JP2007056366A - Method for recovering indium from blast particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for recovering indium where indium is separated from tin, so as to be efficiently recovered from blast particles used for cleaning ITO films or the like. <P>SOLUTION: The method for recovering metal indium from blast particles is characterized by the steps of: indium-containing blast particles are dissolved in hydrochloric acid and/or sulfuric acid to leach indium (a dissolution stage); next, alumina and/or silica as the main component of the blast particles is filtered away as dissolution residue (a filtering stage); a metal baser than indium is added to the filtrate, so as to reduce/precipitate indium in the solution (an indium reduction/precipitation stage); and spongy metal indium is recovered, regarding the blast particles comprising tin and nickel together with indium. After the dissolution-filtering stages, zinc powder or indium is added to the filtrate, and tin and nickel are reduced/precipitated, so as to be filtered away (a tin removal stage), and, if required, the removal of nickel is further performed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a method for recovering indium from blast particles, and more particularly to a method for recovering indium that can be efficiently recovered by separating indium from aluminum or the like from blast particles used for ITO film cleaning or the like.

After ITO sputtering is performed, blasting is performed for a while in order to remove the ITO film attached to the used apparatus and the surroundings. The blast particles used for the removal of the ITO film have ITO components indium and tin attached thereto. In particular, since indium is more expensive than general metals, it is required to collect and reuse it as much as possible.

Conventionally, a technique for recovering indium from ITO scrap is known. For example, ITO scrap is mixed with nitric acid to dissolve indium oxide, while insoluble nitric oxide in nitric acid is separated as a residual residue. After the tin is separated, the indium nitric acid solution is subjected to cation exchange. A method of extracting indium by bringing it into contact with an extraction solvent of a mold (Patent Document 1), or by passing hydrogen sulfide through an indium nitrate solution to precipitate and remove impurities such as zinc, tin, lead, and copper as sulfides. A method of adding ammonia to neutralize and recover as indium hydroxide is known.

However, in the method of dissolving ITO scrap in nitric acid and separating tin as insoluble metastannic acid, separation of nickel becomes a problem when nickel or the like coexists with tin. In addition, the method of extracting indium using an organic extraction solvent has a problem that the cost is high and the extraction effect is affected by the presence of other coexisting metal ions. Furthermore, the method of separating and recovering indium from the indium nitric acid solution by hydroxide precipitation does not provide good separation of zinc and tin.

On the other hand, a method is also known in which ITO scrap is dissolved in hydrochloric acid, sodium hydroxide is added to the solution to form a tin hydroxide precipitate, which is filtered and separated from indium (Patent Documents 2 and 3). ). However, this method takes time for the separation operation because the filterability of tin hydroxide is not good. Further, there is a problem that the water content of tin hydroxide is large and indium is lost along with the attached moisture.

Further, any of the conventional recovery methods described above is a method of recovering indium from ITO slap, and does not recover indium from used blast particles. The blast particles are mainly composed of alumina or silica, and it is necessary to efficiently separate them from indium.
JP 2000-128531 A JP 2002-69544 A JP 2002-201025 A

The present invention solves the above-described problems in the conventional method, and provides a method for efficiently recovering indium from used blast particles. According to the present invention, alumina as a main component of blast particles is provided. And silica can be efficiently separated from indium, and metal indium can be easily recovered with good separability with respect to tin and nickel contained together with indium.

According to the present invention, the following indium recovery method is provided.
(1) Indium-containing blast particles are dissolved in hydrochloric acid and / or sulfuric acid to leach indium (dissolution step), and then alumina and / or silica, which are the main components of the blast particles, are filtered and separated as a dissolution residue (filtering) Process), adding inferior metal to indium to the filtrate to reduce and deposit indium in the liquid (indium reduction deposition process), and recover indium from blast particles characterized by recovering sponge-like metal indium how to.
(2) In the method of (1), the blast particles containing indium are the blast particles used for removing the ITO film, and this is dissolved in hydrochloric acid and / or sulfuric acid to leach indium (dissolution step), The dissolved residue is separated by filtration (filtering step), and zinc powder or indium is added to the filtrate to reduce and precipitate tin (filtering step). Then, zinc is further added to the tin-free filtrate to add indium. A method for recovering sponge metal indium by reducing and precipitating (indium reduction deposition step).
(3) In the above method (2), blast particles containing tin and nickel together with indium are dissolved in hydrochloric acid and / or sulfuric acid to leach indium (filtering step), and then the dissolved residue is separated by filtration (filtering step) ), Zinc powder or indium is added to the filtrate to reduce and precipitate tin and nickel, and then filtered and separated (tin removal process), and a nickel-containing starch is produced by adding a nickel removal agent to the filtrate and filtered. Separating (nickel removal step), adding zinc to the filtrate to reduce and deposit indium (indium reduction deposition step), and recovering sponge-like metal indium.

