TWI385255B - Method and apparatus for recovering indium from discarded liquid crystal displays - Google Patents

Description

Method and device for recovering indium from waste liquid crystal display

The present invention relates to a method and apparatus for recovering indium from a waste liquid crystal display, and more particularly to a liquid crystal television, a mobile phone, a portable game machine, etc., which are discarded, or which are discharged as defective products in a production process. A method and apparatus for recovering valuable indium (In) as an alloy or a metal monomer in a liquid crystal display (hereinafter also referred to as a waste LCD).

An indium tin oxide (ITO) film is used as a transparent electrode in a liquid crystal display (hereinafter also referred to as LCD). The ITO film is mainly formed by sputtering, but indium is used in the target region. Indium is a rare metal obtained in the zinc refining process, and in recent years there has been concern about its depletion. In the waste LCD, which contains about 300 mg/L of indium, the indium is depleted, and the indium is recovered in the recycling process.

In order to meet such a demand, the inventors have attempted to recover the indium in the waste LCD. Such a technique is, for example, the invention described in Non-Patent Document 1 below. The invention relates to a fluidized bed LCD processing system, wherein the fluidized bed LCD processing system is composed of a fluidized bed processing unit, a cyclone, a cooler, a high temperature bag filter, a catalyst flow layer, and a water cleaning tower to make the fluid layer Indium in the processing unit that is mechanically peeled off by the laundering of the flowing medium is accumulated in the flow medium. However, in the method using the processing system, about 60% of the waste LCD is accumulated in the flowing medium, and the rest is collected in the bag filter, so the indium recovery rate is about 60% of the total, and the recovery rate is 60%. Left and right, the lower one.

Non-Patent Document 1: Display Monthly, April 2002, pp. 36-46

In order to improve the low recovery rate of the dry treatment as described above, the industry is currently developing a wet treatment method. For example, Patent Document 1 discloses a method in which ITO is dissolved in an acid such as nitric acid or hydrochloric acid, and impurities such as tin are precipitated and removed, and then ammonia is added for neutralization, and is recovered as indium hydroxide.

Patent Document 1: Japanese Patent Laid-Open Publication No. 2000-128531

However, if the wet processing method as described above is used, there is a problem in that the indium hydroxide obtained by the treatment is inferior in filterability, so that it takes a long time in the operation, and the indium hydroxide obtained by neutralization or the like is used. The nature changes.

The present invention has been made to solve such problems, and the object of the present invention is to provide an indium recovery method and apparatus which can recover indium as a valuable metal without being recovered as in the prior state of indium hydroxide. The operation defects in the case of no indium hydroxide can be easily recovered by a filter or the like, and the recovery rate of indium is remarkably improved.

[Summary of the Invention]

The present invention is directed to the invention of claim 1 relating to a method for recovering indium from a waste LCD, characterized in that a waste liquid crystal display containing indium tin oxide is pulverized, and waste liquid crystal which is self-pulverized using acid is used. A solution containing an indium compound is dissolved in the display to obtain a solution containing an indium compound, and is introduced into the recovery reactor, and metal particles containing a metal having a higher ionization tendency than indium are added to the recovery reactor, and the metal particles are added. Flowing, the indium or indium alloy contained in the solution containing the indium compound is deposited on the surface of the metal particles, and then the precipitated indium or indium alloy is peeled off from the metal particles by a lift-off method to remove the solid. Indium or The indium alloy is separated from the liquid component and recovered.

Further, the invention of claim 2 is characterized in that, in the method for recovering indium from the waste liquid crystal display of claim 1, the metal particles are zinc particles or aluminum particles having a higher ionization tendency than the metal of indium. Further, the invention of claim 3 is characterized in that, in the method of recovering indium from a waste liquid crystal display of claim 1 or 2, a method of separating indium or an indium alloy deposited on the metal particles from the metal particles is performed, A method of vibrating metal particles by ultrasonic waves or a method of agitating metal particles by electromagnetic waves to collide with each other.

Further, the invention of claim 4 is characterized in that in the method for recovering indium from a waste liquid crystal display according to any one of claims 1 to 3, the indium compound containing indium tin oxide is dissolved in the self-depleting liquid crystal display. Before flowing the solution into the recovery reactor, the solution containing the indium compound is flowed into the reactor for removing impurities, and the solution for removing impurities is added to the solution containing the indium compound in addition to indium other than the indium compound. The metal particles of the metal of the impurity metal are then caused to flow, and the impurity metal is deposited on the surface of the metal particle, and then the precipitated impurity metal is removed from the metal particle by a lift-off method and then removed.

Further, the invention of claim 5 is characterized in that, in the method of recovering indium from the waste liquid crystal display of claim 4, the method of separating the impurity metal deposited on the metal particles from the metal particles is performed by A method in which ultrasonic waves vibrate metal particles, or a method in which metal particles are stirred by electromagnetic waves to collide with each other. Further, the invention of claim 6 is characterized in that in the method of claim 4 or 5, in which the indium is recovered from the waste liquid crystal display, the impurity metal is tin. Further, the invention of claim 7 is characterized in that: In the method of recovering indium from the waste liquid crystal display of Items 4 to 6, the metal particles containing a metal having a higher ionization tendency than the impurity metal are iron particles. Further, the invention of claim 8 is characterized in that in the method of recovering indium from the waste liquid crystal display of claim 7, the alkali is added to the solution containing the indium compound after removing the impurity metal, and the iron is used as the hydroxide thereof. The precipitate was removed.

