JP2008208396A - Method for collecting indium, and apparatus therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method that preferably removes an insoluble In compound trapped in a filter therefrom which is arranged in a channel for circulating an oxalic etching solution containing oxalic acid and In, and traps the insoluble In compound contained in the oxalic etching solution, simultaneously regenerates the filter as well, and besides, preferably collects In, In alloy, the insoluble In compound and the like as a valuable source, and to provide an apparatus therefor. <P>SOLUTION: This collecting method comprises the steps of: removing the insoluble In compound from the filter having trapped the insoluble In compound in the oxalic etching solution containing oxalic acid and In by dissolving the insoluble In compound into an inorganic acid; and collecting the In, In alloy or In compound, which has dissolved in the inorganic acid. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method and apparatus for recovering indium, and more specifically, it is contained in an oxalic acid etching solution containing oxalic acid and indium, such as an etching solution such as ITO which is a compound of indium oxide and tin oxide. The present invention relates to a method and an apparatus for removing the insoluble indium compound from the filter that captures the insoluble indium compound, and recovering the indium, indium alloy, indium compound, and the like.

  Indium (In) is a metal used in various fields such as optical materials, optoelectronic materials, and compound semiconductors. In recent years, indium (In) is a transparent electrode that is an electrode of liquid crystal display (LCD) and plasma display (PDP). It is widely used as a raw material for ITO. The ITO transparent electrode is formed by forming an ITO film on a substrate such as glass, applying a resist mask, and etching the ITO film. An oxalic acid aqueous solution is used as an etching solution for the ITO film.

  When such an oxalic acid aqueous solution is used as an etching solution for an ITO film, an In compound insoluble in oxalic acid (considered as an In oxide) remains on the glass substrate as an etching residue. In order to prevent this, an application such as the following Patent Document 1 has been filed.

  The invention according to Patent Document 1 has an organic acid for etching indium tin oxide, a property of adsorbing to the surface of the indium tin oxide film, and negatively charging the surface potential (zeta potential), and has benzene in the molecule. The present invention relates to an etching solution for an indium tin oxide film characterized by containing an anionic surfactant containing no ring. Then, by adding an anionic surfactant to the oxalic acid etching solution, the zeta potential is controlled so that no etching residue remains on the glass substrate.

  Such an etching solution is circulated and used, and is replaced with a new solution when it reaches the end of its life. However, if the insoluble In compound as described above stays in the etching solution, there is a risk of causing damage to the product. A filter such as a pleated filter or a wind filter is attached to the circulation processing pipe, and about 75 to 95% of the insoluble In compound is captured and removed. The filter is replaced when the amount of trapping increases and the pressure loss increases. However, since the insoluble In compound trapped cannot be recovered by the pleated filter or the wind filter, it is treated as waste as it is.

  However, In is a rare metal that is feared to be depleted and whose national stockpiling is being studied. In recent years, various researches have been conducted on its recovery technology. Therefore, it goes without saying that it is desirable to recover the In compound from the oxalic acid etching solution as described above.

  On the other hand, as a patent application relating to the In recovery technology, for example, the following patent document 2 has been filed. The invention according to Patent Document 2 relates to a method for recovering indium, and is an invention for recovering indium by precipitating an In salt using oxalic acid as a precipitant. However, in the technique disclosed in Patent Document 2, oxalic acid is used as a precipitating agent for precipitating In salt, and both oxalic acid and In are used like the oxalic acid etching solution. In the first place, a technique such as Patent Document 2 using oxalic acid as a precipitant cannot be applied.

JP 2002-124506 A JP 2005-314786 A

  The present invention has been made to solve such a problem, and an insoluble In compound captured by a filter disposed in a flow path for circulating an oxalic acid etching solution containing oxalic acid together with In is obtained. It is an object of the present invention to provide a recovery method and apparatus that can be preferably removed and the filter can be regenerated, and that In, In alloy, In compound, etc. can be preferably recovered as valuable materials. .

The present invention has been made as an indium recovery method and apparatus for solving such problems. The indium recovery method is characterized by insolubility in an oxalic acid etching solution containing oxalic acid and indium. The insoluble indium compound is removed from the filter capturing the indium compound by dissolving it in an inorganic acid, and the indium dissolved in the inorganic acid is recovered.
Here, the insoluble indium compound refers to an indium compound that does not dissolve in oxalic acid, and examples thereof include In ₂ O ₃ (crystalline).
In addition, indium which is an object to be recovered of the present invention may be recovered as a simple metal, may be recovered as an alloy, or may be recovered as a compound or the like, and indium contained in an oxalic acid etching solution Are usually in the state of ions, compounds, etc., and it is difficult to distinguish them precisely and clearly, and it is not always necessary to clearly distinguish them all. Therefore, in the present invention, the term “indium” includes not only a simple metal but also an alloy or a compound.
Furthermore, since oxalic acid contained in the oxalic acid etching solution can also be in the state of ions, compounds, etc., in the present invention, when simply referring to “oxalic acid”, it means oxalic acid itself as well as oxalic acid itself. This includes the case of acid ions, oxalic acid compounds and the like.

