JPH09268334A - Method for recovering indium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recovering method capable of recovering high-purity indium by rapidly leaching the indium with a simple operation at a high yield from indium-contg. agglomerate. SOLUTION: The indium-contg. agglomerate is subjected to a pulverization treatment and the pulverized matter is subjected to a leaching treatment in an acidic aq. soln. in the presence of hydrogen peroxide. An aluminum sheet is immersed into this leaching liquid and sponge indium is deposited on this aluminum sheet by a substitution reaction. The sponge indium is then alkaline cast, by which an indium metal is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering indium, and more specifically, a method for recovering indium capable of recovering indium of high purity by leaching indium from an indium-containing lump in a short time in a high yield. Regarding

[0002]

2. Description of the Related Art Indium is used as a minor component for dental alloys, solders, low melting point alloys, and semiconductors, and is generally used for recovering residues of zinc, lead, etc. from the manufacturing process, such as zinc concentrate. Have been recovered by the method. For example, JP-A-55-158125 and JP-A-58-31049
There are recovery methods described in JP-A No. 63-140047 and JP-A No. 63-140047.

[0003]

However, it has been difficult to leaching and recovering indium from the indium-containing material in a short time with a high yield by the conventionally known recovery method. The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to leach indium from an indium-containing lump in a simple operation in a short time in a high yield, and It is to provide a recovery method capable of recovering high indium.

[0004]

Means for Solving the Problems As a result of various investigations by the present inventors in order to solve the above-mentioned problems, as a result of crushing an indium-containing lump and leaching the crushed product in an acidic aqueous solution, Indium can be leached in a high yield in a short time by adding hydrogen peroxide as a leaching accelerator, and the aluminum plate can be highly leached on the aluminum plate by immersing the aluminum plate in the leaching solution to cause a substitution reaction. The inventors have found that sponge indium having a purity can be deposited, and have reached the present invention.

That is, the indium recovery method of the present invention is
Pulverizing the indium-containing lump, leaching the pulverized product in an acidic aqueous solution in the presence of hydrogen peroxide, immersing an aluminum plate in the leaching solution to deposit sponge indium on the aluminum plate by a substitution reaction, Then, the sponge indium is subjected to alkali melting casting to obtain indium metal.

The indium content of the indium-containing lumps used in the recovery method of the present invention is not particularly limited, but for high-grade ones having an indium content of more than 60% by weight, the wet process as in the present invention is used. It is general to adopt a dry process having good efficiency such as reduction and recovery rather than adoption, and therefore, in the recovery method of the present invention, a product having a relatively low indium content is usually used. Is 60 wt% or less, and in many cases 50 wt% or less is used. Specifically, reduction karam [that is, ITO target scrap pulverized product, ITO, which is generated by regenerating ITO (indium tin oxide)]
Mixing grinding dust, coke and soda ash, and reducing them to obtain crude indium metal (In-Sn alloy), recovery residue in zinc manufacturing process, recovery residue in lead manufacturing process, etc. Can be mentioned.

In the recovery method of the present invention, the indium-containing lump is pulverized. This crushing treatment is carried out by roughly crushing the indium-containing lump with a roll crusher or the like and finely crushing with a roll mill, pin mill, hammer mill, jet mill, ball mill or the like. Regarding the degree of pulverization, when the particle size of the indium-containing material is 5 mm or more, the leaching rate in the acidic aqueous solution per unit time begins to decrease, and when it is 10 mm or more, the tendency becomes more remarkable. The particle size is 10 mm or less, usually 5 mm or less, preferably 1 mm or less.

Incidentally, as the indium content in the indium-containing lump decreases, that is, as the quality decreases, the variation in quality tends to increase between individual indium-containing lumps or in each part of the indium-containing lump. There is. However, by crushing the indium-containing lump, this variation can be eliminated and the leaching rate in the acidic aqueous solution can be increased.

The crushed indium-containing product obtained by the crushing treatment is leached in an acidic aqueous solution in the presence of hydrogen peroxide. Examples of the acid used to form this acidic aqueous solution include inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid and acetic acid, and organic acids. The acid concentration is not particularly limited, but 50 g / l
If it is lower than 500 g / l, the leaching rate and leaching rate tend to decrease, and if it exceeds 500 g / l, the leaching rate and leaching rate tend to be saturated. Therefore, the acid concentration is 50 to 500 g /
It is preferably in the range of 1.

In the recovery method of the present invention, hydrogen peroxide is added to the acidic aqueous solution as a promoter for increasing the leaching rate and the leaching rate of indium. The amount added is not particularly limited, but if it is lower than 5 g / l, the effect as a leaching accelerator tends to decrease, and as the amount of hydrogen peroxide added increases, the leaching rate and leaching rate increase, but 100 g If it exceeds / l, the effect as a leaching accelerator tends to be saturated. Therefore, the amount of hydrogen peroxide added is preferably in the range of 5 to 100 g / l, and in terms of economy, the range of 20 to 60 g / l is the most efficient.

