JP5694842B2 - Method for concentrating blasted product containing indium oxide compound - Google Patents

Description

  The present invention relates to a method for efficiently recovering an indium oxide compound. More specifically, the present invention relates to a method for efficiently recovering indium which is a rare metal by concentrating a blast-treated product containing an indium oxide-based compound (increasing the ratio of the indium oxide-based compound in the blast-treated product).

In recent years, digital home appliances such as FPD (Flat Panel Display; liquid crystal panel, plasma display panel, etc.) are rapidly spreading. A transparent conductive film (generally containing ITO which is an indium oxide compound) is applied on a substrate (such as a glass substrate) essential as a device component of these products.
Transparent due to the rapid growth in demand for FPD and the fact that many rare metals such as indium are unevenly distributed, especially in China, and the trend toward export restrictions is increasing. The price of rare metals used for electrodes is rising.

The ITO film is usually formed as a thin film on a glass substrate by sputtering using an ITO target in a vacuum chamber of a PVD (Physical Vapor Deposition) apparatus.
When the thin film is formed, ITO molecules vaporized in the chamber in the PVD apparatus are scattered and attached to the inside of the chamber of the PVD apparatus (such as a removable protective plate) in addition to the glass substrate. These are periodically recycled by removing the deposited ITO film. In addition, the ITO target is also deformed with the lapse of time of use, causing a problem in forming a uniform film, so that it is periodically replaced and recycled as a target material.

Also, in the FPD manufacturing process performed using PVD etc., panels that do not meet the standards are discarded, and panels that meet the standards are used in information display devices, video display devices, etc. However, the transparent electrode contains valuable rare metal (indium) as described above.
Since April 1, 2009, FPD has become a target for home appliance recycling, but the amount of indium contained in FPD is very small (weight ratio: about 0.04%). The current situation is not.

  In order to recycle indium, which is a rare metal, the indium oxide compound-containing film adhered in the PVD chamber, the waste liquid crystal panel, etc. (waste liquid crystal panel, waste plasma display panel, waste solar cell or waste touch panel) Various methods for treating an indium oxide compound containing film so that the indium oxide compound can be reused have been studied.

For example, in Patent Document 1, an indium oxide (In oxide) -based thin film attached to a tool of a PVD apparatus is peeled off by blasting, and a flotation method is used from scrap powder containing oxidized In-based powder and blast powder. Discloses a method for removing the blast powder and increasing the ratio of the oxidized In-based powder.
In this method, the scrap powder is classified in a certain particle size range, and ITO scrap powder having a particle size less than a certain particle size range is put into a floatation machine for coarse beneficiation. A powder and a powder that is a flotation tailing are separated. Next, the powder that has been coarsely separated in the roughing process is put into a flotation beneficiator for fine separation, and the powder that is a flotation concentrate and the powder that is a floating ore are separated. However, this method requires a lot of work such as setting a large-scale beneficiary machine and setting the liquid pH value in the tank of the beneficiary machine.

  In Patent Document 2, a glass plate of a waste liquid crystal panel is cut into a rectangular shape, the glass plate is removed from the liquid crystal panel, the liquid crystal is exposed, and the liquid crystal attached to the glass substrate is scraped off and collected. It is disclosed that it is possible to recover rare metals contained therein. However, the method for recovering the rare metal is not specifically disclosed here, and the process of scraping the liquid crystal from the glass plate cut into a fixed shape is troublesome.

JP 2006-150196 A Japanese Patent No. 3589937

  Therefore, an object of the present invention is to provide a method capable of efficiently recovering an indium oxide-based compound by a simple process without using a large-scale apparatus.

  As a result of intensive studies to solve the above problems, the present inventors generally used an indium oxide compound by utilizing a blasting process used for removal of burrs, surface grinding, satin processing, and the like. As a result of investigating a method for economically recovering an indium oxide compound by removing the film from an object having a film containing and increasing the concentration of the indium oxide compound contained in the blasted product after the treatment A blasting material is used as a blasting material (grinding material), and the blasting material after blasting (including an indium oxide compound and a plant blasting material) is fired to burn the blasting material. The inventors have found that the above problems can be effectively solved by increasing the ratio of the indium oxide compound in the treated product, and have completed the present invention.

