JP5623963B2 - Method for producing indium hydroxide - Google Patents

Description

  The present invention relates to a method for producing indium hydroxide from a material containing indium oxide, for example, indium tin oxide (ITO) scrap.

  The ITO target is sputtered onto a glass substrate as a transparent conductive film for liquid crystal display. Generally, only about 20% of the ITO target is used to maintain the performance of the liquid crystal display, and the rest is recovered as ITO scrap. Therefore, recycling ITO scrap is important from the viewpoint of resource protection.

As a composition often used as an ITO target, for example, about 90% of In oxide is Sn and the remaining about 10% is Sn oxide. These two types of oxides are produced from hydroxide by roasting, but the particle size is adjusted by a ball mill or the like after roasting. Generally, Zr or Al is mixed from the ball mill in this process.
These two types of oxides are sintered at a high temperature of 1500 ° C. or higher in order to obtain a high density, and the ITO target is a very hard and fragile material. Therefore, the ITO target is generally bonded to a Cu backing plate by an In wax material. The ITO scrap is thermally peeled from the backing plate and used for recovery, but Cu diffuses from the backing plate into the wax material, and Cu is mixed as an impurity.
Further, since the ITO scrap hardly dissolves in the acid as it is, it is coarsely pulverized by a jaw crusher, a demon tooth crusher or the like, and is pulverized by a ball mill or a vibration mill. For the ball mill, a hard alloy steel or the like, which is generally a hard material, is selected. Impurities such as Fe, Ni, Mn, Cr, Zn, and Ti are mixed in this pulverization process.
Furthermore, since Si is the most abundant element on the earth, it can be mixed from anywhere and there is a risk of mixing from alkaline chemicals.

  Conventionally, ITO scrap is finally manufactured to metal In and is often highly purified. As representative methods, there are JP-A 2000-169991 and JP-A 10-204673.

  Further, Japanese Patent Application Laid-Open No. 8-91838 and Japanese Patent Application Laid-Open No. 2000-128531 disclose techniques for removing impurities by a solvent extraction method.

  Japanese Patent Laid-Open No. 2001-40436 describes a method of removing Zr by adjusting the pH from 2 to 4.

  In JP 2009-91213 A, an alkaline solution is added to a solution containing indium chloride and neutralized to obtain an indium hydroxide suspension, and then indium hydroxide is filtered and washed to obtain a low chlorine grade indium hydroxide. The use of an aqueous ammonia solution as an alkaline solution is described in the production of

JP 2000-169991 A JP-A-10-204673 JP-A-8-91838 JP 2000-128531 A JP 2001-40436 A JP 2009-91213 A

  As described in Japanese Patent Laid-Open No. 2000-169991 and Japanese Patent Laid-Open No. 10-204673, when metal In is used, an acid dissolution step is required again thereafter, and there is a problem that the cost is increased.

  In the case of solvent extraction methods such as those described in JP-A-8-91838 and JP-A-2000-125331, the solvent extract and the eluate are highly dangerous substances, and thus handling is necessary. It is expensive as an extract and elution method.

  According to the method of Japanese Patent Application Laid-Open No. 2001-40436, Zr may be removed, but other cations such as Fe, Ni, Cu, Zn, and Ti are hardly removed.

  The present invention has been made in view of the above circumstances, and the problem is that Fe, Mn, Cr, Zn, Al, Zr, impurities contained in a substance containing indium oxide, for example, ITO scrap, An object of the present invention is to provide a method for producing high-purity indium hydroxide by removing Si, Ti, Cu, Ni and the like.

