JP5713946B2 - Method for recovering metal component in oxide semiconductor - Google Patents

Description

  The present invention relates to a method for recovering a metal component in an oxide semiconductor used as a material for a transparent conductive film or the like.

  ITO (Indium Tin Oxide), which is an oxide semiconductor, is used as a material for a transparent conductive film used in a liquid crystal display or the like. Since indium (hereinafter also referred to as In) contained in ITO is one of rare metals, it has been a problem to recover In by collecting it from a liquid crystal display or the like. ITO is formed (film formation) on a glass substrate. Since the In content in the entire panel is about several hundred ppm, it is necessary to collect In after separating it from the glass substrate.

  As a method for recovering In from a glass substrate, conventionally, a crushed glass substrate is immersed in an acid to dissolve ITO, and after dissolving In, tin (hereinafter also referred to as Sn), and a liquid crystal containing a liquid crystal containing liquid crystal There is a method in which In and Sn are adsorbed onto an anion exchange resin by bringing a liquid containing In and Sn into contact with the anion exchange resin after separation (see, for example, Patent Document 1). Thereafter, pure water is brought into contact with the anion exchange resin on which In and Sn are adsorbed, whereby In and Sn are desorbed from the anion exchange resin, and a concentrated solution of In and Sn is produced. Thereafter, by adjusting the pH of the concentrated solution of In and Sn, Sn hydroxide is precipitated and removed, and the pH is adjusted to obtain In hydroxide. In addition, as said acid, organic acids, such as formic acid, phosphoric acid, and oxalic acid, and inorganic acids, such as hydrochloric acid, a sulfuric acid, and nitric acid, are used.

  As another method, heat and pressure are applied to a mixture of crushed waste liquid crystal display glass substrate, drug, and water to make a subcritical water state, and after collecting the glass, There is a method for recovering ITO (see, for example, Patent Document 2). The recovered ITO is separated into indium at a smelting factory and reused. In addition, as said chemical | medical agent, it shall improve at least any one of peelability of organic substance, decomposability | degradability, and solubility, and alkali or alcohol is used.

JP 2008-73619 A International Publication No. 2010/090218

  In the conventional method for recovering In, an acid or alkali is used to dissolve ITO from the glass substrate, so that facilities with high acid resistance and alkali resistance are required. In addition, storage facilities for unused acids and alkalis, storage facilities for used waste liquid, and disposal processing are required. Furthermore, when In is recovered after dissolution treatment with acid or alkali, it is necessary to neutralize the treatment solution, so that not only a large amount of acid or alkali is required, but also the number of steps increases and the work is complicated. There was a problem that it became costly.

  The present invention has been made to solve these problems, and an oxide semiconductor capable of recovering a metal component in an oxide semiconductor formed on a glass substrate without using an acid or an alkali. It aims at providing the collection | recovery method of the metal component in it.

In order to solve the above problems, a method for recovering a metal component in an oxide semiconductor according to the present invention includes (a) a step of reducing the oxide semiconductor by performing a reduction treatment on a glass substrate to which the oxide semiconductor is attached. And (b) peeling the reduced oxide semiconductor from the glass substrate . In the step (a), the reduction treatment is performed by placing the glass substrate between the anode and the cathode in the electrolytic solution. In step (b), peeling is performed by barrel polishing, and steps (a) and (b) are performed simultaneously. It shall be the feature.

According to the present invention, (a) a step of reducing the oxide semiconductor by applying a reduction treatment to the glass substrate to which the oxide semiconductor is attached, and (b) a step of peeling the reduced oxide semiconductor from the glass substrate. In the step (a), the reduction treatment is performed by applying a voltage to each of the anode and the cathode in a state where the glass substrate is disposed between the anode and the cathode in the electrolytic solution, (b), the peeling is performed by barrel polishing, the steps (a) and (b), formed on a glass substrate without the use features and to order, an acid or an alkali to be performed simultaneously The metal component in the oxide semiconductor thus obtained can be recovered.

