JPS6330319A - Method for selectively separating and recovering gallium - Google Patents

Abstract

PURPOSE:To selectively separate and recover the titled gallium with a simple operation and a high separating and recovering ratio, even in a strong basic solution, by using a specific water soluble oligomer or polymer having chelate forming ability, and by contacting said oligomer or polymer with a Ga contg. solution through a film. CONSTITUTION:Said water soluble oligomer or polymer comprises those contg. an amidoxim group obtd. by reacting acrylonitrile with polyethylene glycol, followed by forming an amidoxim of the obtd. compd. by reacting it with hydroxylamine. The Ga contg. solution (such as Bayer solution etc.) is contacted with said oligomer or polymer through the film which penetrates especially a metal ion or a hydrogen ion, etc., and does not penetrate said water soluble oligomer or polymer (such as a thin film of cellulose, etc.). Thus, in comparison with a prior method which uses a hydrophobic chelate agent or chelate resin, said method separates and recovers the metal Ga with high selectivity and a simple operation, even in a strong basic aqueous solution such as the Bayer solution.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for selectively separating and recovering gallium.

More specifically, the present invention relates to a method for selectively separating and recovering gallium in a solution that is present across a membrane using a specific water-soluble oligomer or polymer having chelate-forming ability.

[Prior Art] Demand for gallium has been increasing significantly in recent years due to the development of the semiconductor field. Unlike iron and copper, gallium does not have a single ore. Gallium is widely contained in small amounts in bauxite, raw aluminum ore, coal smoke, zinc sulfide ore, Germanic ore, etc., so various methods have been used to separate and recover it, requiring a lot of effort and expense. . In other words, the development of a technology that can separate and recover gallium economically and efficiently with a simple process, with few harmful effects, is expected, and has great commercial value.
In the production of gallium carried out on an industrial scale, in most cases, a gallium-aluminum mixed solution containing a large amount of aluminum, called Bayer liquid, used when producing alumina from bauxite by the Bayer process, is used as a raw material. What is the treatment of bauxite under the Bayer Act?

First, raw ore is thermally decomposed with an aqueous sodium hydroxide solution to prepare a sodium aluminate solution. At this time, most of the gallium is transferred to the sodium aluminate solution.Next, the sodium aluminate is cooled, and aluminum hydroxide is added as a seed to accelerate the hydrolysis reaction. Most of the aluminum is precipitated as aluminum hydroxide, which is separated by furnace. At this time, most of the gallium remains in the r liquid. Liquid F is evaporated and concentrated and reused for bauxite treatment. This p-liquid is called Bayer's liquid, and is essentially a raw material for gallium production.

Various methods have been implemented or proposed for the separation and recovery of gallium using Bayer's liquid.

In addition to the current method using mercury amalgam and the method of blowing carbon dioxide gas, recently there has been a method using solvent extraction using a chelate extractant made of an oxine derivative with increased hydrophobicity (Japanese Patent Laid-Open No. 51-32411, No. 53). -52289
No. 54-40212, No. 54-9972
Publication No. 6.

JP-A-59-50024, JP-A-59-92914, JP-A-59-92915, etc.), adsorption separation method using chelate resin having oxine as a functional group (JP-A-58-7412, JP-A-59-59) -96831 publication,
60-42234, etc.) have been proposed.

However, each of these methods has various drawbacks. Disadvantages of conventional methods include mercury dissolution loss, mercury contamination, loss of caustic alkali content in the sodium aluminate aqueous solution due to carbon dioxide gas, and low gallium recovery efficiency. Even the recently proposed methods
There are many problems in actual use. In the method of solvent extraction using a hydrophobic oxine derivative, the reagent is effective, and furthermore, the selectivity for gallium is low in strong basicity, the recovery efficiency is poor, and the function is degraded due to elution of the reagent into an aqueous solution. , contamination of Bayer fluid has been pointed out as a problem. Further, even in a method using a chelate resin having oxine as a functional group, it is difficult to say that this method is fully satisfactory in practical terms, considering that the chelate functional group has poor alkali resistance and oxidation resistance.

Due to these circumstances, even though the demand for metallic gallium has increased significantly with the development of the electronic industry such as the semiconductor sector, there is still no method of separation and recovery of gallium that is economically satisfactory on an industrial scale. Therefore, the present inventors conducted intensive studies to establish a new gallium separation method that overcomes the above-mentioned disadvantages, and found that a specific water-soluble oligomer or polymer with chelate-forming ability It was discovered that gallium in a strongly basic aqueous solution is selectively adsorbed by contacting with a gallium-containing solution across a membrane, and the present invention was achieved based on this discovery.