Further, the indium recovery device is characterized by circulating an inorganic acid for dissolving and removing the insoluble indium compound from a filter that captures the insoluble indium compound in the oxalic acid etching solution containing oxalic acid and indium. The circulation channel 14 is provided. Still another indium recovery device is characterized by storing an inorganic acid for dissolving and removing the insoluble indium compound from a filter that captures the insoluble indium compound in the oxalic acid etching solution containing oxalic acid and indium. The acid storage tank 12 is provided.

Contained in a solution in which the insoluble indium compound is dissolved in an inorganic acid by adding a deposition metal having a higher ionization tendency than indium to a solution in which the insoluble indium compound is dissolved in an inorganic acid. It is also possible to recover indium by depositing the indium to be deposited on the surface of the deposition metal. In this case, the recovery apparatus further includes a reactor main body for performing a metal deposition reaction that deposits on the surface of the deposition metal.

Further, the electrode is immersed in a solution in which an insoluble indium compound is dissolved in an inorganic acid, and indium or an indium alloy contained in the solution in which the insoluble indium compound is dissolved in an inorganic acid, or an indium compound is added to the electrode. It is also possible to recover indium by precipitating it on the surface.
Here, the type of the electrode is not particularly limited. As the anode electrode, for example, an electrode made of a noble metal such as platinum, a carbon electrode, or a titanium base material is coated with a noble metal such as Pt, Ir, Ir ₂ O ₃ or RuO _2. Electrode (insoluble electrode) or the like can be used. These can suppress dissolution of the electrode base material in the liquid when used as an anode electrode. Also, as the cathode electrode, an electrode of a noble metal such as platinum, a carbon electrode, an insoluble electrode, or the like can be used. In addition, an electrode made of SUS can also be used as the cathode electrode.

Furthermore, it is also possible to collect indium by concentrating the inorganic acid by repeatedly circulating a solution in which the insoluble indium compound is dissolved in the inorganic acid in the circulation channel.

  In the present invention, as described above, the insoluble indium compound captured by the filter is dissolved in the inorganic acid, and the dissolved indium is recovered. Therefore, the insoluble In compound captured by the filter can be suitably removed. Therefore, there is an effect that the filter disposed in the circulation path of this kind of oxalic acid etching waste liquid, which has been conventionally disposed of, can be regenerated and reused.

  Furthermore, there is an effect that In removed from the filter can be suitably recovered.

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

(Embodiment 1)
As shown in FIG. 1, the indium recovery apparatus of the present embodiment includes a reactor main body 1, an acid storage tank 12, and a filter 13, and these are arranged in a circulation channel 14. . And the in-line filter 15 which is a process target object is arrange | positioned between the said reactor main body 1 and the acid storage tank 12 in the said circulation flow path 14, as shown in FIG.

As will be described later, the reactor main body 1 is for depositing In from an inorganic acid by a cementation reaction (metal precipitation reaction). Prior to that, the acid storage tank 12 is circulated in the circulation channel 14 in-line. An inorganic acid for dissolving the insoluble In compound captured by the filter 15 is stored. In this embodiment, hydrochloric acid is used as the inorganic acid.

The filter 13 is for separating and recovering In deposited in the reactor body 1. In addition, in FIG. 1, the pump etc. which circulate a to-be-processed liquid are not shown in figure.

  The reactor body 1 is vertically long as shown in FIG. 2, and includes a reactor upper part 2, a reactor intermediate part 3, and a reactor lower part 4, which are continuously connected via connecting parts 5 and 6, respectively. The reactor upper part 2, the reactor intermediate part 3, and the reactor lower part 4 are formed to have the same width, but the cross-sectional area of the reactor upper part 2 is formed larger than the cross-sectional area of the reactor intermediate part 3, and the reactor intermediate part 3 is cut off. The area is larger than the cross-sectional area of the reactor lower part 4. As a result, as a whole, the cross-sectional area of the reactor body 1 is configured to discontinuously increase upward. The continuous portions 5 and 6 are formed in a taper shape that is wide upward.