It is a flowchart which shows an example of the collection | recovery process of the metal component in the oxide semiconductor by Embodiment 1 of this invention. It is a figure which shows an example of the cross section of the liquid crystal panel by Embodiment 1 of this invention. It is a figure which shows an example of a structure of the ITO electrolytic reduction apparatus by Embodiment 1 of this invention. It is a figure which shows an example of a structure of the ultrasonic peeling apparatus by Embodiment 1 of this invention. It is a figure which shows an example of a structure of the shaking peeling apparatus by Embodiment 2 of this invention. It is a figure which shows an example of a structure of the stirring peeling apparatus by Embodiment 3 of this invention. It is a figure which shows an example of a structure of the barrel grinding | polishing apparatus by Embodiment 4 of this invention. It is a flowchart which shows an example of the collection | recovery process of the metal component in the oxide semiconductor by Embodiment 5 of this invention. It is a figure which shows an example of a structure of the ultrasonic application electrolytic reduction apparatus by Embodiment 5 of this invention. It is a figure which shows an example of a structure of the electrolytic reduction apparatus with a shaking function by Embodiment 6 of this invention. It is a figure which shows an example of a structure of the electrolytic reduction apparatus with a stirring function by Embodiment 7 of this invention. It is a figure which shows an example of a structure of the electrolytic barrel grinding | polishing apparatus by Embodiment 8 of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

<Embodiment 1>
FIG. 1 is a flowchart showing an example of a recovery process of a metal component in an oxide semiconductor according to Embodiment 1 of the present invention. As shown in FIG. 1, the recovery process according to the first embodiment includes a panel separation process, an ITO reduction process, a reduction product peeling process, a glass separation process, and a peeled material collection process. Hereinafter, details of each process will be described in order with reference to FIG.

[1] Panel Separation Process In the panel separation process, a CF (Color Filter) substrate and a TFT (Thin Film Transistor) substrate are separated.

  FIG. 2 is a diagram illustrating an example of a cross section of the liquid crystal panel according to the first embodiment. In the liquid crystal panel shown in FIG. 2, ITO which is an oxide semiconductor is used as a transparent electrode.

  As shown in FIG. 2, an ITO film 1a and an ITO film 1b (hereinafter collectively referred to as the ITO film 1) are formed as transparent electrodes on the CF substrate and the TFT substrate, respectively. An alignment film 2a and an alignment film 2b (hereinafter also collectively referred to as alignment film 2) are formed so as to cover the ITO film 1a and the ITO film 1b, respectively. The liquid crystal 3 is sandwiched between the alignment film 2a and the alignment film 2b, and the CF substrate and the TFT substrate are sealed (sealed) with a sealant 4. A polarizing plate 5a and a polarizing plate 5b are attached to the surfaces of the CF substrate and the TFT substrate, respectively.

  A method for separating the CF substrate and the TFT substrate is not particularly defined. For example, crushing of the entire liquid crystal panel, partial crushing of a portion where the sealing agent 4 is joined, removal of the sealing agent 4 by polishing the sealing agent 4, etc. To separate.

  In addition, after separating the CF substrate and the TFT substrate, the polarizing plate 5a and the polarizing plate 5b remain attached to each substrate, but it is more preferable to remove them.

[2] ITO Reduction Process FIG. 3 is a diagram illustrating an example of the configuration of the ITO electrolytic reduction apparatus according to the first embodiment. As shown in FIG. 3, in the ITO reduction process according to the first embodiment, an ITO film (oxide semiconductor) formed on the glass substrate 17 with ITO by subjecting the glass substrate 17 with ITO to reduction treatment by electrolysis. Is reduced. Here, the glass substrate 17 with ITO means the CF substrate and the TFT substrate, to which the ITO film 1 is adhered, separated in the panel separation step. Hereinafter, the CF substrate and the TFT substrate are also referred to as a glass substrate.

  The electrolytic reduction tank 11 is formed of an insulator, and for example, a resin, glass, ceramic, or a metal container coated with an insulating film is used.

  A neutral electrolytic solution 12 is contained in the electrolytic reduction tank 11. The neutral electrolyte solution 12 is not particularly defined except that it is a fresh water or neutral salt solution having an electric conductivity of 1000 μS / cm or less and has a pH greater than 3.

