 1985-10-04
Publication date: 1987-04-09

Abstract

A process for producing gallium by electrolysis of a gallium-containing solution such as Bayer solution, a gallium extract from gallium-containing waste from semiconductor industry, etc., which comprises bringing the aqueous gallium-containing solution into contact with a solid adsorbent such as gamma-alumina, activated carbon, etc. under an alkaline condition before hydrolysis to thereby selectively remove an iron component from the solution. This removal of the iron component serves to reduce the content of impurities in the deposited gallium and to improve current efficiency of the electrolysis.

Description

Specification

Gallium manufacturing method

The present invention relates to a method for producing a gallium by electrolyzing a gallium-containing aqueous solution. More specifically, the present invention relates to a method for producing a gallium in which iron in an aqueous solution of a gallium is separated and removed using a solid adsorbent and then electrolysis is performed. Background art

Gallium is an extremely important metal as a raw material for electronic materials, but there is no gallium-rich ore, and industrial production methods such as bauxite with a small amount of gallium Known methods include the method of separating and recovering alumina from a vial (sodium aluminate solution) obtained by extracting aluminum ore from ore, and the method of recovering black ore in the zinc smelting process. .

These methods vary widely. Except for the direct electrolysis method using the Bayer solution, the general method is to use a starting material containing a trace amount of gallium by pretreatment such as solvent extraction and sedimentation separation. There is a method in which the components are concentrated and impurities are removed, and the aqueous solution containing the obtained gallium component is electrolyzed in an alkaline aqueous solution to obtain gallium.

As a method for recovering gallium from a sodium aluminate solution, there is, for example, a method described in JP-A-51-32411. This method uses sodium aluminate from the noise process. This is a liquid-liquid extraction of the gallium contained in the aluminum solution with a water-insoluble substituted hydroxyquinoline to remove impurities, and then back-extracting the gallium-containing mineral acid aqueous solution. Is obtained. The electrolysis of this gallium-containing aqueous solution is mostly performed under alkaline conditions.

On the other hand, as already mentioned, and a this there is no ore to rich in Galli um, GaP, GaAs, GaAs, - .. X P x Ga x In have _{_{X P GaxAlx-xAs Gd 3 Ga}} 5 0iz Waste generated when processing such crystal materials into electronic material elements is also an extremely valuable resource. These gully wastes are increasing year by year with the development of the electronics industry, and many gallium recovery technologies from wastes have been proposed. Examples of 'garbage-containing' waste include:

(1) GaP, GaAs, GaAs have _{_X} P _X, Ga _x In have _{_{X P, Ga x Al -!}} X As Gd 3 Ga 5 0 I 2 such intermetallic compounds, polycrystalline and single crystal of the metal oxide Manufacturing waste

(2) Cutting chips when cutting wafers from polycrystals and single crystals

(3) Acid solution for wafer mirror finishing

Etc.

As a method of collecting metal gallium from waste, there is, for example, a method described in Japanese Patent Publication No. 56-38661. In this method, waste containing gallium, that is, a composition containing gallium, such as an intermetallic compound composed of gallium and an element of the Periodic Table Group Vb, is converted to acidic or acidic materials in the presence of an oxidizing agent. After dissolving in a basic solution, the pH was adjusted, and the gallium content was extracted.The effluent was separated, and then these separated materials were dissolved in an alkaline solution. -

--3-

Is electrolyzed to recover gallium. Also, JP-A-59-213622 discloses that a metal composition containing gallium and a Group Vb element of the Periodic Table of Elements is oxidatively decomposed, and the resulting oxidative decomposition solution is filtered, and the pH of the filtrate is adjusted to 0. After adjusting the concentration to 1 to 5.0, the filtrate is brought into contact with the chelating resin to adsorb the gallium component in the filtrate onto the chelating resin, and then passed through an aqueous alkali solution to remove the desorbed solution containing the gallium component. A method for recovering gallium from waste, which comprises adjusting the pH of the desorbed solution to a range in which gallium can be isolated by electrolysis and electrolyzing the solution, is described.

