JP2016094338A - Method for producing indium oxide and indium oxide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing indium oxide in which chlorine and sodium contained in the process is efficiently removed and to provide indium oxide produced by the method.SOLUTION: The method for producing indium oxide comprises adding an indium chloride aqueous solution or an aqueous solution containing a metal salt composed mainly of indium chloride to a sodium hydroxide aqueous solution, adjusting the pH to 9 to 10 to generate indium hydroxide, filtering the generated indium hydroxide, dispersing the indium hydroxide to a solution having a pH of 8 to 9 and stirring/washing the same and filtering the indium hydroxide to recover the same; further dispersing the indium hydroxide to a solution having a pH of 4 to 5 and stirring/washing the same and filtering the indium hydroxide; and then calcining. In the process of neutralizing an indium chloride aqueous solution or an aqueous solution containing a metal salt composed mainly of indium chloride as a raw material to form indium hydroxide and calcining the same to produce indium oxide, chlorine and sodium contained in the process are efficiently removed.SELECTED DRAWING: None

Description

  The present invention is a process for producing indium oxide by neutralizing an aqueous solution containing indium chloride as a raw material or an aqueous solution containing a metal salt containing indium chloride as a main component to produce indium oxide, The present invention relates to a method for producing indium oxide that efficiently removes chlorine and sodium contained therein, and low chlorine and low sodium content indium oxide obtained thereby.

In recent years, indium-tin oxide (ITO) sputtering targets have been widely used for transparent conductive thin films and gas sensors of liquid crystal display devices. In many cases, thin film forming means by sputtering is used on a substrate or the like. A thin film is formed. Although the thin film forming means by this sputtering method is an excellent method, when a transparent conductive thin film is formed using a sputtering target, for example, the target is not consumed uniformly.

A part of the target that is heavily consumed is generally called an erosion part, but the sputtering operation is continued until the erosion part is consumed and the backing plate supporting the target is exposed. After that, it is replaced with a new target. Therefore, many non-erosion portions, that is, unused target portions remain in the used sputtering target, and all of these become scrap. In addition, scrap is generated from the polishing powder and cutting powder during the production of the ITO sputtering target.

Since a high-purity material is used for the ITO sputtering target material and the price is high, indium is generally recovered from such a scrap material.
As this indium recovery method, a method combining wet purification such as an acid dissolution method, an ion exchange method, and a solvent extraction method has been conventionally used.

For example, ITO scrap is washed and ground, dissolved in nitric acid, hydrogen sulfide is passed through the solution, and impurities such as zinc, tin, lead, copper are precipitated and removed as sulfides, and then ammonia is added to neutralize them. , A method of recovering as indium hydroxide.
However, indium hydroxide obtained by this method has poor filterability and takes a long time to operate, and there are many impurities such as Si, Al, etc., and indium hydroxide to be produced depends on its neutralization conditions and aging conditions, etc. Since the particle size and the particle size distribution fluctuate, there is a problem in that the characteristics of the ITO target cannot be stably maintained when manufacturing the ITO target thereafter.

For this reason, the present inventor first dissolved the indium-containing scrap with hydrochloric acid to form an indium chloride aqueous solution, and added the sodium hydroxide aqueous solution to the solution to add tin contained in the scrap to tin hydroxide. And then adding a sodium hydroxide aqueous solution to form indium hydroxide, filtering the indium hydroxide and collecting it as a cake, adding sulfuric acid to make indium sulfate, and removing the indium sulfate by electrowinning. A method for recovering indium has been proposed (patent document 1).

This method was an excellent method for recovering indium from scrap. However, when recovering indium hydroxide, when fine indium hydroxide of 1 micron or less or ionized indium is filtered by a filter press, a mesh is used. It turned out that it passed through and became a loss. For this reason, the improvement which improves the yield of indium hydroxide was required.

For this reason, this was further improved, and indium solution containing fine indium hydroxide or ions was added with sodium hydroxide or ammonium hydroxide aqueous solution to adjust the pH to 7 to 10 to aggregate indium hydroxide. And a step of filtering the indium hydroxide, and proposed a method for recovering indium hydroxide (see Patent Document 2). This method was also an extremely effective method in view of the purpose. Patent Documents 1 and 2 both dissolve scrap with hydrochloric acid.