In one aspect of the present invention, a step (A) of dissolving an indium oxide-containing substance with an acid to form an indium solution,
A step (B) of adding an oxidizing agent to the indium solution to make ORP (silver / silver chloride potential reference) 600-900 mV,
Passing the indium solution added with the oxidizing agent through a strongly acidic cation exchange resin to remove impurity cations (C);
Step (D) of adjusting the pH of the indium solution after passing through a strongly acidic cation exchange resin to 1.5 to 3.0 to produce a precipitate of impurity anions, which is removed by solid-liquid separation ,
A step (E) of obtaining a filtrate of indium hydroxide by producing a precipitate of indium hydroxide by setting the pH of the filtrate after step (D) to 8 or more by alkali addition and solid-liquid separation;
Is a method for producing indium hydroxide.

In one embodiment of the method for producing indium hydroxide according to the present invention, the H ⁺ ion concentration in the indium solution in the step (B) is 0.1 to 2.0 mol / L.

In another embodiment of the method for producing indium hydroxide according to the present invention, in step (B), an oxidizing agent is added to make ORP (silver / silver chloride potential reference) 600-900 mV, and then step (C ), The H ⁺ ion concentration in the indium solution is adjusted to 0.6 to 1.2 mol / L.

  In yet another embodiment of the method for producing indium hydroxide according to the present invention, the step (C) is carried out by setting the SV value (a value obtained by dividing the liquid flow rate by the resin amount) to 3 or less.

  In still another embodiment, the method for producing indium hydroxide according to the present invention further includes a step of washing the indium hydroxide filtrate obtained in step (E) with water.

  In yet another embodiment of the method for producing indium hydroxide according to the present invention, the pH of the washing solution used is increased to more than 10 by adding an alkali at the time of washing, whereby the salt contained in the filtrate of indium hydroxide is added. It further includes a step (F) of removing at least anions.

  In another embodiment of the method for producing indium hydroxide according to the present invention, the acid added in the step (A) is hydrochloric acid, and the indium solution is an indium chloride solution.

  In yet another embodiment of the method for producing indium hydroxide according to the present invention, the substance containing indium oxide is ITO scrap.

  According to the present invention, a substance containing indium oxide, for example, Fe, Mn, Cr, Zn, Al, Zr, Si, Ti, Cu and Ni, which are impurities contained in the ITO scrap, is removed to increase the content. Pure indium hydroxide can be produced. The obtained indium hydroxide can be used again as a raw material for the ITO target.

It is a flowchart which shows an example of the manufacturing method of the indium hydroxide which concerns on this invention.

  The present invention is described in detail below.

<Raw material>
In the present invention, a material containing indium oxide is used as a raw material for indium hydroxide. The substance containing indium oxide is not particularly limited, but typically includes ITO scrap.
The ITO scrap contains, for example, 70 to 95% by mass of oxidized In, 30 to 5% by mass of Sn, and 100 to 1000 ppm by mass of other impurities. Examples of other impurities include Zr, Zn, Fe, Si, Al, Mn, Cr, Ni, Cu, and Ti. Since the ITO scrap hardly dissolves in the acid as it is, it is coarsely pulverized by a crusher such as a jaw crusher and a devil crusher, and is pulverized by a pulverizer such as a ball mill or a vibration mill. Therefore, in a typical embodiment of the present invention, the raw material is provided in powder form, preferably in the form of powder, preferably 5 mmφ under, more preferably 1 mmφ under (passing through a screen having a 1 mm square mesh). .

