KR20160100283A - Method and apparatus for recovering indium and indium alloy - Google Patents

Abstract

The present invention relates to a method of reducing an oxide scrap containing indium, and recovering a metal indium or an indium alloy. The method of the invention comprises: inserting an oxide scrap containing indium into a reducing furnace; reducing the oxide scrap by introducing a reducing gas to a reducing furnace, and heating the same; separating a molten metal of the metal indium or the indium containing alloy obtained by reduction into a lower part of the reducing furnace; and recovering the molten metal using a metal recovery unit. The invention is capable of efficiently recovering the indium or the indium alloy from a scrap containing high-purity indium oxide generated during the manufacturing of an indium-tin oxide (ITO) sputtering target or after being used.

Description

[0001] METHOD AND APPARATUS FOR RECOVERING INDIUM AND INDIUM ALLOY [0002]

The present invention relates to a method and apparatus for recovering an indium-containing oxide scrap (containing an oxide contained in an oxide) and for recovering an indium or indium alloy, and more particularly, to a method for producing an indium-tin oxide (ITO) sputtering target And more particularly, to a method and apparatus for effectively recovering indium or indium alloy from scrap containing indium oxide of high purity occurring after use or after use.

Recently, an indium-tin oxide (ITO) sputtering target has been widely used for a transparent conductive thin film or a gas sensor of a liquid crystal display device. In many cases, a thin film is formed on a substrate or the like using a thin film forming means by a sputtering method.

Though the thin film forming means by this sputtering method is an excellent method, if the transparent conductive thin film is formed by using the sputtering target, for example, the target is not uniformly consumed.

The sputtering operation is continued until the backing plate supporting the target is exposed, although the portion of the target to which the consumption is intensely consumed is generally called all of the sputtering operation. And after that, we are exchanging for a new target.

Therefore, a large number of unused targets, that is, unused target portions, remain in the used sputtering target, and they are all scrapped. Also, at the time of manufacturing the ITO sputtering target, scrap is generated from the abrasive powder and the cutting powder.

Since ITO sputtering target material uses a high purity material and is expensive, in general, indium is recovered from such a scrap material.

As this indium recovery method, a method combining a wet purification such as a conventional acid dissolution method, an ion exchange method, and a solvent extraction method is used.

For example, ITO scrap is cleaned and crushed, dissolved in hydrochloric acid, and hydrogen sulfide is passed through the solution to precipitate and remove impurities such as zinc, tin, lead and copper as sulfides, and then ammonia is added to neutralize , And recovering it as indium hydroxide.

However, the indium hydroxide obtained by this method has a poor filtration property and requires a long time for the operation. The indium hydroxide which is produced in a large amount of impurities such as Si, Al and the like has a particle diameter and a particle size distribution There is a problem that the characteristics of the ITO target can not be stably maintained when the ITO target is manufactured thereafter.

DISCLOSURE OF THE INVENTION In view of the above, the inventors of the present invention have found that, first, a process of dissolving ITO indium-containing scrap with hydrochloric acid to form an indium chloride solution, adding a sodium hydroxide aqueous solution to the indium chloride solution to remove tin contained in the scrap as tin hydroxide, The sponge indium is again dissolved in the solid solution of sodium hydroxide to prepare a crude indium metal. Subsequently, the indium is replaced with zinc, To obtain indium of high purity (see Patent Document 1). According to this, indium of high purity can be efficiently and stably recovered.

However, in the step of recovering indium by the electrolytic refining, it is necessary to cast a metal before the cathode, but there is a problem that oxide-containing cast scrap (cast scrap) floating on the casting metal occurs at this time.

Conventionally, this cast scrap has been problematic in that the cost can not be increased unless the electrolytic refining process such as hydrochloric acid dissolution, pH preparation, zinc reduction, and anodic casting is carried out. In addition, this process has a problem that a large amount of indium metal must be dissolved in order to treat a small amount of nitrous oxide.

