JPH11157835A - Production of high purity indium compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a producing method of an indium compd. of ultrahigh purity which can be used for various purposes such as fluoride glass optical fibers, laser source materials and optical materials. SOLUTION: A soluble salt soln. of indium is kept in pH range of 2 to 4, to which at least one kind of dimethylglyoxime, nitrosonaphtol and ammonium pyrrolidinedithiocarbamate is added in an amt. more than 3 times of the stoichiometric amt. to produce chelate complexes as the amt. of impurities in the salt. Then the precipitate is separated and removed alternatively, after the precipitate is separated and removed, the soln. is refined by extraction with a solvent and concentrated by heating, or crystallized and separated by neutralization with an alkali. Further alternatively, hydrochloric acid is added to the soln. to prepare the 0.1 to 7 N hydrochloric soln., which is extracted with a solvent. Or, cupferron is added to the soln. to separate and remove the precipitate, and then the soln. is extracted with a solvent, concentrated by heating or crystallized and separated by neutralization with an alkali.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an ultra-high-purity indium compound in which transition metal impurities are controlled to the ppb order, which can be applied to various uses such as a fluoride glass optical fiber, a raw material for a laser, and an optical material. It is about.

[0002]

2. Description of the Related Art In recent years, industrial progress in the optical field such as optical fibers, lasers, and other optical instruments has been remarkable, and the market has been expanding year by year. Among them, also in optical communication, a fluoride optical fiber in which praseodymium is doped into zirconium-based fluoride glass is capable of laser oscillation in a 1.3 μm wavelength band, and is capable of 1.3 μm optical amplification. Applications are of particular interest.

[0003] In addition, in the case of fluoride glass, indium-based fluoride glass having a lower phonon energy than zirconium-based fluoride glass is regarded as promising as a host glass realizing quantum efficiency higher than that of zirconium-based fluoride glass. . However, indium fluoride, the main component of indium-based glass, has no high-purity raw material and contains a large amount of transition metals such as iron, copper, nickel, and cobalt that hinder ultra-low loss. It has been difficult to produce lossy indium-based fluoride optical fibers.

[0004] For example, Japanese Patent Application Laid-Open No. 7-330335 discloses a method of adding a fluorinating agent to metal indium, performing heat treatment, heating in a vessel, and evaporating and removing impurities to reduce the impurity content to about 1 ppm. A method for producing a compound is disclosed.

However, these methods are effective in removing oxide impurities, but the transition metal is subjected to fluorination heat treatment at a high temperature, so that there is a problem that impurities are mixed in from a container. Not converted. At present, a method of removing the transition metal impurities all at once to the ppb order has not been developed yet.

[0006]

In view of the above problems, the inventors of the present invention have conducted intensive studies and as a result, have found that a relatively inexpensive and easily available soluble salt of indium metal can be used and that transition metal and the like can be used under specific conditions. The present inventors have found a method for producing an ultra-high purity indium compound which can easily and easily remove and purify impurities, and have reached the present invention.

That is, the present invention provides an aqueous solution of an indium salt in a pH range of 2 to 4 so that impurities in the soluble salt of indium have an amount of dimethyl which is at least three times the theoretical amount of forming a chelate complex. A solution obtained by adding at least one or more of glyoxime, nitrosonaphthol or ammonium pyrrolidinedithiocarbamate and separating and removing a precipitate of the generated chelate complex, or a solution obtained by purifying the solution by solvent extraction, by heat concentration or addition of an alkali solution A method for producing a high-purity indium compound, which is characterized in that precipitation and separation are performed by a neutralization reaction, wherein hydrochloric acid is added to a solution of the high-purity indium compound obtained by these production methods, and a 0.1 to 7N hydrochloric acid solution. After that, the precipitate of the chelate complex formed after solvent extraction or addition of cuperon was separated and removed. The liquid solvent extraction, there is provided a method for producing a high-purity indium compound, characterized in that the purified solution to precipitate separated by heating and concentrating.

[0008] In the present invention, the aqueous solution of soluble salt of indium as a raw material includes indium chloride, indium nitrate,
It is an aqueous solution of indium chlorate, indium oxalate, or the like.
Needless to say, a solution in which an insoluble salt such as indium metal or indium oxide is dissolved with an acid to form a soluble salt and then the pH is adjusted can be used.

In the present invention, the chelating agent used for forming the chelate complex is dimethylglyoxime,
Nitrosonaphthol, ammonium pyrrolidinedithiocarbamate (APDC) or cuperon.