  As described above, the impurity Zr is often originally contained in ITO, and is generally contained in an amount of 100 to 200 ppm by mass, illustratively about 150 ppm by mass. Cu diffuses from the backing plate into the wax material, and is generally contained in the ITO scrap in an amount of 1 to 10 ppm by mass, typically about 5 ppm by mass. Typically, before the ITO scrap is dissolved with hydrochloric acid, there is a pulverization step, in which Fe, Mn, Cr, Ni, Ti and Zn are mixed. The Fe concentration varies widely, and the smaller the particle size after grinding the ITO scrap, the higher the Fe concentration. At 1 to 3 mmφ, Fe is generally 50 to 200 ppm by mass, illustratively about 100 ppm by mass. Is mixed in the ITO scrap powder. Mn, Cr and Ni are usually 10 mass ppm or less. There is an analysis result that Ti is generally contained in an amount of 50 to 200 ppm by mass, for example, about 100 ppm by mass. There is an analysis result that Zn is generally contained in an amount of 50 to 200 ppm by mass, for example, about 100 ppm by mass. Al is mixed from the ball mill and is generally contained in an amount of 10 to 100 mass ppm, illustratively about 50 mass ppm. Si is generally contained in an amount of 10 to 100 ppm by mass, exemplarily about 50 ppm by mass. However, it is necessary to pay attention to contamination from glass materials and alkali chemicals (particularly caustic soda). In any case, impurities in the pulverized powder of ITO scrap raw materials should be analyzed and grasped before the test in order to set the process conditions for removing them accurately and to keep it below the target impurity concentration. is important.

<Process A>
In the step (A), a substance containing indium oxide as a raw material is dissolved with an acid to form an indium solution. Although there is no restriction | limiting in particular as an acid, A sulfuric acid, nitric acid, hydrochloric acid, etc. are mentioned, Especially hydrochloric acid is preferable. The acid concentration and the liquid temperature can be appropriately adjusted from the viewpoint of the dissolution rate. For example, the pH of the acid aqueous solution is 4 or less, and the liquid temperature is 0 ° C. or more and 100 ° C. or less.

  As an example, a method for dissolving hydrochloric acid in ITO scrap powder is dissolved in 200 to 300 mL of concentrated hydrochloric acid (35.5 wt%), typically 250 mL of acid, with respect to 100 g of finely ground ITO. The temperature is from 80 ° C. to 85 ° C., and the total liquid volume is 300 to 500 mL, typically about 400 mL while supplying evaporated water with pure water. Over 90% of ITO dissolves in about one day.

<Process B>
In the step (B), an oxidant is added to the indium solution after the step (A) to set ORP (silver / silver chloride potential reference) to 600 to 900 mV. Cation exchange in the next step is performed by oxidizing metal impurities such as Fe, Mn, Cr, Zn, Al, Zr, Ti, Cu and Ni by adding an oxidizing agent and adjusting the ORP to the range. It can be changed to a chemical form that is easy to remove with a resin.

  As the indium solution after the step (A), it is possible to use an acid solution in which the raw material remains undissolved, but from the viewpoint of increasing the purity of the target product, the acid solution is used. It is preferable to use a supernatant liquid after allowing to stand and let the raw material undissolved settle, or to use a filtrate after filtering the undissolved raw material in the acid solution.

  The oxidizing agent is not particularly limited, and examples thereof include hydrogen peroxide, ozone, NaClO and the like, and hydrogen peroxide is preferable because it is easy to handle.

  The ORP (oxidation-reduction potential) is adjusted to 600 to 900 mV, preferably 700 to 850 mV, in order to sufficiently oxidize impurities and increase the adsorption efficiency of the cation exchange resin. If the ORP is less than 600 mV, for example, oxidation of the divalent Fe ions (divalent) to trivalent to Fe ions becomes insufficient. When the ORP exceeds 900 mV, for example, Cr ions change from trivalent cations to hexavalent anions and are not adsorbed on the cation exchange resin.

Further, there is a correlation between the H ⁺ ion concentration (free acid concentration or pH) and the ORP, and generally the ORP value decreases as the H ⁺ ion concentration decreases (that is, the pH increases). Since oxidative and H ⁺ ion concentration is lowered is lowered, H ⁺ ion concentration is better high in order to increase the oxidizing power of the oxidizing agent. Specifically, the H ⁺ ion concentration is preferably 0.1 mol / L or more (pH 1 or less) in order to maintain the oxidizing power of the oxidizing agent.
On the other hand, if the H ⁺ ion concentration is too high, a large amount of salt is generated during neutralization in step (D), and a large amount of pure water is required to wash away this salt from indium hydroxide. / L or less (pH ≧ −0.3) is preferable.

