JP2006150196A - Powder concentration method for separating abrasive powder from indium oxide based scrap powder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a powder concentration method for separating abrasive powder from indium oxide based scrap powder, in which the abrasive powder for ITO scrap powder containing mainly ITO powder and the abrasive powder is removed as much as possible in order to increase the ratio of the ITO powder. <P>SOLUTION: ITO scrap powder is prepared, classification is performed in a prescribed range of grain size with respect to the ITO scrap powder, and the ITO scrap powder less than the prescribed range of grain size is fed to a floatation machine for rough ore dressing to separate powder which is floatation rough concentrate roughened by floatation ore dressing and powder which is floatation tailings. Subsequently, the powder roughened by a roughening process is fed to a floatation machine for fine ore dressing to separate powder which is floatation concentrate and powder which is floatation cuttings. In the powder concentration method, the ratio of the ITO powder is raised by removing the abrasive powder from ITO scrap powder as much as possible according to a floatation method. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a powder concentration method in which blast powder is separated from scrap powder of oxidized In (indium) powder to improve In quality in the oxidized In powder. More specifically, the present invention relates to a powder concentration method in which blast powder is separated from ITO powder scrap powder as an example of oxidized In powder and the ratio of ITO powder in ITO scrap powder (In quality) is increased.

  In recent years, digital home appliances such as LCD (liquid crystal display) and PDP (plasma display) are rapidly spreading. A transparent electrode having optical transparency and conductivity is provided on glass essential as a component of devices such as LCD and PDP.

The transparent electrode includes In ₂ O ₃ as a main component, for example, IZO (In ₂ O ₃ with 1 wt% to 30 wt% added ZnO), In ₂ O ₃ with various elements added materials in series powder, ZnO-based material of SnO ₂ system is used. A typical example of these is an ITO electrode formed from an ITO film. Therefore, the present invention will be described below by taking an ITO electrode as an example of an electrode formed from an oxidized In-based material.

As described above, due to the rapid spread of digital home appliances, indium oxide (or indium), which is an ITO film material, is in short supply in the market. (Note: The ITO ((Indium-Tin-Oxide ); A stands for indium tin oxide), a typical composition, _{an In} 2 _{O 3} is the remainder tin oxide 70wt% ~99wt% (In particular, In ₂ O ₃ -90 wt% is often used as the material of the ITO film.)

  Generally, ITO is used as a target in a vacuum chamber of a PVD (Physical Vapor Deposition) apparatus, and is sputtered and deposited on a glass substrate to form a thin film.

  In the most basic DC sputtering method in the PVD apparatus, a negative bias is applied to the target electrode to cause a discharge, and then the generated electrons collide with Ar atoms to generate Ar ions (Ar +). The Ar + is attracted to and collides with the negative direction, that is, the target, and the ITO molecules thus ejected are deposited as a thin film on the glass substrate to form a transparent electrode.

  By the way, ITO molecules vaporized in the chamber in the PVD apparatus have a high degree of vacuum in the chamber, so that the mean free path of the ITO molecules (vapor molecules) becomes large. And adheres to the inside of the chamber of the PVD apparatus other than the glass substrate (including an attachable / detachable attachment plate and parts). These deposited ITO materials can contain moisture in the air when the chamber is exposed to the atmosphere.

  For this reason, unless the material is periodically removed, the presence of the water requires a long time to achieve a degree of vacuum capable of vapor deposition inside the chamber in the PVD apparatus, which increases the running cost of the apparatus. Furthermore, there is an adverse effect that ITO powder that spontaneously peels off from an adhesion-preventing plate or the like (including solid cases; the same applies hereinafter) falls on the glass on which the transparent electrode is formed and causes defects.

  Therefore, in order to prevent the occurrence of the above-mentioned adverse effects, it is necessary to periodically remove the ITO powder adhering to the chamber wall of the PVD apparatus as the ITO scrap powder to form the ITO film. Mechanical removal is performed by, for example, spraying the blast powder (grinding abrasive grains) on the ITO firmly adhered with an air gun together with compressed air or high-pressure water.

  According to the blast removal method, ITO scrap powder in which ITO powder, blast powder, and metal powder (for example, SUS304 fine powder), which is an adhesion plate material, are mixed is obtained although ITO is removed from the adhesion plate or the like. It is produced in large quantities. If this can be recycled, it will help to solve the shortage of ITO materials in the market mentioned above.

Until now, such ITO scrap powder has been either (1) discarded as it is or (2) introduced into a process mainly consisting of a so-called acid leaching process, and indium oxide has been separated and recovered (see Patent Document 1). .
JP 2000-169991 A

  However, the price of indium oxide (or indium) has risen due to the lack of indium oxide (or indium) in the market, and in the method of separation and recovery in the acid leaching process (2), indium oxide can be more efficiently and efficiently produced. There has been a demand for separation / recovery (hereinafter, indium oxide includes indium alone).

  Therefore, the present inventors have focused on the fact that the material (ITO scrap powder) in the previous stage of the acid leaching process contributes to the high cost of the separation / recovery method of (2).

  That is, if the overall volume and weight of the ITO scrap powder are large in the acid leaching process, the overall equipment tends to be large, such as increasing the treatment tank in the acid leaching process. In addition, since the dispersion | variation in the tank of acid leaching will arise, so that a tank becomes large, it is unpreferable. For this reason, a large agitation facility is required, and the power consumption for that is not negligible in terms of cost.