That is, the present invention is a method for concentrating a blasted product containing an indium oxide compound,
It includes a step of burning the blasted product containing the indium oxide compound and the plant blast material to burn the blast material and increasing the ratio of the indium oxide compound in the blasted product.

  According to the above method, the concentration of indium in the blasted product can be relatively increased without going through a large-scale apparatus or complicated process.

  Preferable examples of the plant blast material (grinding material) include a blast material derived from a plant selected from walnuts, maize (onion), peach, apricot and bamboo.

  The blast-treated product can be obtained by peeling the film component from an object having a film containing an indium oxide compound attached to the surface by blasting using a plant-based blast material. In the present invention, since the blast material is a plant-based powder, the processed product can be processed without causing a chemical change.

  A typical example of the indium oxide compound is ITO (indium tin oxide) which is indium oxide doped with tin.

  Examples of the object include a waste liquid crystal panel, a waste plasma display panel, a waste solar cell, or a waste touch panel having an ITO-containing film on the surface. For these waste panels, if a blasting material with high Mohs hardness (for example, silicon carbide grid [granulated] Mohs hardness 13) is used, the substrate (glass substrate, plastic substrate, organic film-like support, etc.) itself is damaged. Or the blasting material collides with each other and is finely crushed, thereby reducing the grinding ability. Therefore, the ITO film cannot be ground well, and there are cases where a lot of things other than the ITO film are mixed in the blasted product (a mixture of the blasting material and the material ground by the blasting process). When a blast material of the system is used, damage to the substrate and damage to the blast material are suppressed, so that a blasted product with high ITO purity can be obtained.

  According to the method of the present invention, it is possible to recover an indium oxide-based compound economically and with high purity without using a large-scale apparatus or chemicals (particularly strong acid or alkali agent).

It is a flowchart which illustrates the method of collect | recovering an indium oxide type compound from a waste panel. FIG. 2 shows thermogravimetry (TG) and differential thermal analysis (DTA) of the fired blasted product (sample). FIG. 3 shows X-ray diffraction patterns (XRD) of the blasted product (sample) before and after firing.

  In the present invention, an indium oxide-based compound means an oxide containing indium (In) and includes not only indium oxide but also indium oxide doped with tin (ITO: indium tin oxide).

  The blasted product according to the present invention means a product (scrap powder) obtained after blasting a substance to which an indium oxide compound is adhered, and a powdered exfoliated product (indium oxide based) peeled off by blasting. A compound-containing film peeling powder) and a plant blasting material used for the blasting treatment.

In blasting, silicon carbide (Mohs hardness: 13), which has a large impact force, is generally used as the blasting material (grinding material). By repeating the blasting, the blasting material collides with each other and is finely crushed. If you do not work with additional replenishment of blast material to make up for it.
On the other hand, when a plant-based blast material is used as in the present invention, the Mohs hardness is low (Mohs hardness 3 in the case of walnuts), but it is highly elastic and less crushed and can be used repeatedly. By processing the substrate, the content concentration of ITO can be increased. As a result, the ITO content in the blasted product can be 1% by weight or more, and ITO can be recovered economically.

  Furthermore, in the present invention, since the plant blast material is burned by firing the blast-treated product, the indium quality in the blast-treated product can be increased (concentrated).

  In particular, the present invention relates to a rare metal (indium oxide compound) contained in a transparent electrode used for a substrate of a waste liquid crystal panel or the like (waste liquid crystal panel, waste plasma display panel, waste solar battery or waste touch panel). It is suitable for use as a powder concentration method in which a powder (blast-treated product) obtained by exfoliation treatment by a sandblast method is fired to relatively increase the concentration of indium in the powder.