The indium solution to which the oxidizing agent has been added then passes through the cation exchange resin. However, if the H ⁺ ion concentration is too high, it is difficult to adsorb on the resin and Fe, Zn, Ti, etc. leak, while H ⁺ ions are also leaked. If the concentration is too low, even In is adsorbed on the cation exchange resin, and the recovery rate of In decreases. In order to suppress leakage of Fe ions or the like and to keep the yield of In high (for example, 95% or more), the H ⁺ ion concentration is preferably 0.6 to 1.2 mol / L in advance, 0.8 -1.0 mol / L is more preferable. When the H ⁺ ion concentration is lower than 0.6 mol / L, the In recovery rate deteriorates rapidly, and when the H ⁺ ion concentration exceeds 1.2 mol / L, Fe ions that are difficult to adsorb on the resin leak. The amount increases.

<Process C>
In the step (C), the indium solution added with the oxidizing agent is passed through a strongly acidic cation exchange resin to remove impurity cations. As described above, it is preferable to adjust the H ⁺ ion concentration before passing the liquid. No particular limitation is imposed on the strongly acidic cation-exchange resins, resins having as the exchange group, for example, a sulfonic acid group (-SO ₃ H).

  The SV value (space velocity = value obtained by dividing the liquid flow rate by the resin volume) is preferably 3 or less, and preferably 2.5 or less from the viewpoint of preventing leakage of Fe ions and the like that are difficult to adsorb on the resin. Is more preferable, typically 0.5 to 2.5.

<Process D>
In step (C), the cation in the indium solution is adsorbed and removed by the cation exchange resin, but Si is not removed. Therefore, a step of adjusting the pH of the indium solution after passing through the strong acid cation exchange resin to 1.5 to 3.0 to produce a precipitate of impurity anions, and removing this by solid-liquid separation ( D) is carried out.

  When carrying out this process, it is desirable to measure up the In concentration beforehand with pure water so that the In concentration is 5 to 30 g / L, preferably 10 to 20 g / L (for example, 15 g / L). When the In concentration exceeds 30 g / L, the recovery rate of In deteriorates, so care must be taken.

  Next, the pH of the indium solution is adjusted to 1.5 to 3.0 with an alkaline chemical, and anions of impurity metals such as Si are removed by Sn coprecipitation. The pH is preferably 2.0 to 2.5. When pH is less than 1.5, since Si does not precipitate, Si cannot be removed. When the pH exceeds 3.0, In begins to precipitate, and the recovery rate of In deteriorates.

<Process E>
In the step (E), the pH of the filtrate after the step (D) is neutralized by adding an alkali to produce a precipitate of indium hydroxide at a pH of 7 or higher, and solid-liquid separation is performed, whereby the indium hydroxide filtrate is obtained. Get.

  The alkali that can be used is not particularly limited, and examples thereof include caustic soda, aqueous ammonia, calcium hydroxide, and magnesium hydroxide. Caustic soda and aqueous ammonia are preferable because they are easily removed during washing with water.

  The reason why the pH is 7 or more is that if it is less than this, the precipitation property of indium hydroxide is poor and the filterability is deteriorated. On the other hand, depending on the type of alkali used for neutralization, as shown below, the optimum pH range during neutralization varies in order to remove the salt produced by the neutralization reaction in advance when it is filtered.

  In this step, since a large amount of salt is produced by the neutralization reaction, the salt component also adheres to the filtrate of indium hydroxide after solid-liquid separation. Therefore, in order to increase the purity of indium hydroxide, it is preferable to remove it. As a method for removing the salt, washing with water is common, and typically, repulping with water can be performed. The removal efficiency can be increased by adjusting the pH of the washing solution during washing with water. The pH at this time varies depending on the alkali used, and is specifically shown below.

