Cleaning device for metal recovery equipment

Abstract

To solve the problem that metal precipitated by electrolysis contains strong acid, and is not easily treated.SOLUTION: A device for cleaning a metal recovery device, which is a cleaning device provided below a storage tank of a metal recovery device that has a filter for electrolyzing a solution containing metal existing in an ionic state and thereby recovering the metal and is provided, includes a recovery device for recovering cleaning water below the filter, a spray nozzle for spraying the cleaning water to the storage tank, return piping for returning the cleaning water in the recovery device back to the spray nozzle, a circulation pump provided on the return pipe, a pH meter provided on the return piping, and a controller for stopping supply of the cleaning water when the pH of the cleaning water flowing in the return piping by the pH meter becomes a prescribed value, and neutralizes the pH of the recovered metal.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a cleaning apparatus for cleaning a recovery apparatus that recovers metals present in a waste liquid in an ionic state, and particularly relates to a cleaning apparatus for cleaning a recovery apparatus that recovers copper from a waste liquid in which the metal is copper and the solution contains a large amount of hydrogen peroxide water. [Background Art]

[0002] In recent years, highly conductive copper has been used for fine wiring used in ICs and the like. When forming extremely fine wiring, a subtractive method is used for circuit formation, in which copper is deposited over the entire surface and unnecessary portions are removed by etching. Such a method generates waste liquid containing a large amount of copper.

[0003] Electrolysis is often used to recover metals from waste liquids containing metal ions. Patent Document 1 discloses a method for electrolytically extracting powdered metal from a solution in which, in a cylindrical electrolytic cell, a columnar cathode is formed on the inside, the inner surface of the electrolytic cell is used as an anode, and metal is deposited while flowing a treatment liquid. In Patent Document 1, a flushing solution is flowed in the direction opposite to the flow direction of the treatment liquid when depositing metal, to remove the metal powder deposited on the cathode. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese National Publication of International Patent Application No. 2003-505598 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] Electrolysis is preferable for recovering metals from wastewater because it increases the recovery rate. However, the metal deposited by electrolysis becomes integrated with the cathode, and although it can be solidified from the wastewater, actual recovery requires removing the cathode and scraping its surface to recover the metal. Patent Document 1 attempts to improve the ease of recovery by finding that lowering the velocity of the fluid passing through the electrolytic cell and the current density makes it easier to generate powdered metal rather than plate-like metal on the cathode.

[0006] However, even with this method, if the waste liquid is flushed during processing, metal deposits will form on the cathode, and once they grow, the deposited metal cannot be recovered even by flushing with a flushing solution. As a result, the device had to be disassembled, the electrodes removed, and the deposited metal scraped off.

[0007] Therefore, it was conceived to recover metals from wastewater using a sponge-like porous material composed of fine particles and hydrogen bubbles. In a device that realizes this, the metals are recovered by solid-liquid separation of the sponge-like porous material and the wastewater from which the metals have been recovered. However, there was a problem in that the recovered metals were difficult to handle because they were coated with highly acidic solutions from the wastewater. [Means for solving the problem]

[0008] The present invention was conceived in view of the above-mentioned problems, and provides a cleaning device for a metal recovery device that recovers metal from waste liquid as a sponge-like porous body, and for cleaning the metal recovery device itself along with the recovered metal.

[0009] More specifically, the cleaning apparatus for the metal recovery apparatus according to the present invention is: Electrolysis of a solution containing metals that exist in an ionic state. A storage tank in which electrode plates are placed inside, and the precipitates deposited by electrolysis Metal recovery device having a filter for recovering the aforementioned metal Wash It is a purification device, A recovery device for collecting the washing water below the aforementioned filter, The aforementioned storage tank Inside and the electrode plate to TowardsA spray nozzle for spraying the aforementioned cleaning water, A return pipe that returns the cleaning water in the recovery device to the spray nozzle, A circulation pump is provided in the return piping, A pH meter is installed in the return piping, The device is characterized by having a controller that stops the supply of cleaning water when the pH of the cleaning water flowing through the return pipe, as measured by the pH meter, reaches a predetermined value. [Effects of the Invention]

[0010] The cleaning device for the metal recovery device according to the present invention cleans the metal to which the strong acid solution recovered by the filter has adhered, together with the metal recovery device, below the metal recovery device. This makes the recovered metal safe to handle and also cleans the metal recovery device itself. [Brief explanation of the drawing]