Next, the range of the pH at which the chelating agent is added must be maintained at pH = 2-4. When the pH is 2 or less, the precipitation of the transition metal is not sufficiently generated, and the purification becomes insufficient. If the pH is 4 or more, precipitation of indium hydroxide is generated, which is not preferable. The dimethylglyoxime, nitrosonaphthol or ammonium pyrrolidinedithiocarbamate (APDC) used in the present invention may be added at the same time, or may be purified by adding one by one. In order to further improve the degree of purification, it is preferable to add a chelating agent one by one, and to perform precipitation removal and solvent extraction each time. Each chelating agent used in the present invention is usually used near neutrality.

In the present invention, Ni in dimethylglyoxime, Co in nitrosonaphthol, AP from
It has been found that Cu selectively forms a complex in DC. APDC forms a complex with indium, but is very small within this pH range and selectively forms a complex with Cu. In the dimethylglyoxime method, which is known as a method for quantifying Ni, the quantification is performed at around pH = 7, but a sufficient complex is formed within the pH range of the present invention.

Next, the amount of each chelating agent varies depending on the amount of transition metal contained in the aqueous solution of indium soluble salt. The amount of addition of the chelating agent is at least three times the theoretical amount at which the transition metal and each chelating agent form a complex. is necessary. Although there is no inconvenience from the viewpoint of reaction if the amount is excessively added, it is better to avoid excessive addition from the economical viewpoint.

The chelating agent may be added in the form of a powder. For example, dimethylglyoxime and nitrosonaphthol are hardly soluble in water and are once dissolved (dimethylglyoxime is dissolved by adding ammonia, nitrosonaphthol is acetic acid). Is added and dissolved), and then dissolved in water or the like before use.

[0014] As for the fractional removal of the precipitate, fine precipitation occurs due to the addition of the chelating agent. Therefore, it is preferable to separate and remove the precipitate with a precision filter such as a membrane filter.
Note that this separation and removal is for facilitating extraction,
Purification is possible even if this operation is omitted.

In the present invention, in order to further increase the degree of purification, purification by solvent extraction is more effective. Examples of the solvent to be used include, but are not particularly limited to, methyl isobutyl ketone, diisobutyl ketone, chloroform, carbon tetrachloride, and the like. The amount used depends on the solubility of the solvent in the solution, but in consideration of economics, the amount to be purified is usually 3 to 15% by volume, and the degree of purification is increased by repeating this extraction operation. . Since the solution (purified liquid) thus obtained has already been freed of metal impurities, water is removed by heating and concentrating as it is, and crystals are deposited and separated to form high-purity salts. Further, by adding an alkaline solution to the purified solution and neutralizing the solution, a hydroxide precipitates and indium hydroxide is precipitated and separated to form a high-purity salt. The alkaline solution used here is an ammonia solution, a sodium hydroxide solution, or a potassium hydroxide solution. Furthermore, various indium compounds can be synthesized by performing various treatments in the form of an aqueous solution or after crystallization by precipitation and separation.

Next, in the present invention, Ni, Co, Cu
The solution from which Fe has been removed may contain Fe,
Need to be removed. Therefore, in order to form a complex of Fe, it is necessary to set the pH to 1 or less. Therefore, it is necessary to add hydrochloric acid to the above purified solution to obtain a hydrochloric acid solution having a concentration of 0.1 to 7 N. There is. This hydrochloric acid solution is 0.1 mL.
If it is lower than 1N, a complex with chlorine cannot be formed, and it cannot be purified by solvent extraction, which is not preferable.
When the hydrochloric acid solution is higher than 7N, no particular inconvenience arises, but it is better to avoid excessive addition from an economic viewpoint. In addition, cupperon forms a complex with Fe, and is generally used at pH = 0 to 10. However, a high pH is not preferable because it forms a complex of both Fe and indium. As in the present invention,
When the acid concentration is high, such as a hydrochloric acid solution in the range of 0.1 to 7N, the formation of a complex with indium is reduced, and a complex is selectively formed with Fe to form a precipitate, so that Fe can be purified. . Purification is performed by a treatment such as hydrochloric acid treatment or precipitation removal, followed by solvent extraction in the same manner as described above, and the indium compound is subjected to heat concentration or alkali neutralization in the same manner as in the above method.

By oxidatively decomposing the soluble salt of indium obtained by the above-mentioned production method, a high-purity indium oxide can be produced. For example, an ultra-high purity indium oxide can be produced by calcining and decomposing a soluble salt as it is in an oxygen atmosphere or by adding an alkali such as ammonia to form a hydroxide, and calcining and decomposing the hydroxide.

