KR20130031198A - Method and apparatus for recovering indium and indium alloy - Google Patents

Abstract

PURPOSE: A method and an apparatus for collecting indium or an indium alloy are provided to recycle collected metal indium or indium alloys to a material of indium tin oxide. CONSTITUTION: A method for collecting indium and an indium alloy is as follows: Oxide scraps(6) containing indium are inserted into a reducing furnace(1). While introducing reducing gas to the reducing furnace, the reducing furnace is heated to reduce the oxide scraps. Molten metal of the metal indium or indium-contained alloy is separated from the lower part of the reducing furnace, and is collected to a metal collecting part(4).

Description

METHOD AND APPARATUS FOR RECOVERING INDIUM AND INDIUM ALLOY}

The present invention relates to a method and apparatus for recovering an indium-containing oxide scrap (containing a suboxide contained in an oxide) and recovering indium or an indium alloy, in particular in the production of an indium-tin oxide (ITO) sputtering target. Or a method and apparatus for effectively recovering indium or indium alloy from high purity indium oxide containing scraps generated after use.

In recent years, indium-tin oxide (ITO) sputtering targets are widely used in transparent conductive thin films, gas sensors and the like of liquid crystal displays, but in many cases, thin films are formed on substrates or the like using thin film forming means by sputtering.

Although the thin film formation 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 will not be consumed uniformly.

Although the part where the exhaustion of a part of this target is intense is generally called the whole part of an ear, the consumption of this whole part advances and a sputtering operation is continued until just before the backing plate which supports a target becomes exposed. After that, it is replaced with a new target.

Therefore, many non-erosion parts, ie, unused target parts, remain in the used sputtering target, and these are all scrap. Moreover, also at the time of manufacture of an ITO sputtering target, scrap generate | occur | produces from abrasive powder and cutting powder.

Since a high purity material is used for an ITO sputtering target material, and price is expensive, it is generally performed to collect indium from such a scrap material.

As this indium recovery method, the method which combined wet purification, such as an acid dissolution method, an ion exchange method, and a solvent extraction method, is used conventionally.

For example, after ITO scrap is washed and pulverized, it is dissolved in hydrochloric acid, hydrogen sulfide is passed through the solution, and impurities such as zinc, tin, lead, and copper are precipitated and removed as sulfides, and then neutralized by adding ammonia thereto. And recovery as indium hydroxide.

However, the indium hydroxide obtained by this method is poor in filtration and requires a long time for operation, and there are many impurities such as Si and Al, and the indium hydroxide produced has a particle size or particle size distribution due to polymerization conditions and aging conditions. Since it fluctuates, there exists a problem that the characteristic of an ITO target cannot be stably maintained at the time of manufacturing an ITO target after that.

In this regard, the present inventors firstly dissolve ITO indium-containing scrap with hydrochloric acid to form an indium chloride solution, adding sodium hydroxide aqueous solution to the indium chloride solution, and removing tin contained in the scrap as tin hydroxide, After removing the tin hydroxide, indium was substituted and recovered by zinc from the liquid solution, and the substituted and recovered sponge indium was dissolved together with solid sodium hydroxide to produce a crude indium metal. A method of recovering indium that electrolytically purifies to obtain high purity indium was proposed (see Patent Document 1). According to this, it became possible to collect high purity indium efficiently and stably.

However, in the process of recovering indium by the above-mentioned electrolytic purification, an operation of casting a metal deposited on the cathode is required, but there is a problem that an oxide-containing casting scrap (casting scrap) floating on the cast metal is generated 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. Moreover, this process also had a problem that a large amount of indium metal had to be dissolved in order to treat a small amount of suboxide.

In order to solve this problem, in the process of recovering indium from a high-purity indium oxide-containing scrap generated during the production or after use of an indium-tin oxide (ITO) sputtering target, casting occurs during the casting of metal deposited on the cathode. A method of effectively recovering metal indium from scrap has been proposed (Patent Document 2). However, in this case, since it is a limited object called the suboxide-containing casting scrap which floats on the cast metal, there exists a problem that it is lacking in versatility.

In addition, the following documents are disclosed as a technique for high purity or recovery of indium, but all have a problem of a complicated process or a low recovery rate. Post it for reference.