[Means for Solving the Problems] That is, the present invention uses a water-soluble oligomer or polymer having an amidoxime group, which is brought into contact with a solution containing gallium, particularly a strongly basic aqueous solution such as Bayer's solution, through a membrane. An object of the present invention is to provide a method for selectively separating and recovering gallium from a solution.

Examples of the water-soluble oligomers or polymers having an amidoxime group used in the present invention include polyethylene glycol, polyvinyl alcohol, polyhydroxyethyl methacrylate, copoly N-vinylpyrrolidone-hydroxyethyl methacrylate, and copoly N-
Vinylpyrrolidone - A water-soluble oligomer or polymer having a hydroxyl group such as vinyl alcohol, carboxyethyl cellulose, hydroxypropyl cellulose, amylose, or amylopectin is added with a compound having a nitrile group such as 7-crylonitrile, meta-7-crylonitrile, or α-chloroacrylonitrile. Water-soluble oligomers or polymers obtained by reaction and then amidoximation with hydroxylamine or hydroxylamine derivatives; hydroxyacetic acid, After reacting with hydroxyacetic acid, hydroxybenzoic acid, hydroxyphenylacetic acid, or their acid chlorides, etc., a nitrile group is introduced with acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, etc., and then amidoximation with hydroxylamine or a hydroxylamine derivative. The resulting water-soluble oligomer or polymer; a water-soluble oligomer or polymer such as an ethylene oxide polymer having an acid chloride group at the end is treated with ammonia, then dehydrated with phosphorus pentoxide, etc., and then hydroxylamine or a hydroxylamine derivative Water-soluble oligomers or polymers obtained through amidoxime formation by; mixtures of water-soluble oligomers or polymers having the above-mentioned amidoxime groups obtained by various methods; water-soluble oligomers having the above-mentioned amidoxime groups obtained by various methods. Or polymers and polyvinylpyrrolidone.

Examples include mixtures with water-soluble oligomers or polymers such as sodium polyacrylate, sodium polystyrene sulfonate, and quaternized polyvinylpyridine. When the obtained oligomer or polymer having an amidoxime group is made into an aqueous solution, it is desired that the viscosity of this aqueous solution is not very high, so the original polymer is preferably one with a relatively low degree of polymerization, and has a number average molecular weight of 500- 20,0
00, preferably t, ooo-to, ooo.

The separation membrane used in the present invention is not particularly limited as long as it is a membrane that permeates low molecular weight substances such as metal ions but does not permeate water-soluble oligomers or polymers. Cellulose-based, polyacrylonitrile, polymethyl methacrylate, polyethylene vinyl alcohol, commercially available as
Thin films such as polysulfone and polyamide can be mentioned. The film thickness may be as long as it does not physically break, and 33
Approximately 0-501 L is sufficient, and even thinner membranes can be used if a support material is used in conjunction with the membrane. Further, the shape of the membrane may be either a flat membrane or a hollow fiber membrane.

The gallium-containing solution in the present invention is not particularly limited as long as it is a gallium-containing solution. For example,
Gallium obtained in the industrial aluminum manufacturing process
Examples include aluminum mixed liquid, aluminum alloy manufacturing waste liquid, and leachate of zinc sulfide ore, germanite, etc.
Considering the industrial scale and commercial value, it is called Bayer liquid, which is produced in the process of producing alumina by the Bayer process. A gallium-aluminum mixture liquid in which most of the aluminum content has been removed and the gallium concentration ratio is increased is preferably used.

To selectively separate and recover gallium from a gallium-containing solution according to the present invention, the gallium-containing solution is simply brought into contact with the specific water-soluble oligomer or polymer having chelate-forming ability through the membrane. The contacting method is not particularly limited. For example, a cylindrical column may be filled with the oligomer or polymer, both ends of the column may be sealed with membranes, and a solution containing gallium may be passed through the column. A method is adopted in which an aqueous solution and a solution containing gallium are brought into contact while being circulated through a hollow fiber membrane, and the equipment for using the oligomer or polymer is appropriately selected depending on the gallium concentration in the solution.

The operating temperature is 5-100°C, preferably 10-80°C. Although the contact time is selected appropriately, the purpose is achieved within a few minutes.

As described above, the water-soluble oligomer or polymer adsorbing gallium according to the present invention can be eluted by contacting with an aqueous solution of about 1 to 2N hydrochloric acid, sulfuric acid, nitric acid, phosphorus Pf11, or the like. Leave the eluent as is.
Alternatively, metallic gallium can be obtained by treating with an alkali to form, for example, an aqueous solution of sodium galmate, and subjecting it to electrolysis, which is a known method. Further, the water-soluble oligomer or polymer from which gallium has been eluted can adsorb gallium repeatedly according to the above-described procedure.