Further, a high-purity indium halide can be produced by reacting the soluble salt obtained by the above production method or the solution with a halogenating agent. Examples of the halogenating agent to be used include a fluorinating agent, a brominating agent, an iodinating agent and the like. For example, fluoride is currently attracting attention as a raw material for fluoride optical fibers. In order to obtain these fluorides, a fluorination treatment or the like is performed by a wet synthesis, either as a soluble salt or once as an oxide. Or by reacting the oxide with a gaseous fluorinating agent, but to obtain a higher purity fluoride,
After the wet synthesis, impurities such as oxygen are reduced by further treating with a gaseous fluorinating agent. Examples of the fluorinating agent used here include hydrofluoric acid, hydrogen fluoride gas, ammonium fluoride, ammonium acid fluoride, fluorine gas, fluorine halide, and nitrogen trifluoride.

Furthermore, a high-purity indium salt can be produced by reacting the soluble salt obtained by the above production method or the solution with sulfuric acid, carbonic acid, nitric acid or the like.
For example, high-purity indium carbonate can be obtained by adding high-purity ammonium carbonate to the obtained soluble salt.

[0020]

The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples.

Embodiment 1 A description will be given with reference to the process chart of FIG. 200 g of an In (10%) solution obtained by heating and dissolving metal In with hydrochloric acid was placed in a beaker, and ammonia water was added while stirring with a stirrer.
The pH was adjusted to 3. 10 ml of dimethylglyoxime (2% solution) was added thereto, and the mixture was stirred for 30 minutes, and then filtered with a membrane filter (pore size: 0.2 μm). The pH of the filtrate was adjusted to 3 while nitrosonaphthol (1%
After adding 5 ml of the solution and stirring for 30 minutes, the mixture was filtered through a membrane filter (pore size: 0.2 μm). PH of the filtrate
= 3, 5 ml of APDC (4% solution) was added, and the mixture was stirred for 30 minutes.
2 μm). The filtrate (purified liquid) is heated and concentrated to obtain I
A hydrated salt of nCl ₃ was obtained. After dissolving the obtained hydrated salt of InCl ₃ , it was analyzed by flameless atomic absorption spectrometry (solvent extraction). The results are shown in Table 1. The analytical values in Table 1 are
It is a value of 100% conversion of metal In. The raw materials in Table 1 are
It is an analysis value in metal In.

Comparative Example 1 200 g of an In (10%) solution obtained by heating and dissolving metal In with hydrochloric acid was placed in a beaker, and ammonia water was added thereto while stirring with a stirrer to adjust the pH to 1. 10 ml of dimethylglyoxime (2% solution) was added thereto, and the mixture was stirred for 30 minutes, and then filtered with a membrane filter (pore size: 0.2 μm). The filtrate was adjusted to pH = 1, 5 ml of nitrosonaphthol (1% solution) was added, the mixture was stirred for 30 minutes, and then filtered through a membrane filter (pore size: 0.2 μm). The filtrate was adjusted to pH = 1 while APDC (4%
(Solution), and the mixture was stirred for 30 minutes, and then filtered through a membrane filter (pore size: 0.2 μm). The filtrate (purified liquid) was heated and concentrated to obtain a hydrated salt of InCl ₃ . After dissolving the obtained hydrated salt of InCl ₃ , it was analyzed by flameless atomic absorption spectrometry (solvent extraction). The results are shown in Table 1.

Embodiment 2 A description will be given with reference to the process chart of FIG. 200 g of an In (10%) solution obtained by heating and dissolving metal In with hydrochloric acid was placed in a beaker, and ammonia water was added while stirring with a stirrer.
The pH was adjusted to 3. 10 ml of dimethylglyoxime (2% solution) was added thereto, and the mixture was stirred for 30 minutes, and then filtered with a membrane filter (pore size: 0.2 μm). The pH of the filtrate was adjusted to 3 while nitrosonaphthol (1%
After adding 5 ml of the solution and stirring for 30 minutes, the mixture was filtered through a membrane filter (pore size: 0.2 μm). PH of the filtrate
= 3, 5 ml of APDC (4% solution) was added, and the mixture was stirred for 30 minutes.
2 μm). 30 ml of high-purity MIBK (methyl isobutyl ketone) was added to the filtrate for extraction. 200 ml of high-purity hydrochloric acid was added to the purified solution, and MIBK was added to 30 ml.
ml was added for extraction. The purified solution is concentrated by heating.
A hydrated salt of nCl ₃ was obtained. After dissolving the obtained hydrated salt of InCl ₃ , it was analyzed by flameless atomic absorption spectrometry (solvent extraction). The results are shown in Table 1.