  In addition, there is Patent Document 3 as a method for producing indium hydroxide. This patent document 3 has an object to provide a method for producing an indium hydroxide powder having a small amount of residual chlorine at a low cost even when indium chloride is used as a raw material. In a method of adding a solution and neutralizing to obtain an indium hydroxide suspension, then filtering the indium hydroxide and washing to obtain a low chlorine grade indium hydroxide, an aqueous ammonia solution is used as the alkaline solution and added. The amount of ammonia is more than 0.8 times and less than 1.0 times in terms of the amount of indium ions in the solution, and then the pH of the resulting indium hydroxide suspension is 8.0 to 10.0. A method for producing indium hydroxide has been proposed, characterized in that it is filtered and washed after being controlled (Patent Document 3).

  In Patent Document 3, the paragraph number 0003 states, “Since conductive fillers or transparent conductive film paints are used for electronic materials, impurities, especially halogen elements, are problematic. If present, the metal used in the electronic device is likely to corrode and dissolve, and the resin mixed with the indium oxide powder is likely to change over time. As the indium hydroxide to be obtained, halogen, specifically, chlorine having a content of 50 ppm or less is required.

  Further, in paragraph No. 0004 of Patent Document 3, “indium oxide powder is generally neutralized by adding an alkali such as ammonia or an aqueous sodium hydroxide solution to an indium salt aqueous solution to crystallize indium hydroxide, Since it is difficult to remove the halogen element by calcination, in order to obtain an indium oxide powder having a sufficiently low halogen element quality, the indium hydroxide before calcination is used. It is necessary to sufficiently reduce the halogen element quality. " Although patent document 3 was illustrated typically, patent document 4-patent document 8 is mentioned as a thing relevant to this. All of these have a problem of reducing halogen, particularly chlorine.

  Each of the above patent documents has a problem of reducing halogen such as indium hydroxide, particularly chlorine, but since indium chloride is used as a raw material, mixing of chlorine is unavoidable. In spite of the purpose of precipitation (aggregation) of indium hydroxide, there is a problem that a large amount of chlorine is mixed in indium hydroxide during the manufacturing process. In order to avoid this, after depositing indium hydroxide, the indium hydroxide washes with water until it was able to remove chlorine, or it had to be washed repeatedly or other costly means. .

  In addition, it is generally inexpensive to use sodium hydroxide (NaOH) as a neutralizing agent, but if sodium remains in the target, there is a drawback that the sputtered film is likely to be deteriorated by oxidation. Therefore, it is not preferable. For this reason, it is desirable to use ammonia without using sodium hydroxide as the neutralizing agent. However, when ammonia is used, it is necessary to dispose of the nitrogen component in order to meet the recent strict drainage standards. Is very expensive. Therefore, sodium hydroxide is used in production, but removal of sodium is an essential requirement.

JP 2002-69684 A JP 2002-201025 A JP 2009-91213 A JP 2007-331975 A JP 2008-137825 A JP 2008-174399 A JP 2008-195560 A JP 2009-1114013 A Japanese Patent Laid-Open No. 5-201731 JP-A-10-182150

  In order to solve the above problems, the present invention neutralizes an aqueous solution of indium chloride as a raw material or an aqueous solution containing a metal salt containing indium chloride as a main component with sodium hydroxide to form indium hydroxide. In the process of producing indium oxide by baking, chlorine and sodium contained in the process can be removed efficiently and at low cost, and the low chlorine and low sodium obtained thereby It is an object to provide a contained indium oxide.

In the method for producing indium oxide according to the present invention, as an example, an indium chloride aqueous solution as a raw material or an aqueous solution containing a metal salt mainly composed of indium chloride is neutralized to form indium hydroxide, which is roasted. A method for producing indium oxide, comprising adding an aqueous solution of indium chloride or an aqueous solution containing a metal salt containing indium chloride as a main component to an aqueous solution of sodium hydroxide, adjusting the pH to 9 to 10 The generated indium hydroxide is filtered, dispersed in a solution of pH 8-9, washed with stirring, indium hydroxide is collected by filtration, and further dispersed in a solution of pH 4-5, stirred. It is characterized by being roasted after washing and filtering indium hydroxide.