[0011] [Figure 1] This figure shows the configuration of the cleaning device for the metal recovery device according to the present invention. [Figure 2] This diagram shows the discharge of waste liquid from the storage tank of a metal recovery device. [Figure 3] This diagram shows the process of cleaning the metal recovery device and the recovered metal using a cleaning device. [Figure 4] This is a flowchart showing the process of the cleaning controller. [Figure 5] This is a diagram showing the configuration of a metal recovery apparatus for implementing the metal recovery method according to the present invention. [Figure 6] This is a partially enlarged view of Figure 5. [Figure 7] This is a flowchart showing the controller's processing (main flow). [Figure 8] This is a flowchart showing the process of adding hydrogen peroxide during step S108. [Figure 9] This is a conceptual diagram illustrating the process by which a sponge-like porous metal body is formed. [Figure 10] This is a conceptual diagram showing a sponge-like porous metal material growing on a cathode plate. [Figure 11] This is a conceptual diagram illustrating how a sponge-like porous metal material on the cathode is detached by air bubbles. [Figure 12] This diagram shows the configuration when an electrode vibrator is provided to vibrate the electrode plates. [Modes for carrying out the invention]

[0012] The cleaning apparatus for the metal recovery apparatus according to the present invention will be described below with reference to the drawings. The following description illustrates one embodiment of the present invention and one example, and the present invention is not limited to the following description. The following description may be modified without departing from the spirit of the present invention.

[0013] [Explanation of Components] Figure 1 shows the configuration of the cleaning device (hereinafter also simply referred to as the "cleaning device") of the metal recovery device 1 according to the present invention. The cleaning device 100 according to the present invention includes a recovery container 110 located at the bottom of the storage tank 10 of the metal recovery device 1, a return pipe 112, a circulation pump 114, a pH meter 116, a spray nozzle 120, a cleaning controller 122, and a cleaning water valve 130a for taking in cleaning water. It is also desirable to have an alkaline agent adder 118.

[0014] The metal recovery device 1 is a device that can recover metals remaining as ions in waste liquid as a sponge-like porous metal body formed of metal nanoparticles and tiny hydrogen bubbles by electrolysis.

[0015] The metal recovery device 1 is equipped with a drainable outlet 10a at the bottom of the storage tank 10 where the electrode plates 12 are placed, followed by a filter 26. The sponge-like porous material detaches from the electrode plates 12 and accumulates as sediment at the bottom of the storage tank 10 (see Figure 1), where it is discharged together with the liquid to be treated, and the metal portion is recovered by the filter 26. The detailed configuration will be described later.

[0016] The filter 26 of the cleaning device 100 according to the present invention is provided directly below the outlet 10a and the filter 26.

[0017] <Recovery container 110> The recovery container 110 is provided below the metal recovery device 1, and stores the liquid that has passed through the filter 26. The recovery container 110 is provided with a drain outlet 110a. The liquid in the recovery container 110 is discharged from the drain outlet 110a. The opening and closing of the drain outlet 110a is controlled by an instruction signal C from the cleaning controller 122 DV and can be controlled thereby. In addition, a return pipe 112 is in communication with the recovery container 110.

[0018] <Return pipe 112> The return pipe 112 is a pipe arranged from the recovery container 110 to the spray nozzle 120 provided at the upper part of the metal recovery device 1.

[0019] <Circulation pump 114> The circulation pump 114 is provided in the middle of the return pipe 112. It sends the cleaning water in the recovery container 110 to the spray nozzle 120. The operation of the circulation pump 114 is controlled by an instruction signal C from the cleaning controller 122 WP and can be controlled thereby.

[0020] <pH meter 116> The pH meter 116 is provided in the middle of the return pipe 112. It measures the pH of the liquid in the return pipe 112. The measurement result of the pH meter 116 is notified to the cleaning controller 122 by a reception signal S pH and is notified to the cleaning controller thereby.

[0021] <Spray nozzle 120> The spray nozzle 120 is provided at the upper part of the storage tank 10 of the metal recovery device 1. The spray nozzle 120 sprays cleaning water onto the inner wall of the storage tank 10 and the electrode plate 12.

[0022] <Cleaning water valve 130a> Washing water is supplied from a washing water source 130. At least neutral water can be suitably used. The washing water source 130 may be a tank or an industrial water service. A washing water pipe 130b from the washing water source 130 is communicated with a return pipe 112. A washing water valve 130a is provided on the washing water pipe 130b side before the washing water pipe 130b communicates with the return pipe 112. The washing water valve 130a stops the washing water from the washing water source 130 from flowing into the return pipe 112. The opening and closing of the washing water valve 130a is controlled by a command signal C from a washing controller 122 WV and can be controlled thereby.