  That is, from the waste liquid crystal panel discarded in the manufacturing process of the liquid crystal panel, first, plastic materials other than the substrate material, metal member, organic film, etc. are excluded, then the substrate is cut, and the cut substrate is disassembled and separated, The transparent electrode material adhering to the material is peeled off by blasting (peeling treatment), and the blasted product containing the peeling powder of the transparent conductive film (containing indium oxide) is collected (stored in some cases) In addition, a powder in which the indium oxide compound is concentrated can be obtained by a simple method such as firing.

When the above method is described using a liquid crystal panel as an example, for a defective panel generated in the panel manufacturing process or a liquid crystal panel of discarded products,
(1) The panel is cleaved and separated into glass substrates on the array side and the color filter side;
(2) The ITO transparent conductive film contained in both substrates is peeled off with a sandblasting device using plant powder (powder made of walnuts, maize, peach, apricot, bamboo, etc.) as a blasting material;
(3) The powder (including the ITO transparent conductive film peeling powder and blasting material) is fired and the plant-based blasting material is burned to increase the ITO ratio in the powder (concentrate the ITO-containing powder) ;
A method is mentioned.

  Although the liquid crystal panel has been described as an example in the above method, the blasted product according to the present invention is obtained by peeling a thin film containing an oxidized In-based compound adhering to the jigs and tools of the PVD apparatus by blasting. It may be a thing.

As the plant blasting material of the present invention, powders made of walnuts, maize, peach, apricot, bamboo, etc. can be used, and these are available on the market. Preferred blast materials include those having a screen size of # 16 to # 80 (center particle size of 149 to 1000 μm). The Mohs hardness of the plant blast material is in the range of 2.0 to 3.5, but it is particularly preferable to use a plant blast material having a Mohs hardness of 3.0 to 3.5.
Moreover, as a blasting method, the pneumatic blasting method which projects a blast material with compressed air is preferable.
As an example of a preferable blasting treatment, a transparent conductive film (ITO) is projected on the side of the cut panel where the transparent conductive film is adhered using walnuts of # 16 to 80 as a blasting material at an injection pressure of 0.2 to 0.5 MPa. ).

  In addition, the content of the indium oxide compound can be increased by repeatedly treating a large amount of the substrate with the same blast material. The content of the indium oxide compound in the blasted product is preferably 1% by weight or more.

  The present invention is characterized in that the blasted product obtained as described above is fired to concentrate the indium oxide compound, and the firing conditions at this time are in the air or 0.5% to 5% (volume%) ) Is preferably fired at 400 ° C. or higher in contact with an oxygen-containing gas, and is 40% or more (more preferably 50% or more) based on the weight of the blasted product (plant-based blasting material + exfoliated material). It is preferable to carry out the baking until disappears. A more preferable firing temperature is 500 ° C. or higher. The upper limit of the firing temperature is not particularly limited, but 600 ° C. to 1000 ° C. is not so different in the concentration ratio, and therefore 600 ° C. or less is appropriate from the viewpoint of cost.

One embodiment of the present invention will be described with reference to FIG.
<S1> Pretreatment process Waste liquid crystal panel, etc. (for example, waste liquid crystal panel discarded in a liquid crystal panel manufacturing factory, waste liquid crystal panel discarded in a liquid crystal display assembly factory, disassembled and discharged, and in the market For discarded liquid crystal panels and the like that are discharged after dismantling the discarded products, plastic members, metal members, organic films, etc. other than the substrate material are excluded.
<S2> Panel cutting step The peripheral portion (sealing portion) of the pretreated substrate is cut.
<S3> Separation Step In the case of a liquid crystal panel, the cut substrate is separated into a color filter side and an array (TFT) side.
<S4> Blasting (Peeling) Processing Step The thin film material formed on the separated substrate is blasted to peel and collect the thin film material (transparent conductive film containing an indium oxide compound) formed on the substrate. .
<S5> Firing The blasted product obtained after the blasting treatment (a powder containing an indium oxide compound and a blasting material. The powder may contain an organic thin film or the like) may be fired to concentrate the blasted product. .
<S6> Inspection It is confirmed that the target indium oxide compound (for example, ITO) is contained at a set concentration or more.