  Further, blast powder using alumina powder or the like among ITO scrap powder accounts for a large percentage by weight, and the overall bulk becomes large. Therefore, it is necessary to secure a temporary stock area for unnecessary blast powder. Furthermore, since the whole volume is similarly large, the cost at the time of moving or transporting the ITO scrap powder to the acid leaching process is increased. Therefore, even if indium oxide can be used as an ITO material after it is separated and collected from ITO scrap powder, there is a problem that it is not commensurate with cost.

  On the other hand, ITO powder, blast powder, and other fine powders contained in ITO scrap powder have a certain physical beneficiation method (for example, specific gravity sorting method, electrostatic sorting method or liquid cyclone classification method) or other Although it is sufficient if separation can be performed in advance using a separation method, the above-described beneficiation method is technically difficult even when applied under various conditions. The reason for this is considered that the ITO powder in the ITO scrap powder is very fine, so that it cannot be separated by the above physical beneficiation method.

  Therefore, as a result of intensive studies, the present inventors, as a representative example of scrap powder of oxidized In-based powder, blast powder other than ITO powder from ITO scrap powder and other unnecessary fine powder (in this application, other than ITO powder) "Blasting powder and other unnecessary fine powder" shall be collectively referred to as "blasting powder".) By removing as much as possible, the total volume and weight of ITO scrap powder are reduced and the ratio of ITO powder is increased. The present inventors have found a method for concentrating ITO scrap powder that can be used ("concentration" as used in the present application refers to increasing the ratio of ITO powder to the entire ITO scrap powder, that is, increasing the In quality). The In quality (%) was obtained by ICP analysis of the metal In content in the ITO powder as a product.

  That is, the inventors of the present invention suppress at least the temporary stock cost until the acid leaching step after the ITO powder is separated from the ITO scrap powder, the transfer or transportation cost, and the processing cost in the acid leaching step as much as possible. Therefore, after the ITO blast powder is classified and the particle size is made uniform, the ITO blast powder is classified in advance by using a flotation technique (referred to as “flotation” as appropriate in this application) for the classified ITO blast powder. It is possible to reduce the cost by removing concentrated blast powder as much as possible and producing a concentrated powder with an increased ITO powder component ratio (In quality), and then introducing the concentrated powder into a process such as acid leaching. It came to know.

The present invention is for recycling oxidized In-based scrap powder that removes blast powder from oxidized In-based scrap powder containing oxidized In-based powder and blast powder by a flotation method to increase the ratio of oxidized In-based powder. A powder concentration method comprising:
Step a. A powder classification process for classifying scrap powder containing oxidized In-based powder and classifying oxidized In-based scrap powder to a particle size less than an appropriate range, and
Step b. For the scrap powder containing oxidized In-based powder separated into a particle size in the above-mentioned appropriate range, by mainly precipitating the powder containing blast powder while floating the powder containing mainly oxidized In-based powder The present invention provides a powder concentration method characterized by including a flotation process that removes powder mainly containing blast powder while collecting powder mainly containing oxidized In-based powder.

The present invention is a powder concentration method for recycling scrap powder containing the oxidized In-based powder,
Step b-1. Coarse flotation in which scrap powder containing oxidized In-based powder separated in step a is put into a flotation machine for roughing, flotation coarse concentrate powder is floated, and flotation tailing powder is settled Selection process,
Step b-2. Including a fine-flotation step in which the coarse concentrate powder obtained in step b-1 is put into a flotation beneficiator for flotation, the flotation concentrate powder is floated, and the ore powder is settled during flotation. A powder concentration method is provided.

  The present invention is a powder concentration method for recycling the above scrap powder containing oxidized In-based powder, wherein the process of step b-1 is performed a predetermined number of times, and the process of step b-2 is performed a predetermined number of times. A method is provided.

  The “predetermined number of times” includes the case of one time. For example, the case where the process b-1 is performed multiple times and the process b-2 is performed once is included, or the process b-1 is performed once and the process b-2 is performed multiple times. In some cases, the process b-1 and the process b-2 include a plurality of cases.

The present invention is a powder concentration method for recycling ITO scrap powder that removes blast powder from ITO scrap powder consisting of ITO powder and blast powder by a flotation method to increase the ratio of ITO powder (In quality),
Step a. A powder classification process for classifying ITO scrap powder and classifying ITO scrap powder to a particle size below an appropriate range; and
Step b. For the ITO scrap powder sorted into the appropriate particle size, the powder mainly containing ITO powder is collected by allowing the powder mainly containing ITO to settle while allowing the powder mainly containing ITO to float. The blast powder is removed from the ITO scrap powder containing the ITO powder and the blast powder by the flotation method, which includes a flotation process that removes the powder mainly containing the blast powder that has settled down. Provided is a powder concentration method for recycling ITO scrap powder that increases the ratio of In addition, “mainly” does not necessarily mean that the powder containing ITO is 100% selectively floated in manufacturing, and the powder containing blast powder is not necessarily 100% selectively settled. The purpose is to show that there is not.

  “ITO scrap powder” means a mixed powder of ITO powder, blast powder, and other fine powders removed from the deposition plate of the PVD apparatus by the injected blast powder together with compressed air or high-pressure water from the blaster Shall. The compressed air needs to be supplied with oil-free air.