[0023] <Alkaline agent adder 118> The alkaline agent adder 118 is constituted by an alkaline agent tank 118a and an alkaline agent valve 118b. The alkaline agent adder 118 is communicated with the return pipe 112. An alkaline agent is stored in the alkaline agent tank 118a. Opening the alkaline agent valve 118b discharges the alkaline agent in the alkaline agent tank 118a into the return pipe 112. The opening and closing of the alkaline agent valve 118b is controlled by a command signal C from the washing controller 122 AV and can be controlled thereby.

[0024] <Washing controller 122> The washing controller 122 is constituted by a CPU (Central Processor Unit), a memory, an input / output device, and the like. The washing controller 122 acquires the pH of the solution in the return pipe 112 from a received signal S pH Further, the washing controller 122 controls, via a command signal C DV , a command signal C WV , a command signal C AV , and a command signal C WP respectively, the opening and closing of the drain outlet 110a, the opening and closing of the washing water valve 130a, the opening and closing of the alkaline agent valve 118b, and the operating state of the circulation pump 114. Furthermore, activation of the washing controller 122 can be started by a notification signal SF indicating the end of recovery processing of the metal recovery device 1. Note that the washing controller 122 may be shared with the controller 18 of the metal recovery device 1.

[0025] [Operation of the cleaning device] Figure 4 shows the processing flow of the cleaning controller 122. See also Figures 1 to 3. The cleaning controller 122 can be started by receiving the notification signal SF, which is transmitted when the metal recovery of the metal recovery device 1 is completed. Of course, it can also be started manually.

[0026] When the washing device 100 starts (step S1000), the drain outlet 110a of the recovery container 110 is signaled by instruction signal C DV This opens (step S1020). As a result, the solution remaining in the recovery container 110 after solid-liquid separation is released from the drain outlet 110a. Since this solution is strongly acidic, it is disposed of separately.

[0027] Next, the cleaning controller 122 closes the drain outlet 110a and sends an instruction signal C to the cleaning water valve 130a to introduce cleaning water from the cleaning water source 130. WV The signal is sent (step S1040). This process causes the cleaning water to flow from the cleaning water pipe 130b into the return pipe 112, and through the spray nozzle 120, wash the inner wall of the storage tank 10 and the electrode plate 12. This is the process of spraying cleaning water from the cleaning water source 130.

[0028] These washes flow towards the bottom of the storage tank 10 and come into contact with the recovered metal in the filter 26 through the outlet 10a. The washes that have come into contact with the recovered metal are then stored in the recovery container 110. Once washes begin to accumulate in the recovery container 110, the wash controller 122 signals the circulation pump 114 to activate with instruction signal C. WP Activate the system (step S1060). Whether or not washing water has accumulated in the recovery container 110 can be determined by observing the time elapsed since opening the washing water valve 130a, or a recovery container water level gauge or the like may be installed in the recovery container 110.

[0029] When the circulation pump 114 is activated, the cleaning water in the recovery container 110 is transported through the return pipe 112 towards the spray nozzle 120. The cleaning water flowing through the return pipe 112 may be called "return cleaning water." It is then sprayed again together with the cleaning water from the cleaning water source 130. In other words, the return cleaning water is added to the cleaning water from the cleaning water source 130.

[0030] Next, the pH value of the washing water is measured using pH meter 116. pH Measure the pH reference value M pHs Compare with (step S1080). The pH value of the washing water is the pH reference value M. pHs If the value falls within a certain range ε1 (Y branch in step S1080), post-processing is performed (step S1180) by closing the wash water valve 130a, stopping the circulation pump 114, and opening the drain outlet 110a to discard the wash water in the recovery container 110. After that, the washing device 100 is stopped (step S1200). Note that the pH reference value M is set here. pHs The value is 7, and a certain range ε1 is preferably around 0.8. That is, when the pH of the return wash water falls within a predetermined standard range, the spraying of the wash water is stopped.

[0031] Furthermore, the post-processing step may include generating a cleaning completion signal SE and transmitting it to a designated device. For example, this could be the controller 18 of the metal recovery device 1. Alternatively, the cleaning controller 122 itself may utilize this signal.

[0032] The pH value of the washing water is pH standard value M pHs If the result is not within a certain range ε1 (N branch in step S1080), it is determined whether or not an alkaline agent is needed (step S1100). Whether or not an alkaline agent is needed is calculated from the time the washing water valve 130a is opened, the flow rate of washing water flowing through the washing water pipe 130b, and the contents of the storage tank 10 and the recovery container 110.