In any of the above gallium recovery methods, gallium is usually finally recovered by electrolysis after making the solution alkaline.However, if iron is contained in the electrolyte, gallium is generated. Iron and the like are contained in the gallium, which not only lowers the purity of gallium, but also lowers the current efficiency of electrolysis, and depending on the concentrations of gallium and iron in the electrolyte, particularly the concentration of gallium. In the case where the water content is reduced, there is a serious drawback that the gallium cannot be electrolyzed. In addition, there was a problem that the operation rate of the electrolysis was reduced, each unit of production of the gallium was deteriorated, and a great deal of labor was required for replacement and regeneration of the electrodes.

When electrolysis of a gallium-containing alkaline aqueous solution without removing the iron component, the current efficiency is reduced or the electrolysis becomes impossible. Gallium is a very base metal (oxidation-reduction potential-0.56 V). ), It is a metal that is difficult to electrolyze, and its electrolytic deposition reaction is a competitive reaction with the generation of hydrogen, and it is necessary to select and use an electrode with a large hydrogen overvoltage as the electrode. Absent. However, the hydrogen in gallium itself Electrolysis is possible because the overvoltage is higher than other elements, but when a metal with a small hydrogen overvoltage such as iron is mixed in as an impurity, hydrogen generation is promoted, resulting in low current efficiency. It is considered that the electrolysis becomes impossible. If the electrode is poisoned and degraded by iron, current efficiency is reduced, and electrolysis becomes impossible, there is no other way to recover the electrode except to replace and regenerate it. If the electrolyte continues to flow without noticing that the electrolysis has become impossible, the concentration of gallium in the tank and the electrolysis termination liquid will increase, which will lead to deterioration of each basic unit. When replacing or regenerating the electrode, the electrolysis is stopped, the electrolytic cell and the electrode are disassembled, and gallium and iron adhering to the cathode surface are completely removed using nitric acid. If the removal is incomplete, the life of the electrode will be reduced to about one tenth. Disclosure of the invention

In view of such a situation, the present inventors have repeated research on a method of extending the electrode life and recovering high-purity gallium with high efficiency from a gallium-containing solution, and completed the present invention. That is, the present invention provides a method for producing gallium by electrolyzing a gallium-containing aqueous solution, comprising a step of contacting the gallium-containing aqueous solution with a solid adsorbent under alkaline conditions to separate and remove iron before the electrolysis step. It is in the manufacturing method of the garden.

The present inventors have found that when an aqueous solution containing gallium is brought into contact with a solid adsorbent under alkaline conditions, iron is selectively separated and removed. Contains gallium by contact with solid adsorbent The iron content in the aqueous solution was completely removed, and at the same time, a decrease in gallium was considered, but the gallium concentration in the aqueous solution changed before and after contact with the solid adsorbent. No gallium was detected even when the solid adsorbent deposit was analyzed.

Thus, when the gallium is produced by electrolyzing the gallium-containing aqueous solution after the iron component is separated and removed according to the present invention, impurities such as iron disappear from the gallium that is deposited or the content of the gallium is remarkably reduced. Not only does this lower the purity of the gallium, but also the gallium is produced efficiently. In other words, the current efficiency of electrolysis is improved, and the situation where electrolysis is impossible due to the presence of iron is eliminated. As a result, the operation rate and the basic unit are improved, and the labor for replacing and regenerating electrodes is reduced.

According to a preferred embodiment of the present invention, after preparing an aqueous solution containing an alkaline gallium having an alkali concentration capable of isolating the gallium by electrolysis, the aqueous solution containing an alkaline gallium is prepared by solidifying the aqueous solution containing the alkaline gallium. The iron is separated and removed by contact with the adsorbent, and then the alkaline aqueous solution is electrolyzed and recovered. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a flowchart showing a typical production process of gallium according to the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

In the method for producing a gallium of the present invention, the aqueous solution of the gallium is contacted with a solid adsorbent under alkaline conditions to separate and remove iron. The step of removing can basically achieve the object of the present invention anywhere before electrolysis. If iron is not contained in the electrolytic solution at the time of electrolysis, there are no inconveniences such as a decrease in purity of the recovered gallium and a decrease in electrolysis current efficiency.