The method for producing indium oxide according to the present invention includes, as part 2, neutralization of an aqueous solution of indium chloride as a raw material or an aqueous solution containing a metal salt containing indium chloride as a main component to form indium hydroxide, which is roasted. A method for producing indium oxide, comprising simultaneously adding a sodium hydroxide aqueous solution and an indium chloride aqueous solution or an aqueous solution containing a metal salt mainly composed of indium chloride to a water bath, adjusting the pH to 9 to 10 Indium oxide is generated, the generated indium hydroxide is filtered, this is dispersed in a solution of pH 8-9, washed with stirring, and indium hydroxide is recovered by filtration, and further dispersed in a solution of pH 4-5. The mixture is washed with stirring, and after indium hydroxide is filtered off, it is roasted.

The third aspect of the present invention provides the method for producing indium oxide according to any one of the above items 1 and 2, wherein the content of indium chloride after roasting is 5 ppm or less.

  As the fourth aspect of the present invention, there is provided the method for producing indium oxide according to any one of the above items 1 to 3, wherein the sodium content of the indium oxide after roasting is 10 ppm or less.

  As part 5 of the present invention, an indium chloride aqueous solution prepared by dissolving indium-containing scrap with hydrochloric acid is used as a raw material, and sodium hydroxide is used as a neutralizing agent. A manufacturing method is provided.

  6. The indium oxide according to any one of 1 to 5 above, wherein the raw material is neutralized to generate indium hydroxide, and then components other than indium hydroxide are removed. A manufacturing method is provided.

  According to the seventh aspect of the present invention, there is provided indium oxide, wherein the chlorine content obtained by the method for producing indium oxide according to any one of 1 to 6 is 5 ppm or less.

  As an eighth aspect of the present invention, there is provided indium oxide, wherein the sodium content obtained by the method for producing indium oxide according to any one of 1 to 7 is 10 ppm or less.

The present invention is a process for producing an indium oxide by neutralizing an aqueous solution of indium chloride as a raw material or an aqueous solution containing a metal salt containing indium chloride as a main component with sodium hydroxide to roast it. In this process, it is possible to provide a method for producing indium oxide capable of efficiently removing chlorine and sodium contained in the step at low cost, and a low chlorine and low sodium content indium oxide obtained thereby. It has an excellent effect.

The method for producing indium oxide according to the present invention does not require repeated washing of indium hydroxide, which was a conventional production method until chlorine and sodium can be removed, or selection of other costly means. At the stage of producing indium, low chlorination and low sodium can already be realized. Furthermore, the indium oxide produced in the present invention is excellent in sinterability, density and yield, for example, when producing a sintered body target such as an indium-tin oxide (ITO) sputtering target. It has the effect of improving the quality.

  In the method for producing indium oxide of the present invention, an aqueous solution of indium chloride as a raw material or an aqueous solution containing a metal salt mainly composed of indium chloride is added to an aqueous solution of sodium hydroxide, and the pH is adjusted to 9 to 10 to adjust the water. Indium oxide is generated, and the generated indium hydroxide is filtered. In Step A, if the pH is less than 9, the effect of indium hydroxide generation (aggregation) is lowered, so it is necessary to set the pH to 9 or more. Moreover, if it is less than pH 9, it will become extremely difficult to wash | clean chlorine at the time of washing | cleaning, Therefore It needs to set it as pH 9 or more. Furthermore, if it exceeds pH 10, it becomes difficult to wash sodium at the time of washing.

Next, the indium hydroxide obtained in the step A is dispersed in a pH 8-9 solution and stirred and washed, and the indium hydroxide is recovered by filtration, and further dispersed in a pH 4 to 5 solution and stirred and washed. Then, indium hydroxide is filtered off (step B). A step of roasting indium hydroxide obtained in step B is employed.
In Step B, when the pH is less than 8, the effect of indium hydroxide formation (aggregation) is lowered, so that the pH needs to be 8 or more. Moreover, if it is less than pH 8, it will become extremely difficult to wash | clean chlorine at the time of washing | cleaning, Therefore It needs to set it as pH 8 or more. Furthermore, if it exceeds pH 9, it becomes difficult to wash sodium at the time of washing.