Further, the invention of claim 9 is characterized in that, in a state in which the discarded liquid crystal display is housed in a bag, indium tin oxide is dissolved from the discarded liquid crystal display to obtain a solution containing an indium compound, and The waste liquid crystal display placed in the bag is subjected to washing neutralization treatment, and then dried.

Further, the invention of claim 10 relating to the apparatus for recovering indium from a waste liquid crystal display is characterized by comprising: a pulverizer for pulverizing a waste liquid crystal display containing indium tin oxide; and dissolving in a self-grinding waste liquid crystal display using an acid An indium dissolution device that obtains a solution containing an indium compound, and a solution containing an indium compound obtained by flowing into the indium dissolution device, and simultaneously adding a metal particle containing the metal having a higher ionization tendency than indium a reactor for recovering a metal precipitation reaction in which an indium or an indium alloy is deposited on the surface of the metal particles; and a peeling mechanism for recovering the precipitated indium or indium alloy from the metal particles; and a solid to be peeled off A separation mechanism in which indium or indium alloys are separated from liquid components.

Further, the invention of claim 11 is characterized in that, in the apparatus for recovering indium recovered from a waste liquid crystal display according to claim 10, the metal particles containing a metal having a higher ionization tendency than indium are zinc particles or aluminum particles. Further, the invention of claim 12 is characterized in that the waste liquid is as claimed in claim 10 or In a device for recovering indium from a crystal display, a device for separating indium or an indium alloy deposited on a metal particle from the metal particle is a device for vibrating metal particles using ultrasonic waves, or a metal particle is stirred and collided with each other using an electromagnet. Device.

Further, the invention of claim 13 is characterized in that the reactor for removing impurities is provided on the side of the reactor for recovery, and the reactor has the following method: self-depletion according to any one of claims 10 to 12. In the apparatus for recovering indium in a liquid crystal display, after the solution containing the indium compound obtained in the indium dissolving device flows in, a metal particle containing a metal having an ionization tendency larger than that of the impurity metal other than indium in the solution containing the indium compound is added. The metal particles are caused to flow, and the impurity metal is deposited on the surface of the metal particles, and the precipitated impurity metal is peeled off from the metal particles and removed.

Further, the invention of claim 14 is characterized in that, in the apparatus for recovering indium from a waste liquid crystal display according to claim 13, the method of separating the impurity metal deposited on the metal particles from the metal particles is performed by A method in which ultrasonic waves vibrate metal particles, or a method in which metal particles are stirred by electromagnetic waves to collide with each other. Further, the invention of claim 15 is characterized in that, in the apparatus for recovering indium from the waste liquid crystal display of claim 13 or 14, the impurity metal is tin.

Further, the invention of claim 16 is characterized in that, in the apparatus for recovering indium from the waste liquid crystal display according to claims 13 to 15, the metal particles containing the metal having a higher ionization tendency than the impurity metal are iron particles. Further, the invention of claim 17 is characterized in that, in the apparatus for recovering indium from a waste liquid crystal display according to claim 16, the indium-containing solution after removing the impurity metal A precipitation removing device is prepared by adding a base to the liquid to cause the iron to become a hydroxide and to precipitate and remove it.

According to the present invention, as described above, a waste liquid crystal display (waste LCD) containing indium tin oxide is pulverized, and indium tin oxide is dissolved in a waste LCD which is acid-pulverized to obtain a solution containing an indium compound, and then flows into a recovery reactor. Further, metal particles composed of a metal having a higher ionization tendency than indium (In) are added to the recovery reactor, and the metal particles are caused to flow, so that the indium or indium alloy contained in the indium compound-containing solution is contained. The surface of the metal particles is deposited, and then the precipitated indium or indium alloy is peeled off from the metal particles by a peeling mechanism, and the peeled solid indium or indium alloy is separated from the liquid component and recovered; And efficiently dissolving ITO from the waste LCD, and in the method of recovering indium from the solution in which indium is dissolved, the chemical displacement reaction using the ionization tendency is combined with the lift-off technique, that is, by using metal particles. In the metal precipitation reaction, the total surface area of the metal is increased, and the precipitation reaction rate is increased, and the precipitation metal which is grown to a certain extent by the peeling mechanism is peeled off. Often make the new metal surface is exposed to maintain the reaction rate, even when compared with a method according to any preceding dry and wet method, the lift having a significant recovery from waste recovered indium LCD of effect. Incidentally, in the present invention, with respect to the recovery rate of indium recovered from the waste liquid, a high recovery rate of 80% or more can be obtained.

Further, it is possible to recover indium as a valuable metal without recovering it in the state of indium hydroxide by the previous wet method, and thus has the following effects: in the case of recovery, there is no operational defect in the case of indium hydroxide, and a filter or the like can be used. Capacity Easily recycle.

Further, when a reactor for removing impurities which generates the same metal precipitation reaction as the recovery reactor is provided on the side of the reactor for recovery, the following metal is added: the ionization tendency is also larger than that in the waste LCD. A metal other than indium contained in a solution containing indium tin oxide containing indium tin, for example, an impurity metal such as tin (Sn), such as metal particles such as iron (Fe), flows to cause the waste liquid to be contained therein An impurity metal such as tin is deposited on the surface of the metal particles such as iron, and then the precipitated impurity metal is peeled off from the metal particles by a peeling mechanism, whereby tin or the like as an impurity metal can be appropriately removed.