In order to solve this problem, in a process of recovering indium from scrap containing indium oxide of high purity occurring during or after the production of an indium-tin oxide (ITO) sputtering target, the casting occurring at the time of casting of metal pre- A method of effectively recovering metal indium from scrap has been proposed (Patent Document 2). However, in this case, there is a problem in that the versatility is insufficient because it is a limited object of the scrap metal containing castings floating on the casting metal.

In addition, the following documents have been disclosed as techniques for improving the purity or recovery of indium. However, there are problems that the process is complicated or the recovery rate is low. Post as a reference.

Patent Document 3 describes a process for producing high purity indium used as a raw material for a compound semiconductor by reducing a positive trivalent indium oxide present in indium and denaturing it to a positive monovalent oxide, And a step of removing impurities remaining at a predetermined temperature.

Patent Document 4 discloses a method for recovering indium from ITO scrap, reducing ITO scrap at 750 to 1200 ° C by a reducing gas to convert it to metal indium, and then electrolytically refining the indium.

Patent Document 5 discloses a process of pulverizing IXO scrap, mixing carbon powder, putting it into a reduction furnace, and heating and reducing it, and discharging zinc out of the system using steam as a method of recovering indium from IXO scrap And the step of electrolytically refining the crude indium obtained in this step is disclosed.

Patent Document 6 discloses a method in which a hydrochloric acid solution containing indium having a hydrochloric acid concentration of 1 to 12 N and an indium concentration of 20 g / ℓ or less is extracted with a solvating-extraction-type extractant, And recovering indium by electrolytic extraction with water, followed by back extraction with an activated carbon to remove oil, electrolysis or neutralization to give hydroxides, reduction with carbon or hydrogen, or dissolution with sulfuric acid, and electrolysis.

In Patent Document 7, tin-containing indium hydroxide is sintered in an atmosphere of an inert gas and a reducing gas, and is treated with an inert gas and / or a reducing gas containing moisture at a temperature of 0 to 100 캜 before being exposed to the atmosphere, A method of obtaining a powder is disclosed.

Patent Document 8 discloses a method for recovering indium from a waste in which a splash condenser for condensing indium in a gaseous state is formed using a plasma furnace.

Prior Art Documents (Patent Literature)

(Patent Document 1) Japanese Laid-Open Patent Publication No. 2002-69544

(Patent Document 2) Japanese Unexamined Patent Application Publication No. 2002-241865

(Patent Document 3) JP-A-63-250428

(Patent Document 4) JP-A-7-145432

(Patent Document 5) Japanese Laid-Open Patent Publication No. 2002-3961

(Patent Document 6) Japanese Laid-Open Patent Publication No. 2002-201026

(Patent Document 7) Japanese Laid-Open Patent Publication No. 2008-50234

(Patent Document 8) JP-A-2009-293065

DISCLOSURE OF THE INVENTION In order to solve the above problems, the present invention provides an indium-containing oxide scrap, particularly an indium-indium-tin oxide (ITO) sputtering target, And also to provide a method for effectively recovering the same. There are cases in which oxides are contained in the oxide scrap, but the oxide scraps described in the present specification include them.

From the above, the present invention provides the following invention.

1) A method for recovering an indium-containing oxide scrap to recover metal indium or indium alloy, comprising the steps of: inserting an oxide scrap containing indium into a reducing furnace, introducing a reducing gas into the reducing furnace, A method for recovering a metal indium or indium alloy according to claim 1, wherein the metal scum is reduced and reduced to separate the molten metal of the metal indium or indium-containing alloy into the lower part of the reduction furnace and recovered in the metal recovery part.

2) The method for recovering a metal indium or indium alloy according to 1) above, wherein the vapor of the acid is withdrawn from the reducing furnace.

3) A method for recovering metal indium or indium alloy according to 2) above, wherein the vapor of the suboxide is introduced into the cooling bath from the side wall of the reduction furnace, and the vapor is recovered by cooling.

4) A method for recovering metal indium or indium alloy according to 2) or 3), wherein the recovered ash is introduced into the reducing furnace and recycled.

5) An apparatus for recovering indium-containing oxide scrap to recover metal indium or indium alloy, comprising: a reducing unit for reducing an oxide scrap containing indium; a metal recovery unit for recovering the reduced metal; And a cooling section for collecting the generated nitrous oxide.