  Under the reactor lower part 4, a substantially conical inflow chamber 7 for inflowing the waste liquid to be treated is provided, and an inflow pipe 8 is provided in the lower part thereof. Although not shown, the inflow pipe 8 is provided with a check valve. Further, an upper chamber 9 is provided on the upper side of the reactor upper portion 2, and a discharge pipe 10 for discharging the recovered flake-like or particulate recovery target metal is provided on the side portion thereof. The upper chamber 9 is a part for discharging the metal recovered by such a discharge pipe 10 and also causes a so-called cementation reaction (metal precipitation reaction) based on the difference in ionization tendency from the metal to be recovered. This is also a portion into which metal particles of a deposition metal having a larger ionization tendency than the metal to be collected are introduced. Actually, the cementation reaction between the input metal and the recovered metal occurs in the entire reactor body 1.

  And while the waste liquid which flowed in from the inflow pipe 8 reaches the discharge pipe 10, it is comprised so that the fluid bed may form the fluidized bed by a metal particle, rising that vertical direction. Furthermore, ultrasonic oscillators 11a, 11b, and 11c serving as peeling means for peeling the metal to be collected, which is a metal contained in the waste liquid and deposited on the charged metal particles by the cementation reaction, are reactors. It is provided in the upper part 2, the reactor intermediate part 3, and the reactor lower part 4, respectively.

  In this embodiment, zinc (Zn) or aluminum (Al) particles are used as the metal particles to be input. The liquid flowing into the reactor main body 1 is hydrochloric acid that circulates in the circulation flow path 14. Metal particles having an average particle diameter of 2 mm are used in the present embodiment, although metal particles having an average particle diameter of 0.1 to 8 mm can be used. The average particle diameter is measured by an image analysis method or a JIS Z 8801 sieving test method.

  A method for recovering indium by the indium recovery apparatus having such a configuration will be described. First, hydrochloric acid stored in the acid storage tank 12 is circulated in the circulation flow path 14. By repeatedly circulating hydrochloric acid in the circulation flow path 14, the insoluble In compound captured by the in-line filter 15 disposed in the circulation flow path 14 is gradually dissolved in hydrochloric acid.

  On the other hand, hydrochloric acid circulated in the circulation channel 14 flows into the reactor main body 1 from the inflow pipe 8 through the inflow chamber 7, but the insoluble In compound gradually dissolves in hydrochloric acid as described above. After a certain amount of In compound is dissolved in hydrochloric acid, metal particles (Zn or Al particles) for causing a cementation reaction are introduced from the upper chamber 9. In the reactor main body 1, the hydrochloric acid containing the In compound that has flowed in rises in the vertical direction, while the metal particles introduced from the upper chamber 9 are in a fluidized state so as to form a fluidized bed.

  Then, a so-called cementation reaction is caused based on a difference in ionization tendency between In contained in hydrochloric acid and Zn or Al as the charged metal particles. This will be described in more detail. The reduction reaction of each metal ion is as shown in the following formulas (1) to (3), and the standard electrode potential (E °) of each metal ion is shown respectively.

In ³⁺ + 3e → In (1) -0.34V
Zn ²⁺ + 2e → Zn (2) −0.76V
Al ³⁺ + 3e → Al (3) -1.66V

As is clear from the above (1) to (3), the standard reduction potential of Zn ²⁺ and Al ³⁺ is smaller than that of In ³⁺ . In other words, the ionization tendency of Zn and Al is larger than that of In. Therefore, Zn or Al having a large ionization tendency becomes Zn ²⁺ or Al ^{3+ in the} fluidized state as described above and is eluted into the waste liquid, and together with the In ³⁺ contained in the waste liquid. Becomes In and precipitates on the surface of Zn or Al particles.

  And after precipitating In on the surface of Zn or Al particle | grains by such a cementation reaction, the ultrasonic oscillators 11a, 11b, and 11c are operated. By operating the ultrasonic oscillators 11a, 11b, and 11c, ultrasonic waves oscillated from the ultrasonic oscillators 11a, 11b, and 11c are vibrated and stirred by the Zn particles or Al particles in which the In is precipitated. Thus, the deposited In is forcibly separated from the Zn particles or Al particles. In this case, the ultrasonic oscillators 11a, 11b, and 11c can be operated continuously. However, if the ultrasonic oscillators are operated continuously, the ultrasonic oscillator generates heat, and the ultrasonic oscillator is operated for a long time. May become difficult.

Further, when the ultrasonic oscillator is continuously operated, the deposited metal (In) is peeled off sequentially before growing to a certain size, and as a result, a certain size of metal (In) is obtained. There is a risk of not. In this regard, when the ultrasonic oscillator is operated intermittently, there is little risk of inadvertent peeling until the deposited metal becomes large to some extent, so that the separated metal can be easily separated. Therefore, it is preferable to operate the ultrasonic oscillators 11a, 11b, and 11c intermittently. The intermittent operation in this case is performed, for example, by turning on for 2 seconds, turning off for 8 seconds, or the like.