In the recovery method of the present invention, indium-containing blast particles are dissolved in hydrochloric acid or sulfuric acid or a mixed acid thereof, and alumina or silica, which is the main component of the blast particles, is first separated as a dissolved residue, so that indium can be efficiently recovered. Can do.

In addition, the recovery method of the present invention has good separability between indium and tin, and even when nickel coexists with tin, nickel is precipitated together with tin and separated, so that indium can be easily recovered from blast particles. Can do. Furthermore, since the method of the present invention recovers spongy metallic indium, the recovery process is simple and indium can be recovered at low cost.

In the method for recovering indium according to the present invention, blast particles containing indium are dissolved in hydrochloric acid and / or sulfuric acid to leach indium (dissolution step), and then alumina and / or silica which are the main components of the blast particles are used as dissolution residues. Blasting characterized by filtering and separating (filtering step), adding a base metal lower than indium to the filtrate to reduce and deposit indium in the solution (indium reducing and depositing step), and recovering sponge-like metal indium This is a method for recovering indium from particles. The indium recovery method of the present invention is shown in FIG.

In the recovery method of the present invention, the blast particles containing indium are, for example, blast particles used for removing the ITO film. Indium and tin as ITO film components adhere to the blast particles, and steel components such as iron, nickel, and chromium as components of the sputtering apparatus may adhere.

As shown in the figure, the blast particles are dissolved in hydrochloric acid and / or sulfuric acid to leach out indium and tin as ITO components contained in the blast particles (dissolution step). Moreover, when iron, chromium, and nickel are contained in the blast particles, these are also leached together with indium and tin. On the other hand, alumina and silica, which are the main components of the blast particles, do not dissolve and become a residue.

If nitric acid is used instead of hydrochloric acid or sulfuric acid, tin reacts with nitric acid to produce an insoluble metastannic acid precipitate, which is not preferred because the filterability is not good. The concentration of hydrochloric acid or sulfuric acid is suitably 2 mol / L or higher for hydrochloric acid and 100 g / L or higher for sulfuric acid, and the liquid temperature is 50 ° C. or higher, preferably 70 ° C. or higher.

The leaching solution is filtered to separate dissolved residues of alumina and silica from the filtrate (filtration step). Next, the pH of the filtrate is adjusted to 0 to 2, and a metal lower than tin, such as zinc powder, is added to the filtrate to reduce tin in the liquid to metal, thereby producing a metal tin starch. On the other hand, since indium is not reduced and remains in the liquid, it is filtered to separate a tin-containing starch, thereby obtaining a tin removal filtrate (tin removal step).

When nickel is contained in the blast particle together with tin, a part of nickel together with tin is reduced to metal in the detinning step to produce a starch containing tin and nickel. The tin-nickel-containing starch is separated by filtration. In this tin removal step, the amount of zinc powder added is preferably equivalent to the tin and nickel content in the liquid. The atmosphere in which zinc powder is added is more preferably an inert atmosphere than in the air.

To further remove nickel from the tin removal filtrate, a nickel-containing starch is produced by adding a nickel removal agent to the tin removal filtrate, and the nickel removal proceeds by solid-liquid separation of the starch (denicking step). ). For example, dimethylglyoxime may be used as the nickel removal agent. When the pH of the tin-free filtrate is adjusted to 1 to 3.5 and dimethylglyoxime is added, nickel ions remaining in the liquid react with dimethylglyoxime to form a chelate complex compound, and the nickel-containing starch is formed. Since it is formed, it can be filtered and removed to remove nickel ions in the liquid.

A metal that is lower than indium, such as zinc, is added to the above tin-free or tin-free nickel filtrate to reduce indium, thereby depositing sponge-like metal indium (indium reduction step). This is separated by filtration and recovered. The pH at the time of indium reduction is not particularly limited as long as it is below the region where indium hydroxide precipitate is generated, but it is preferably maintained at pH 1 to 3 from the viewpoint of zinc consumption.

Examples of the present invention are shown below. The results are shown in Table 1.
[Example A1]
200 g of blast particles (alumina 75 wt%) used for removing the ITO film were mixed with 1 L of hydrochloric acid (concentration 2 mol / L) and dissolved by heating to 60 ° C. This hydrochloric acid solution was filtered to separate 160 g of the dissolution residue. This residue was 94 wt% alumina. On the other hand, the pH of the filtrate was adjusted to 1.0, zinc powder was added in an air atmosphere, and 5.1 g of the produced starch was separated by filtration. The starch was 70 wt% tin and 20 wt% nickel. The pH of the filtrate from which the nickel tin-containing starch was separated was adjusted to 1 to 3.5, and 1.2 g of the starch produced by adding dimethylglyoxime was separated by filtration. This starch was 20 wt% nickel. Zinc powder was added to the filtrate from which the nickel starch had been separated, and 35 g of the spongy metal indium deposited was recovered. The contents of tin and nickel in the metal indium were 30 ppm and 50 ppm, respectively.