Therefore, in the state in which the impurity metal other than indium is removed from the waste liquid in advance, the waste liquid is supplied to the recovery reactor, and the purity of the indium recovered by the recovery reactor is further improved. . Incidentally, 95% or more of high-purity indium can be recovered by providing such an impurity-removing reactor on the front side of the reactor for recovery.

In the case where the impurity metal is removed by the reactor for removing impurities, the metal-added ions such as iron are eluted, but a metal such as iron may be precipitated as a hydroxide by adding a base to the precipitation removing device in the subsequent stage. On the other hand, before the waste liquid is supplied to the recovery reactor, the hydroxide such as iron is removed in advance. In this case, if the pH is increased, there is a ruthenium which forms an indium hydroxide precipitate, but since the rate of formation of the precipitate is absolutely fast on the iron hydroxide side, it can be controlled by the residence time in the precipitation removal device. Indium hydroxide is not formed, so that indium is supplied to the next recovery reactor with almost no loss. Further, even if a part of indium is present in the solution as indium hydroxide, the indium hydroxide is again dissolved by adjusting the pH value in the next recovery reactor, so that the recovery rate of indium is not lowered.

Further, when the waste LCD is placed in a bag and the indium acid elution treatment, the cleaning neutralization treatment, and the drying treatment are performed, the fine waste LCD which can be pulverized in the waste LCD pulverization step is accommodated. The continuous treatment is carried out directly in the bag, and the effect of the entire treatment can be simplified. Further, it is not necessary to process the fine waste LCD sheet received from the waste LCD pulverization step, and thus it is easy to handle.

As described above, according to the present invention, it is possible to provide a method for recovering indium having a high recovery rate, and therefore, in the future, in the case of recycling the LCD in accordance with the regulations of the home appliance circulation method, indium in the circulation process in the recycling plant of the liquid crystal television. The recycling method has the practical benefit of applying the invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)

In the apparatus for recovering indium from a waste LCD according to the present embodiment, as shown in FIG. 1, an indium dissolution device (hereinafter also referred to as In dissolution device) 1 for dissolving ITO from a waste LCD using hydrochloric acid is provided for use in the indium. In the solution of the indium compound containing indium dissolved in the dissolution apparatus 1, iron particles (Fe particles) are added, and the reactor 2 for impurity removal of the impurity metal other than indium is removed; the reactor 2 for impurity removal is removed. a precipitation removing device 3 for precipitating and removing the iron particles in the waste liquid of the impurity metal as a hydroxide of iron (Fe); and a waste liquid for removing hydroxide from the precipitate in the precipitation removing device 3 The reactor 4 for recovery of indium is recovered. Further, although not shown, a pulverizer for pulverizing the waste LCD is provided in the front stage of the indium dissolution apparatus 1. Further, in the present invention, the pulverization means that the waste LCD is pulverized, and the size of the pulverized shards is not a problem. For example, if it is usually finely pulverized into a dusty state, it is also included in a state of being pulverized.

The indium dissolving device 1 is for obtaining a solution containing an indium compound by dissolving indium from a pulverized waste LCD by hydrochloric acid (aqueous hydrochloric acid). A solution containing an indium compound is prepared in such a manner that the indium content is 100 to 300 mg/L. Further, the solution containing the indium compound was prepared so that the hydrochloric acid concentration was 20% and the hydrochloric acid pH was 1.5.

The reactor 2 for removing impurities is configured to remove tin as an impurity from the solution containing the indium compound, and to have a reactor body 5 of a length as shown in FIG. 2 . As shown in the same figure, the reactor body 5 is composed of a reactor upper portion 6, a reactor middle portion 7, and a reactor lower portion 8, and is connected via connection portions 9, 10, respectively. The reactor upper portion 6, the reactor middle portion 7, and the reactor lower portion 8 are respectively formed to have the same width, but the cross-sectional area of the upper portion 6 of the reactor is formed to be larger than the cross-sectional area of the central portion 7 of the reactor, and the cross-sectional area of the central portion 7 of the reactor is formed to be larger than The cross-sectional area of the lower portion 8 of the reactor. As a result, the cross-sectional area of the entire reactor main body 5 is configured to increase the upward discontinuity. Further, the connecting portions 9, 10 are formed in a wide tapered shape upward.

On the lower side of the reactor lower portion 8, a slightly conical inflow chamber 11 for inflowing a solution containing an indium compound as a processing target is provided, and an inflow pipe 12 is further provided at a lower portion thereof. A check valve is provided in the inflow pipe 12, but is not shown. Further, an upper chamber 13 is provided on the upper side of the reactor upper portion 6, and a discharge pipe 14 for depositing tin as an impurity metal on the surface of the metal particles (iron particles) and discharging it is provided on the side portion. The upper chamber 13 is not only used for discharging the tin and the iron particles at the same time by discharging the tube 14, but also is applied to a portion of the iron particles based on ionization of tin removed as an impurity. The tendency is to produce a so-called chemical displacement reaction (metal precipitation reaction). In fact, the chemical displacement reaction of iron and tin is produced in the entirety of the reactor body 1 described above.

Then, the solution containing the indium compound flowing from the inflow pipe 12 reaches the discharge pipe 14, and the waste liquid is configured to form a fluidized bed of iron particles while rising in the vertical direction. Further, the ultrasonic oscillators 15a, 15b, and 15c, which are exfoliating means for separating the impurity metal contained in the solution containing the indium compound, that is, the tin deposited on the surface of the iron particle by the chemical substitution reaction, respectively, It is disposed in the upper portion of the reactor 6, the middle portion of the reactor 7, and the lower portion 8 of the reactor.