The treatment liquid containing In thus peeled is discharged from the upper chamber 9 through the discharge pipe 10 to the outside of the reactor main body 1, separated by the filter 13, and the separated In is recovered. is there. On the other hand, the separated hydrochloric acid circulates in the circulation channel 14.
In this case, in this embodiment, since the particulate metal is used as the deposition metal to be added to deposit the metal to be collected, the surface area of the metal for causing the cementation reaction is increased. The speed of the In precipitation reaction will be improved.

  Then, after the deposition of the metal that has grown to some extent is recognized, a new metal surface can always be exposed and the reaction rate can be maintained by forced peeling by ultrasonic vibration as described above. Further, the separated recovered metal contains very little impurities other than In.

Further, since the metal particles made of Zn flow in the reactor main body 1 and Zn ²⁺ is eluted by the above cementation reaction, the particle size at the initial charging time of the metal particles charged into the upper chamber 9 is It will inevitably decrease over time. As a result, since the hydrochloric acid ascends in the reactor main body 1 at substantially the same upward flow rate, the metal particles whose particle size decreases and becomes smaller toward the upper part are inadvertently overflowed from the reactor main body 1. There is a risk of flowing.

  However, in this embodiment, since the cross-sectional area of the reactor main body 1 is formed so as to increase discontinuously as it goes upward, the upward flow rate of hydrochloric acid in the reactor main body 1 gradually decreases. Therefore, the metal particles whose particle size is reduced by the cementation reaction or the like as described above are held in the reactor body 1 without inadvertently overflowing in the upper part of the reactor body 1 where the cross-sectional area increases. Is more likely.

In addition, hydrochloric acid flows in from the lower side of the reactor main body 1, and when passing through the reactor main body 1, In that is to be recovered is precipitated on metal particles made of Zn by a cementation reaction. The concentration of the metal to be recovered in hydrochloric acid decreases as the distance increases. However, in this embodiment, it is recognized that finer metal particles are present in the upper part of the reactor body 1 and that the number of metal particles increases as the upward flow rate of hydrochloric acid gradually decreases. The total surface area of the metal particles increases toward the top of 1. As a result, the reaction rate of the cementation reaction (efficiency of deposition of the recovery target metal) is improved, so that the recovery target metal is efficiently recovered even at the upper part of the reactor body 1 where the concentration of the recovery target metal is lower. It becomes possible to do.
In this embodiment, the inline filter is started to be washed with an inorganic acid, and the deposition metal is put into the reactor main body after a certain period of time. However, the present invention is not limited to this, and the cleaning starts in the reactor main body. A deposited metal may be added from the beginning.

(Embodiment 2)
In the present embodiment, the structure of the reactor main body 1 is different from that of the first embodiment. That is, in this embodiment, as shown in FIG. 3, the entire peripheral surface of the reactor main body 1 is formed to be tapered upward, and the cross-sectional area of the reactor main body 1 continuously increases upward. It is configured. This is different from the case of the first embodiment in which the cross-sectional area of the reactor body 1 discontinuously increases upward. Since the cross-sectional area is not discontinuous, and is configured to continuously increase upward, in this embodiment, the reactor upper portion 2, the reactor intermediate portion 3, and the reactor lower portion 4 as in the first embodiment. It is not configured in such a way.

  However, the ultrasonic oscillators 11a, 11b, and 11c are common to the first embodiment in that the ultrasonic oscillators 11a, 11b, and 11c are provided at three locations from the upper part to the lower part of the reactor body 1. Therefore, also in this embodiment, as in the first embodiment, the recovery target metal deposited on the metal particles can be forcibly separated by the ultrasonic waves oscillated from the ultrasonic oscillators 11a, 11b, and 11c. The effect that can be obtained.

  In addition, although there is a difference between discontinuous and continuous, this embodiment is common to Embodiment 1 in that the cross-sectional area is configured to increase upward. In this case, the fine metal particles having a reduced particle size are held at the upper part of the reactor main body 1 to prevent inadvertent overflow, and the upper part of the reactor main body 1 at which the concentration of the metal to be collected is low. In this case, there is an effect that the recovery target metal can be efficiently recovered.

(Embodiment 3)
The reactor main body 1 of this embodiment is the same as that of the first and second embodiments in that it is vertically long, but is formed so that the cross-sectional area is the same in the vertical direction as shown in FIGS. 4 and 5. In this respect, the second embodiment is different from the first and second embodiments that are configured such that the cross-sectional area increases upward.