  An anode 13 and a cathode 14 are installed in the electrolytic reduction tank 11. The anode 13 and the cathode 14 are connected via a power source 18. As a material for the anode 13 and the cathode 14, metal or carbon is used. In addition, when using a metal as the material of the anode 13 and the cathode 14, what coated the thin film which has electroconductivity, such as corrosion resistance metals, such as Pt (platinum), or TiN (titanium nitride), is used.

  A holding table 15 is installed between the anode 13 and the cathode 14. The holding table 15 is formed using an insulator, and for example, resin, glass, ceramic, or metal coated with an insulating film is used. The pedestal portion of the holding table 15 is formed by a net 16, and a glass substrate 17 with ITO is placed on the net 16. The net 16 has a mesh shape using an insulator, and is formed of, for example, a resin net, glass, ceramic, or a metal coated with an insulating film. Although the size of the hole of the net 16 is not particularly defined, it is more preferable that it is as large as possible as long as the glass substrate 17 with ITO does not fall.

  In FIG. 3, the anode 13 and the cathode 14 are arranged in a direction perpendicular to the net 16, but the glass substrate 17 with ITO is arranged between the anode 13 and the cathode 14, and the anode 13 and the cathode 14 are arranged. Any arrangement may be used as long as 14 does not contact. For example, the anode 13 and the cathode 14 may be disposed at a position sandwiching the glass substrate 17 with ITO and parallel to the net 16.

  In the ITO electrolytic reduction apparatus shown in FIG. 3, the ITO film on the glass substrate 17 with ITO is reduced by applying a voltage to each of the anode 13 and the cathode 14 using the power source 18. The applied voltage depends on the distance between the anode 13 and the cathode 14, but is 2 V or more and 200 V or less in the first embodiment. Note that the applied voltage may be pulsed, and the polarity of the anode 13 and the cathode 14 may be switched at regular intervals. An AC power source may be used as the power source 18.

In the electrolytic reduction process using the ITO electrolytic reduction apparatus according to the first embodiment, indium oxide (In ₂ O ₃ ) and tin oxide (SnO ₂ ) constituting the ITO film are represented by the following chemical reaction formulas (1), Reduction to metal In and metal Sn by (2).

In ₂ O ₃ + 6H ⁺ + 6e → 2In + 3H ₂ O (1)
SnO ₂ + 4H ⁺ + 6e → Sn + 2H ₂ O (2)
As shown in the chemical reaction formulas (1) and (2), oxygen (O) is released from the ITO film during the reduction, so that the ITO film is reduced to a low-density and sparse In film containing Sn.

[3] Reduced product peeling step FIG. 4 is a diagram showing an example of the configuration of the ultrasonic peeling device according to the first embodiment. As shown in FIG. 4, in the reduced product peeling process according to the first embodiment, the ITO film (corresponding to the ITO film 1 in FIG. 2) reduced in the ITO reduction process is ultrasonically cleaned to reduce the glass substrate 22 with reduced ITO. Peel from. Here, the glass substrate 22 with reduced ITO refers to a glass substrate that has been subjected to reduction treatment in the ITO reduction step.

  The cleaning tank 21 contains a glass substrate 22 with reduced ITO and a cleaning solution 23. The cleaning liquid 23 is not particularly defined as long as the pH is higher than 3, but for example, tap water, ion-exchanged water, or pure water is more preferable.

  The cleaning tank 21 is installed on the ultrasonic transducer 24. The oscillation frequency of the ultrasonic vibrator 24 varies depending on the amount of the glass substrate 22 with reduced ITO to be put into the cleaning tank 21 and the amount of the cleaning liquid 23, but is not particularly defined, but is 20 to 20 as a frequency at which the cavitation effect is efficiently generated. 200 kHz is more preferable. Further, in order to enhance the cleaning effect, ultrasonic waves with different frequencies may be generated alternately. In the first embodiment, the ultrasonic transducer 24 is installed outside the cleaning tank 21, but may be installed in the cleaning tank 21.