6) An end of a conduit for discharging the vapor of an acid vapor is provided in the reducing furnace, and the other end of the conduit is installed in a cooling tank, and the vapor of the suboxide is introduced into the cooling tank, The metal indium or indium alloy recovering apparatus according to the above 5).

(7) The apparatus for recovering metal indium or indium alloy according to (5) or (6) above, which comprises a device for heating and controlling oxide scrap containing indium in the reduction furnace.

Further, the present invention provides the following inventions from the above problems.

8) A method for reducing indium-containing oxide scraps in a crucible provided in a vessel and recovering indium metal or indium alloy, wherein an oxide scrap containing indium is inserted into the crucible and hydrogen (H ₂ ) Or carbon monoxide (CO), and heating the scrap to reduce the oxide scrap by setting the partial pressure ratio of H ₂ O / H ₂ or CO ₂ / CO to 1 or less Wherein the metal indium or indium alloy is recovered.

9) A method for recovering metal indium or indium alloy as described in 1) above, wherein the yield of metal indium or indium alloy by reduction is 80% or more.

(10) A method for recovering a metal indium or indium alloy according to (8) or (9), wherein the yield of the metal indium or indium alloy by reduction is 90% or more.

The present invention relates to a process for recovering metal indium or indium alloy from indium-containing oxide scrap, especially high-purity indium oxide-containing scrap which occurs during or after the production of an indium-tin oxide (ITO) sputtering target, The indium alloy can be recovered easily and effectively.

The recovered metal indium or indium alloy obtained by this process can be reused as an ITO raw material.

1 is a schematic explanatory view showing an example of a metal indium or indium alloy and an apparatus for recovering these oxides.

Fig. 1 shows an example of an apparatus for recovering metal indium or indium alloy by reducing an oxide scrap containing indium of the present invention.

This apparatus comprises a reducing furnace 1 for reducing indium-containing oxide scrap, a reducing gas introducing tube 2 for introducing hydrogen gas (H ₂ ) or carbon monoxide (CO) into the reducing furnace, a reducing furnace 1, A metal recovery unit 4 disposed below the reduction furnace 1 and a metal recovery unit 4 disposed between the metal recovery unit 4 and the reduction furnace 1, And a metal separator plate (5) disposed at the lower portion.

In the reduction, an oxide scrap 6 containing indium is inserted into the reduction furnace 1. Introducing hydrogen gas or carbon monoxide into the reducing furnace via a reducing gas introducing pipe 2 and heating the scrap 6 to 800 to 1500 ° C. to heat and oxidize the oxide scrap 6, do. In the vessel, it is reduced by reduction gas and dissolved at the same time.

As the reducing gas, in addition to hydrogen and CO gas, a reducing gas such as RX gas may be used. The molten metal indium or indium-containing alloy obtained by reduction is dropped as a liquid in the lower part of the reduction furnace 1 and is recovered as a metal indium or indium alloy molten metal 8 in the metal recovery section 4. [ The molten metal 8 of the metal indium or indium alloy in the reducing furnace 1 can be taken out as it is in the molten state or solidified after the completion of the reduction once (batchwise). In the present invention, the yield of metal indium or indium alloy by reduction can be 90% or more.

When the scrap (6) is heated to 800 to 1500 占 폚 and reduced, a part of the scrap (raw material) is volatilized as the suboxide. According to the present invention, the partial pressure ratio of H ₂ O / H ₂ or H ₂ O / CO is set to 1 or less, whereby volatilization as the suboxide can be suppressed and the yield can be improved. The partial pressure ratio is preferably 0.5 or less.

On the other hand, in order to recover the hydrocarbons, the steam discharging conduit 10 and the other end 11 of the conduit 10, to which the one end 9 is attached to the reducing furnace 1, The submerged vapor is introduced into the cooling tank 12, cooled, and the hydrocarbons can be recovered.