  Also in the present embodiment, as in the first embodiment, the inflow chamber 7 is provided on the lower side of the reactor body 1 and the upper chamber 9 is provided on the upper side of the reactor body 1. The shape is different from that of the first embodiment formed in a substantially conical shape. That is, the upper chamber 9 is formed in a shallow cylindrical shape as shown in FIGS. 4 and 5, and the inflow chamber 7 includes a central cylinder portion 20 and the central cylinder as shown in FIGS. 6 and 7. It is formed in the shape which consists of the side cylinder parts 21 and 21 provided in the right and left in communication with the part 20.

  In the present embodiment, the inflow pipes 8 and 8 are respectively provided on the distal end sides of the side tube portions 21 and 21 of the inflow chamber 7. Further, two baffle plates 22 and 23 are provided in the longitudinal direction in the side tube portions 21 and 21 of the inflow chamber 7, and hydrochloric acid flowing in from the inflow pipes 8 and 8 is supplied to the baffle plates 22 and 23. It is comprised so that a flow may be disturbed by 23 (FIG. 7).

The upper chamber 9 is composed of an inner cylinder 9a and an outer cylinder 9b as shown in FIG. 5, and the upper chamber 9a is externally fitted to the upper portion of the reactor body 1 as shown in FIG. 9 is attached to the reactor body 1. Further, the discharge pipe 10 is attached to a position below the upper chamber 9 and between the inner cylinder 9a and the outer cylinder 9b.
As a result of such a configuration, hydrochloric acid flowing upward in the reactor main body 1 overflows from the upper opening of the inner cylinder 9a between the outer cylinder 9b and the inner cylinder 9a, and is discharged from the discharge pipe 10 to the outside. Will be discharged.

  Further, the metal particles for causing the cementation reaction are introduced from the upper opening of the inner cylinder 9a. And it is comprised so that the waste fluid which flowed in from the inflow pipe 8 of the inflow chamber 7 may reach the discharge pipe 10 of the upper chamber 9 to form a fluidized bed of metal particles while the hydrochloric acid rises vertically. The point that the cementation reaction between the input metal and the metal to be recovered occurs in the entire reactor body 1 is the same as in the first and second embodiments.

  Furthermore, also in the present embodiment, an ultrasonic oscillator is employed as a stripping means for stripping the metal to be collected, which is a metal contained in hydrochloric acid and deposited on the metal particles by the cementation reaction. That is, in this embodiment, four ultrasonic oscillators 11 a, 11 b, 11 c, and 11 d are attached to the outer peripheral surface of the reactor main body 1. The four ultrasonic oscillators 11a, 11b, 11c, and 11d are all attached to the reactor main body 1 at an angle of about 45 degrees with respect to the horizontal plane, and two of these ultrasonic oscillators 11a and 11c are attached in the same direction, and the other two ultrasonic oscillators 11b and 11d are attached so as to face in opposite directions.

  Also in this embodiment, hydrochloric acid is used as the inorganic acid for dissolving the insoluble In compound.

  In the case where indium is recovered by the indium recovery device of the present embodiment, hydrochloric acid first flows into the reactor body 1 from the inflow pipe 8 through the inflow chamber 7. In this case, the inflow chamber 7 is composed of the central cylindrical portion 20 and the side cylindrical portions 21 and 21 as described above, and the side cylindrical portions 21 and 21 are provided with two baffle plates 22 and 23 in the vertical direction. Since it is provided, the hydrochloric acid flowing in from the inflow pipes 8, 8 attached to the side tube portion 21 in a horizontal direction does not flow in the horizontal direction at once, but the baffle plate 22 provided in the vertical direction, Then, the gas flows into the central cylindrical portion 20 while alternately flowing up and down in the side cylindrical portion 21 along the flow path 23, and flows upward from the central cylindrical portion 20 toward the reactor body 1.

  Accordingly, the flow of hydrochloric acid flowing in from the inflow pipes 8 and 8 is disturbed by the baffle plates 22 and 23, and it becomes easy to flow upward in the reactor main body 1 without causing drift. If necessary, for example, a cylindrical basket containing glass or ceramic balls can be installed in the inflow chamber 7, thereby making it possible to prevent drifting more reliably.

  The action of so-called cementation reaction based on the difference in ionization tendency between In contained in hydrochloric acid and input metal particles such as Zn and Al, stirring by an ultrasonic oscillator, and action of metal peeling, etc. Since it is the same as that of the said embodiment, the detailed description is abbreviate | omitted.