[0033] In other words, an amount of washing water equivalent to the capacity of the storage tank 10 and the recovery container 110 is used until the pH of the washing water is judged to be close to neutral. If it is determined that the pH will not settle within a certain range even after using this much washing water (Y branch in step S1100), an alkaline agent is added to neutralize the washing water (step S1120). For example, if the amount of washing water used reaches 40% of the capacity of the storage tank 10 and the recovery container 110, and the pH of the return water is still not within the predetermined range relative to the pH standard value, it is determined that an alkaline agent needs to be added. This amount of washing water is called the "maximum amount of alkali-free washing water".

[0034] More generally, if the pH of the return water is not within the specified range relative to the pH standard value when the amount of wash water used reaches the maximum amount of non-alkaline wash water, then an alkaline agent is added. It is desirable that the "maximum amount of non-alkaline wash water" is less than the "maximum wash water volume" described later.

[0035] Next, it is determined whether the total amount of washing water ΣW is greater than the sum of the capacities of the storage tank 10 and the recovery container 110 ΣMaxV (step S1140). This is to prevent the washing water from overflowing. If the total amount of washing water ΣW is greater than or equal to the sum of the capacities of the storage tank 10 and the recovery container 110 ΣMaxV (Y branch in step S1140), the washing water valve 130a is closed (step S1160). Then the process returns to step S1080.

[0036] Here, the relationship between the total amount of washing water ΣW and the sum of the capacities of the storage tank 10 and the recovery container 110, ΣMaxV, is expressed. However, it is preferable to set ΣMaxV to a value smaller than the sum of the capacities of the storage tank 10 and the recovery container 110. This is because if washing water is injected until the amount of washing water used reaches ΣMaxV, which is equal to the sum of the capacities of the storage tank 10 and the recovery container 110, there is a risk of overflow. This amount is called the "maximum washing water amount." It can be said that the maximum washing water amount is ΣMaxV. In other words, if the amount of washing water used exceeds the maximum washing water amount, the washing water from the washing water source is stopped.

[0037] On the other hand, if the total amount of washing water ΣW is not greater than the sum of the capacities of the storage tank 10 and the recovery container 110 ΣMaxV (N branch in step S1140), the process returns to step S1080.

[0038] As described above, the cleaning apparatus 100 according to the present invention generates a sponge-like porous metal body, which allows the storage tank 10, the electrode plate 12, and the recovered metal to be cleaned to a pH level suitable for handling, in relation to the apparatus for recovering metal from waste liquid.

[0039] The following describes in detail an example of a device that recovers metal from waste liquid by generating a sponge-like porous metal material.

[0040] [Explanation of the components of the metal recovery device] Figure 5 shows an example of the configuration of an apparatus for implementing the metal recovery method targeted by the present invention (hereinafter also referred to as "metal recovery apparatus 1"). Figure 6 shows a partially enlarged view. Referring to Figures 5 and 6, the metal recovery apparatus 1 comprises a storage tank 10 for storing the liquid to be treated, electrode plates 12 that serve as electrodes, a power supply 14 that supplies power to the electrode plates 12, a bubble generator 16, and a controller 18. It is more preferable if a concentration meter 20 and a water level gauge 22 are also provided. A filter 26 may be provided below the storage tank 10 to separate the metal recovered after processing from the liquid from which the metal was recovered.

[0041] Furthermore, the storage tank 10 may be provided with an injection pipe 40 for injecting the liquid to be treated, and an injection pipe on / off valve 40a for opening and closing the injection pipe 40. In addition, the storage tank 10 may be provided with an additional tank 28 and an additional on / off valve 28a for adding hydrogen peroxide solution to it.

[0042] <Storage tank 10> The storage tank 10 is a container for storing the liquid to be treated and for electrolyzing the liquid. It may be sealed, but since hydrogen is generated by electrolysis, an outlet (not shown in the drawing) is necessary to release the hydrogen. The top of the storage tank 10 is also provided with an inlet for injecting the liquid to be treated. In the drawing, the top of the storage tank 10 is shown as open, so the inlet is the top opening of the storage tank 10. Note that the inlet may be provided in a location other than the top of the storage tank 10.

[0043] At the bottom of the storage tank 10, there is an outlet 10a for recovering the treated liquid after electrolysis and the metal deposited by electrolysis. A funnel shape around the outlet 10a is preferable because it pushes out the sponge-like porous metal body that has settled from the treated liquid. The sponge-like porous metal body will be described in detail later.