The leaching rate and the leaching rate tend to decrease sharply as the temperature of the acidic aqueous solution during the leaching process becomes lower than 50 ° C. On the other hand, if the temperature becomes too high, there are problems in workability and loss of heat energy. Therefore, the temperature of the acidic aqueous solution when carrying out the leaching treatment is preferably 50 to 90 ° C., and most efficiently 75 to 85 ° C.
It is in the range of ° C. In the recovery method of the present invention, by performing the leaching treatment under the above conditions, the leaching rate of indium in the acidic aqueous solution is 80% by weight or more in 1 hour. The leaching speed can be increased by stirring the leaching process.

When an aluminum plate is dipped in the leaching solution obtained by the leaching process, indium sponge is deposited on the aluminum plate by the substitution reaction. When the pH value of the leachate is lower than 0.5 or higher than 1.5, the substitution reactivity between indium in the leachate and the aluminum plate is lowered, so that the pH of the leachate after the leach treatment is completed. It is preferable to adjust the value within the range of 0.5 to 1.5 by adding an alkaline substance. Examples of such alkaline substances include sodium hydroxide, potassium hydroxide, calcium hydroxide and aqueous ammonia.

The substitution reaction of indium with the aluminum plate in the leachate tends to decrease sharply as the temperature of the leachate drops below 50 ° C., resulting in a decrease in the deposition of sponge indium on the aluminum plate. To do. On the other hand, if the temperature becomes too high, there are problems in workability and loss of heat energy. Therefore, the temperature at which the substitution reaction is carried out is preferably 50 or higher, more preferably 50 to 80 ° C.

Next, the sponge indium obtained as described above is alkali-melt cast to obtain indium metal. Although sponge indium is easily oxidized, oxidation can be prevented by performing alkali melt casting, that is, casting in an alkaline atmosphere. Further, by this alkali melting casting, the oxide film existing on the surface of the sponge indium and the impurities in the sponge indium can be separated and removed. The alkali compound used in this alkali melt casting is not particularly limited, but sodium hydroxide is industrially preferable. The indium metal obtained by this alkali melt casting has an indium quality of 80% by weight or more.

[0015]

【Example】

Example 1 As an indium-containing lump as a starting material, an ITO target scrap pulverized product, ITO grinding waste, coke and soda ash were mixed and reduced to obtain a crude indium metal (I
n-Sn alloy) was used.
The indium grade of this Karami is 36.8% by weight,
The main impurities were as follows (analysis was performed by X-ray qualitative analysis and I
Conducted by CP emission spectroscopy): tin: 4.4% by weight, lead: 2.5% by weight, sodium: 25.7% by weight,
Iron: 5,6% by weight, copper: 3,8% by weight, zinc: 2.6% by weight, the above-mentioned reduced kalami was roughly crushed by a roll crusher and further crushed by a pin mill crusher. All of the obtained pulverized products passed through a 60-mesh sieve. This crushed product 30k
g was added to an acidic aqueous solution containing 900 liters of water, 80 liters of concentrated sulfuric acid and 27 liters of hydrogen peroxide, and stirred. The temperature of the acidic aqueous solution was maintained within the range of 75-85 ° C. The leaching time was 90 minutes. The amount of indium in the leachate obtained by this leaching treatment was 9.7 kg (the yield was 8
7.8%). An aqueous sodium hydroxide solution was added to this leachate to adjust its pH value to 0.7. Width 100 mm, length 700 m in this pH adjusted leachate
An aluminum plate having a thickness of 8 mm and a thickness of 8 mm was dipped, the temperature of the leachate was maintained within the range of 55 to 65 ° C., and the substitution reaction was continued for 18 hours. The indium sponge on the obtained aluminum plate was recovered to remove water and the like. Alkali melt casting was performed using sodium hydroxide, and indium metal was extracted into a mold. The amount of recovered indium metal was 9.9 kg. IC of recovered indium metal
When analyzed by P emission spectroscopy, the indium grade was 92.3% by weight and the yield was 82.7%.

[0016]

By adopting the method for recovering indium of the present invention, it is possible to recover indium of high purity by leaching indium from a lump containing indium in a high yield in a short time by a simple operation.

Claims (7)

[Claims] 1. An indium-containing lump is pulverized, the pulverized product is leached in an acidic aqueous solution in the presence of hydrogen peroxide, an aluminum plate is dipped in the leaching solution, and a sponge is formed on the aluminum plate by a substitution reaction. Deposit indium,
Then, the indium metal is obtained by subjecting the sponge indium to alkali casting to obtain indium metal. 2. A method for recovering indium according to claim 1, wherein the indium content of the indium-containing lump is 60% by weight or less. 3. The method for recovering indium according to claim 1 or 2, wherein the indium-containing lump is a reduced kalami produced in the regeneration treatment of ITO. 4. The method for recovering indium according to claim 1, 2 or 3, wherein the indium-containing lump is pulverized to a particle size of 5 mm or less. 5. The method for recovering indium according to claim 1, 2, 3 or 4, wherein the leaching treatment is carried out under a temperature condition of 50 ° C. or higher. 6. The method for recovering indium according to claim 1, 2, 3, 4, or 5, wherein the substitution reaction is carried out under a temperature condition of 50 ° C. or higher. 7. The method according to claim 1, wherein the substitution reaction is carried out under a condition of pH within a range of 0.5 to 1.5.
The method for recovering indium according to 2, 3, 4, 5 or 6.