(Embodiment 4)
In this embodiment, as a means for recovering In contained in hydrochloric acid, a so-called cementation reaction based on a difference in ionization direction from Zn or Al, which are metal particles as in Embodiments 1 to 3 above, is used. Instead of the above-described means, a means for applying a voltage to the electrode and depositing and collecting In on the cathode electrode is employed.

That is, in this embodiment, as shown in FIG. 8, in addition to the acid storage tank 12 and the in-line filter 15 that is the object to be treated, an electrolytic tank 16 in which an electrode plate is installed is installed in the circulation channel 14. ing. As the anode electrode plate, for example, an electrode plate made of a so-called insoluble electrode in which titanium is used as a base and platinum is coated is used. As the cathode electrode plate, SUS is used. By using an electrode plate coated with a noble metal as the anode electrode plate, it is possible to suppress dissolution of the components of the electrode plate in the solution. On the other hand, since an In precipitation reaction occurs at the cathode, the electrode plate does not dissolve.
A more specific configuration of the electrolytic cell 16 is shown in FIG. That is, as shown in FIG. 9, the electrolytic cell 16 of this embodiment is configured by alternately arranging three anode electrode plates 18 and three cathode electrode plates 19 in the cell body 17. The anode electrode plate 18 and the cathode electrode plate 19 on both outer sides are connected to a power source 21 via a connection line 20, and the three anode electrode plates 18, 18, 18 are connected to each other via a connection line 22. Further, the three cathode electrode plates 19, 19, 19 are connected to each other via a connection line 23.

Also in the present embodiment, the hydrochloric acid stored in the acid storage tank 12 is circulated in the circulation channel 14 as in the first embodiment. The point that the insoluble In compound captured by the in-line filter 15 disposed in the circulation channel 14 is gradually dissolved in hydrochloric acid by repeatedly circulating the hydrochloric acid in the circulation channel 14 is the above-described implementation. This is the same as the first embodiment. The insoluble In compound is gradually dissolved in hydrochloric acid, and when a certain amount of In compound is dissolved in hydrochloric acid, In contained in the hydrochloric acid is deposited on the insoluble electrode 16. In this way, In or the like is recovered.

In the present embodiment, there is an advantage that there is no metal elution compared to the case of using the metal precipitation reaction using the metal particles of the first embodiment. Therefore, zinc and aluminum do not dissolve in the solution after the treatment as in the first embodiment, the post-treatment can be simplified, and sludge and the like can be reduced.

Also in the present embodiment, the insoluble In compound captured by the inline filter 15 is dissolved in hydrochloric acid, and the insoluble In compound is suitably removed from the inline filter 15, whereby the inline filter 15 is regenerated and reused. As it becomes possible,
In deposited on the insoluble electrode 16 can be recovered.

(Embodiment 5)
In the present embodiment, as shown in FIG. 10, only the acid storage tank 12 and the inline filter 15 are provided in the circulation channel 14.

  In this embodiment, hydrochloric acid having a higher concentration than in Embodiments 1 to 4 (for example, adjusting the concentration of hydrochloric acid in the circulating solution to be 10%) is used, and as in Embodiments 1 to 4, an acid is used. The hydrochloric acid stored in the storage tank 12 is circulated in the circulation channel 14. Similar to Embodiments 1 to 4, the hydrochloric acid is repeatedly circulated in the circulation flow path 14 so that the insoluble In compound captured by the in-line filter 15 is gradually dissolved in hydrochloric acid.

By circulating hydrochloric acid having a relatively high concentration in the circulation flow path 14 as described above, the dissolution rate of the insoluble In compound becomes faster than those in the first to fourth embodiments. Further, the temperature may be increased in order to increase the dissolution rate (for example, about 50 to 60 ° C.). Furthermore, by replacing the in-line filter that has been cleaned with an acid, a liquid having a high In content can be obtained. In this embodiment, it becomes possible to collect as a high concentration In-containing hydrochloric acid solution in this way.

  In the present embodiment, there is an advantage that the metal eluate is not generated as a waste liquid as in the case of utilizing the metal precipitation reaction using the metal particles as in the first embodiment. On the other hand, since it is recovered as an In-containing hydrochloric acid solution, the value as a valuable resource cannot be increased as in the case of utilizing the metal precipitation reaction as in the first embodiment.

  Therefore, according to the present embodiment, after recovering a highly concentrated In-containing hydrochloric acid solution, it is possible to recover In from the hydrochloric acid solution by using, for example, a metal precipitation reaction as in the first embodiment. In can be recovered from the hydrochloric acid solution using an insoluble electrode such as 2.