In the present embodiment, iron particles are used as the input metal particles as described above. It is preferred to use metal particles having an average particle diameter of iron particles of 0.1 to 8 mm, but in the present embodiment, an average particle diameter of about 3 mm is used. Further, the average particle diameter was measured by a video analysis method or a JIS Z 8801 sieving test method or the like.

The precipitation removing device 3 is for removing the above iron particles by hydroxide precipitation. The precipitation of the hydroxide is carried out by adding an alkali (alkaline solution) such as sodium hydroxide. The pH of the waste liquid in the precipitation removing device 3 was adjusted to 8 to 9.

The reactor 4 for recovery is used to remove impurity tin as described above, and to recover indium from a solution containing an indium compound after the iron is precipitated by hydroxide precipitation, and thus has the reactor 2 for removing impurities described above. The same composition. That is, as shown in Fig. 2, the reactor main body 5 including the reactor upper portion 6, the reactor middle portion 7, and the reactor lower portion 8 is connected via the connecting portions 9, 10. In the recovery reactor 4, the pH is adjusted to 1.5 or less.

The inflow chamber 11, the inflow tube 12, the upper chamber 13, and the discharge tube 14 are provided, and the ultrasonic oscillators 15a, 15b, 15c are respectively disposed in the upper portion of the reactor 6, the middle portion of the reactor 7, and the reaction. The lower portion 8 of the device is also the same as the reactor 2 for impurity removal.

Then, if a device for recovering indium from a waste LCD having such a configuration and a method for recovering indium from a waste LCD are used, the waste LCD is first pulverized in a pulverizer (not shown) and will be pulverized. The waste LCD is supplied to the indium dissolution device 1. To the indium dissolution apparatus 1, hydrochloric acid (aqueous hydrochloric acid solution) is added, and indium is eluted from the waste LCD using the hydrochloric acid, and a solution containing an indium compound having an indium content of 100 to 300 mg/L is obtained in the indium dissolution apparatus 1.

Next, the solution containing the indium compound is supplied to the reactor 2 for impurity removal. The solution containing the indium compound supplied to the reactor 2 for impurity removal flows into the reactor main body 5 through the inflow chamber 11 from the inflow pipe 12 of the reactor 2 for impurity removal. On the other hand, metal particles (iron particles) for generating a chemical displacement reaction are introduced from the upper chamber 13. In the reactor main body 5, the solution containing the indium compound flowing in is raised in the vertical direction, and on the other hand, the solution containing the indium compound and the iron particles charged from the upper chamber 13 are in a fluid state to form a fluidized bed.

Then, the ionization tendency of tin, which is an impurity metal other than indium contained in the solution containing the indium compound, is different from that of the metal particle to be charged, and a so-called chemical replacement reaction occurs. More specifically, the reduction reaction of each metal ion is as follows, and the standard electrode potential (E°) of each metal ion is shown.

Iron ^{2 +} +2e → Iron.........(1) -0.44 V Tin ^{2 +} +2e → Tin... (2) -0.14 V

As also shown in the above (1) and (2), the standard electrode potential of iron ^{2 +} is smaller than that of tin ^{2 +} . In other words, iron ionization tends to be larger than tin. Thus, as in the state in which the flow becomes a state, the larger the ionization tendency of iron to become iron ^{+ 2 (in} contrast to the reaction of (1) above) and the compound was dissolved in a solution containing indium, a solution containing both of indium compound Tin ^{2 +} contained in it is tin and precipitates on the surface of iron particles.

Then, the tin is deposited on the surface of the iron particles by such a chemical displacement reaction, and then the ultrasonic oscillators 15a, 15b, and 15c are activated. By operating the ultrasonic oscillators 15a, 15b, and 15c, the ultrasonic waves emitted from the ultrasonic oscillators 15a, 15b, and 15c impart a vibration force and a stirring force to the iron particles deposited by the tin. The precipitated tin is peeled off from the iron particles.

The tin stripped in this manner is discharged from the upper chamber 13 through the discharge tube 14 to the outside of the reactor body 5, and finally removed from the solution containing the indium compound. In this case, in the present embodiment, a particulate material is used as the metal (iron) to be used for removing the impurity metal. Therefore, for example, a metal for generating a chemical displacement reaction (iron) is used as compared with the case of inputting an iron block or the like. The surface area increases, and the precipitation reaction rate of tin increases. Then, after the precipitation of the metal having a certain degree of growth is confirmed, the new metal surface (the surface of the iron particle) can be often exposed by the forced peeling of the vibration of the ultrasonic wave as described above, thereby maintaining the reaction rate.

Further, the iron metal particles constituting the flow within the reactor body 5, as described above by substitution reaction of chemical dissolution of the iron ^{+ 2,} and therefore into upper chamber 13 of the particle diameter of metal particles at the time of the initial investment, will over time After a certain reduction. As a result, the original waste liquid rises in the reactor main body 5 at almost the same upward flow velocity, so that the metal particles which are smaller in the upper portion and which become smaller and smaller in size are inadvertently overflowed from the reactor body 5.

However, in the present embodiment, the cross-sectional area of the reactor body 5 is formed so as to become more discontinuous toward the upper side, so that the upward flow velocity of the waste liquid in the reactor body 5 is slowly decreased, so as described above, The metal particles having a reduced particle size due to a chemical substitution reaction or the like are likely to remain in the reactor body 5 without being inadvertently overflowed in the upper portion of the reactor body 5 whose cross-sectional area is increasing.