  “Classification” refers to, for example, setting two threshold values for a desired particle size by vibrating a powder using a sieve such as a vibrating screen, and sieving powders that are less than these two threshold values (under threshold value). It is a method of sorting. There are a wet method and a dry method, but in this embodiment, a wet method using a vibration sieving device (vibration screen) that performs sieving while applying water after slurrying the powder is used.

Furthermore, the present invention is a powder concentration method for recycling the ITO scrap powder,
Step b-1. A rough flotation step in which the ITO scrap powder classified in the step a is put into a roughing flotation machine, the coarse concentrate powder is floated, and the tailing powder is settled, and a step b-2. Including a fine-flotation step in which the coarse concentrate powder obtained in step b-1 is put into a flotation machine for fine-drawing, the flotation fine-powder powder is floated, and the ore-powder is settled during flotation. A method is provided.

  In the present invention, “floating beneficiation machine” refers to “rough beneficiation” when distinguishing between coarse beneficiation and fine beneficiation. A mechanically agitated flotation machine is used. For example, a mass production flotation machine such as a Fahrenworld flotation machine (Denver sub-A type flotation machine) or a Foguegren flotation machine, or an MS type flotation machine (“MS” is an abbreviation for Mineral Separation). This applies to the pilot test flotation machine such as 2).

  “Flotation tailings” and “flotation medium ores” are powders (mineral powders) that have settled in the flotation process using the flotation machine.

  In the present invention, the “floating beneficiator for fine beneficiation” is a special flotation method that uses fine bubbles (micro bubbles) and long column (cylindrical) parts to finely select useful metal powder in the powder. For example, a microbubble type column flotation machine (FIG. 3) is applicable (details will be described later).

  Furthermore, the present invention provides a powder concentration method for recycling the above-mentioned ITO scrap powder, wherein the liquid pH value in the flotation tank is set to 2.5 to 4.5. To do.

  The reason why the liquid pH value in the flotation tank is set to 2.5 to 4.5 is that the brown corundum to be settled has a hydrophilic particle surface in the acidic region where the pH value is less than 2.5. Therefore, when the pH exceeds 4.5, the brown corundum particle surface becomes hydrophobic and easily floats, making it impossible to perform the selection by flotation, and the pH is less than 2.5. This is because the effectiveness of the flotation agent is significantly impaired, and elution of indium oxide occurs. In view of the above points, it is desirable in manufacturing to set the pH value to 2.5 to 4.5.

Furthermore, the present invention is a powder concentration method for recycling the ITO scrap powder,
A foaming agent in which the liquid in the tank of the flotation machine makes it easy to generate bubbles, a surfactant that activates the surface of the powder, and a collector that hydrophobizes the surface of the activated powder And a method for concentrating the powder.

  Foaming agents, surfactants, and collectors are essential for flotation. Although it is necessary to use a predetermined thing when implementing this invention about each, it mentions later for details.

Furthermore, the present invention provides the above powder concentration method, wherein the blast powder is a powder made of corundum. “Corundum” generally includes brown corundum and white corundum. The blast powder is not limited to corundum, and there are various types such as SiO ₂ and Fe. Therefore, it goes without saying that blast powder other than corundum can be used in carrying out the present invention.

Brown corundum is a brown abrasive (abrasive) made by melting and purifying bauxite. It has a brown color due to titania (TiO ₂ ) contained. Although there are abrasives (abrasives) made of white corundum made of high-purity alumina, brown corundum tends to be easily suppressed (controlled) in the flotation process of the present invention.

  Furthermore, the present invention provides the powder concentration method described above, wherein an appropriate range of the classification is from 25 μm to 75 μm.

  Here, in order to classify the ITO scrap powder at 25 μm to 75 μm, a vibrating screen sieving apparatus provided with a square or circular net of 25 μm to 75 μm is used. This is because ITO particles in the ITO scrap powder are almost 25 μm or less, whereas most particles of the blast powder are 75 μm or more. Therefore, the larger the mesh than 75 μm, the more blast powder goes down the net (the amount that passes through the mesh), which causes the In quality to deteriorate. The smaller the mesh than 75 μm, the more ITO powder goes onto the mesh. It becomes easy to go (it becomes easy to remain), and causes the yield to be lowered.

  Furthermore, some ITO particles are 25 μm or more, and some blast powder particles are 75 μm or less. Therefore, the appropriate classification point is selected by giving a range to the classification point according to the particle size of the original powder (ITO scrap powder). Sift through.

  In addition, since the particle | grains of ITO powder are fine and classification is performed by a dry method, since loss will become large by surface adhesion to a blast powder particle | grain, the wet sieving which can be washed with water is preferable. Therefore, a vibrating screen type (wet type) is used for carrying out the present invention.

The present invention is a powder concentration method for recycling the above ITO scrap powder,
There is provided a method characterized by performing the process of step b-1 a predetermined number of times and performing the process of step b-2 a predetermined number of times.

  The “predetermined number of times” includes the case of one time. For example, the case where the process b-1 is performed multiple times and the process b-2 is performed once is included, or the process b-1 is performed once and the process b-2 is performed multiple times. In some cases, the process b-1 and the process b-2 include a plurality of cases.

  In step b, since the flotation process is performed at a low pH as described below, the flotation agent is easily decomposed and the effect is not durable. Therefore, it is preferable to repeat step b-1 or step b-1 2 to 5 times, and more preferably 3 to 4 times. The reason is that if it is once, the concentration is insufficient, and if it is six times or more, it is not preferable because it is not economical in terms of production cost.