Comparative Example 2 200 g of an In (10%) solution obtained by heating and dissolving metal In with hydrochloric acid was put into a beaker, and ammonia water was added thereto while stirring with a stirrer to adjust the pH to 1. 10 ml of dimethylglyoxime (2% solution) was added thereto, and the mixture was stirred for 30 minutes, and then filtered with a membrane filter (pore size: 0.2 μm). The filtrate was adjusted to pH = 1, 5 ml of nitrosonaphthol (1% solution) was added, the mixture was stirred for 30 minutes, and then filtered through a membrane filter (pore size: 0.2 μm). The filtrate was adjusted to pH = 1 while APDC (4%
(Solution), and the mixture was stirred for 30 minutes, and then filtered through a membrane filter (pore size: 0.2 μm). MIB in filtrate
30 ml of K (methyl isobutyl ketone) was added to perform extraction. The purified solution was concentrated by heating to obtain a hydrated salt of InCl ₃ . After dissolving the obtained hydrated salt of InCl ₃ , it was analyzed by flameless atomic absorption spectrometry (solvent extraction). The results are shown in Table 1.

Embodiment 3 A description will be given with reference to the process chart of FIG. 200 g of an In (10%) solution obtained by heating and dissolving metal In with hydrochloric acid was placed in a beaker, and ammonia water was added while stirring with a stirrer.
The pH was adjusted to 3. 10 ml of dimethylglyoxime (2% solution) is added thereto, and while adjusting pH = 3, 5 ml of nitrosonaphthol (1% solution) and further A
After adding 5 ml of PDC (4% solution) and stirring for 30 minutes, the mixture was filtered through a membrane filter (pore size: 0.2 μm).
30 ml of IBK (methyl isobutyl ketone) was added for extraction. After adding 20 ml of high-purity hydrochloric acid to the purified solution, 5 ml of cupron (4% solution) was added, and after stirring for 30 minutes,
After filtration through a membrane filter, 30 ml of methyl isobutyl ketone was added to the filtrate for extraction. 80 ml of high-purity 28% aqueous ammonia was added to the purified liquid to obtain about 25 g of indium hydroxide. After washing, it was dried at 120 ° C. all day and night, put in a platinum container and calcined at 600 ° C. to obtain indium oxide. After dissolving the indium oxide with an acid, it was analyzed by flameless atomic absorption spectrometry (solvent extraction). The results are shown in Table 1.

Comparative Example 3 200 g of an In (10%) solution obtained by heating and dissolving metal In with hydrochloric acid was placed in a beaker, and 40 ml of high-purity ammonia water was added thereto while stirring with a stirrer to obtain about 30 g of indium hydroxide. After washing, it was dried at 120 ° C. for a day and night, and put in a platinum container and fired at 600 ° C. After dissolving the indium oxide with an acid, it was analyzed by flameless atomic absorption spectrometry (solvent extraction). The results are shown in Table 1.

Embodiment 4 A description will be given with reference to the process chart of FIG. 200 g of an In (10%) solution obtained by heating and dissolving metal In with hydrochloric acid was placed in a beaker, and ammonia water was added while stirring with a stirrer.
The pH was adjusted to 3. 10 ml of dimethylglyoxime (2% solution) was added thereto, and the mixture was stirred for 30 minutes, and then filtered with a membrane filter (pore size: 0.2 μm). The pH of the filtrate was adjusted to 3 while nitrosonaphthol (1%
After adding 5 ml of the solution and stirring for 30 minutes, the mixture was filtered through a membrane filter (pore size: 0.2 μm). PH of the filtrate
= 3, 5 ml of APDC (4% solution) was added, and the mixture was stirred for 30 minutes.
2 μm). To the filtrate was added 30 ml of MIBK (methyl isobutyl ketone) for extraction. 200 ml of high-purity hydrochloric acid was added to the purified solution, and 30 ml of MIBK (methyl isobutyl ketone) was added for extraction. 180 ml of high-purity 28% aqueous ammonia was added to the purified liquid to obtain about 23 g of indium hydroxide. After washing, drying all day and night at 120 ° C., and reacting with 50% HF (for semiconductors) for about 2 hours
2 g of indium fluoride hydrate were obtained. This was dried in a fluororesin dryer all day and night, and the dried product was placed in a glassy carbon container and placed in an HF atmosphere (HF 500 ml / m2).
(in, N ₂ 3000 ml / min) calcination at 600 ° C. for 2 hours to obtain indium fluoride. After dissolving the indium fluoride with acid, flameless atomic absorption method (solvent extraction)
Was analyzed. The results are shown in Table 1.