It is preferable that the inside of the steam discharge conduit 10 is maintained at 300 DEG C or more so as to prevent the evaporated suboxide from solidifying. As shown in Fig. 1, the cooling bath 12 is provided separately from the reducing furnace 1 and the metal recovery unit 4. As shown in Fig. A small amount of steam or the like is discharged from the cooling tank (12).

The recovered ash-oxide can be introduced into the reducing furnace after the dried powder is dried. Then, the recovered ashaside powder can be recycled to the reducing furnace 1 together with other scrap. Thus, the recovery rate (yield) can be improved.

In the reducing furnace, when the scrap containing indium is heated, the heating time can be appropriately adjusted depending on the temperature.

The metal indium recovery method described above is characterized in that it can be recovered much more easily and inexpensively than in the prior art.

Example

Next, examples and comparative examples will be described. It should be noted that the present embodiment is for illustrating an example of the invention, and the present invention is not limited to these embodiments. That is, the present invention includes other aspects and modifications included in the technical idea of the present invention.

As an example of the metal indium or indium-containing alloy recovery of the present invention, a process for recovering indium from high purity indium oxide-containing scrap that occurs during or after the production of an indium-tin oxide (ITO) sputtering target will be described.

(Example 1)

Using the apparatus shown in Fig. 1, ITO scrap of 5 kg was reduced in terms of metal. The mixture was reduced to a reduction temperature of 1000 占 폚 and reduced for 10 hours. 4.5 kg of indium tin alloy was obtained in the recovery part. On the other hand, in the cooling bath, 0.4 kg of ash was obtained in terms of the metal.

The yield of the indium tin alloy was calculated from the weighed amount of the nitrous oxide in order to investigate the recovery rate. {(0.4 + 4.5) /5=0.98}.

As a result, the recovery rate is 98%, indicating that the ITO scrap can be reduced to an alloy containing metal indium or indium by a relatively simple process.

(Example 2)

Using the apparatus shown in Fig. 1, ITO scrap of 5 kg was reduced in terms of metal. The mixture was reduced to 900 DEG C for 20 hours. 4.5 kg of indium tin alloy was obtained in the recovery part. On the other hand, in the cooling bath, 0.3 kg of a reduced amount of a metal oxide was obtained.

The yield of the indium tin alloy was calculated from the weighed amount of the suboxide in order to investigate the recovery rate. {(0.3 + 4.5) /5=0.96}.

As a result, the recovery rate is 96%, and it can be seen that the ITO scrap can be reduced to an alloy containing metal indium or indium by a relatively simple process.

(Comparative Example 1)

Although the apparatus shown in Fig. 1 was used, the evaporated ash was discharged without being recovered, and only the metal was recovered. In the same manner as in Example 1, ITO scrap of 5 kg in terms of a metal was reduced to a reduction temperature of 1000 캜 and reduced for 10 hours. 4.5 kg of indium tin alloy was obtained in the recovery part. As described above, there is no recovery of the powder of the suboxide in the water tank.

As a result, the recovery rate was 85%, and the recovery rate was lower than that in the examples.

(Comparative Example 2)

In the same manner as in Example 1, ITO scrap of 5 kg in terms of a metal was added to the reducing furnace, and the temperature was reduced to 1000 deg. C for 10 hours. In this case, a method of reducing the indium tin alloy melt in the reduction furnace without dropping the molten indium tin alloy was adopted.

As a result, the recovered indium tin alloy was 1.5 kg, and the recovery rate was 30%. Compared with the examples, the recovery rate was remarkably reduced. In addition, it was difficult to separate the scrap residues and the reduced indium tin alloy.

(Example 3)

Using the apparatus shown in Fig. 1, ITO scrap of 5 kg in terms of metal was introduced at a rate of 5 L / min and reduced in a hydrogen atmosphere. The mixture was reduced to a reduction temperature of 1000 占 폚 and reduced for 10 hours. 4.4 kg of indium tin alloy was obtained in the recovery part of the crucible. In this case, the partial pressure ratio of H ₂ O / H ₂ was set to 1.0.

By setting the partial pressure ratio of H ₂ O / H ₂ to 1.0, the recovery rate could be 88%. Thus, it can be seen that the ITO scrap can be reduced and recovered with an alloy containing metal indium or indium by a simple process.