  According to the present invention, scrap powder of In-containing powder (ITO scrap powder is represented in the present specification) and blast powder from the scrap powder of In-containing powder are removed as much as possible by flotation. The ratio of In-containing powder to the scrap powder of the contained powder (In quality) is increased, and the scrap powder of In-containing powder is concentrated, that is, the total bulk volume and weight of the In-containing powder scrap powder are reduced as a result. Furthermore, it is possible to achieve a reduction in the cost of a series of recycling processes for separating and recovering indium oxide from scrap powder of In-containing powder.

  Hereinafter, the best mode for carrying out the present invention will be described briefly with reference to FIG. 1 and then the detailed contents will be described.

  BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the best mode for carrying out the present invention, particularly the production method will be described. In the following description, the numerical values of each reagent, each solution, etc. are shown. For example, depending on the type of blast powder of In-based powder contained in the pilot scale or mass production scale or scrap powder, the amount of each reagent, each solution, etc. is appropriately determined by those skilled in the art. Needless to say, it can be changed.

  First, for example, ITO scrap powder removed from a deposition plate of a PVD apparatus is prepared (S1). Next, the ITO scrap powder is classified in a certain particle size range (S2). The ITO scrap powder is put into a roughing flotation machine, and the powder that is a flotation coarse concentrate and the powder that is a flotation tailing, which have been roughed by flotation, are preferably separated in multiple stages. (S3). Next, the coarse concentrate powder coarsely selected in the coarse selection step is put into a fine fractionation flotation machine, and a powder that is a flotation concentrate and a powder that is a flotation medium are preferably Separated in multiple stages (S4). Thus, the powder concentration which raises the ratio of ITO powder can be performed by removing blast powder from ITO scrap powder as much as possible by the flotation method.

  Further, each step will be described in detail.

<ITO scrap powder preparation process; S1>
ITO scrap powder has basically been treated as waste in production sites where a transparent electrode is applied to a glass substrate with a PVD apparatus. ITO scrap powder is deposited inside the PVD apparatus after PVD treatment. The ITO material adhering to the outer wall or other part of a plate or the like is removed by blast powder sprayed with compressed air from an air gun. In the present invention, corundum is used as the blast powder. However, brown corundum (Al ₂ O ₃ ) is preferably used.

<Classification step; S2>
Next, the ITO scrap powder prepared in S1 is classified to prepare powder before flotation. Specifically, ITO scrap powder is classified to obtain a powder having a particle size of 25 μm to 75 μm, more preferably 30 μm to 50 μm. A classification method is a wet classification method using a known vibrating screen.

<Coarse selection step; S3>
Next, the classified ITO scrap powder is put into a roughing flotation machine (mechanical stirring type flotation machine), and flotation is carried out with the powder that is the coarsely flotated coarse concentrate by the flotation method. The powder which is tailing is separated.

  In the following description, this roughing process will be described by taking as an example the case where an MS type flotation machine (for processing 500 g) is used as the flotation machine for roughing as shown in FIG.

  As shown in FIG. 2, the MS type flotation machine 100 mainly includes a stirring chamber 5 and a foam chamber 7, and the stirring chamber 5 and the foam chamber 7 communicate with each other through a slit portion 9 and a narrow tube 17. is doing.

  The stirring chamber 5 is provided with a stirring impeller 11 for stirring the liquid in the tank that rotates at a peripheral speed of about 6 m to 7 m.

  An appropriate amount of liquid (for example, a ratio of water 9 to ITO scrap powder 1 by weight is desirable) to which additives for flotation such as a foaming agent, a surface active agent, and a collection agent are added is stirred from the inlet 6. While being supplied to the chamber 5, the ITO scrap powder is vigorously stirred by the impeller 11. At the same time, air mixing is also performed. The liquid is sent from the slit portion 9 to the foam chamber 7 while containing the bubbles.

  The foam chamber 7 is in a static state, and bubbles are floated and the foam state is formed near the liquid surface of the liquid in the foam chamber 7. The hydrophobic ITO powder in the ITO scrap powder floats on the water surface of the foam chamber 7 together with the bubbles, and the selected ITO powder (concentrate) is collected into the tank 21 through the outlet 19. At this time, in order to make the foam easily flow out, the wings 13 and 15 are rotated to scrape the foam.

  On the other hand, since there is ITO powder among the ITO scrap powder that could not be reached in order to reach the bubbles, it is necessary to repeat the treatment and float them. Therefore, in the case of the batch system, the liquid in which the ITO scrap powder is dispersed is further returned from the foam chamber 7 to the stirring chamber 5 by the suction force by the rotation of the impeller 11 of the adjacent stirring chamber 5. Repeat the operation. (Refer to “Preparation Engineering” (Kyoritsu Publishing)).

  In this way, the rough selection process is completed by performing the flotation process for a predetermined time.

  In the embodiment according to the present invention, it is preferable to perform the process by the MS type floatation machine three times (in FIG. 1, N = 3 is set) (described later). However, the same process can be repeated as long as flotation roughing can be obtained by further repeating in consideration of the trade-off between quality and manufacturing cost.

  The flotation conditions of the MS type flotation machine 100 when implementing the present invention are as follows.

  A mixture (hereinafter referred to as “slurry”) prepared by mixing 100 g of ITO scrap powder under the range, classified in the range of 25 μm to 75 μm, and water of 0.8 L to 1.0 L is prepared. The liquid temperature is room temperature.