  The indium oxide compound thus obtained is then subjected to a mechanochemical reaction with stirring with silicon powder based on the methods described in JP2010-43306A and JP2010-222641A. Indium oxide compounds may be reduced to indium compounds.

The following examples explain the present invention in more detail, but the present invention is not limited to the examples.
[Example 1]
Using the blast cabinet BS-2 type (suction type) made by Atsugi Iron Works, using walnut # 16-80 as the blasting material, and the injection pressure 0.2-0.5 Blasting was performed on a 12-inch substrate size with a jetting time of 120 seconds at MPa / cm ² , a nozzle diameter of 8φ, a work distance of 50 mm, and a jetting angle of 30 ° to 60 °.
The transparent conductive film layer (ITO) could be peeled off under any condition, but the substrate was thin and fragile, especially when blasting was performed with walnut size # 36, spray pressure 0.4 MPa / cm ² and spray angle 45 degrees. Even in the case of a glass substrate, the transparent conductive film layer adhering to the substrate surface could be completely peeled off with high processing efficiency without cracking the substrate.

  Moreover, the blasting material made of walnuts was highly elastic and could be used repeatedly with little crushing. Therefore, it was possible to increase the ITO content concentration to 1% by weight or more by treating a large amount of glass substrate with a transparent conductive film (200 or more 12-type panels).

The blasted product was fired in the atmosphere at a heating rate of 10 ° C./min. FIG. 2 shows the results of thermogravimetry (TG) and differential thermal analysis (DTA) of the calcined powder. As can be seen from FIG. 2, the decrease in the weight of the blasted product near 20 ° C. was 20%, but after that, the decrease rate increased remarkably up to 500 ° C., and decreased at about 40% at 400 ° C. It decreased about 50% at 500 ℃.
The residue after firing is presumed to be mainly carbon and ash. FIG. 3 shows an X-ray diffraction diagram (XRD) of a sample before calcination (blasted product) and a sample collected after calcination at 1000 ° C. for 1 hour and 40 minutes. From FIG. 3, it is confirmed that ITO is contained in the sample after firing, and that the ITO concentration is increased. By firing, the blast material (walnut component in this embodiment) is fired and burned, so that the indium oxide type It was demonstrated that the compound (ITO in this example) component is concentrated.
In addition, when firing in the atmosphere at 500 ° C. and firing until 50% disappears based on the weight of the blasted product (plant blasting material + peeled product), the firing time is 50 minutes. The ITO concentration in the blasted product increased from 1.7% by weight (before firing) to 3.3% by weight (after firing).

In the method of the present invention, an indium oxide compound can be recovered economically and with high purity without using a large-scale apparatus or chemicals (particularly strong acid or alkali agent). In addition, when the blast treatment of the present invention is applied to treatment of waste liquid crystal panels and the like, even if the substrate material is glass, the indium oxide compound-containing film can be peeled without damaging the glass. It can be reused as an alternative material for quartz stone.
Therefore, according to the present invention, recycling with little waste is possible, and an ideal waste panel processing method can be provided.

Claims (4)

A method for concentrating a blasted product containing an indium oxide compound,
The blast-treated product is obtained by peeling the film component from an object to which an indium oxide-based compound-containing film is attached by blasting using a plant blast material; and
By firing the blasting comprising an indium-oxide-based compound and a plant-based blast material, and combusting the blast material, characterized in that it comprises a step of increasing the proportion of indium oxide-based compounds in the blasting material , Method for concentrating blasted product. The method of claim 1, wherein the blasting material comprises a plant selected from the group consisting of walnuts , onions , peaches, apricots and bamboo. The method according to claim 1, wherein the indium oxide-based compound is ITO. The method according to any one of claims 1 to 3, wherein the object is a waste liquid crystal panel, a waste plasma display panel, a waste solar cell, or a waste touch panel having an ITO-containing film.

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