(Example 4)

Using the apparatus shown in Fig. 1, 5 kg of ITO scrap in terms of metal was introduced at a rate of 20 l / min and reduced in a carbon monoxide atmosphere. The mixture was reduced to a reduction temperature of 1000 占 폚 and reduced for 10 hours. 4.6 kg of indium tin alloy was obtained in the recovery part of the crucible.

By setting the partial pressure ratio of CO ₂ / CO to 0.05, the recovery rate could be 92%. Thus, it can be seen that the ITO scrap can be reduced and recovered with an alloy containing metal indium or indium by a simple process.

(Comparative Example 3)

Using the apparatus shown in Fig. 1, 5 kg of ITO scrap in terms of metal was introduced at a rate of 2 L / min and reduced in a hydrogen atmosphere. The mixture was reduced to a reduction temperature of 1000 占 폚 and reduced for 10 hours. 3.5 kg of indium tin alloy was obtained in the recovery part of the crucible. In this case, and the partial pressure ratio of H ₂ O / H ₂ to 2. The only change from the embodiment is the partial pressure ratio of H ₂ O / H ₂ .

As a result, when the partial pressure ratio of H ₂ O / H ₂ was set to 2, the recovery rate deteriorated (deteriorated) to 70%. Thus, it can be seen that the partial pressure ratio of H ₂ O / H ₂ greatly affects the number of times.

(Comparative Example 4)

Using the apparatus shown in Fig. 1, 5 kg of ITO scrap in terms of metal was introduced at a rate of 0.5 l / min and reduced in a hydrogen atmosphere. The mixture was reduced to a reduction temperature of 1000 占 폚 and reduced for 10 hours. 2.5 kg of indium tin alloy was obtained in the recovery part of the crucible.

In this case, the partial pressure ratio of H ₂ O / H ₂ was set to 10. The only change from the embodiment is the partial pressure ratio of H ₂ O / H ₂ . As a result, by setting the partial pressure ratio of H ₂ O / H ₂ to 10, the recovery rate was further reduced (deteriorated) to 50%. Thus, it can be seen that the partial pressure ratio of H ₂ O / H ₂ greatly affects the number of times.

(Comparative Example 5)

Using the apparatus shown in Fig. 1, 5 kg of ITO scrap in terms of metal was introduced at a rate of 2 L / min and reduced in a hydrogen atmosphere. The mixture was reduced to a reduction temperature of 1000 占 폚 and reduced for 10 hours. 3.5 kg of indium tin alloy was obtained in the recovery part of the crucible. In this case, the partial pressure ratio of CO ₂ / CO was 2. As a result, when the partial pressure ratio of CO ₂ / CO was set to 2, the recovery rate deteriorated (deteriorated) to 70%. Thus, it can be seen that the partial pressure ratio of CO ₂ / CO has a great influence on the number of times.

(Comparative Example 6)

Using the apparatus shown in Fig. 1, 5 kg of ITO scrap in terms of metal was introduced at a rate of 0.5 l / min and reduced in a hydrogen atmosphere. And the temperature was reduced to 1000 deg. C for 100 hours. 2.5 kg of indium tin alloy was obtained in the recovery part of the crucible. In this case, the partial pressure ratio of CO ₂ / CO was 5.

As a result, when the partial pressure ratio of CO ₂ / CO was 5, the recovery rate was further lowered (deteriorated) to 50%. Thus, it can be seen that the partial pressure ratio of CO ₂ / CO has a great influence on the number of times.

1: reduction furnace
2: reducing gas introduction pipe
3: Heating device
4: Metal recovery unit
5: metal separator plate
6: scrap (raw material)
7: volume
8: Melting of metal indium or indium containing alloy
9: A section of the conduit for the vapor discharge of the suboxide
10: Conduit for the discharge of nitrous oxide
11: the other end of the conduit for discharging the vapor of the nitrous oxide immersed in the cooling bath
12: Cooling tank

Claims (1)

A method for recovering a metal indium or indium alloy, characterized in that it is described in the detailed description of the present invention.

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