Next, the indium hydroxide obtained (aggregated) by the steps A and B is collected by filtration, and the indium hydroxide after filtration is washed with water and then roasted to produce indium oxide. As a result, indium oxide with significantly reduced chlorine can be obtained.
The chlorine content in indium oxide can be reduced to 5 ppm or less. Conventionally, a process of adding an aqueous sodium hydroxide solution to an aqueous solution containing an indium chloride aqueous solution or a metal salt containing indium chloride as a main component as a raw material has been employed, and this can be said to be a completely reverse process.

As described above, the chlorine content in the indium oxide can be 5 ppm or less. By this, for example, when an ITO sputtering target is manufactured using this indium oxide, the sinterability is improved and the density is increased. It is easy to increase the yield, the generation of defective products is reduced, the yield is improved, and as a result, the quality of the target can be improved.

The hydroxide particle surface is positively charged when the liquid is acidic, and negatively charged when alkaline, and in the case of alkaline, the chlorine ion itself is negatively charged, so it is difficult to be adsorbed on the hydroxide surface. . However, since indium hydroxide is generated from about pH 3, in the process of adding sodium hydroxide to indium chloride for neutralization, chlorine ions are adsorbed in the acidic region.

Finally, even if the pH is made alkaline, the adsorbed chlorine is difficult to remove. This is considered to be a cause of containing chlorine at a high concentration in the stage of producing indium hydroxide from indium chloride in the conventional method.
In the present invention, since neutralization with sodium hydroxide is performed while maintaining alkalinity, chlorine ions are hardly adsorbed on the surface of indium hydroxide, and as a result, chlorine ions can be greatly reduced.

As is clear from the above, when neutralizing an indium chloride aqueous solution or an aqueous solution containing a metal salt containing indium chloride as a main component to form indium hydroxide, sodium hydroxide can be used in a water bath if the alkalinity can be maintained. It will be understood that chlorine adsorbed on indium hydroxide can be similarly reduced by simultaneously adding an aqueous solution and an indium chloride aqueous solution or an aqueous solution containing a metal salt mainly composed of indium chloride.

In this case, similarly, the pH is adjusted to 9 to 10 to generate indium hydroxide, and the generated indium hydroxide is filtered and recovered. After the filtered indium hydroxide is washed with water, it is roasted and oxidized. It can be indium. Thereby, the chlorine content in indium oxide can be reduced to 5 ppm or less. However, in this case, there is a disadvantage that sodium used as a neutralizing agent remains. This is because sodium is easily adsorbed to the alkaline and negatively charged hydroxide.

As a result of intensive studies to solve this problem, it has been found that sodium can be washed by using a weakly acidic solution for the washing water. More specifically, after suspending the obtained hydroxide in water, the pH of the suspension is adjusted to 4 to 5 using nitric acid, stirred, and filtered, so that Of sodium can be reduced to less than 10 ppm. At this time, if the pH is less than 4, re-dissolution of indium becomes intense and the yield of indium is extremely deteriorated. On the other hand, when the pH is higher than 5, since the effect of washing sodium is small, a large amount of water is required for washing.

In addition, when the neutralized indium hydroxide is washed with an acidic solution from the beginning, a slight amount of chlorine is re-adsorbed, so that it is difficult to obtain a chlorine removal effect. For this reason, after neutralization, the hydroxide after neutralization is washed with weak ammonia water having a pH of about 8 to 9 once to remove chlorine, and then washed with water with a pH of 4 to 5 to remove sodium. Can also be removed.

(Raw material adjustment)
The raw material used in the present invention is basically an indium chloride aqueous solution, but an aqueous solution containing indium chloride as a main component and containing other metal salts can also be used. For example, it is possible to dissolve a scrap of an ITO sputtering target with hydrochloric acid to prepare a mixed solution of indium hydroxide and tin hydroxide.