Patent Literature 3 discloses a method of producing high purity indium used as a raw material for compound semiconductors, the process of reducing the regular trivalent indium oxide present in indium to modify it to a regular monovalent oxide, followed by evaporation of the second heating. Disclosed is a method for purifying indium that consists of a step of removing residual impurities at a temperature.

Patent Document 4 discloses a method of recovering indium from ITO scrap, and after reducing the ITO scrap with a reducing gas at 750 to 1200 ° C to form metal indium, a method of electrolytic purification of indium is disclosed.

Patent Literature 5 discloses a method of recovering indium from an IXO scrap, in which the IXO scrap is pulverized, carbon powder is mixed, put into a reducing furnace, heated and reduced, and zinc is vaporized and discharged out of the system. The collection method of the indium which consists of a process of electrolytically refine | purifying the indium obtained by this process is disclosed.

Patent Literature 6 discloses a hydrochloric acid solution containing indium having an indium concentration of 20 g / L or less with a hydrochloric acid concentration of 1 to 12 N, using a solvating extraction extractant, followed by dilute acid having a pH of 0 to 6. There is disclosed a method of back extraction, which is treated with activated carbon to remove oil, and then electrolytically collected or neutralized to form a hydroxide, followed by reduction with carbon or hydrogen, or dissolution with sulfuric acid and electrolysis to recover indium.

Patent Document 7 discloses that tin-containing indium hydroxide is calcined in an atmosphere of an inert gas and a reducing gas, and treated with an inert gas and / or a reducing gas containing water at a temperature of 0 to 100 ° C. before being exposed to the air, and then subjected to ITO. A method of obtaining the powder is disclosed.

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

Japanese Unexamined Patent Publication No. 2002-69544 Japanese Unexamined Patent Publication No. 2002-241865 Japanese Laid-Open Patent Publication No. 63-250428 Japanese Laid-Open Patent Publication No. 7-145432 Japanese Laid-Open Patent Publication No. 2002-3961 Japanese Laid-Open Patent Publication 2002-201026 Japanese Unexamined Patent Publication No. 2008-50234 Japanese Unexamined Patent Publication No. 2009-293065

In order to solve the above problems, the present invention provides an indium or indium alloy easily from an indium-containing oxide scrap, in particular from a high-purity indium oxide-containing scrap generated during or after the production of an indium-tin oxide (ITO) sputtering target, Moreover, it is providing the method of recovering effectively. In addition, although there exist some cases in which an oxide contains in an oxide scrap, the oxide scrap described in this specification contains these.

From the above, this invention provides the following invention.

1) A method of recovering a metal indium or an indium alloy by reducing an oxide scrap containing indium, by inserting an oxide scrap containing indium into a reduction furnace, heating with introducing a reducing gas into the reduction furnace, A method for recovering a metal indium or indium alloy, wherein the molten metal of indium or an indium-containing alloy obtained by reducing the oxide scrap is reduced to a lower part of a reduction furnace and recovered in a metal recovery unit.

2) A method for recovering the metal indium or indium alloy according to the above 1), wherein the vapor of the suboxide is extracted and recovered from the reduction furnace.

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

4) A method for recovering the metal indium or the indium alloy according to the above 2) or 3), wherein the recovered suboxide is introduced into the reduction furnace to be reduced again.

5) An apparatus for recovering a metal indium or an indium alloy by reducing an oxide scrap containing indium, the apparatus comprising: a reducing part for reducing an oxide scrap containing indium, a metal recovering part for recovering the reduced metal, and a A recovery device for a metal indium or indium alloy, characterized in that the cooling section for collecting the generated suboxide.

6) The end of the conduit for discharging the suboxide vapor is provided in the reduction furnace, and the other end of the conduit is installed in the cooling tank, the vapor of the suboxide is introduced into the cooling tank, cooled and recovered. The recovery apparatus of the metal indium or indium alloy as described in said 5).

7) A recovery apparatus for the metal indium or indium alloy according to the above 5) or 6), which has a device for heating control of an oxide scrap containing indium in the reduction furnace.

Moreover, this invention provides the following invention from the said subject.