In order to selectively separate and remove iron by bringing the aqueous solution containing gallium into contact with the solid adsorbent, the aqueous solution containing gallium must be alkaline. Galli © beam is while in the aqueous alkaline solution is fully dissolved as gully Umusan Ion Ga0 ₂ _, iron many have become iron hydroxide _{_{_{F e 2 0 3 · xH 2}}} 0. Therefore, when the gallium-containing aqueous solution is brought into contact with a solid adsorbent under an alkaline condition, it is considered that only iron is selectively adsorbed, and gallium is not adsorbed. At this time, the adsorption of iron should be larger as the adsorption speed becomes higher, the adsorption speed should not be directly proportional to the area of the solid adsorbent, and the iron once adsorbed would not be easily desorbed by heating. Therefore, it is considered to be chemisorption.

As an alkaline condition for selectively adsorbing and separating iron from a gallium-containing aqueous solution, the alkali concentration of the liquid is preferably in the range of 0.1 N to 5 N. If the aluminum concentration is less than 0.1 N, the gallium may be bent out in the form of gallium hydroxide or the like, and may be adsorbed by the solid adsorbent, and the loss of gallium may increase. Because there is. When the alkali concentration is higher than 5 N, it is possible to selectively remove the iron itself, but the alkali concentration is too high, and the handling properties such as the viscosity of the liquid increase, and the handling becomes worse. Requires expensive equipment In addition, the solubility of gallium tends to decrease, which is disadvantageous.

According to a preferred embodiment of the present invention, particularly industrially, after preparing an aqueous gallium-containing aqueous solution having an alkaline concentration capable of separating gallium by electrolysis, the alkaline gallium is prepared. The aqueous solution is brought into contact with a solid adsorbent to separate and remove iron, and then the aqueous solution containing alkaline gallium is electrolyzed to recover gallium. In the present invention, as described above, the separation and removal of iron from the gallium-containing aqueous solution may be performed at any place before the electrolysis, but the gallium-containing aqueous solution is always finally made alkaline for the electrolysis. Therefore, it is not only reasonable to use this alkaline property stage, but also before the adjustment to the alkalinity required for electrolysis, the gallium-containing aqueous solution contains many impurities. In addition, the iron content is high, so there is the disadvantage that the adsorption efficiency of iron by the solid adsorbent decreases.

A typical manufacturing process of the present invention will be described below with reference to FIG.

As described above, gallium raw material 1 is a gallium-containing waste from the electronics industry, even if it is separated from the refining process of other metals in ores containing gallium. Is also good. In most cases, these gallium raw materials 1 pass through the state of the gallium-containing mineral acid aqueous solution 2 once as a scouring solution or a gallium extract from gallium-containing waste. In general, this gallium-containing mineral acid aqueous solution 2 is converted into an alkali 3 to isolate the gallium by electrolysis. I

--8 However, a gallium-containing alkali solution generated in the gallium extraction process, etc. is used as a starting material, neutralized or further alkalized 5 as necessary, and adjusted to a concentration of aluminum that can separate gallium by electrolysis. It may be adjusted to obtain an aqueous solution containing an alkaline grit.

Typical examples of the gallium-containing mineral acid aqueous solution obtained from the gallium raw material 1 include gallium in a sodium aluminate solution obtained by a via method described in JP-A-51-32411. Was extracted with a water-insoluble substituted hydroxyquinoline to remove impurities and then back-extracted with a strong mineral acid. Dissolve the gallium-containing waste described in Japanese Patent Publication No. 56-38661, a solution or solution back-extracted with a mineral acid after extraction with a solution, in concentrated hydrochloric acid and concentrated nitric acid in the presence of an oxidizing agent. The resulting solution, a solution obtained by dissolving a gallium-owned waste described in JP-A-54-117315, JP-A-56-9223 and JP-A-9-213622 with a mineral acid, etc. is there.