In addition, when a solution containing an indium compound flows in from the lower side of the reactor main body 5 and passes through the inside of the reactor main body 5, a metal such as tin is precipitated by a chemical substitution reaction to form a metal particle composed of iron. Therefore, the concentration of the impurity metal in the solution containing the indium compound is lowered toward the upper portion of the reactor body 5.

However, in the present embodiment, it was confirmed that the finer metal particles were present in the upper portion of the reactor main body 5, and the upward flow velocity of the solution containing the indium compound was gradually decreased, so that the number of metal particles was increased, so that the reactor was more toward the reactor. The larger the total surface area of the metal particles on the upper portion of the body 5 is. As a result, since the reaction rate of the chemical substitution reaction (efficiency of precipitation of the impurity metal) is improved, Ni which is an impurity metal can be effectively removed from the waste liquid in the upper portion of the reactor main body 5 in which the impurity metal concentration is further lowered. tin.

Next, a solution containing the indium compound containing tin is supplied to the precipitation removing device 3. To the precipitation removing device 3, an alkali (alkaline solution) such as sodium hydroxide is added. Thereby, a solid of iron hydroxide and indium hydroxide is produced. In other words, in the reactor 2 for removing impurities, the tin is deposited on the iron particles by a chemical substitution reaction, and then the iron ions (iron ^{2 +} ) are dissolved in the solution containing the indium compound. Therefore, before the solution containing the indium compound is supplied to the recovery reactor 4 in the subsequent stage, the iron ^{2 +} must be removed from the solution containing the indium compound in advance. Therefore, iron hydroxide and indium hydroxide solid matter are formed by adding a base as described above, but the precipitate of iron hydroxide is formed at a speed substantially faster than that of indium hydroxide, and thus is controlled by, for example, agglomerating sedimentation tank. The residence time of the liquid to be treated in the precipitation removing device 3 and the like are easily removed in the precipitation removing device 3 to remove the iron hydroxide.

Next, the pH of the solution containing the indium compound after the precipitation of the hydroxide of iron is adjusted to 1.5 or less, and the indium hydroxide is dissolved again, and then supplied to the recovery reactor 4. The solution containing the indium compound supplied to the recovery reactor 4 flows into the reactor main body 5 from the inflow pipe 12 through the inflow chamber 11 in the same manner as in the case of the impurity removal reactor 2. On the other hand, metal particles (Zn particles or Al particles) for generating a chemical displacement reaction are introduced from the upper chamber 13. Similarly to the case of the reactor 2 for impurity removal, the solution containing the indium compound flowing in the reactor main body 5 rises, and the metal particles introduced from the upper chamber 13 become in a flowing state.

Then, a so-called chemical replacement reaction occurs depending on the difference in the ionization tendency of indium in the solution containing the indium compound to be recovered and Zn or Al as the metal particles to be charged. The reduction reaction of each metal ion is as follows, and the standard electrode potential (E°) of each metal ion is shown.

Indium ^{3 +} +3e → Indium... (3) -0.34 V Zn ^{2 +} +2e → Zn......(4) -0.76 V Al ^{3 +} +3e → Al.........(5) -1.66 V

As indicated by the above (3) to (5), the standard electrode potential of Zn ^{2 +} or Al ^{3 +} is smaller than that of indium ^{3 +} . In other words, the ionization tendency of Zn or Al is larger than that of indium. Therefore, in the state of the flow state as described above, Zn or Al having a large ionization tendency becomes Zn ^{2 +} or Al ^{3 +} (reaction opposite to the above formulas (4) and (5)) and is dissolved therein. In the solution of the indium compound, indium ^{3 +} contained in the solution containing the indium compound is changed to indium and precipitated on the surface of the Zn or Al particles.

Then, indium is deposited on the surface of the Zn or Al particles by such a chemical displacement reaction, and then the ultrasonic oscillators 15a, 15b, and 15c are activated. By operating the ultrasonic oscillators 15a, 15b, and 15c, the ultrasonic waves emitted from the ultrasonic oscillators 15a, 15b, and 15c are supplied with vibration force and stirring force by the Zn or Al particles in which the indium is precipitated. The precipitated indium is forcibly peeled off from the Zn or Al particles.

The indium stripped in this manner is discharged from the upper chamber 13 through the discharge tube 14 to the outside of the reactor body 5, whereby indium is recovered as a valuable metal. In this case, in the present embodiment, as in the case of the iron of the impurity-removing reactor 2, since the Zn or Al-based particles are used, the surface area of the metal for chemical substitution reaction increases. And the precipitation reaction rate of indium is increased.

Then, after the precipitation of the metal having a certain degree of growth is confirmed, the surface of the new Zn or Al particles is often exposed by forced peeling of the ultrasonic vibration as described above, thereby maintaining the reaction rate.

Further, since Zn ^{2 +} or Al ^{3 +} is eluted from the Zn or Al particles by the chemical substitution reaction, the particle diameter of the Zn or Al particles charged into the upper chamber 13 at the initial stage of introduction is inevitably decreased over time. As a result, if the solution containing the indium compound originally rises in the reactor main body 5 at almost the same upward flow velocity, the Zn or Al particles which are smaller in the upper portion and smaller in size from the reactor body 5 do not exist. Cautious overflow.

However, in the present embodiment, the cross-sectional area of the reactor body 5 is formed such that the more discontinuous the uppermost portion is, the upward flow velocity of the solution containing the indium compound in the reactor body 5 is slowly decreased. Therefore, as described above, the metal particles having a reduced particle diameter by a chemical substitution reaction or the like are likely to remain in the reactor main body 5 without being inadvertently overflowed in the upper portion of the reactor main body 5 having a large cross-sectional area.