When the alkaline chemical is caustic soda, the residue produced by neutralization contains a large amount of NaCl.
In order to remove NaCl from In hydroxide in the residue, the neutralization pH is first set to 7 to 9, preferably 7.5 to 8.5. When pH is less than 7, sedimentation property and filterability deteriorate as already stated. On the other hand, when the pH is 9 or more, Na is difficult to remove. Next, repulp water washing is performed at least twice with pure water. In this water washing, when the repulp liquid becomes pH 7 or less, the pH is returned to 8 ± 0.5 with aqueous ammonia.
Na ion is first removed from In hydroxide by this repulp water washing method.
Next, the pH of the repulp liquid is more than 10, preferably more than 10 and 11 or less at the third or fourth repulse washing. When the pH is 10 or less, Cl is not removed, and when the pH is more than 11, a large amount of aqueous ammonia is required. In this water washing, when the repulp liquid becomes pH 9.5 or less, the pH is adjusted to more than 10 with ammonia water, and the repulp water washing is repeated.
When the cloudiness disappears due to the silver nitrate check, the repulp washing is terminated.
Through the above steps, Cl is removed from In hydroxide.

When the alkaline chemical is aqueous ammonia, the residue produced by neutralization contains a large amount of NH ₄ Cl.
Because NH ₄ Cl in NH ₄ ions are removed in the step of oxidizing after the indium hydroxide, describes a method of removing only Cl below.
In order to remove Cl from In hydroxide in the porridge, the neutralization pH is first set to more than 10, preferably more than 10 and 10.5 or less. If the pH is 10 or less, Cl is difficult to remove, and if it exceeds 10.5, a large amount of ammonia water is required.
Subsequently, repulp water washing is performed, and in this water washing, when the repulp liquid becomes pH 8 or less, the pH is returned to 9 to 9.5 with aqueous ammonia.
The repulp washing is repeated, and when the white nitrate disappears by the silver nitrate check, the repulp washing is finished.

A method for reducing the amount of ammonia water added will be described below.
When the neutralization pH is 10 or more, a large amount of ammonium chloride is contained in the neutralization solution, and thus a large amount of aqueous ammonia is required to raise the pH.
Therefore, the neutralization pH is first adjusted to 8 to 9, and repulp washing is performed about 2 or 3 times.
When the repulp solution becomes pH 8 or less, the pH is returned to 9 ± 0.5 with ammonia water.
Thereafter, when the number of washings with repulp water is 2 or 3, the pH of the repulp liquid is more than 10, preferably more than 10 and 11 or less. When pH is 10 or less, Cl is difficult to remove, and when it exceeds pH 11, a large amount of aqueous ammonia is required.
Thereafter, when the repulp liquid becomes pH 9.5 or less, the pH is adjusted to more than 10 with ammonia water, and the repulp water washing is repeated.
When the cloudiness disappears due to the silver nitrate check, the repulp washing is terminated.
Through the above steps, Cl can be removed from the hydroxide In.

  The allowable amount of impurities contained in indium hydroxide is 5 ppm or less for Fe, Mn, Cr, Zn, Al, Zr, Ti, Cu, Ni, 10 ppm or less for Na and Si, and 5 ppm or less for Cl. Thus, indium hydroxide suitable for the allowable amount as a raw material of the ITO target to be marketed can be obtained.

  The purified indium hydroxide obtained as described above becomes In oxidized oxide by being treated in a roasting furnace at 700 to 1000 ° C. for 7 to 10 hours, and can be used as an ITO raw material.

  Examples of the present invention will be described below together with comparative examples, but these examples are provided for better understanding of the present invention and its advantages, and are not intended to limit the invention.

<Example 1>
(Hydrochloric acid dissolution: Step A)
The ITO scrap was mechanically pulverized to a particle size under 1 mmφ. The pulverization was performed by roughly pulverizing with a juicy crusher or a demon crusher and then finely pulverizing with a ball mill or a vibration mill. Next, 100 g of ITO scrap powder was dissolved in 250 mL of concentrated hydrochloric acid (35.5 wt%). The temperature was 80 ° C. to 85 ° C., and the total liquid volume was about 400 mL while supplying pure water with pure water. By vigorous stirring, 95% of ITO scrap powder was dissolved in about one day.