If excess acid is present in the aqueous solution of mineral acid in galleria, a large amount of alcohol is required to adjust the concentration of the alkali, and the solution contains a large amount of salts. As described in Japanese Patent Application Laid-Open No. Sho 60-2636, the method of diffusing and diffusing (using the difference in the diffusion rate of acids and salts through an ion-exchange membrane to efficiently remove acids and salts) It is preferable to separate and recover the excess acid in the stock solution and then to carry out alkalization 3 by the method of separation. This eliminates the need for extra alkali and can reduce the salt concentration in the solution. If the gallium-containing mineral acid aqueous solution 2 or a solution in which the concentration of the mineral acid is reduced by diffusion and diffusion through the solution 6 is low, the alkali is added to neutralize the solution (pH 5 to 5). 8) to form a gel containing gallium, filtered 8, washed, dehydrated, and then alkalized 3 to make the gallium in the alkaline gallium-based aqueous solution (electrolyte) 4 By increasing the electrolyte concentration, the current efficiency of electrolysis can be improved, the unit electrolyte volume can be reduced, and each basic unit can be improved. Even when the starting material is a gallium-containing alkaline solution, when the gallium concentration is low, the gallium concentration can be increased by the same procedure as described above. The appropriate concentration of gallium in the electrolyte is 0.01 to: L.5 mol Z. If the concentration of gallium in the aqueous solution of gallium is less than 5 / /, the above neutralization 7 It is desirable to increase the gallium concentration by filtration, filtration, washing and dehydration steps.

The gali- lic concentration for effectively isolating the gallium from the gallium-containing aqueous solution by electrolysis is 0.5% or more. If the alkali concentration is less than 0.5%, hydrogen generation is promoted during electrolysis. However, the alkaline concentration of the electrolyte is preferably 0.5 to 5 mm. If the alkali concentration exceeds 5 5, the current efficiency will decrease due to insufficient degassing of generated gas and insufficient diffusion in the electrolyte due to the increase in the viscosity of the electrolyte.

Next, according to the method of the present invention, the aqueous solution containing alkaline gallium is brought into contact with a solid adsorbent to selectively and hardly remove iron (iron removal 9). Galli um is Gari um San'i on Ga0 ₂ in alkaline solution - whereas completely dissolved as a trace Iron contained in the many cases have become iron hydroxide _{_{_{Fe 2 0 3 · xH 2 0}}} . As a result, when the alkaline aqueous solution containing gallium is brought into contact with the solid adsorbent, only iron is selectively adsorbed.

The solid adsorbent used for deironing 9 is not particularly limited as long as it is stable in alkalinity due to the above-described adsorption mechanism. However, in consideration of the adsorption rate, alumina-activated carbon or a mixture thereof is preferable. The specific surface area of r-alumina is preferably 120 to 160 nf / g (average pore diameter 100 to 120 A). When the specific surface area is less than 120 «f / g (average pore size of more than 120 people), the adsorption speed decreases, and when the specific surface area exceeds 160π? 160g (average pore size of less than 100 A), the adsorption area becomes smaller and the adsorption speed decreases. Become. The particle size of r-alumina is not restricted by the speed and efficiency of de-ironing, but it is desirable that the particle size is coarser in view of the separation from the Al-Li solution after de-ironing. Considering the cost of raw materials (hydroxide aluminum) that can be used in λ, a particle size of δθ δθ m is preferable. Such r-alumina is obtained by calcining aluminum hydroxide (preferably the static calcining method). Aluminum hydroxide can be obtained, for example, from Showa Light Metal Co., Ltd. using H-10 (trade name), H-10C (trade name). Is commercially available.