In addition, there can be used a sputtering target scrap such as IZO, IGO, and IGZO, and there is no particular limitation as long as the main component is indium chloride.
For example, in the case of an ITO sputtering target, the component composition ratio of the aqueous solution reflects the component composition of the ITO sputtering target.

Indium chloride containing tin chloride can be neutralized with sodium hydroxide to produce indium hydroxide containing tin hydroxide, which can be roasted to produce indium oxide containing tin oxide. Furthermore, when reusing an ITO sputtering target using this as a raw material, the target material before being scraped and the material after recovery may fluctuate compositionally. You can play the target.

In the above, the reuse of the ITO target has been described, but the present invention can be similarly applied to other sputtering targets such as an IZO target.
When a solution containing only indium hydroxide is used, components other than indium hydroxide may be removed when indium hydroxide is generated. Further, when impurities are mixed at the stage of scrap recycling, it can be said that it is desirable to remove the impurities at the stage of indium chloride or indium hydroxide solution.

An example of generating indium hydroxide from a scrap of a target containing indium oxide will be described as follows using an ITO target as an example.
First, a step of dissolving indium-containing scrap such as ITO target polishing powder with hydrochloric acid is employed. Specifically, the amount of hydrochloric acid is set to 300 L to 600 L with respect to 100 kg of indium-containing scrap and melted at a temperature of 100 to 110 ° C. This melting temperature is in a boiling state. The dissolution time is about 3 to 5 hours, and is adjusted as appropriate.
The amount of hydrochloric acid is 300L to 600L. 300 L is a reaction equivalent, and adding more than 600 L is useless because the reaction is not particularly accelerated. By adjusting the amount of hydrochloric acid and dissolving at a temperature of 100 to 110 ° C., the undissolved residue can be reduced as much as possible.

Next, the pH of the indium chloride aqueous solution is adjusted to 1.5 to 2.0 with respect to the indium chloride aqueous solution thus obtained by using a sodium hydroxide aqueous solution or the like. In addition to the aqueous sodium hydroxide solution, an aqueous potassium hydroxide solution can also be used. As a result, most of the tin contained in the scrap can be precipitated as tin hydroxide (Sn (OH) ₄ ) and removed.
The remaining indium hydroxide can be converted into indium oxide by performing the above treatment. It can select suitably according to the material (oxide) to manufacture.

Next, examples will be described. In addition, a present Example is for showing an example of invention, This invention is not restrict | limited to these Examples. That is, other aspects and modifications included in the technical idea of the present invention are included. In the following, comparative examples will be described in comparison with the examples.

Example 1
In this example, an aqueous solution of indium chloride is neutralized by adding an aqueous solution of sodium hydroxide to generate indium hydroxide, which is roasted to form indium oxide.

<Details of Example 1>
To 2240 ml of pure water, 157.4 ml of 25% aqueous sodium hydroxide solution was added to make it alkaline. While stirring, an In: 50 g / L aqueous solution of In chloride was added to this solution at 10 ml / min. Was set to 9.5. In the process of adding sodium hydroxide to indium chloride for neutralization, the alkalinity was always maintained, and no adsorption of chlorine on indium hydroxide was observed.

The total amount added was 1100 ml. The generated indium hydroxide was filtered, 9 L of pure water was added to the filtered indium hydroxide, and several drops of aqueous ammonia were added to the pH to 8.5 while stirring. This was filtered, 9 L of pure water was added to the filtered indium hydroxide, and several drops of nitric acid were added to the pH of 5 while stirring. This was filtered, washed with water on a funnel, and then the hydroxide was roasted at 950 ° C. to obtain indium oxide. When this indium oxide was analyzed, the chlorine concentration was 5 ppm and the sodium concentration was less than 10 ppm.

Using this indium oxide with reduced chlorine and sodium to produce an ITO sputtering target, the sinterability is improved, the density is easily increased, the generation of defective products is reduced, and the yield is improved. As a result, the quality of the target could be improved.

(Example 2)
In this example, an aqueous sodium hydroxide solution and an indium chloride aqueous solution are simultaneously added to a water bath to generate indium hydroxide, which is roasted to form indium oxide.