8) In a crucible installed in a vessel, an oxide scrap containing indium is reduced and a metal indium or indium alloy is recovered. An oxide scrap containing indium is inserted into the crucible, and hydrogen (H ₂₎ is contained in the crucible. Or a reducing gas composed of carbon monoxide (CO) and heating the scrap, thereby reducing the oxide scrap with a partial pressure ratio of H ₂ O / H ₂ or CO ₂ / CO being 1 or less. A method of recovering a metal indium or indium alloy.

9) The method for recovering the metal indium or indium alloy according to the above 1), wherein the yield of the metal indium or the indium alloy by reduction is 80% or more.

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

The present invention relates to a process for recovering a metal indium or an indium alloy from a high purity indium oxide containing scrap generated during or after the production of an oxide scrap containing indium, particularly an indium-tin oxide (ITO) sputtering target. It has an excellent effect of effectively recovering the indium alloy.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic explanatory drawing which shows an example of the apparatus which collect | recovers a metal indium or an indium alloy and these suboxides.

In FIG. 1, an example of the apparatus which reduces the oxide scrap containing indium of this invention, and collect | recovers a metal indium or an indium alloy is shown.

The apparatus includes a reduction furnace (1) for reducing oxide scrap containing indium, a reduction gas introduction tube (2) for introducing hydrogen gas (H ₂ ) or carbon monoxide (CO) into the reduction furnace (1) Of the reduction furnace 1 between the heating device 3 disposed around the metal recovery unit 4 disposed below the reduction furnace 1, the metal recovery unit 4, and the reduction furnace 1. It has the metal separating plate 5 arrange | positioned at the lower part.

At the time of reduction, the oxide scrap 6 containing indium is inserted into the reduction furnace 1. Hydrogen gas or carbon monoxide is introduced into the reduction furnace via a reducing gas inlet tube 2, the scrap 6 is heated to 800 to 1500 ° C., and the oxide scrap 6 is heated and reduced. do. In the vessel, it is reduced by the reducing gas and simultaneously dissolved.

As the reducing gas, a reducing gas such as RX gas can be used in addition to hydrogen and CO gas. The molten metal of indium or indium containing alloy obtained by the reduction is dripped as a liquid in the lower part of the reduction furnace 1, and it is collect | recovered as the molten metal 8 of the indium or indium alloy in the metal recovery part 4. The molten metal 8 of the metal indium or the indium alloy in the reduction furnace 1 can be taken out as it is, or solidified as a molten metal after completion of one reduction (batch type). In this invention, the yield of a metal indium or an indium alloy by reduction can be made into 90% or more.

When the scrap 6 is heated to 800 to 1500 ° C for reduction, a part of the scrap (raw material) is volatilized as a suboxide. According to the present invention, by setting the partial pressure ratio of H ₂ O / H ₂ or H ₂ O / CO to 1 or less, volatilization as a suboxide can be suppressed, and the yield can be improved. It is preferable that the partial pressure ratio is further 0.5 or less.

On the other hand, in order to recover the suboxide, the condensate 10 for discharging vapor of the suboxide having one end 9 attached to the reduction furnace 1 and the other end 11 of the conduit 10 are cooled by the cooling tank 12. It is immersed and installed under the surface of water, the vapor of a suboxide is introduce | transduced into the cooling tank 12, and it can recover, and this suboxide can be collect | recovered.

The vapor discharge conduit 10 is preferably maintained at 300 ° C or higher so that the evaporated suboxide does not solidify. As shown in FIG. 1, the cooling tank 12 is provided separately from the reduction furnace 1 and the metal recovery part 4. From the cooling tank 12, some steam etc. are discharged | emitted.

The recovered suboxide can be introduced into the reduction furnace after drying the suboxide powder. And the recovered nitrous powder can be re-reduced together with the other scrap in the said reduction furnace (1). Thereby, a recovery rate (yield) can be improved.

When heating the oxide scrap containing indium in a reduction furnace, heating time can be suitably adjusted according to temperature.

The recovery method of the metal indium by the above has the characteristics that it can collect | recover much more easily and inexpensively compared with the past.

Example

Next, an Example and a comparative example are demonstrated. In addition, this Example is for showing an example of invention, This invention is not restrict | limited to these Examples. In other words, it includes other aspects and modifications included in the technical idea of the present invention.