  In the ultrasonic peeling apparatus as shown in FIG. 4, by oscillating the ultrasonic vibrator 24 and ultrasonically cleaning the glass substrate 22 with reduced ITO, In25 and Sn26 constituting the ITO film formed on the glass substrate. Is peeled off from the glass substrate. At this time, the alignment film 27 (corresponding to the alignment film 2 in FIG. 2) formed on the ITO film is also peeled off. As described above, since the pH of the cleaning liquid 23 is greater than 3, the peeled In25, Sn26, and alignment film 27 are not dissolved but separated from the glass substrate in a suspended state.

  From the above, by the previous ITO reduction process, the oxygen in the ITO film is released and becomes a low density state, and the adhesion between the ITO film and the glass substrate is lowered. Therefore, in the reduced product peeling step, the ITO film can be easily separated from the glass substrate and recovered by ultrasonic cleaning of the ultrasonic peeling device.

[4] Glass Separation Step In the glass separation step, the glass is separated and recovered from the cleaning liquid 23 remaining after the reduced product peeling step.

  As a recovery method, the glass is separated from the cleaning liquid 23 by sieving about 1 to 10 times using a sieve having a particle size of about 1/2 to 1/20 of the crushed glass. When sieving a plurality of times, a coarse sieve is used first, and the sieve is made finer as the number of times is repeated.

  The method for separating the glass may be any method that uses the difference in particle size and density between glass and In25 and Sn26. For example, centrifugation, shaking separation, sedimentation separation, etc. Absent.

[5] Exfoliated material recovery process In the exfoliated material recovery process, In25 and the like are separated and recovered from the cleaning liquid 23 remaining after the glass separation process.

  Examples of the recovery method include precipitation, filtration, and centrifugation. Further, the precipitation rate may be accelerated by using a flocculant. In addition, as for the mesh size of the filter used at the time of collection | recovery, 0.1 micrometer-50 micrometers are preferable.

  The recovered material obtained by the above recovery method includes In25, Sn26, and alignment film 27. By refining the recovered material, high-purity In can be separated and recovered and recycled. Similarly, Sn can be recovered.

  From the above, according to the first embodiment, the oxide semiconductor (ITO film) is reduced to make the oxide semiconductor easily peelable from the glass substrate, and the oxide semiconductor is removed from the glass substrate by ultrasonic cleaning. The metal component (in particular, In which is a rare metal) can be easily peeled off. Therefore, the metal component in the oxide semiconductor can be recovered without using an acid or an alkali.

<Embodiment 2>
FIG. 5 is a diagram showing an example of the configuration of the shaking peeling apparatus according to Embodiment 2 of the present invention. In the second embodiment, a shaking peeling device is used in the reduced product peeling step (see FIG. 1). Other configurations and operations are the same as those of the first embodiment, and thus description thereof is omitted here.

  As shown in FIG. 5, the cleaning tank 21 is installed on a shaker 31.

  By shaking the washing tank 21 with the shaker 31, the glass substrates 22 with the reduced ITO are rubbed together, and the In25, Sn26, and the alignment film 27 are scraped off with the glass and peeled off from the glass substrate 22 with the reduced ITO. The

  Thereafter, reduction ITO is performed by processing the peeled In25, Sn26, alignment film 27, and cleaning liquid 23 containing glass in the same steps (glass separation step, peeled material collecting step) as in the first embodiment. A metal component (particularly, In that is a rare metal) in the oxide semiconductor can be separated and recovered from the attached glass substrate 22.

  From the above, according to the second embodiment, by reducing the oxide semiconductor (ITO film), the oxide semiconductor can be easily peeled from the glass substrate, and shaken from the glass substrate in the oxide semiconductor. Metal components (particularly, In, which is a rare metal) can be easily peeled off. Therefore, the metal component in the oxide semiconductor can be recovered without using an acid or an alkali.

<Embodiment 3>
FIG. 6 is a diagram showing an example of the configuration of the stirring and peeling apparatus according to Embodiment 3 of the present invention. In the third embodiment, a stirring and peeling device is used in the reduced product peeling step (see FIG. 1). Other configurations and operations are the same as those of the first embodiment, and thus description thereof is omitted here.