At this time, the slurry pH is preferably set to 2.5 to 4.5. Furthermore, it is desirable to set pH to 3-4. In the present invention, an acid such as H ₂ SO ₄ is used as a condition agent for pH adjustment.

  Hereinafter, the condition of the additive amount necessary for the flotation will be described by taking the case where the In quality of the ITO scrap powder of the original powder is 10% as an example, but the added amount is proportional to the In quality of the original powder. However, it is not necessary to determine the optimum conditions each time.

Furthermore, in order to activate the surface, 100 g to 500 g of CuSO ₄ and 500 g to 2000 g of Na ₂ S are added to the slurry solution as an activator for 1 ton of the original powder. Conditioning time is set to 2 to 10 minutes each.

The reason for adding CuSO ₄ is that by using the fact that In has a stronger ionization tendency than Cu, a part of In of ITO scrap powder and Cu ^{2+ of} CuSO ₄ are substituted to replace the surface of ITO scrap powder particles. This is because Cu is considered to be coated. In this way, when Cu partially substitutes for In, Cu is attached to the particle surface of the ITO scrap powder, and it becomes easy to float on the water surface. The reason for adding Na ₂ S is that it is considered that the ITO scrap powder has a more hydrophobic property by forming a sulfide-based film on the particle surface of the ITO scrap powder.

Further, in order to make the ITO scrap powder hydrophobic and easily float on the water surface, a flotation agent (collecting agent and foaming agent) is added to the liquid. As the collecting agent, 100 g / t to 1000 g / t of KAX (potassium amyl xanthate) is preferably used. Further, 10 g / t to 50 g / t of MIBC (methyl isobutyl carbinol) is preferably added to the solution as a foaming agent. It should be noted that at this time, CuSO ₄ , Na ₂ S, and xanthate react directly with each other and cannot be added simultaneously.

  Here, KBX (kalibutyl xanthate), KEX (kaliethyl xanthate) or the like can be used instead of KAX. Dow floss 250 (diethylene glycol monobutyl ether) or Elo floss 65 (polyglycol ester) can be used instead of MIBC. ) Etc. can also be used.

  Further, the pH is adjusted again to the above-mentioned initial set value with sulfuric acid or the like.

  The slurry produced as described above is charged so as to satisfy both the stirring chamber 5 and the foam chamber 7 and subjected to the flotation process by the above-described MS type flotation machine 100, so that the coarse flotation is performed in the foam chamber 7. The powder (ITO blast powder rich in ITO) floats on the liquid filled in the foam chamber 7 together with the foam, and is discharged from the coarse concentrate outlet 19 and stored in the coarse concentrate tank 21. In this way, the rough selection process proceeds.

<Selection process; S4>
Further, referring to FIG. 3, the following fine selection process will be described by taking as an example the case of using a microbubble column flotation machine 200 (MINEALS AND COAL TECHNOLOGIES) as a representative example of a fine flotation machine. .

  First, it is necessary to adjust the pH and adjust and add the flotation agent as in the rough selection process. Since the prescription is the same as the rough selection process, the description is omitted here.

  After filling the column with the solution containing the above flotation agent, the powder slurry (ITO-rich ITO blast powder) in the tank 21 (FIG. 2) of the MS type flotation machine obtained by flotation in the above process. It is put into the flotation feed tank 35 of the fine flotation machine 200 (the microbubble column flotation machine shown in FIG. 3).

  FIG. 3A is a schematic cross-sectional view of the microbubble column flotation machine 200. As shown in FIG. 3A, the microbubble column flotation machine 200 includes a column cell 23, a bubble generating pump 25, an in-line mixer 27, a recycle conduit 29, an air compressor 31, and a concentrate floss. It mainly includes a cleaning water supply unit 33, a flotation feed tank 35, and a feed pump 37 (in FIG. 3, “FC” means a device that controls the flow of water and air).

  The column cell 23 has a hollow cylindrical shape. For example, the column cell 23 has a height of approximately 250 cm and an inner diameter of 5 cm. The reason for the vertically long shape is to increase the floatation / sediment separation time in the column cell 23 by increasing the floating distance of the process by flotation. Further, since there is no influence of stirring, the inside of the column cell 23 has an advantage that even a very quiet and fine particle can be separated sharply. The column cell 200 can be disassembled at the three divided portions 23A, 23B, and 23C of the cylinder, and the length can be adjusted by adding and removing the column according to the flotation situation.

  The bubble generating pump 25 is a pump for sending air necessary for creating bubbles essential for the flotation process and the settled powder slurry from the top and bottom surfaces of the column cell 200 to the column cell 200 through the in-line mixer 27 again.

  As shown in FIG. 3B, the inline mixer 27 has a cylindrical shape, and has a zigzag structure in the hollow inside the cylinder. The air and the slurry sent from the bubble generating pump 25 pass through the in-line mixer 27, whereby the air is made into microbubbles, and the slurry is sent vertically upward into the column cell 23 while being in contact with the microbubbles. .

  The recycle conduit 29 is coupled to the bubble generating pump 25 installed near the bottom of the column cell 200 and below the column cell 23. In order to circulate the settled powder and move it upward again in the column cell 23 together with the bubbles from the bubble generating pump 25 to reselect the suspended matter (ITO powder) remaining in the precipitate. is there.

  The air compressor 31 includes a flow controller FC, and is used to send compressed air to an air introduction portion (see FIG. 3B) of an in-line mixer 27 located at the bottom of the column cell 23.