The activated carbon is desirably carbon black, wood, or coal. The activated carbon is preferably in the form of powder because the contact area with the liquid is increased. The specific surface area of activated carbon is generally 300 to 1500 nf / g, but is preferably 400 to 900 nf / g for deironing. When the specific surface area is less than 400 «f / g, the adsorption rate is low because the specific surface area is small. Become. The average pore size of the activated carbon is important, and an average pore size of 30-50 A is desirable. At less than 30 A, the effective adsorption area is small, so that the adsorption speed is high. At more than 50 A, the specific surface area is small, so that the adsorption speed is low.

For r-alumina and activated carbon, r-alumina has a higher adsorption rate. This is considered to be due not to the total specific surface area of the solid adsorbent but to the ratio of pores having a size larger than that capable of adsorbing iron hydroxide.

The method of contacting the alkaline gallium-containing aqueous solution with the solid adsorbent is not particularly limited, but the solid adsorbent particles are charged into the alkaline gallium-containing aqueous solution in the container so that both are sufficiently contacted. Stirring is preferred. There is no particular limitation on the stirring method, and general mechanical stirring is sufficient. However, it is preferable that the number of surface turns is equal to or higher than the solid adsorbent is uniformly dispersed in the liquid. However, the aqueous solution containing the alkaline gallium may be circulated and passed through a column filled with the solid adsorbent. Although the material of the contact device is not particularly strongly specified, it is preferable to use polyethylene, teflon, etc. instead of steel products such as steel plates and stainless steel. In particular, it is desirable that the stirrer, heater, etc. are coated with Teflon. At the time of this contact, it is preferable to heat the aqueous solution containing alkaline gallium to 50 or more, and more preferably to 70 or more. Unless the aqueous solution containing alkaline gallium is heated, it takes a long time to separate and remove iron. The heating method may be any method such as heater heating and steam suction.

The amount of solid adsorbent used depends on the type of solid adsorbent, For example, if τ-alumina (Β 150 Τ surface area: about 150 nfZg), 5 to 50 g / & is appropriate, and more preferably 20 to 30 g / H. In the case of 5 g / pound ^: it takes a long time for adsorption. Also, 5 0

In the case of adding iron, since the amount of iron adsorbed is the same, the subsequent separation and removal step becomes complicated and the solid adsorbent is wasted.

The adsorption time depends on the heating temperature, the type of adsorbent, and the amount used, but at 70, when 20 g of r-alumina is added, the iron content is reduced by approximately one hour of contact. It can be completely removed.

Although there is concern about the loss of gallium due to such adsorption and removal, there is no change in the concentration of gallium in the aqueous solution containing the alkaline gallium before and after the adsorption. When no was analyzed, no gallium was detected.

The image adsorbent that has adsorbed iron is filtered 10 to separate it from the aqueous solution containing the alkaline gallium.

Electrolysis is performed using the alkaline gallium-containing aqueous solution from which iron has been removed as described above.

The electrolysis is a normal aqueous electrolysis, and is preferably performed under the following conditions. That is, nickel plate, liquid metal gallium, etc. are used as the cathode, platinum plate, nickel plate, etc. are used as the anode, and the cathode current density is 0.01 to 0.5 A / cnf. Gallium Metal concentration 0.01 ~: L.5m ₀ l / ^ is appropriate. These conditions are necessary to obtain high current efficiency.

The gallium in the solution exists as gallium ion GaO ₂ , The solution turns out to the cathode.

Thus, by the method of the present invention, high-purity gallium 12 is efficiently produced by electrolyzing the electrolytic solution from which iron has been removed.

Since a small amount of gallium remains in the electrolysis termination solution, it can be recycled and used effectively in the process of the present invention. That is, the aqueous solution of gallium-containing mineral acid and / or mineral acid is added to the electrolyte to neutralize (about pH 5 to 8) 7 to precipitate the gel containing gallium, In the same manner as in the concentration step of the gallium concentration, filtration 8, washing, dehydration and alkalization 3 are performed to obtain a gallium-containing alkaline aqueous solution 4. Further, the electrolysis 11 can be performed again after the removal of iron 9 and the filtration 10.