(Other embodiments)
In the above embodiment, hydrochloric acid is used as the inorganic acid that circulates in the circulation channel 14, but the kind of the inorganic acid is not limited to the hydrochloric acid in the above embodiment, and for example, nitric acid, sulfuric acid, mixed acid, aqua regia Etc. can also be used. In particular, in the case of the fifth embodiment, since the inline filter is washed with an acid and only the indium compound captured by the inline filter is dissolved, any of the acids described above may be used. On the other hand, when an electrodeposition method or a cementation method is used, it is preferable to use an acid such as hydrochloric acid or sulfuric acid in order to suppress corrosion of the electrode to be used or inadvertent dissolution reaction of the deposition metal. Regarding the acid concentration of the solution, it is preferable to use a high-concentration acid for the In recovery treatment (dissolution), and to adjust the pH to a pH suitable for the treatment during precipitation (recovery).

  In the first embodiment, Zn or Al is used as a metal for depositing In. However, the type of metal for depositing In is not limited to the Zn or Al in the present embodiment, and in short, a metal having a higher ionization tendency than In. Should just be used.

  Further, in the above embodiment, the acid storage tank 12 is installed in the circulation channel 14, hydrochloric acid is stored in the acid storage tank 12, and the hydrochloric acid stored in the acid storage tank 12 is circulated in the circulation channel 14. However, it is also possible to add hydrochloric acid directly into the circulation channel 14 without installing such an acid storage tank 12.

Moreover, in this embodiment, although the average particle diameter of metal particles shall be about 2 mm, the average particle diameter of metal particles is not limited to this embodiment, and it is preferable that it is 0.1-8 mm. When the thickness is less than 0.1 mm, the cementation reaction is not always preferably performed, and there is a possibility that the recovery target metal peeled from the metal particles may not be easily recovered. The number of metal particles that can be held in the body decreases, and as a result, the total surface area of the metal particles may decrease and the efficiency of the precipitation reaction may decrease, and the flow rate needs to be increased in order to cause the metal particles to flow. This is because it is necessary to increase the reactor size (reactor height) in order to maintain the necessary reaction time.

  From this viewpoint, the thickness is more preferably 0.5 to 6 mm. Furthermore, in order to improve the fluidity and reactivity in the reactor main body and to facilitate the holding in the reactor main body, the range of 1.0 to 2.0 mm is more preferable. The average particle diameter of the metal particles is measured by an image analysis method, a JIS Z 8801 sieving test method, etc. as described above. For example, Millitrack JPA manufactured by Nikkiso Co., Ltd. is used for the measurement of the average particle diameter by the image analysis method. Further, in the JIS sieving method, when the average particle size is in the range of 1 to 2 mm, for example, metal particles that are on a 1000 μm sieve are used under a nominal size of 2000 μm sieve.

Furthermore, the uniformity of the metal particles is preferably less than 5 from the viewpoints of processing efficiency and operation control. Here, the uniformity of the metal particles refers to a transmittance curve formed by particle size distribution measurement or sieving or the like (the percentage of the mass of particles smaller than a certain particle size with respect to the total sample mass, that is, the transmittance is drawn with respect to a certain particle size. In this case, the value obtained by dividing the 60% particle size under the screen by the 10% particle size under the screen. It represents the width of the particle size distribution. Furthermore, in this embodiment, although the metal particle utilized the metal single-piece | unit, an alloy may be sufficient.

  Further, in the first and second embodiments, since the cross-sectional area of the reactor main body 1 is formed so as to increase toward the upper part, the above-described preferable effect is obtained. However, the reactor main body 1 is formed in this way. These are not essential conditions for the present invention. It is also possible to form the reactor main body 1 so that the cross-sectional area is the same as in the third embodiment and the whole is substantially cylindrical.

  Further, the means for separating the metal to be recovered from the metal particles is not limited to the ultrasonic vibration of the first embodiment, and the metal particles are collided by stirring the metal particles by other means, for example, a water flow. A means for peeling the metal to be collected by use, or a means for causing stirring and collision of metal particles using a magnet may be used. Further, from the point that the metal for precipitation can be effectively reused while easily separating and recovering the metal to be recovered, the above embodiments 1 to 3 are configured to peel the metal to be recovered from the metal for precipitation in the reactor. However, the present invention is not limited to this, and the recovery target metal may be recovered in a state where the recovery target metal is deposited on the deposition metal. In the first to third embodiments, metal particles are used as the deposition metal. However, the present invention is not limited to this, and a metal wire, a metal wire processed into a mesh shape, a plate-like metal, or the like may be used. .

(Example 1)
The exchanged filter was attached to a treatment line (flow path) through which 1% hydrochloric acid solution can be circulated, and circulated, and the insoluble In compound trapped in the filter was dissolved in hydrochloric acid. In this case, in order to increase the dissolution rate, a heating device is installed in the processing line to raise the temperature.