  The cleaning water supply unit 33 includes a flow controller FC, and is used for final cleaning before the concentrate floating from the top port of the column cell 23 is discharged from the discharge port 41.

  The tank 35 for flotation supply mine is a tank into which the pulp concentration of the coarse concentrate obtained in the rough selection process is adjusted and the same hydrophobization treatment as in the rough selection is performed again.

  The feed pump 37 feeds the micro-valve flotation machine 200 after processing the coarse concentrate slurry obtained from the flotation supply tank 35 in the rough selection process with a flotation agent such as a necessary collection agent. It is for moving to the part.

  The operation of the microbubble column flotation machine 200 having the above configuration will be described below.

  First, the ITO powder slurry obtained in the tank 21 of the MS type float beneficiator 100 is introduced from the flotation feed tank 35 to the feed section 39 via the feed pump 37 into the upper part of the liquid level of the column cell 23.

  And what floats adheres to the bubbles and floats, and those that should settle and those that settle without being settled settle to the bottom of the column cell 200, so the ITO powder slurry is combined with the air from the bubble generating pump 25. In the in-line mixer 27, while the ITO powder precipitation slurry is sheared, the bubbles indispensable for the flotation are refined (microbubbles), and the contact between the bubbles and the ITO powder particles is promoted. Thereafter, the floating concentrate as the ITO powder adhered to the fine bubbles (microbubbles) effective for the collection of the ITO powder floats up to the upper part 39 of the column cell 23, and the concentrate of the ITO powder can be taken out from the outlet 41. It is possible to perform a highly selective flotation process with higher purity. In this way, the selection process proceeds.

  In addition, in the Example which concerns on this invention, it is supposed that it is suitable to perform the refinement | purification process by a microbubble type | formula floatation sorter 3 times (it sets with N '= 3 in FIG. 1) similarly to the rough | crude selection process mentioned above. . However, the same process can be repeated as long as flotation roughing can be obtained by further repeating in consideration of the trade-off between quality and manufacturing cost.

  After this, the concentrated powder of ITO scrap powder obtained by the above method is subjected to an acid leaching method, a solvent extraction method, an ion exchange method, etc. to obtain indium oxide, and the ITO material is recycled (details) (See Japanese Patent Application No. 2004-02777 filed by the present applicant).

  Here, a method for obtaining indium oxide by the acid leaching method and recycling the ITO material will be briefly described.

  Concentrated ITO scrap powder (hereinafter simply referred to as “ITO concentrated powder”) is leached with an acid to obtain, for example, a compound of acid and indium, and indium ions are solvent-extracted from this compound using an extractant. The obtained extract is back-extracted with an inorganic acid to obtain an indium solution, this solution is reacted with alkali, and the obtained indium hydroxide is roasted to obtain indium oxide. In this way, indium oxide of the ITO material can be collected from the ITO scrap powder, and as a result, the ITO material can be recycled.

  Further, when the present invention is carried out, blast powder (including ITO) is produced as a by-product at the same time, so that the blast powder for ITO can also be recycled.

Furthermore, the present invention not only ITO powder, which was mainly composed of _In 2 _{O 3,} for example, IZO _(In 2 _{O 3} that was added 1 wt% 30 wt% of ZnO in), such as the _In 2 _{O 3} The present invention can be applied to scrap powder of oxidized In-based powder to which various elements are added, and can also be applied to ZnO-based and SnO ₂ -based materials used as a transparent conductive film in the same manner as ITO.

  An embodiment according to the present invention will be described below with reference to FIGS.

S1: First, 1000 kg (1 ton) of ITO scrap powder (original powder) was prepared. The In quality of this original powder was 3.3%.
S2: 1600 L of water was added to the original flour so that the pulp concentration was 40%, and then sufficiently stirred in the tank.
S3: A classification process (sieving process) was performed with a vibrating screen capable of being classified (sorted) at 38 μm while releasing 1200 L of spray water on the base powder. As a result, a powder of less than 38 μm (−38 μm) and a powder of 38 μm or more (+38 μm) were obtained. The former was ITO concentrated blast powder with increased ITO powder concentration, and the latter was coarse blast powder.

S4: The coarse blast powder had a dry weight (dry weight) of 700 kg and an In quality of 0.4%. Incidentally, the yield was about 10% and contained 200 L of water.
S5: The coarse blast powder was dehydrated and filtered with a pan filter. The filtrate was 150L.
S6: Next, the coarse blast powder dehydrated in S5 was dried with a cyclone dryer to remove the remaining 50 L of water.

  As described above, this coarse blast powder is a blast powder made of corundum containing ITO powder (In quality 0.4%) of 38 μm or more. Therefore, the dry coarse blast powder obtained in S6 can be used again (recyclable) when mechanically removing ITO with a blaster.

  S7: On the other hand, a screen under slurry (powder slurry after classification) composed of 300 kg of ITO concentrated blast powder and 2600 L of water was put into a condition tank (pulp concentration 10%). At this time, the In quality in dry ore (ITO concentrated blast powder in a dry state) was 10%.

S8-1: First, an appropriate amount of sulfuric acid was added to set the pH of the solution to 4 while 150 g of CuSO 4 was put into the condition tank.
S8-2: Next, 600 g of NaS ₂ was put into the above-mentioned condition tank.
S8-3: Next, 150 g of KAX and 15 g of MIBC were put into the above-mentioned condition tank.
S8-4: An appropriate amount of H2SO4 was added here to reset the solution pH to 4.