Further, when the solution containing the indium compound flows in from the lower side of the reactor main body 5 and passes through the inside of the reactor main body 5, the indium which is the target is deposited on the Zn or Al particles by the chemical substitution reaction, so that the reaction proceeds more. Above the body 5, the concentration of indium in the solution containing the indium compound decreases.

However, in the present embodiment, it has been confirmed that finer Zn or Al particles are present in the upper portion of the reactor main body 5, and the upward flow velocity of the solution containing the indium compound is gradually decreased to increase the number of Zn or Al particles. Thus, the more the upper portion of the reactor body 5, the greater the total surface area of the Zn or Al particles. As a result, since the reaction rate of the chemical substitution reaction (efficiency of indium precipitation) is improved, the upper portion of the reactor main body 5 having a lower indium concentration can be efficiently recovered from the solution containing the indium compound as the object to be recovered. indium.

(Embodiment 2)

The structure of the reactor 2 for removing impurities and the reactor body 5 of the reactor 4 for recovery of the present embodiment is different from that of the first embodiment. That is, in the present embodiment, as shown in Fig. 3, the entire peripheral surface of the reactor main body 5 is formed in a tapered shape, and the cross-sectional area of the reactor main body 5 is configured to increase in continuity. In this regard, the case of the first embodiment in which the cross-sectional area of the reactor body 5 is increased upward is different.

Since the cross-sectional area is configured to increase in continuity rather than discontinuity, in the present embodiment, it is not divided into the reactor upper portion 6, the reactor middle portion 7, and the lower reactor portion 8 as in the first embodiment. It is constituted by the way.

However, the ultrasonic oscillators 15a, 15b, and 15c are provided in three places from the upper portion to the lower portion of the reactor body 5, and are the same as those in the first embodiment. Therefore, in the present embodiment, as in the first embodiment, the ultrasonic waves emitted from the ultrasonic oscillators 15a, 15b, and 15c are used to obtain an impurity metal which can be removed from the surface of the metal particles. Or the effect of forcibly peeling off the target metal, ie, indium.

Further, although there is a difference in discontinuity or continuity, the cross-sectional area is increased in the upward direction, and is the same as in the first embodiment. Therefore, in the present embodiment, fine metal particles having a reduced particle diameter are also retained. The effect of preventing the inadvertent overflow of the upper portion of the reactor body 5 and the effect of effectively removing or recovering the target metal at the upper portion of the reactor body 5 having a lower concentration of the target metal.

(Embodiment 3)

In the present embodiment, as a method of peeling the precipitated metal from the metal particles, a method of stirring by ultrasonic waves is used instead of the ultrasonic waves emitted from the ultrasonic oscillator in the first and second embodiments. That is, in the present embodiment, as shown in FIG. 4, the slide plate 17 provided with the electromagnet 16 as shown in FIG. 5 is attached to the rail 18 having a rectangular horizontal section and provided on the side surface of the reactor main body 5. As shown in FIG. 5, the slide plate 17 has a space portion 19 at its center, and the reactor body 5 is inserted into the space portion 19 to surround the reactor body 5. Further, the metal particles used in the present embodiment are iron or the like of a magnetic body.

Then, as shown by an arrow 20 in FIG. 4, the metal particles in the reactor body 5 are stirred by moving them up and down, and a plurality of metal particles collide with each other, thereby forcibly separating the precipitated metal from the metal particles. . Although the method of separating the precipitated metal from the metal particles is different, in the present embodiment, the precipitated metal may be appropriately peeled off from the metal particles, and the removal of the impurity metal or the recovery of the indium as the valuable metal may be appropriately performed. .

(Embodiment 4)

In the present embodiment, a case where the waste LCD is placed in a bag and the indium acid elution treatment, the cleaning neutralization treatment, and the drying treatment are used will be described. As shown in FIG. 6, the apparatus for recovering indium from the waste LCD of the present embodiment includes a elution processing device 25, a cleaning neutralization processing device 26, and a drying processing device 27. As shown in FIG. 7, the elution processing apparatus 25 is provided with the elution processing container 22, such as an FRP tank. The elution processing container 22 is formed into a size that can be accommodated in a bag 21 such as a resin or a cloth, such as a flexible packaging bag. Further, a porous plate 23 and a porous plate support 24 are provided in the lower portion of the elution treatment container 22. Then, the bag 21 is configured to be held by the perforated plate 23.

Then, the waste LCD pulverized by the pulverizer or the like is circulated in the state in which the indium is dissolved and extracted with the hydrochloric acid solution, and the hydrochloric acid solution is passed through the waste LCD layer 28, and is dissolved and extracted from the waste LCD. Indium. That is, indium tin oxide was dissolved from the waste LCD using hydrochloric acid to obtain a solution containing an indium compound.

On the other hand, the waste LCD after the dissolution extraction treatment is directly placed in the bag 21, moved to the next cleaning and neutralizing treatment device 26, and placed in the cleaning and processing device 26 for carrying out Cleaning and neutralization treatment. The movement from the elution processing device 25 to the cleaning and neutralizing processing device 26 is performed by a crane or the like. As in the indium dissolution treatment, water is used in the cleaning treatment, and an alkaline solution is used in the neutralization treatment for the circulation treatment. In this case, the circulating flow direction of the liquid can flow downward or upward. The waste LCD which has been subjected to the cleaning neutralization process is moved to the drying processing device 27 in a state of being directly accommodated and held in the bag. The drying treatment device 27 is dried by, for example, air drying, but may be dried by a drying method such as exposure drying without using the drying treatment device 27. The waste LCD after the completion of the drying process is directly held in the bag 21, and is transported to a brick factory, a glass factory, or the like as a circulating material.