[Effects of the Invention] Therefore, according to the present invention described in more detail, gallium can be removed even in a strongly basic aqueous solution such as Bayer's solution, compared to the conventional method using a hydrophobic chelating agent or chelating resin. It has a high selectivity for ions and is of great practical value.In terms of operation, a wide range of operating methods can be adopted, such as column flow method and liquid/liquid contact method through a membrane.
In the liquid/liquid contact method, the solvent is wood, so there is no need to pay special attention to organic solvents as was the case with conventional liquid/liquid extraction methods using kerosene as a solvent. It has the advantage of separation and recovery.

[Embodiments of the invention] Hereinafter, the present invention will be explained in more detail with reference to Examples.

Note that the present invention is not limited to the following examples.

Example 1 Polyethylene glycol with a number average molecular weight of 3,000 was reacted with 7-crylonitrile to form a nitrile group at the end, then dissolved in methanol, hydroxylamine hydrochloride and sodium carbonate were added, and the mixture was kept under reflux for 3 hours. Ta. The produced sodium chloride was removed and methanol was distilled off to obtain a water-soluble oligomer having 7 midoxime groups at the end. 30g of this oligomer to a diameter of 20mm
Fill a φ glass cylindrical column, seal both ends of the column with cellophane film with a thickness of 50 ILm, and add gallium 200
9P11, 100 mJL of a 3N aqueous sodium hydroxide solution containing 40,000 ppm of aluminum was passed through it repeatedly at room temperature for 2 hours.Next, 50m of water was passed through it for 10 minutes, and then 100mJL of a 2N aqueous salt solution was passed through it for 10 minutes.
1 was passed through the solution for 30 minutes at room temperature, and a gallium elution and recovery solution was obtained.The metal ion concentration in the recovery solution was measured.

Example 2 The same procedure as in Example 1 was carried out except that polyethylene glycol having an average molecular weight of e and ooo was used as the material for obtaining a water-soluble oligomer having chelate-forming ability.

Example 3 Copoly N-vinylpyrrolidone-hydroxyethyl methacrylate (5-5, molar ratio) with an average molecular weight of to, 000 was used as a material for obtaining a water-soluble oligomer having chelate-forming ability, and a solution containing this and gallium was used. The operation was carried out in the same manner as in Example 1, except that a cellulose acetate membrane with a thickness of 50 gm was used as the membrane separating the two.

Example 4 Example 4 except that polyethyleneimine having an average molecular weight of 4,000 to 5,000 was reacted with hydroxyacetic acid chloride to form a hydroxyl group at the end as the material for obtaining a water-soluble oligomer having chelate-forming ability. It was operated in the same manner as in 1.

Example 5 As a material for obtaining a water-soluble oligomer having chelate-forming ability, an ethylene oxide polymer having an average molecular weight of 4,000 and an acid chloride group at the end was treated with ammonia, dehydrated with phosphorus pentoxide, and the end was converted into a cyano group. The procedure was carried out in the same manner as in Example 1, except for using the same method as in Example 1.

Comparative Example 1 Instead of a water-soluble oligomer having an amidoxime group, 8 g of Kelex 100 (7-furkyl-8-hydroxyquinoline compound, manufactured by Schuling) was used, and a gallium extractant consisting of 10 g of decanol and 80 ml of kerosene was used. Prepared. To this, 10% of the same strongly basic gallium-aluminum mixed aqueous solution used in Example 1 was added.
After adding 0 m of water and shaking vigorously for 2 hours at room temperature, the water tank and oil layer were separated.Next, 100 m of a 2N 1fl acid aqueous solution was added to the oil layer and mixed vigorously for 30 minutes at room temperature.
The metal ion concentration in an aqueous hydrochloric acid solution was measured.

Comparative Example 2.3 Instead of using the water-soluble oligomers having amidoxime groups used in Examples 1 and 4, the average molecular weight used to prepare them was 2.000. (7) Polyethylene glycol was used in Comparative Example 1. In Comparative Example 3, the same procedure as in Example 1 was performed except that polyethyleneimine having an average molecular weight of 4,000 to 5,000 was used.

The above results are shown in Table 1.

i1 table

Claims (4)

[Claims] (1) A method for selective separation and recovery of gallium, which uses a water-soluble oligomer or polymer having an amidoxime group and is brought into contact with a solution containing gallium through a membrane. (2) The membrane that separates the water-soluble oligomer or polymer from the gallium-containing solution contains metal ions, hydroxide ions,
2. The method for selective separation and recovery of gallium according to claim 1, wherein the membrane is permeable to ions such as hydrogen ions but not to water-soluble oligomers or polymers. (3) The method for selectively separating and recovering gallium according to claim 1, wherein the solution containing gallium is a strongly basic aqueous solution. (4) The method for selectively separating and recovering gallium according to claim 1, wherein the solution containing gallium is an aqueous sodium aluminate solution used in the process of producing alumina by the Bayer method.