Hereinafter, the present invention will be described with reference to Examples and Comparative Examples.

Example 1

The method for recovering sodium aluminate from the buyer method will be described with reference to examples.

The method of JP 51-32411 Patent forth, Ga 0. 2 g Z to including aluminate one preparative liquid (^ aOH 150 g / 6.. A1 2 0 3 8 0 g) and extract CKelexlOO (main Sazua off 8%, 4% of n-decanol, 4% of nosatic acid, 84% of kerosene), and after extracting Ga, 0.6 N- After removing impurities such as Al and Na with HC1, Ga was back-extracted with 2N-HC1. The gallium-containing aqueous solution of a mineral acid is passed through a diffusion-permeation tank (using Asahi Glass Co., Ltd.'s Ceremion DMV- as a diffusion-permeation membrane) at a rate of Zirfhr. Water was similarly placed through the membrane, and the acid was diffused to the water side and collected.

Table 1 shows the composition of the back extract, the recovered acid, and the permeate. Table Unit ¾i

C 1 G a

Reverse extraction liquid 2.0 0.03 Permeable liquid 0.4 0.4 0.03 Recovered acid 1.6 0.00 Add 4N sodium hydroxide solution to this permeate and adjust it to pH6. occured. After concentration of the slurry to 10 g / S. By decantation, the solution was passed through a filter press (filter cloth air permeability about 20 cc / cm ² · min, filtration pressure 4.0 kg / αί). Further, the same amount of pure water heated to 50 ° C. was passed, washed and dehydrated to obtain 0.2 kg / nf · hr of a cake having a water content of 80%. The Ga concentration in the cake was 7% by weight. 300 parts by weight of this cake was dissolved in 120 parts by weight of 10N sodium hydroxide solution to obtain 100 g of Na ₂₀ concentration and an aqueous solution of sodium gallium salt having a gallium concentration of 0.39 mol. The Fe concentration was measured. It was 5 PPm. To the solution was added 40 g of activated carbon (reagent grade powder manufactured by Wako Pure Chemical Industries, Ltd.), and the mixture was kept at 70 with heating and stirring for 4 hours. Then, solid-liquid separation was performed by filtration. When the concentration was measured, it was not detected. Cathode current density of 10 A / dnf, tank volume of 40 £, average residence time of 24 hours using a platinum plate as an anode and a nickel plate as a cathode. After performing, the Ga concentration of the electrolysis termination solution was measured to be 0.01 mol /. The surface of the cathode was completely covered with Ga metal. The Ga metal obtained during this period was 10.6 kg and the purity was 99.99%. The calculated current efficiency was 15%.

Example 2

Gallium Lin (GaP) Lumped gallium lin, which is a by-product waste generated during the production of crystals, was pulverized to obtain a Tyler Standard Sieve 60 Mesh powder. An oxidizing mixed acid (3.6 parts by weight of concentrated hydrochloric acid, 8.4 parts by weight of concentrated nitric acid) was added to 1.0 part by weight of this powder, and the solution was stirred.

GaP was oxidatively decomposed. Next, the oxidative decomposition solution was filtered, and 1 g of the undissolved residue was separated by filtration to obtain a transparent gallium-containing mineral acid aqueous solution. The aqueous solution of mineral acid is passed through a diffusion / permeation tank using Neocebuta AFN manufactured by Tokuyama Soda Co., Ltd. as a diffusion / permeable membrane at a speed of 1 / πί · hr, and simultaneously through the diffusion / permeation membrane. The water was placed in the same manner as above and the acid was diffused to the water side and collected.

Table 2 shows the composition of the mineral acid solution, the permeate, and the recovered acid.