In the present embodiment, the process can be simplified by continuously processing the fine waste LCD pulverized in the waste LCD pulverization step in the state of being placed in the bag 21 as described above. Further, it is not necessary to process the fine waste LCD sheet received in the waste pulverization step and then process it, which is easy to handle.

Further, the bag 21 may have a mesh (porosity) such that the waste LCD does not fall, and a cloth maker is sufficient. In addition to the porosity of the hydrochloric acid solution, the entire bag may be formed only by the porosity at the bottom of the bag 21. In either case, by providing the bag 21 on the perforated plate 23 in the dissolution processing container 22, the bag and the wall surface of the dissolution processing container 22 are closely followed by the own weight of the waste LCD in the bag 21, whereby the hydrochloric acid solution passes through the waste. The LCD layer is moved from the bottom of the bag 21 to the bottom of the elution processing container 22 via the perforated plate 23, so that indium can be subjected to a solution extraction treatment in the waste LCD by a circulation process.

(Other embodiments)

Further, in the above-described embodiment, the case where tin as an impurity metal other than indium contained in the solution containing the indium compound obtained by dissolving ITO in the waste LCD is used is described. It can remove metals other than tin. In this case, metal particles other than iron may also be added.

Further, in this embodiment, the case where indium is precipitated on the metal particles and the indium precipitated from the metal particles is peeled off from the metal particles is described. However, the indium is not limited to the metal indium, and the indium is used. The present invention can also be applied to the case where an alloy of another metal, that is, an indium alloy is deposited on the metal particles, and the indium alloy precipitated therefrom is peeled off from the metal particles.

Further, in the above embodiment, hydrochloric acid is used as the acid which dissolves ITO in the waste LCD, but the type of the acid is not limited to hydrochloric acid, and for example, sulfuric acid, nitric acid or the like may be used, or a mixed acid or the like may be used.

Further, in the above-described embodiment, the above-described impurity removing reactor 2 is provided to obtain the above-described preferable effects. However, it is not essential for the present invention to provide the reactor 2 for removing impurities. Further, in the above-described embodiment, the case where Zn or Al particles are added to recover indium is described. However, the metal particles added to the recovery reactor are not limited to the Zn or Al particles of the embodiment, and the key is to use The ionization tendency is greater than the metal of indium.

Further, in this embodiment, the particle diameter of the metal particles is set to about 3 mm, but the particle diameter of the metal particles is not limited to the embodiment, and is preferably 0.1 to 8 mm. The reason for this is that if the particle diameter is less than 0.1 mm, there is a possibility that the chemical substitution reaction does not proceed smoothly, and it is difficult to recover the precipitated metal which is peeled off from the metal particles; and if it exceeds 8 mm, it may be stored in the case where it is more than 8 mm. The number of metal particles in the reactor body is reduced, and as a result, the total surface area of the metal particles is reduced, and the efficiency of the precipitation reaction is lowered, and a metal other than the valuable metal or the impurity metal for the purpose of recovery is precipitated on the metal particles.

Further, in the above-described first and second embodiments, the cross-sectional area of the reactor main body 5 is formed so that the larger the upper portion is, the better the effect as described above is obtained, but the reactor body 5 is formed in this manner, not The necessary conditions of the present invention. Further, the method of separating the precipitated metal from the metal particles is not limited to the method of using ultrasonic waves according to the first and second embodiments or the method of using the electromagnet according to the third embodiment, and may be a method other than the above.

Example

The indium dissolution extraction treatment for indium recovery treatment was carried out in a device as shown in Fig. 8 using a 1%, 3%, and 10% hydrochloric acid solution. In Fig. 8, reference numeral 28 denotes a waste LCD layer also illustrated in Fig. 7, 29 denotes a tube pump, 30 denotes hydrochloric acid, 31 denotes a resin container, and 32 denotes a net cage. According to the analysis, the waste LCD contains 400 mg/kg of indium. The dissolution treatment is: holding a 24 kg waste LCD in a cotton bag, and placing the bag into a resin container 31 having a plurality of holes on the bottom surface of the cage 32 provided in the 100 L resin container as shown in FIG. Further, 14 L of hydrochloric acid was introduced, and the tube pump 29 was used for the circulation treatment at room temperature. At the time of the elution treatment, a gasket is provided on the lid of the 100 L resin container so that the concentration and amount of hydrochloric acid are not changed without evaporating the water; a tube pump which can seal the lid between the 100 L resin container and the lid 29 The insertion and removal portions are sealed with a shimming agent.

The test results are shown in Table 1.

As shown in Table 1, in any of the treatments, a sufficient indium recovery rate of 98% or more was also obtained by a 24 hour dissolution treatment. Further, the recovery rate was calculated based on the weight of the waste LCD, the indium content, the indium concentration in the hydrochloric acid after the treatment, and the amount of hydrochloric acid.

2. . . Impurity removal reactor

3. . . Precipitation removal device

4. . . Recycling reactor

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic block diagram showing an embodiment of an apparatus for recovering indium from a waste LCD.

Fig. 2 is a schematic front view showing a reactor for removing impurities or a reactor for recovery in the same indium recovery apparatus.