  S9: A flotation machine using the principle of the MS type flotation machine that is compatible with the mass production scale and has the same mechanism and principle as the MS type flotation machine 100 described above is used. The ITO blast powder slurry prepared in step 1 was added and the flotation process (coarse selection) was performed (the flow of the rough selection flotation process using the MS type flotation machine 100 as an example is as described above. The description is omitted here). In this example, the flotation process (coarse selection) was performed three times. By the said process, it fractionated into the flotation rough concentrate (S10) and the flotation tailing (S12). A flotation crude concentrate containing ITO powder weighing 140 kg was obtained, and the In quality was 20%. The recovery rate at this time was 85%.

  S11: The flotation tailings were dehydrated and discarded as industrial waste. This is because the flotation tailings at this stage are not suitable as blast powder because the particle size is too fine unlike that of S6. On the other hand, the dehydrated water at this time is reused as water used in a series of steps.

S13: The following solutions were prepared in a condition tank in order to perform further selective beneficiation processing.
S13-1: First, 300 L of water and 150 g of CuSO4 were put into this condition tank, and an appropriate amount of sulfuric acid was added to set the liquid pH to 4.
S13-2: Next, 600 g of NaS ₂ was put into the above-mentioned condition tank.
S13-3: Next, 150 g of KAX and 50 g of MIBC were put into the above-mentioned condition tank.
S13-4: Here, an appropriate amount of H ₂ SO ₄ was added to reset the solution pH to 4.

  S14: Further, the selective flotation process was performed on the flotation rough concentrate (the detailed flotation process by the microbubble column flotation machine 200 is as described above, and the description thereof is omitted here). In this example, the selective beneficiation process was performed three times. By the said process, it fractionated into the flotation middle ore (S15) and the flotation concentrate (S17).

  S16: The ore during flotation (S15) is repeated in the coarse beneficiation process (return to S7).

S17: The flotation concentrate contains ITO powder, 80 kg was obtained, and the In quality was 30%. The recovery rate at this time was 72%.
S18: The flotation concentrate was dehydrated using a pan filter. At this time, 280 L of water was dehydrated, and a powder in which 80 kg of ITO powder was concentrated was obtained. At this time, the In quality was 30%, and the recovery rate was 72%. The amount of water that could not be dehydrated was 20 L.

  Through the above, from 1 ton ITO scrap powder of 3.3% In grade, blast powder is classified and passed through three coarsely selected flotation processes (S9) and three finely selected flotation processes (S14), 80 kg of In concentrated powder of 30% In grade was obtained. The recovery rate was 72%.

  From this, it was possible to significantly reduce the overall weight from 1000 kg to 80 kg by removing the blast powder from the ITO scrap powder using the flotation method. In other words, it means that the overall weight could be reduced to 12.5. At the same time, the In quality was improved (concentrated) from 3.3% to 30%.

  From this, according to the present Example, it turned out that the effect of the above-mentioned this invention can be show | played by implementing the method of this invention.

Comparative example

<Comparative Example 1>
4 and the flow of the embodiment shown in FIG. 5, the flotation process liquid, tonnage when not added and copper sulfate CuSO ₄ when the addition of copper sulfate CuSO ₄ (yield of concentrate (%) ), In quality (%), and In distribution ratio (%) are shown in Table 1 (other processing conditions were the same). With regard to the amount of addition of copper sulfate CuSO ₄ upon addition of copper sulfate CuSO ₄ at this time was 500 g / t.

According to Comparative Example 1 of the results shown in Table 1, excellent In the distribution ratio (%) than when the person upon addition of copper sulfate CuSO ₄ is not added copper sulfate CuSO _4, recovered efficiently I understood that I could do it.

<Comparative example 2>
4 and the flow of the embodiment shown in FIG. 5, the flotation process liquid, In grade (%) when not added and sodium sulphide Na 2 _S when added sodium sulfide Na 2 _S, and In distribution The rate (%) is shown in Table 1 (other processing conditions were the same). With regard to the amount of addition of the case of adding sodium sulfide Na ₂ S at this time it was 2000 g / t.

According to Table 2 in Comparative Example 2 of the results shown, In grade (%) than when no addition of sodium Na 2 _S disulfide who upon addition of sodium sulphide Na 2 _S, and In the distribution ratio (% ) In all points.

<Comparative Example 3>

In the flow of the example shown in FIG. 4 and FIG. 5, when the collection agent of the flotation treatment liquid is KAX, when the collection agent is sodium oleate, and when it is sodium dodecyl sulfate, In quality (%) And In distribution ratio (%) are shown in Table 3 (other processing conditions were the same). The amount of each collector added at this time was 500 g / t for KAX, 1000 g / t for sodium oleate, and 200 g / t for sodium dodecyl sulfate.

  According to the results of Comparative Example 3 shown in Table 3, the In quality (%) and In were higher when KAX was used as the collector than when sodium oleate or sodium dodecyl sulfate was used as the collector. It was found that the distribution ratio (%) was excellent in all points (more specifically, sodium oleate had a low In distribution ratio (%), and sodium dodecyl sulfate had an In grade (% ) Was low.)