  Here, in order to analyze the impurity concentration, 86 mL of a hydrochloric acid solution was collected and made up to 1,000 mL with pure water. At this time, the In concentration was 15 g / L, and the hydrogen ion concentration was 0.15 mol / L. Next, the solution was neutralized to pH 8 with alkaline chemicals (caustic soda) to precipitate hydroxide, washed with filtered water, and dried. The obtained hydroxide was dissolved in aqua regia and analyzed by ICP. The analysis results (mass% or mass ppm) are shown in Table 1 (# 1).

(Oxidizing agent addition: Step B)
On the other hand, 86 mL of the supernatant (indium solution) was collected after allowing the hydrochloric acid solution to stand for the impurity removal test to settle the undissolved residue of the ITO scrap, and 2 mL of 36 wt% hydrogen peroxide was added thereto. did. The ORP (silver / silver chloride potential reference) before the addition of the hydrogen peroxide solution was about 300 mV, but after the addition of 2 mL of the hydrogen peroxide solution, the ORP increased to about 800 mV. The H ⁺ ion concentration before the addition of the hydrogen peroxide solution was 1.77 mol / L.
The color of the liquid changed from colorless and transparent to brown. The indium solution added with the hydrogen peroxide solution was made up to 186 mL with pure water. At this time, the In concentration in the indium solution was 80 g / L, and the H ⁺ ion concentration (free hydrochloric acid concentration) was 0.8 mol / L.

(Liquid flow through cation exchange resin: Process C)
This solution was passed through a strongly acidic cation exchange resin tower (Mitsubishi Chemical Diaion SKIB, 200 mL) at SV2.5. In order to push out the hydrochloric acid solution remaining in the cation exchange resin tower, 200 mL of 0.1 mol / L hydrochloric acid was used. Thereafter, the volume was increased to 1,000 mL with pure water. The In concentration in the indium solution after passing through the cation exchange resin tower was 15 g / L, and the H ⁺ ion concentration (= free hydrochloric acid concentration) was 0.15 mol / L.

(PH adjustment: Process D)
Next, the pH of the indium solution was adjusted to 2.5 with alkaline chemicals, and Si was precipitated by Sn coprecipitation. The starch contained Sn and Si and was removed by filtration. The filtered solution contained almost no impurities.

(Indium hydroxide precipitation filtration: Step E)
Next, the solution was neutralized with an alkaline chemical (ammonia water) to adjust the pH to 10 to obtain a precipitate of indium hydroxide.
It was filtered off and the filtrate was washed with repulp water to remove the salt produced during neutralization from indium hydroxide.

(Removal of halide ions: Step F)
When the alkaline chemical is aqueous ammonia, the residue produced by neutralization contains a large amount of NH ₄ Cl. When the repulped water is washed with water and repulped to pH 8 or less, the pH is returned to 9 to 9.5 with aqueous ammonia, and in the latter half of the water washing, the pH is increased from 10 to 11 or less. Then, the repulp water washing was repeated. The repulp water washing was completed when the cloudiness disappeared due to the silver nitrate check. The number of repulp water washing was 6 times. The analytical value (mass% or mass ppm) of the hydroxide is shown in Table 1 (# 2). From the analysis value of # 2 in Table 1, it was found that indium hydroxide having a purity that can be used as a raw material for an ITO target that is generally marketed is obtained.

<Comparative Example 1>
Here, a comparative example in which both the addition of the hydrogen peroxide solution and the treatment of the cation exchange resin in Example 1 are omitted will be described.