Fig. 3 is a schematic front view showing a reactor for removing impurities or a reactor for recovery according to another embodiment.

Fig. 4 is a schematic front view showing a reactor for removing impurities or a reactor for recovery according to another embodiment.

Fig. 5 is a schematic plan view of a skateboard including the electromagnet used in the embodiment of Fig. 4.

Fig. 6 is a schematic block diagram showing an indium recovery apparatus according to another embodiment.

Fig. 7 is a schematic cross-sectional view showing a dissolution processing apparatus in the same apparatus.

Fig. 8 is a schematic explanatory view of the apparatus used in the embodiment.

1. . . Indium dissolution device

2. . . Impurity removal reactor

3. . . Precipitation removal device

4. . . Recycling reactor

Claims (16)

A method for recovering indium from a waste liquid crystal display, characterized in that a waste liquid crystal display containing indium tin oxide is pulverized, and indium tin oxide is dissolved in a waste liquid crystal display which is self-pulverized by an acid to obtain a solution containing an indium compound, and then flows in In the reactor for recovery, metal particles containing a metal having a higher ionization tendency than indium are added to the recovery reactor, and the metal particles are flowed, and the indium or indium alloy contained in the solution containing the indium compound is added. The surface of the metal particles is deposited on the surface of the metal particles, and then the precipitated indium or indium alloy is peeled off from the metal particles by a lift-off method, and the peeled solid indium or indium alloy is separated from the liquid component and recovered. A method for recovering indium from a waste liquid crystal display according to claim 1, which comprises a metal particle-based zinc particle or an aluminum particle having a higher ionization tendency than a metal of indium. A method for recovering indium from a waste liquid crystal display according to claim 1, wherein the method of separating the indium or indium alloy deposited on the metal particles from the metal particles is a method of vibrating the metal particles by ultrasonic waves, or A method of agitating metal particles by an electromagnet and colliding with each other. A method for recovering indium from a waste liquid crystal display according to claim 1, wherein the solution containing the indium compound is poured into the reactor for recycling before the solution containing the indium tin oxide obtained by dissolving the indium tin oxide in the self-depleting liquid crystal display In the reactor for removing impurities, a metal particle containing a metal having an ionization tendency larger than the impurity metal other than indium in the solution containing the indium compound is added to the reactor for removing impurities, and the metal is added to the metal. The particles flow so that the impurity metal is deposited on the surface of the metal particles, and then the precipitated impurity metal is removed from the metal particles by a lift-off method and then removed. A method for recovering indium from a waste liquid crystal display according to claim 4, wherein the method of separating the impurity metal deposited on the metal particles from the metal particles is performed by ultrasonically vibrating the metal particles or by electromagnet stirring A method in which metal particles collide with each other. A method of recovering indium from a waste liquid crystal display according to claim 4, wherein the impurity metal is tin. A method of recovering indium from a waste liquid crystal display according to claim 4, which comprises metal particles of iron particles having a tendency to ionize more than a metal of the impurity metal. A method of recovering indium from a waste liquid crystal display according to claim 7, wherein a base is added to the solution containing the indium compound after removing the impurity metal to cause the iron to be a hydroxide to be precipitated and removed. An apparatus for recovering indium from a waste liquid crystal display, comprising: a pulverizer for pulverizing a waste liquid crystal display containing indium tin oxide; dissolving and dissolving out indium tin oxide using an acid to obtain an indium-containing compound a solution for indium dissolution of the solution; flowing a solution containing the indium compound obtained in the indium dissolution apparatus, and adding the metal particles containing a metal having a higher ionization tendency than indium to perform precipitation of the indium or indium alloy to the metal particles a recovery reactor for a metal precipitation reaction on the surface; a peeling mechanism for recovering the precipitated indium or indium alloy from the metal particles; and a solid indium or indium alloy to be stripped from the liquid component Separation mechanism for separation. A device for recovering indium from a waste liquid crystal display according to claim 9, which comprises a metal particle-based zinc particle or aluminum particle having a metal ionization tendency greater than that of indium. The apparatus for recovering indium from a waste liquid crystal display according to claim 9, wherein the method of separating the indium or the indium alloy deposited on the metal particles from the metal particles is a method of vibrating the metal particles by ultrasonic waves, or A method of agitating metal particles by electromagnetic waves to collide with each other. An apparatus for recovering indium from a waste liquid crystal display according to claim 9, wherein a reactor for removing impurities is provided on a front side of the reactor for recovery, the reactor having: a solution containing an indium compound obtained in an indium dissolution apparatus Inflowing, adding metal particles having an ionization tendency larger than an impurity metal other than indium in the solution containing the indium compound, and flowing the metal particles to precipitate the impurity metal on the surface of the metal particles, and then depositing the precipitated metal The impurity metal is removed from the metal particles and removed. A device for recovering indium from a waste liquid crystal display according to claim 12, wherein the method for separating the impurity metal deposited on the metal particles from the metal particles is performed by ultrasonically vibrating the metal particles or by electromagnet stirring A method in which metal particles collide with each other. A device for recovering indium from a waste liquid crystal display according to claim 12, wherein the impurity metal is tin. A device for recovering indium from a waste liquid crystal display according to claim 12, wherein the metal particles containing a metal having a higher ionization tendency than the impurity metal are iron particles. A device for recovering indium from a waste liquid crystal display according to claim 15, which comprises adding a base to the indium-containing solution after removing the impurity metal to cause the iron to be a precipitate removing device for hydroxide precipitation removal.