Table 2 Display units (mol /)

By adding 1 5 N caustic soda solution Toru圻液of, Na ₂ 0 concentration A sodium gallinate solution having a gallium concentration of 0.7 mol / pound was obtained at a concentration of 100 g / ί, and the Fe concentration was measured to be 1 O ppra. This solvent solution was obtained form electrostatic置焼at 4 hours electric furnace at an average particle diameter of 5 O m of aluminum hydroxide _{_{560 r - A1 2 0 3 (}} BET surface area

150 m '/ g) was added at 20 g / H, and the mixture was kept at <0> with heating and stirring for 1 hour.Then, solid-liquid separation was performed by filtration, and the Fe concentration in the liquid was measured. Was. Platinum plate as an anode and a cathode nickel plate, cathode current density 1 0 A / dm ^l, the bath volume 4 0, 360 hours continuous electrolysis while passing liquid electrolyte solution at an average residence time of 3 6 hours After this, the Ga concentration of the electrolysis solution was measured and found to be O. Olmol / ^. The surface of the cathode was completely covered with Ga metal. The Ga metal obtained during this period was 19.2 te and 99.99% pure. The current efficiency was calculated to be 20%.

Example 3

The recovered acid obtained in Example 2 and the electrolysis termination solution were mixed and neutralized (pH 6) to generate a Ga (0H) ₃ gel. After deca Ntesho down, filtered through a Filter Press, washing, was subjected to dehydration, water content 80% cake 0. 2 kg_ m ^l. Hr was obtained. The Ga concentration in the cake was 7% by weight. The cake 300 parts by weight were dissolved in caustic soda 120 parts by weight of 1 0 N. Na ₂ 0 concentration

An aqueous sodium gallium salt solution having a gallium concentration of 100 g and a gallium concentration of 0.39 mol Zjg was obtained, and the Fe concentration was measured to be 6 ppm.

After the Fe component was completely removed by the same method as in Example 2, the platinum plate was used as the anode, the nickel plate was used as the cathode, and the cathode current density was 10 A / After performing continuous electrolysis for 240 hours while passing the electrolyte with a d nf tank volume of 4 & and an average residence time of 24 hours, the Ga concentration of the electrolysis termination solution was measured to be O. Olmol / i. Was. The surface of the cathode was completely covered with Ga metal. The Ga metal obtained during this period was 1.0 kg and the purity was 99.99%. The current efficiency during this period was 15%.

Comparative Example 1

The gallium-containing mineral acid aqueous solution of Example 1 was folded, neutralized, washed, and dehydrated in the same manner as in Example 1, and then adjusted for alkalinity. Na ₂₀ concentration 100 g / g An aqueous solution of 0.39 mol g of sodium gallate was obtained, and the Fe concentration was measured to be 5 ppm. With a platinum plate as the anode and a nickel plate as the cathode, current density is 10 A / dm ', tank volume is 40 S, average residence time is 24 hours. Table 3 shows the results of measurement of the Ga concentration in the electrolysis termination solution afterwards. Table 3

Electrolysis was interrupted 24 hours after the start of electrolysis, and the cathode surface was observed to be black. When the surface was qualitatively analyzed by EPMA (Electron Probe Micro Analysis), Ga, Fe, and Ni were detected. The current efficiency during this period was 3%. The Fe concentration in the electrolysis solution (after 2 hours) was 0.4 ppm. Comparative Example 2

The gully © beam舍有aqueous mineral acid in Example 2 was dialyzed in Example 2 in the same way, Na ₂ 0漶度100 g Roh added caustic soda solution of 1 5 N to the dialyzed solution, Galli A sodium gallate solution having a 0.7tnol / pium concentration was obtained, and the Fe concentration was measured to be 1 O ppm. Using this solution as an electrolytic solution, a platinum plate as an anode, a nickel plate as a cathode, and continuous electrolysis while passing at a cathode current density of 10 A / dirf, a tank volume of 40 &, and an average residence time of 36 hours. Table 4 shows the results of the measurement of the Ga concentration in the electrolysis solution after the start of electrolysis. Table 4

The electrolysis was interrupted 36 hours after the start of electrolysis, and the cathode surface was observed. The cathode was blackened, and when EPMA qualitative analysis was performed on the surface, Ga, Fe, and Ni were detected. The current efficiency calculated during this time was 4%. The Fe concentration in the electrolysis solution (24 hours) was 0.4 ppm.