  As shown in FIG. 6, a stirring bar 32 is provided in the cleaning tank 21.

  By stirring the glass substrate 22 with the reduced ITO in the cleaning tank 21 by the stirrer 32, the glass substrates 22 with the reduced ITO are rubbed together, and the In25, Sn26, and the alignment film 27 are scraped with glass to attach the reduced ITO. It is peeled from the glass substrate 22.

  Thereafter, the peeled In25, Sn26, alignment film 27, and cleaning solution 23 containing glass are processed in the same steps (glass separation step, peeled material collecting step) as those in the first embodiment, whereby a glass substrate is obtained. Thus, a metal component in the oxide semiconductor (particularly, In which is a rare metal) can be separated and recovered.

  From the above, according to the third embodiment, the oxide semiconductor (ITO film) is reduced to make the oxide semiconductor easily peelable from the glass substrate, and the metal in the oxide semiconductor is stirred from the glass substrate. The component (particularly, In which is a rare metal) can be easily peeled off. Therefore, the metal component in the oxide semiconductor can be recovered without using an acid or an alkali.

<Embodiment 4>
FIG. 7 is a diagram showing an example of the configuration of a barrel polishing apparatus according to Embodiment 4 of the present invention. In the fourth embodiment, a barrel polishing apparatus is used in the reduced product peeling step (see FIG. 1). Other configurations and operations are the same as those of the first embodiment, and thus description thereof is omitted here.

  As shown in FIG. 7, the glass substrate 22 with reducing ITO and the cleaning solution 23 are charged from the sample loading port 41 of the rotary barrel polishing machine 40. Then, by rotating the rotating barrel polishing machine 40 around the rotating shaft 42 to perform barrel polishing, the glass substrates 22 with reduced ITO are rubbed together, and the In25, Sn26, and alignment film 27 are scraped off with glass. It peels from the glass substrate 22 with reduced ITO.

  Thereafter, the peeled In25, Sn26, alignment film 27, and cleaning solution 23 containing glass are processed in the same steps (glass separation step, peeled material collecting step) as those in the first embodiment, whereby a glass substrate is obtained. Thus, a metal component in the oxide semiconductor (particularly, In which is a rare metal) can be separated and recovered.

  As described above, according to the fourth embodiment, the oxide semiconductor (ITO film) is reduced to make the oxide semiconductor easily peelable from the glass substrate, and barrel polishing is performed from the glass substrate to the oxide semiconductor. Metal components (particularly, In, which is a rare metal) can be easily peeled off. Therefore, the metal component in the oxide semiconductor can be recovered without using an acid or an alkali.

<Embodiment 5>
In the first embodiment, the ITO reduction step and the reduced product peeling step are performed as separate steps. In the fifth embodiment, the ITO reduction step and the reduced product peeling step in the first embodiment are performed simultaneously. It is characterized by.

  FIG. 8 is a flowchart illustrating an example of a recovery process of a metal component in an oxide semiconductor according to Embodiment 5 of the present invention. As shown in FIG. 8, the ITO reduction and the reduction product peeling are performed in the same process. Since other operations (steps) are the same as those in the first embodiment, description thereof is omitted here.

  FIG. 9 is a diagram showing an example of the configuration of the ultrasonic application electrolytic reduction apparatus according to the fifth embodiment. The ultrasonic application electrolytic reduction apparatus shown in FIG. 9 is an apparatus that combines the ITO electrolytic reduction apparatus (see FIG. 3) in the first embodiment and the ultrasonic peeling apparatus (see FIG. 4).

  As shown in FIG. 9, the electrolytic reduction tank 11 is installed on the ultrasonic transducer 24. The electrolytic reduction tank 11 contains a neutral electrolytic solution 12.

  An anode 13 and a cathode 14 are installed in the electrolytic reduction tank 11. The anode 13 and the cathode 14 are connected via a power source 18.