<Comparative example 4>
In the flow of the examples shown in FIGS. 4 and 5, when the pH of the flotation treatment liquid is less than 2.5, when the pH is 2.5 to 4.5, and when the pH is 4.5 to Table 4 shows the In quality (%) and the In distribution ratio (%) when 6 (the other processing conditions were the same). The pH was adjusted with sulfuric acid.

  According to the results of Comparative Example 4 shown in Table 4, the In quality is higher when the pH is 2.5 to 4.5 than when the pH is less than 2.5 or 4.5 to 6. (%) And In distribution ratio (%) were excellent in results and found to be excellent.

  According to the present invention, a certain amount of blasting powder can be removed from scrap powder containing In-based powder recovered from an adhesion plate or the like of a PVD apparatus for forming a transparent electrode such as an ITO electrode. Can be provided. Furthermore, after that, in a process including acid immersion, indium oxide (indium) can be separated and recovered, and the indium oxide can be recycled as a material for a transparent electrode.

It is a flowchart for demonstrating the best embodiment of this invention. It is a conceptual diagram for demonstrating the floatation machine for rough selection. (A) It is a conceptual diagram for demonstrating the flotation beneficiary machine for refinement | purification. (B) It is a conceptual diagram for demonstrating the in-line mixer built in the floatation separator for fine selection. It is a flowchart for demonstrating the suitable Example of this invention. FIG. 5 is a flowchart for explaining a preferred embodiment of the present invention following FIG. 4.

Explanation of symbols

5 Stirring chamber 7 Foam chamber 9 Slot 11 Impeller 13, 15 Feather 17 Circulating conduit 19 Outlet 21 Tank 23 Column cell 25
23A, 23B, 23C Dividing part 25 Bubble generating pump 27 In-line mixer 29 Recycle conduit 31 Air compressor 33 Washing water supply part 35 Flotation solution tank 37 Feed pump 41 Discharge port 100 MS type flotation machine (rough flotation machine) )
200 Micro bubble column flotation machine (Flotation machine for fine selection)

Claims (10)

Blast powder is removed from oxidized In-based powder-containing scrap powder containing oxidized In-based powder and blast powder by a flotation method, and includes the following steps a and b. A powder concentration method for recycling scrap powder containing oxidized In-based powders that increases the ratio of slag.
Step a. A powder classification step of classifying the scrap powder containing the oxidized In-based powder to classify the scrap powder containing the oxidized In-based powder to a particle size less than a suitable range, and
Step b. For the oxidized In-based powder-containing scrap powder sorted into the appropriate range of particle size, by mainly precipitating the powder containing mainly blast powder while floating the oxidized In-based powder, mainly oxidized In A flotation process that removes powder containing mainly blast powder while collecting powder containing system-containing powder. A powder concentration method for recycling scrap powder containing oxidized In-based powder according to claim 1, wherein the step b includes the following steps b-1 and b-2. .
Step b-1. A rough flotation process in which the oxidized In-based powder-containing scrap powder sorted in step a is put into a flotation machine for roughing, the flotation coarse concentrate powder is floated, and the flotation tailing powder is settled. ,
Step b-2. A fine flotation step in which the coarse concentrate powder obtained in step b-1 is charged into a flotation beneficiation machine for flotation, the flotation concentrate powder is floated, and the ore powder is settled during flotation. A powder concentration method for recycling scrap powder containing oxidized In-based powder according to claim 2,
A method comprising performing the process of step b-1 a predetermined number of times and performing the process of step b-2 a predetermined number of times. For recycling ITO scrap powder, which includes the following steps a and b, removes the blast powder from the ITO scrap powder containing the ITO powder and the blast powder by a flotation method, and increases the ratio of the ITO powder. Powder concentration method.
Step a. A powder classification process for classifying ITO scrap powder and classifying ITO scrap powder to a particle size below an appropriate range; and
Step b. For the ITO scrap powder sorted into the appropriate particle size, the powder mainly containing ITO powder is collected by allowing the powder mainly containing ITO to settle while allowing the powder mainly containing ITO to float. A flotation process that removes powder containing mainly blast powder while sinking. The method for concentrating powder for recycling ITO scrap powder according to claim 4, wherein the step b includes the following steps b-1 and b-2.
Step b-1. A rough flotation step in which the ITO scrap powder sorted in step a is put into a flotation machine for roughing, the flotation coarse concentrate powder is floated, and the flotation tailing powder is settled,
Step b-2. A fine flotation step in which the coarse concentrate powder obtained in step b-1 is charged into a flotation beneficiation machine for flotation, the flotation concentrate powder is floated, and the ore powder is settled during flotation. A powder concentration method for recycling ITO scrap powder according to claim 5,
A method comprising performing the process of step b-1 a predetermined number of times and performing the process of step b-2 a predetermined number of times. A powder concentration method for recycling ITO scrap powder according to any one of claims 4 to 6,
The powder concentration method characterized by setting the liquid pH value in the flotation machine tank of the flotation machine for rough beneficiation and the flotation beneficiation machine for fine beneficiation to 2.5-4.5. A powder concentration method for recycling ITO scrap powder according to any one of claims 4 to 7,
A foaming agent in which the liquid in the tank of the flotation machine makes it easy to generate bubbles, a surfactant that activates the surface of the powder, and a collector that hydrophobizes the surface of the activated powder And a powder concentration method. The powder concentration method according to any one of claims 1 to 8, wherein the blast powder is a blast powder containing corundum. The powder concentration method according to any one of claims 1 to 9, wherein an appropriate range of the classification is a range of 25 µm to 75 µm.

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