  The hydrochloric acid solution in which the insoluble In compound is dissolved as described above is caused to flow into the reactor as in the above embodiment, Al is added, and the In alloy is formed using the metal precipitation reaction between the Al and In. It was collected. As Al, the In alloy recovery process was started using particles having an average particle diameter of 2 mm by an image analysis method. The In alloy deposited on the Al particles was sponge-like and aggregated during the stirring process to form a large lump, so that it could be easily peeled and collected by ultrasonic treatment. Sonication was performed once every 2 minutes for 2 seconds each.

  As a result of such treatment, the insoluble In compound captured by the filter and the hydrochloric acid solution could be dissolved, and the insoluble In compound could be suitably removed from the filter.

  The insoluble In compound dissolved in the hydrochloric acid solution could be recovered at a high recovery rate of about 95% by the metal precipitation reaction using Al as described above.

(Example 2)
In place of the metal precipitation reaction using Al in Example 1, the electrode as in Embodiment 4 was used, and an Insoluble In compound was deposited on the electrode to collect In. As described in the fourth embodiment, the electrode used was a titanium base and platinum coated. In the same manner as in Example 1, the filter after replacement was attached to a treatment line capable of circulating a 1% hydrochloric acid solution and subjected to a circulation treatment, and the insoluble In compound captured in the filter was dissolved in hydrochloric acid.

An insoluble electrode was installed in the treatment line, and the insoluble In compound dissolved in hydrochloric acid as described above was deposited on the insoluble electrode to collect In. Also in this example, In could be recovered with a high recovery rate of about 95%.

The schematic block diagram of the collection | recovery apparatus of indium as one Embodiment. The schematic block diagram which shows a reactor main body. The schematic block diagram of the reactor main body of other embodiment. The schematic perspective view of the reactor main body of other embodiment. The schematic sectional drawing of the embodiment. The schematic plan view of the chamber for inflow of the embodiment. The AA line expanded sectional view of FIG. The schematic block diagram of the collection | recovery apparatus of the indium of other embodiment. The schematic sectional drawing of the electrolytic cell used for the embodiment. The schematic block diagram of the collection | recovery apparatus of the indium of other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Reactor main body 12 ... Acid storage tank 14 ... Circulation flow path

Claims (8)

  Removing the insoluble indium compound by dissolving the insoluble indium compound in the oxalic acid etching solution containing oxalic acid and indium by dissolving it in an inorganic acid, and collecting the indium dissolved in the inorganic acid. A feature of the indium recovery method.   Contained in a solution in which the insoluble indium compound is dissolved in an inorganic acid by adding a deposition metal having a higher ionization tendency than indium to a solution in which the insoluble indium compound is dissolved in an inorganic acid. The indium recovery method according to claim 1, wherein indium is recovered by precipitating indium to be deposited on the surface of the deposition metal.   The electrode is immersed in a solution in which an insoluble indium compound is dissolved in an inorganic acid, and indium contained in the solution in which the insoluble indium compound is dissolved in an inorganic acid is precipitated on the surface of the electrode. The indium recovery method according to claim 1, wherein the indium is recovered.   The method for recovering indium according to claim 1, wherein a solution obtained by dissolving an insoluble indium compound in an inorganic acid is repeatedly circulated in a circulation channel to concentrate the inorganic acid and recover indium.   A circulation channel (14) is provided for circulating an inorganic acid for dissolving and removing the insoluble indium compound from the filter capturing the insoluble indium compound in the oxalic acid etching solution containing oxalic acid and indium. And an indium recovery device. An acid storage tank (12) is provided for storing an inorganic acid for dissolving and removing the insoluble indium compound from a filter that captures the insoluble indium compound in the oxalic acid etching solution containing oxalic acid and indium. And an indium recovery device.   A liquid in which a solution in which an insoluble indium compound is dissolved in an inorganic acid flows in and a deposition metal having a higher ionization tendency than indium is added, and the insoluble indium compound is dissolved in the inorganic acid due to a difference in ionization tendency The indium recovery apparatus according to claim 5 or 6, further comprising a reactor main body (1) for performing a metal precipitation reaction for precipitating indium contained therein on the surface of the precipitation metal.   An electrode (16) for immersing an insoluble indium compound in a solution obtained by dissolving in an inorganic acid and precipitating indium contained in the solution obtained by dissolving the insoluble indium compound in an inorganic acid is further provided. Item 7. An apparatus for recovering indium from the oxalic acid etching waste liquid according to Item 5 or 6.

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