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

(Example 1)

Using the apparatus shown in the said FIG. 1, 5 kg of ITO scraps were reduced in conversion of metal. It was made into reducing temperature of 1000 degreeC and it reduced for 10 hours. 4.5 kg of indium tin alloy was obtained by the recovery part. On the other hand, 0.4 kg of suboxide was obtained in conversion of the metal in the cooling tank.

Usually, after several reductions, the nitrous oxide powder is recovered and reduced together with the scrap. However, in order to investigate the recovery rate, the yield of the indium tin alloy was calculated from the weighed amount of suboxide {(0.4 + 4.5) /5=0.98}.

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

(Example 2)

Using the apparatus shown in the said FIG. 1, 5 kg of ITO scraps were reduced in conversion of metal. It was made into reducing temperature of 900 degreeC, and it reduced for 20 hours. 4.5 kg of indium tin alloy was obtained by the recovery part. On the other hand, 0.3 kg of suboxide powder was obtained in conversion of the metal in the cooling tank.

Usually, after several reductions, the nitrous oxide powder is recovered and reduced together with the scrap. However, in order to investigate the recovery rate, the yield of the indium tin alloy was calculated from the weighed amount of nitrous oxide {(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 metal indium or an alloy containing indium by a relatively simple process.

(Comparative Example 1)

Although the apparatus shown in the said FIG. 1 was used, it discharged without collect | recovering the evaporated suboxide, and only metal was collect | recovered. In the same manner as in Example 1, 5 kg of ITO scrap was converted to metal at a reduction temperature of 1000 ° C., and reduced for 10 hours. 4.5 kg of indium tin alloy was obtained by the recovery part. As described above, there is no recovery of the powder of the suboxide in the bath.

As a result, the recovery was 85%, and the recovery was inferior to that of the example.

(Comparative Example 2)

In the reduction furnace, 5 kg of ITO scraps were put in conversion of metal similarly to Example 1, it was reduced to 1000 degreeC, and it reduced for 10 hours. In this case, the method of reducing in a reducing furnace was employ | adopted without dripping an indium tin alloy molten metal in a collection part.

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

(Example 3)

Using the apparatus shown in FIG. 1, 5 kg of ITO scrap was introduced in terms of metal at a rate of 5 L / min, and reduced in a hydrogen atmosphere. It was made into reducing temperature of 1000 degreeC and it 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%. As described above, it can be seen that the ITO scrap can be reduced and recovered to the metal indium or the alloy containing indium by a simple process.

(Example 4)

Using the apparatus shown in FIG. 1, 5 kg of ITO scrap was introduced in terms of metal at a rate of 20 L / min, and reduced in a carbon monoxide atmosphere. It was made into reducing temperature of 1000 degreeC and it 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%. As described above, it can be seen that the ITO scrap can be reduced and recovered to the metal indium or the alloy containing indium by a simple process.

(Comparative Example 3)

Using the apparatus shown in FIG. 1, 5 kg of ITO scrap was introduced in terms of metal at a rate of 2 L / min, and reduced in a hydrogen atmosphere. It was made into reducing temperature of 1000 degreeC and it reduced for 10 hours. 3.5 kg of an 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 examples is the partial pressure ratio of H ₂ O / H ₂ .

As a result, the recovery rate was reduced (deteriorated) to 70% by setting the partial pressure ratio of H ₂ O / H ₂ to 2. In this way, it can be seen that the partial pressure of H ₂ O / H ₂ ratio gives a significant effect on recovery.

(Comparative Example 4)

Using the apparatus shown in FIG. 1, 5 kg of ITO scrap was introduced at the rate of 0.5 L / min in terms of metal, and reduced in a hydrogen atmosphere. It was made into reducing temperature of 1000 degreeC and it 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 examples 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 was further lowered (deteriorated) to 50%. In this way, it can be seen that the partial pressure of H ₂ O / H ₂ ratio gives a significant effect on recovery.