  A holding table 15 is installed between the anode 13 and the cathode 14. The pedestal portion of the holding table 15 is formed by a net 16, and a glass substrate 17 with ITO is placed on the net 16.

  In the ultrasonic application electrolytic reduction apparatus shown in FIG. 9, a voltage is applied to each of the anode 13 and the cathode 14 using the power source 18, and an ultrasonic wave is oscillated by the ultrasonic vibrator 24. Then, the ITO reduction process by electrolytic reduction and the reduction product peeling process by ultrasonic cleaning are simultaneously performed, and In25, Sn26, and the alignment film 27 can be separated from the glass substrate 17 with ITO while performing electrolytic reduction. .

  After that, by treating the peeled In25, Sn26, alignment film 27, and neutral electrolyte solution 12 containing glass in the same steps (glass separation step, peeled material collecting step) as in the first embodiment. In addition, the metal component (particularly, In which is a rare metal) in the oxide semiconductor can be separated and recovered from the glass substrate 17 with ITO.

  The electrolytic reduction tank 11, the holding table 15, and the net 16 are not made of a material (material) that absorbs ultrasonic waves, but are made of hard plastic, glass, or an insulated metal.

  Further, when ultrasonic cleaning is performed, the glass substrate 17 with ITO moves due to cavitation, and if the glass substrate 17 falls from the gap between the anode 13 and the cathode 14 and the net 16, there is a possibility that electrolytic reduction cannot be performed. Needs to be installed so that there is no gap between the anode 13 and the cathode 14.

  From the above, according to the fifth embodiment, in addition to the effects of the first embodiment, since the ITO reduction process and the reduction product peeling process are simultaneously performed, the time required for the reduction and the peeling is less than that of the first embodiment. Can also be shortened.

<Embodiment 6>
The sixth embodiment is characterized in that the ITO reduction step and the reduction product peeling step in the second embodiment are performed simultaneously. Other operations (steps) are the same as those in the second embodiment, and thus description thereof is omitted here.

  FIG. 10 is a diagram illustrating an example of the configuration of the electrolytic reduction apparatus with a shaking function according to the sixth embodiment. The electrolytic reduction apparatus with a shaking function shown in FIG. 10 is an apparatus that combines the ITO electrolytic reduction apparatus (see FIG. 3) in Embodiment 2 and the shaking peeling apparatus (see FIG. 5).

  As shown in FIG. 10, the electrolytic reduction tank 1 is installed on a shaker 31.

  When the electrolytic reduction tank 11 is shaken by the shaker 31, the glass substrates 17 with ITO are rubbed with each other, and the In25, Sn26, and the alignment film 27 are scraped with glass to be separated from the glass substrate 17 with ITO. .

  After that, by treating the peeled In25, Sn26, alignment film 27, and neutral electrolyte solution 12 containing glass in the same steps (glass separation step, peeled material collecting step) as in the second embodiment. In addition, the metal component (particularly, In which is a rare metal) in the oxide semiconductor can be separated and recovered from the glass substrate 17 with ITO.

  From the above, according to the sixth embodiment, in addition to the effect of the second embodiment, the ITO reduction process and the reduced product peeling process are simultaneously performed, so that the time required for reduction and peeling is less than that of the second embodiment. Can also be shortened.

<Embodiment 7>
The seventh embodiment is characterized in that the ITO reduction step and the reduced product peeling step in the third embodiment are performed simultaneously. Since other operations (steps) are the same as those in the third embodiment, the description thereof is omitted here.

  FIG. 11 is a diagram illustrating an example of a configuration of an electrolytic reduction apparatus with a stirring function according to the seventh embodiment. The electrolytic reduction apparatus with a stirring function shown in FIG. 11 is an apparatus that combines the ITO electrolytic reduction apparatus (see FIG. 3) in Embodiment 3 and the stirring and peeling apparatus (see FIG. 6).

  As shown in FIG. 11, a stirring bar 32 is provided in the electrolytic reduction tank 11.

  By stirring the glass substrate 17 with ITO in the electrolytic reduction tank 11 by the stirrer 32, the glass substrates 17 with ITO are rubbed with each other, and the In25, Sn26, and the alignment film 27 are scraped off with glass, whereby the glass substrate with ITO 17 is peeled off.