  The ITO scrap was mechanically pulverized to a particle size under 1 mmφ. The pulverization was performed by roughly pulverizing with a juicy crusher or a demon crusher and then finely pulverizing with a ball mill or a vibration mill. Next, 100 g of ITO scrap powder was dissolved in 250 mL of concentrated hydrochloric acid (35.5 wt%). The temperature was 80 ° C. to 85 ° C., and the total liquid volume was about 400 mL while supplying pure water with pure water. By vigorous stirring, 95% of ITO scrap powder was dissolved in about one day.

  Here, in order to analyze the impurity concentration, 86 mL of a hydrochloric acid solution was collected and made up to 1,000 mL with pure water. At this time, the In concentration was 15 g / L, and the free hydrochloric acid concentration was 0.15 mol / L. Next, the solution was neutralized to pH 8 with an alkali chemical (for example, caustic soda) to precipitate a hydroxide, washed with filtered water, and dried. The obtained hydroxide was dissolved in aqua regia and analyzed by ICP. The analysis results (mass% or mass ppm) are shown in Table 2 (# 1).

  Next, 86 mL of the supernatant was collected after allowing the hydrochloric acid solution to stand for the impurity removal test to settle the ITO scrap, and then made up to 1,000 mL with pure water. At this time, the In concentration was 15 g / L, and the free hydrochloric acid concentration was 0.15 mol / L. Thereafter, the pH of the hydrochloric acid solution was adjusted to 2.5 with an alkaline chemical (caustic soda) and filtered. The filtered solution was neutralized with alkaline chemicals (caustic soda) to pH 8 to obtain indium hydroxide precipitate. It was filtered off and the salt formed during neutralization was removed from indium hydroxide by washing the filtrate with repulp water. The analytical value (mass% or mass ppm) of the hydroxide is shown in Table 2 (# 2). The number of repulp water washing was 6 times. Comparing Table 1 and Table 2, it can be seen that there is a large difference in the impurity removal rate.

Claims (8)

A step of dissolving a substance containing indium oxide with an acid to form an indium solution (A),
A step (B) of adding an oxidizing agent to the indium solution to make ORP (silver / silver chloride potential reference) 600-900 mV,
Passing the indium solution added with the oxidizing agent through a strongly acidic cation exchange resin to remove impurity cations (C);
Step (D) of adjusting the pH of the indium solution after passing through a strongly acidic cation exchange resin to 1.5 to 3.0 to produce a precipitate of impurity anions, which is removed by solid-liquid separation ,
A step (E) of obtaining a filtrate of indium hydroxide by producing a precipitate of indium hydroxide by setting the pH of the filtrate after step (D) to 8 or more by alkali addition and solid-liquid separation;
A method for producing indium hydroxide, comprising: The method for producing indium hydroxide according to claim 1, wherein the H ⁺ ion concentration in the indium solution in the step (B) is 0.1 to 2.0 mol / L. In step (B), an oxidizing agent is added to make ORP (silver / silver chloride potential reference) 600-900 mV, and then before step (C), the H ⁺ ion concentration in the indium solution is 0.6- The manufacturing method of indium hydroxide of Claim 1 or 2 adjusted to 1.2 mol / L.   A process (C) is a manufacturing method of the indium hydroxide as described in any one of Claims 1-3 implemented by making SV value (value which divided the amount of liquid flow by the amount of resin) into 3 or less.   The method for producing indium hydroxide according to any one of claims 1 to 4, further comprising a step of washing the filtrate of indium hydroxide obtained in the step (E) with water.   6. The method according to claim 5, further comprising the step (F) of removing at least anions of the salt contained in the filtrate of indium hydroxide by making the pH of the washing solution to be used more than 10 by adding an alkali during washing with water. A method for producing indium hydroxide.   The method for producing indium hydroxide according to any one of claims 1 to 6, wherein the acid added in the step (A) is hydrochloric acid and the indium solution is an indium chloride solution.   The manufacturing method according to claim 1, wherein the substance containing indium oxide is ITO scrap.

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