(Comparative Example 5)

Using the apparatus shown in FIG. 1, 5 kg of ITO scrap was introduced in terms of metal at a rate of 2 L / min, and reduced in a hydrogen atmosphere. It was made into reducing temperature of 1000 degreeC and it reduced for 10 hours. 3.5 kg of an indium tin alloy was obtained in the recovery part of the crucible. In this case, the partial pressure ratio of CO ₂ / CO was set to 2. As a result, the recovery rate was reduced (deteriorated) to 70% by setting the partial pressure ratio of CO ₂ / CO to 2. In this way, it can be seen that the partial pressure ratio of CO ₂ / CO significantly affects the recovery.

(Comparative Example 6)

Using the apparatus shown in FIG. 1, 5 kg of lTO scrap was introduced at the rate of 0.5 L / min in terms of metal, and reduced in a hydrogen atmosphere. It was made into reducing temperature of 1000 degreeC, and it reduced 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 set to 5.

As a result, by setting the partial pressure ratio of CO ₂ / CO to 5, the recovery was further reduced (deteriorated) to 50%. In this way, it can be seen that the partial pressure ratio of CO ₂ / CO significantly affects the recovery.

The present invention relates to a process for recovering a metal indium or an indium alloy from a high purity indium oxide containing scrap generated during or after the production of an oxide scrap containing indium, particularly an indium-tin oxide (ITO) sputtering target. It has the excellent effect that an indium alloy can be collect | recovered simply and effectively. The recovered metal indium or indium alloy obtained by this step can be reused as an ITO raw material.

1: reduction furnace
2: reducing gas introduction pipe
3: heating device
4: metal recovery unit
5: metal separator
6: scrap (raw material)
7: volume
8: molten metal of indium or indium containing alloy
9: one end of the conduit for releasing the vapor of nitrous oxide
10: conduit for vapor emission of nitrous oxide
11: the other end of the conduit for releasing the vapor of nitrous oxide immersed in the cooling tank
12: cooling tank

Claims (10)

A method for recovering an indium-containing oxide scrap and recovering a metal indium or indium alloy, the method comprising: inserting an oxide scrap containing indium into a reducing furnace; introducing a reducing gas into the reducing furnace and heating the oxide scrap; A method for recovering metal indium or indium alloy according to claim 1, wherein the metal indium or indium-containing alloy obtained by reducing and reducing scrap is separated into a lower part of the reduction furnace and recovered in a metal recovery part. The method of claim 1,
And withdrawing vapor of the hydrocarbons from the reducing furnace to recover the metal indium or indium alloy. The method of claim 2,
A method of recovering a metal indium or indium alloy, wherein a vapor of a suboxide is introduced into a cooling tank from a side wall of the reduction furnace, and the steam is cooled and recovered. The method according to claim 2 or 3,
And recovering the recovered metal oxide by introducing the recovered metal oxide into the reduction furnace to recycle the metal indium or indium alloy. An apparatus for reducing an oxide scrap containing indium and recovering a metal indium or an indium alloy, the apparatus comprising: a reducing part for reducing an oxide scrap containing indium, a metal recovering part for recovering a reduced metal, and nitrate generated in the reduction furnace A recovery device for metal indium or indium alloy, characterized by comprising a cooling section for collecting cargo. The method of claim 5, wherein
The metal is characterized in that one end of the conduit for discharging the suboxide vapor is provided in the reduction furnace, the other end of the conduit is installed in the cooling tank, and the vapor of the suboxide is introduced into the cooling tank, cooled and recovered. Recovery device for indium or indium alloy. The method according to claim 5 or 6,
An apparatus for recovering a metal indium or indium alloy, comprising a device for heating and controlling an oxide scrap containing indium in a reduction furnace. In a crucible installed in a container, an oxide scrap containing indium is reduced, and a metal indium or an indium alloy is recovered, and an oxide scrap containing indium is inserted into the crucible, and hydrogen (H ₂ ) or The indium metal is reduced by introducing a reducing gas made of carbon monoxide (CO) and heating the scrap to reduce the oxide scrap with a partial pressure ratio of H ₂ O / H ₂ or CO ₂ / CO of 1 or less. Or a method for recovering the indium alloy. The method of claim 8,
A method for recovering a metal indium or indium alloy, characterized in that the yield of the metal indium or the indium alloy by reduction is 80% or more. 10. The method according to claim 8 or 9,
A method for recovering a metal indium or an indium alloy, wherein the yield of the metal indium or the indium alloy by reduction is 90% or more.

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