<Details of Example 2>
While stirring 2240 ml of pure water, adding an In: 50 g / L In chloride solution at 10 ml / min, adding about 4.5 ml of a 25% aqueous sodium hydroxide solution to bring the pH of the solution to 10 or more. And indium hydroxide was generated. The total amount added was 1100 ml for the indium chloride solution and 158.9 ml for the 25% aqueous sodium hydroxide solution. In the process of adding sodium hydroxide to indium chloride for neutralization, the alkalinity was always maintained, and no adsorption of chlorine on indium hydroxide was observed.

The generated indium hydroxide was filtered, 9 L of pure water was added to the filtered indium hydroxide, and several drops of aqueous ammonia were added to the pH to 8.5 while stirring. This was filtered, 9 L of pure water was added to the filtered indium hydroxide, and several drops of nitric acid were added to the pH of 5 while stirring. This was filtered, washed with water on a funnel, and then the hydroxide was roasted at 950 ° C. to obtain indium oxide. When this indium oxide was analyzed, the chlorine concentration was 4 ppm and the sodium concentration was less than 10 ppm.

Using this indium oxide with reduced chlorine and sodium to produce an ITO sputtering target, the sinterability is improved, the density is easily increased, the generation of defective products is reduced, and the yield is improved. As a result, the quality of the target could be improved.

(Comparative Example 1)
This is an example in which an aqueous solution of sodium hydroxide is added to an indium chloride solution for neutralization to generate indium hydroxide.

<Details of Comparative Example 1>
1100 ml of In: 50 g / L In chloride solution was added to 2240 ml of pure water, and while stirring this, 25% aqueous sodium hydroxide solution was added thereto at 1 ml / min to adjust the pH of the solution to 9.5. . The total amount of 25% aqueous sodium hydroxide solution added was 157.4 ml. In the process of adding and neutralizing indium chloride sodium chloride, it initially showed acidity, and the possibility of adsorption of chlorine on indium hydroxide was high.

The generated indium hydroxide was filtered, 9 L of pure water was added to the filtered indium hydroxide, and several drops of aqueous ammonia were added to the pH to 8.5 while stirring. This was filtered, and 9 L of pure water was added to the filtered indium hydroxide. After stirring and washing, this was filtered and washed on the funnel, and then the hydroxide was roasted at 950 ° C. to obtain indium oxide. . When this was analyzed, the sodium concentration was less than 10 ppm, but the chlorine concentration was 310 ppm.

In addition, the said water washing was washing | cleaning using the liquid amount comparable as Example 1,2. In this way, in the step of adding sodium hydroxide to indium chloride aqueous solution to adjust the pH to 9.5 and making indium hydroxide, chlorine is adsorbed by indium hydroxide, and this is roasted to form indium oxide. It was almost impossible to reduce this. Conversely, sodium is hardly adsorbed because neutralization precipitation is in the acidic region and the hydroxide is positively charged.
When an ITO sputtering target was manufactured using indium oxide containing a high concentration of chlorine, the sinterability was poor, it was difficult to increase the density, the incidence of defective products was increased, and the yield was reduced. .

(Comparative Example 2)
This is an example in which an aqueous solution of indium chloride is neutralized by adding an aqueous solution of sodium hydroxide to generate indium hydroxide, which is washed with a solution of pH 8.5, washed with pure water, and roasted to obtain indium oxide. .

<Details of Comparative Example 2>
To 2240 ml of pure water, 157.4 ml of 25% aqueous sodium hydroxide solution was added to make it alkaline. While stirring, an In: 50 g / L aqueous solution of In chloride was added to this solution at 10 ml / min. Was set to 9.5. In the process of adding sodium hydroxide to indium chloride for neutralization, the alkalinity was always maintained, and no adsorption of chlorine on indium hydroxide was observed.