Comparative Example 3

Neutralized from the recovered acid obtained in Example 2 and the electrolyzed solution in the same manner as in Example 3. Filtration ♦ After washing and dehydration steps, add alkali to add 100 g of Na _{20 and} 0.39 g of gallium. A molZ aqueous sodium gallate solution was obtained and the Fe concentration was measured to be 6 ppm. Using a platinum plate as the anode and a nickel plate as the cathode, continuous electrolysis is performed while passing the above solution at a cathode current density of 10 A / d trf. A tank volume of 4 、 and an average residence time of 24 hours. Table 5 shows the results of measuring the Ga concentration in the electrolysis solution after the start. Table 5

Electrolysis was interrupted 24 hours after the start of electrolysis, and the cathode surface was observed to be black. When the surface was analyzed, Ga, Fe, and Ni were detected. During this period, the current efficiency was calculated to be 3%. The concentration of Fe in the electrolysis termination solution (24 hours) was 0.4 ppm.

The method of the present invention can be applied to the production of high-purity gallium by electrolysis from a gallium-containing raw material, whether natural ore or industrial waste.

Claims

The scope of the claims

1. A method for producing a gallium by electrolysis of a gallium-containing aqueous solution, comprising a step of contacting the gallium-containing aqueous solution with a solid adsorbent under alkaline conditions to separate and remove iron before the electrolysis step. The manufacturing method of the garden.

2. The method according to claim 1, wherein an alkali concentration of the gallium-containing aqueous solution to be brought into contact with the solid adsorbent is in a range of 0.1 N to 5 N.

3. After preparing an alkaline aqueous solution having an alkaline concentration capable of isolating the aqueous solution by electrolysis,-contact the aqueous solution with an alkaline concentration with the solid adsorbent. 2. The method according to claim 1, wherein the iron is separated and removed at least, and then the aqueous solution containing the alkaline gallium is electrolyzed to recover the gallium.

4. The method according to claim 3, wherein the concentration of the alkali for isolating the gallium by electrolysis is in the range of 0.5 N to 5 N.

5. The method according to any one of claims 1 to 4, wherein the solid adsorbent comprises Γ-alumina or activated carbon or a mixture thereof.

6. The method according to any one of claims 1 to 5, wherein the contact between the aqueous solution of the solvent and the solid adsorbent is carried out while heating the mixture.

7. The method according to any one of claims 1 to 5, wherein the aqueous solution is passed through a column filled with the solid adsorbent and brought into contact with the solid adsorbent. the method of.

8. The method of claim 7, wherein the aqueous gallium-containing aqueous solution contacted with the solid adsorbent is heated.

9. The method according to claim 6, wherein the heating temperature is 50 or more.

10. The method according to claim 9, wherein the heating temperature is 70 or more.

2. The method according to claim 1, wherein said aqueous solution of mineral acid having 11 g of potassium is converted into an aqueous solution containing said alkaline gallium.

12. The method according to claim 11, wherein the gallium-containing mineral acid aqueous solution is derived from a viar solution.

13. The method according to claim 11, wherein the gallium-containing mineral acid aqueous solution is derived from a zinc refining process.

14. The method according to claim 11, wherein said gallium-containing aqueous solution of mineral acid is derived from gallium-containing waste.

15. The method according to any one of claims 11 to 14, wherein the aqueous solution of the gallium-containing mineral acid is subjected to a diffusion-filtration method to reduce the concentration of the mineral acid, followed by alkalizing. Method.

16. The aqueous solution containing gallium is neutralized to separate gel-like sediment containing gallium, washed, and then alkalized to obtain the alkaline gallium-containing aqueous solution. Item 1 to Item 15 φ method.

17. The electrolytic termination solution of the electrolysis is neutralized to separate the gel-containing precipitate containing gallium, washed, and then alkalized to obtain the alkaline gallium-containing aqueous solution. The method described in paragraph 1.