[Examples A2 to A4]
Indium metal was obtained in the same manner as in Example A1, except that the dissolution conditions were adjusted as shown in Table 1. The results are shown in Table 1.

[Test No. B1-No. B2]
Indium metal was obtained in the same manner as in Example A1, except that the dissolution conditions and the treatment steps were changed as shown in Table 1. The results are shown in Table 1.

[Example C1]
250 g of silica particles (main component silica) used for removing the ITO film were mixed with 1 L of hydrochloric acid (concentration 2 mol / L) and dissolved by heating to 60 ° C. This hydrochloric acid solution was filtered to separate 210 g of the dissolution residue. This residue was 94 wt% silica. On the other hand, the pH of the filtrate was adjusted to 1.0, zinc powder was added in an air atmosphere, and 5.0 g of the produced starch was separated by filtration. The starch was 70 wt% tin and 20 wt% nickel. The pH of the filtrate from which the nickel tin-containing starch was separated was adjusted to 1 to 3.5, and 1.3 g of the starch produced by adding dimethylglyoxime was separated by filtration. This starch was 20 wt% nickel. Zinc powder was added to the filtrate from which the nickel starch had been separated, and 35 g of the spongy metal indium deposited was recovered. The contents of tin and nickel in the metal indium were 25 ppm and 45 ppm, respectively.

[Examples C2 to C3]
Indium metal was obtained in the same manner as in Example A1, except that the dissolution conditions were adjusted as shown in Table 1. The results are shown in Table 1.

As shown in Table 1, A1 to A4 and B1 to B2 all use the same blast powder, but No.B1 and No.B2 whose solution temperatures are 20 ° C and 40 ° C are dissolved. The In concentration in the liquid is lower than that of No. A1 to No. A4 where the temperature is high. On the other hand, in No. A1 to No. A4, the In concentration in the liquid is 34 g / L or more, and the indium concentration of the solution is high.

Sample No. B1 is obtained by omitting the tin removal step with zinc powder, and the Sn content in the final In sponge is 11.4%, which is extremely high. In addition, since the solubility of dimethylglyoxime in an alcohol solution is low in the nickel removal step, it is necessary to add a large amount of alcohol solution, and since tin removal is not performed, the pH in the nickel removal step is set to 3.5. Since it is difficult to raise to the extent, the Ni concentration in the In sponge is also increased.

Sample No. B2 is obtained by omitting the nickel removal step after the tin removal step. Since nickel is removed together with tin by the tin removal step, the Ni content in the In sponge is higher than that of sample No. B1. Although it is low and about 0.5%, it is higher than Sample Nos. A1 to A4 subjected to the nickel removal step.

Process drawing which shows the outline of the collection | recovery method of this invention

Claims (3)

Indium-containing blast particles are dissolved in hydrochloric acid and / or sulfuric acid to leach indium (dissolution step), and then alumina and / or silica, which are the main components of the blast particles, are filtered and separated as a dissolution residue (filtration step). A method for recovering indium from blast particles, comprising adding a metal lower than indium to the filtrate to reduce and deposit indium in the solution (indium reduction deposition step), and recovering sponge-like metal indium.
2. The method according to claim 1, wherein the blast particles containing indium are blast particles used for removing the ITO film, and the blast particles are dissolved in hydrochloric acid and / or sulfuric acid to leach indium (dissolution step), and then the dissolution residue is filtered. Separate (filtering step), and add zinc powder or indium to the filtrate to reduce and precipitate tin, and filter and separate (tin removal step). Add zinc to the detinned filtrate to reduce and deposit indium. (Indium reduction deposition step), a method of recovering sponge-like metal indium.
3. The method according to claim 2, wherein blast particles containing tin and nickel together with indium are dissolved in hydrochloric acid and / or sulfuric acid to leach indium (filtering step), and then the dissolved residue is separated by filtration (filtering step). Zinc powder or indium is added to the solution to reduce and precipitate tin and nickel (tin removal process), and a nickel removal agent is further added to the filtrate to form a nickel-containing starch, which is separated by filtration (denitration). Nickel step), adding zinc to the filtrate to reduce and deposit indium (indium reduction deposition step), and recovering sponge-like metal indium.

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