The generated indium hydroxide was filtered, 9 L of pure water was added to the filtered indium hydroxide, and several drops of aqueous ammonia were added to the pH to 8.5 while stirring. This was filtered, and 9 L of pure water was added to the filtered indium hydroxide. After stirring and washing, this was filtered and washed on the funnel, and then the hydroxide was roasted at 950 ° C. to obtain indium oxide. . When this was analyzed, the chlorine concentration was 5 ppm, but the sodium concentration was 210 ppm.

In addition, the said water washing was washing | cleaning using the liquid amount comparable as Example 1,2. In this way, in the step of adding indium chloride solution to sodium hydroxide aqueous solution to pH 9.5 to make indium hydroxide, it is always alkaline and the surface of indium hydroxide is negatively charged, so sodium ions are adsorbed. When washing is not performed at a low pH during washing, sodium is not removed by washing with water and remains in the hydroxide.
When an ITO sputtering target is manufactured using indium oxide containing sodium at a high concentration, the target film contains sodium at a high concentration, so that the sputtered film is easily deteriorated by oxidation.

In the process of producing indium oxide by neutralizing an indium chloride aqueous solution or an aqueous solution containing a metal salt containing indium chloride as a main component to produce indium oxide, Method of producing indium oxide capable of efficiently removing chlorine and sodium contained therein at low cost, and excellent effect of providing low chlorine and low sodium content indium oxide obtained thereby Have

The indium oxide production method of the present invention does not require repeated washing or other costly means until chlorine and sodium can be removed from the conventional indium hydroxide washing with water, without the need to select water-soluble water. In the stage of producing indium oxide, there is a remarkable effect that low chlorination has already been realized and sodium can be effectively washed.

The indium oxide produced in the present invention is excellent in sinterability, for example, when producing a sintered body target such as an indium-tin oxide (ITO) sputtering target, and the density and yield are improved. Since the sputtered film is hardly deteriorated, the quality of the target can be improved. Thus, an industrially useful invention can be provided that an electronic component material containing indium as a main raw material can be manufactured at high quality and at low cost.

Claims (8)

  A method for producing an indium oxide by neutralizing an aqueous solution containing an indium chloride aqueous solution or a metal salt containing indium chloride as a main component to produce indium hydroxide, and producing the indium oxide, the aqueous solution of sodium hydroxide Indium chloride aqueous solution or an aqueous solution containing a metal salt containing indium chloride as a main component is added to adjust pH to 9 to 10 to generate indium hydroxide, and the generated indium hydroxide is filtered. Disperse in a solution of ~ 9 and stir and wash, filter and collect indium hydroxide, further disperse this in a liquid of pH 4 to 5 and stir and wash, filter the indium hydroxide, and then roast. A method for producing indium oxide. An indium chloride aqueous solution or an aqueous solution containing a metal salt containing indium chloride as a main component is neutralized to form indium hydroxide, which is then baked to produce indium oxide. A sodium oxide aqueous solution and an indium chloride aqueous solution or an aqueous solution containing a metal salt containing indium chloride as a main component are added simultaneously to adjust pH to 9 to 10 to generate indium hydroxide, and the generated indium hydroxide is filtered. This is dispersed in a solution of pH 8-9 and stirred and washed, and indium hydroxide is filtered and recovered. Further, this is dispersed in a solution of pH 4 to 5 and washed with stirring, and the indium hydroxide is separated by filtration. A method for producing indium oxide, characterized by roasting.   The method for producing indium oxide according to claim 1 or 2, wherein the content of indium chloride after roasting is 5 ppm or less.   The method for producing indium oxide according to any one of claims 1 to 3, wherein the sodium content of the indium oxide after roasting is 10 ppm or less.   The method for producing indium oxide according to any one of claims 1 to 4, wherein the indium-containing scrap is dissolved in hydrochloric acid to be used as a raw material for the indium chloride solution.   The method for producing indium oxide according to any one of claims 1 to 5, wherein components other than indium hydroxide are removed after neutralizing the raw material to generate indium hydroxide.   The chlorine content obtained by the manufacturing method of indium oxide as described in any one of Claims 1-6 is 5 ppm or less, The indium oxide characterized by the above-mentioned.   Indium oxide, wherein the sodium content obtained by the method for producing indium oxide according to any one of claims 1 to 7 is 10 ppm or less.