Comparative Example 4 200 g of an In (10%) solution obtained by heating and dissolving metal In with hydrochloric acid was placed in a beaker, and while stirring with a stirrer, 40 ml of 28% ammonia water for precision analysis was added to obtain about 30 g of indium hydroxide. Was. After washing and drying at 120 ° C. for 24 hours, it was reacted with 50% HF (for semiconductor) to obtain about 25 g of indium fluoride hydrate. This was dried all day and night in a fluororesin drier, and the dried product was placed in a glassy carbon container and placed in an HF atmosphere (HF 500 ml / min,
Calcination was performed at 600 ° C. for 2 hours (N ₂ 3000 ml / min) to obtain indium fluoride. After dissolving the indium fluoride with an acid, it was analyzed by flameless atomic absorption spectrometry (solvent extraction). The results are shown in Table 1.

Example 5 A 200 g In (10%) solution obtained by heating and dissolving metal In with hydrochloric acid was put into a beaker, and ammonia water was added to the mixture while stirring with a stirrer to adjust the pH to 3. 10 ml of dimethylglyoxime (2% solution) was added thereto, and the mixture was stirred for 30 minutes, and then filtered with a membrane filter (pore size: 0.2 μm). The filtrate was adjusted to pH = 3, added with 5 ml of nitrosonaphthol (1% solution), stirred for 30 minutes, and filtered with a membrane filter (pore size 0.2 μm). The filtrate was adjusted to pH = 3 while APDC (4%
(Solution), and the mixture was stirred for 30 minutes, and then filtered through a membrane filter (pore size: 0.2 μm). MIB in filtrate
30 ml of K (methyl isobutyl ketone) was added to perform extraction. 200 ml of high-purity hydrochloric acid was added to the purified solution, and MI
30 ml of BK (methyl isobutyl ketone) was added for extraction. High-purity ammonium carbonate (20
% Solution) was added with stirring to obtain indium carbonate. After washing with water, filtration and drying at 100 ° C., the sample was dissolved in an acid and analyzed by flameless atomic absorption spectrometry (solvent extraction). The results are shown in Table 1.

[0030]

[Table 1]

[0031]

By using the method of the present invention, it is possible to produce an ultra-high purity indium compound in which transition metal impurities are controlled to the order of ppb.

[Brief description of the drawings]

FIG. 1 shows a manufacturing process diagram of Example 1.

FIG. 2 shows a manufacturing process diagram of Example 2.

FIG. 3 shows a manufacturing process diagram of Example 3.

FIG. 4 shows a manufacturing process diagram of Example 4.

Claims (4)

[Claims] 1. An aqueous solution of a soluble salt of indium having a pH of 2
And at least one of dimethylglyoxime, nitrosonaphthol or ammonium pyrrolidinedithiocarbamate in an amount of at least three times the theoretical amount of forming a chelate complex with respect to impurities in the soluble salt of indium. A method for producing a high-purity indium compound, wherein a solution obtained by separating and removing a precipitate of a generated chelate complex is separated by precipitation by heat concentration or a neutralization reaction by adding an alkali solution. 2. An aqueous solution of a soluble salt of indium having a pH of 2
And at least one of dimethylglyoxime, nitrosonaphthol or ammonium pyrrolidinedithiocarbamate in an amount of at least three times the theoretical amount of forming a chelate complex with respect to impurities in the soluble salt of indium. A method for producing a high-purity indium compound, comprising: subjecting a solution obtained by separating and removing a precipitate of a generated chelate complex to a solvent, and purifying the solution by heat concentration or a neutralization reaction by adding an alkali solution to precipitate and separate the solution. 3. A solution obtained by adding hydrochloric acid to a solution of a high-purity indium compound obtained by the production method according to claim 1 to obtain a 0.1 to 7N hydrochloric acid solution, and then purifying the solution by solvent extraction. A high-purity indium compound, which is separated by precipitation by heat concentration or neutralization reaction by addition of an alkali solution. 4. A solution of the high-purity indium compound obtained by the production method according to claim 1 or 2, wherein hydrochloric acid is added to obtain a 0.1 to 7N hydrochloric acid solution, and then cupperone is added. A method for producing a high-purity indium compound, comprising subjecting a solution obtained by separating and removing a precipitate of the chelate complex to solvent extraction, and subjecting the purified solution to precipitation separation by heat concentration or neutralization reaction by addition of an alkali solution.