  After that, by treating the peeled In25, Sn26, alignment film 27, and neutral electrolyte solution 12 containing glass in the same steps (glass separation step, peeled material collecting step) as in the third embodiment. The metal component (particularly, In which is a rare metal) in the oxide semiconductor can be separated and recovered from the glass substrate.

  From the above, according to the seventh embodiment, in addition to the effects of the third embodiment, since the ITO reduction step and the reduced product peeling step are simultaneously performed, the time required for the reduction and the peeling is less than that of the third embodiment. Can also be shortened.

<Eighth embodiment>
The eighth embodiment is characterized in that the ITO reduction step and the reduction product peeling step in the fourth embodiment are performed simultaneously. Other operations (steps) are the same as those in the fourth embodiment, and thus description thereof is omitted here.

  FIG. 12 is a diagram showing an example of the configuration of the electrolytic barrel polishing apparatus according to the eighth embodiment. The electrolytic barrel polishing apparatus shown in FIG. 12 is an apparatus that combines the ITO electrolytic reduction apparatus (see FIG. 3) in Embodiment 4 and the barrel polishing apparatus (see FIG. 7).

  As shown in FIG. 12, the anode 13 and the cathode 14 are provided in the tank of the rotary barrel polishing machine 40 so as not to contact each other, and the glass substrate 17 with ITO 17 and the neutral electrolyte solution 12 are supplied from the sample insertion port 41. throw into. Then, by applying a voltage to each of the anode 13 and the cathode 14 using the power source 18 and performing electrolytic reduction, rotating the rotating barrel polishing machine 40 around the rotating shaft 42 to perform barrel polishing, with ITO The glass substrates 17 are rubbed with each other, and the In25, Sn26, and alignment film 27 are scraped off with glass to be peeled from the glass substrate 17 with ITO.

  After that, by treating the peeled In25, Sn26, alignment film 27, and neutral electrolyte solution 12 containing glass in the same steps (glass separation step, peeled material collecting step) as in the fourth embodiment. The metal component (particularly, In which is a rare metal) in the oxide semiconductor can be separated and recovered from the glass substrate.

  From the above, according to the eighth embodiment, in addition to the effects of the fourth embodiment, the ITO reduction process and the reduced product peeling process are simultaneously performed, so that the time required for reduction and peeling is less than that of the fourth embodiment. Can also be shortened. Moreover, it can have the function that the uniformity of the electrolytic reduction of ITO improves by barrel polishing.

  It should be noted that the present invention can be freely combined with each other within the scope of the invention, and each embodiment can be appropriately modified or omitted.

  DESCRIPTION OF SYMBOLS 1 ITO film, 2 Alignment film, 3 Liquid crystal, 4 Sealant, 5 Polarizing plate, 11 Electrolytic reduction tank, 12 Neutral electrolyte, 13 Anode, 14 Cathode, 15 Holding stand, 16 Net, 17 Glass substrate with ITO, 18 Power supply, 21 Cleaning tank, 22 Glass substrate with reduced ITO, 23 Cleaning liquid, 24 Ultrasonic vibrator, 25 In, 26 Sn, 27 Oriented film, 31 Shaker, 32 Stirrer, 40 Rotating barrel polisher, 41 Sample input Mouth, 42 axis of rotation.

Claims (2)

(A) performing a reduction treatment on the glass substrate to which the oxide semiconductor is attached, and reducing the oxide semiconductor;
(B) peeling the reduced oxide semiconductor from the glass substrate;
Equipped with a,
In the step (a), the reduction treatment is performed by applying a voltage to each of the anode and the cathode in a state where the glass substrate is disposed between the anode and the cathode in the electrolytic solution. ,
In the step (b), the peeling is performed by barrel polishing,
Wherein the the step (a) and said step (b), you characterized by being performed at the same time, the method of recovering the metal components in the oxide semiconductor.   The method for recovering a metal component in an oxide semiconductor according to claim 1, wherein the oxide semiconductor contains indium.

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