[0044] Furthermore, the opening and closing of the discharge port 10a is controlled by instruction signals C from the controller 18, which will be described later. EV It may be possible to make it so that it can be opened and closed by means of a door.

[0045] A through-hole 10b is provided on the side of the storage tank 10 to guide the power line 14c from the power source 14 into the storage tank 10. The power line 14c passes through the through-hole 10b in a liquid-tight manner. Therefore, even if the liquid to be treated enters the storage tank 10, there will be no leakage from the through-hole 10b.

[0046] <Electrode plate 12> The electrode plate 12 is a conductive material that serves as either the cathode or anode. Its shape is usually plate-like, but it does not have to be plate-like. Titanium or stainless steel are preferably used for the electrode plate 12 because they are less prone to the adhesion of deposited metal. Furthermore, its surface should be smooth, as this makes it difficult for sponge-like porous metal materials to bond to it. A mirror finish is even better.

[0047] The electrode plates 12 are connected so that opposing electrode plates 12 are opposite poles. In other words, except for the electrode plates 12 at both ends, electrode plates 12 of the same pole are arranged with opposing electrode plates 12 in between. Figure 6 shows a state in which five electrode plates 12 are arranged. These are electrode plates 12a, 12b, 12c, 12d, and 12e. In these electrode plates 12, opposing electrode plates 12 are opposite poles.

[0048] More specifically, the set of electrode plates 12a, 12c, and 12e, and electrode plates 12b and 12d constitute the same electrode plate 12. These are always electrode plates with the same polarity. These sets may also be called identical electrode plates 12A and identical electrode plates 12B. That is, one identical electrode plate 12A consists of electrode plates 12a, 12c, and 12e, and the other identical electrode plate 12B consists of electrode plates 12b and 12d. Of course, "one" and "the other" can be reversed.

[0049] <Power supply 14> The power supply 14 may be either a constant voltage power supply or a constant current power supply, but a constant current power supply is preferred. A bipolar power supply is even more preferred. Here, a bipolar power supply is a power supply that can reverse the positive and negative terminals of the electrode terminals. The power supply 14 has at least two terminals 14a and 14b. A power line 14c is connected to each terminal. The power supply 14 also receives instruction signals C from the controller 18, which will be described later. VI It is controlled by [this method].

[0050] Furthermore, one pole (terminal) of the power supply 14 is connected to one identical electrode plate of the electrode plate 12, and the other pole (terminal) is connected to another identical electrode plate of the electrode plate 12. Figure 6 shows that terminal 14a of the power supply 14 is connected to one identical electrode plate 12A, and the other terminal 14b is connected to the other identical electrode plate 12B. The power line 14c is electrically connected to the electrode plate 12 at connection terminal 14d.

[0051] <Bubble Generator 16> The bubble generator 16 consists of a blower pump 16a, a blower pipe 16b, and a diffuser nozzle 16c. When the blower pump 16a operates and sends air through the blower pipe 16b to the diffuser nozzle 16c, air is ejected from the outlet 16d of the diffuser nozzle 16c (see Figure 6). In the liquid, the ejected air forms bubbles and rises.

[0052] The diffuser nozzle 16c is positioned below the electrode plate 12. The bubble generator 16 is responsible for directing the generated bubbles onto the electrode plate 12, causing the electrode plate 12 to vibrate. Therefore, it is preferable that the bubbles generated from the diffuser nozzle 16c have a diameter sufficient to cause the electrode plate 12 to vibrate when they strike it.

[0053] The diameter and velocity of bubbles sufficient to shake the electrode plate 12 cannot be determined solely by the position of the storage tank 10 and the aeration nozzle 16c, but bubbles smaller than 100 μm in diameter at the point of contact with the electrode plate 12 are unlikely to shake it. On the other hand, bubbles that are too large will pulverize the sponge-like porous metal material, returning it to fine particles, making them difficult to recover. The operation of the bubble generator 16 is controlled by an instruction signal C from the controller 18, which will be described later. B It is controlled by [something].

[0054] <Controller 18> The controller 18 consists of a CPU (Central Processor Unit), memory, and input / output devices. The controller 18 controls the operation of at least the power supply 14 and the bubble generator 16. More specifically, the controller 18 controls the instruction signal C VI This allows control of the ON / OFF state of power supply 14, applied power (voltage or current), polarity, etc. Also, the received signal S from power supply 14 VI This allows us to know the current operating status of power supply 14. The operating status includes information such as the currently applied voltage and current, as well as polarity.

[0055] Furthermore, the controller 18 receives instruction signal C B This allows control of the ON / OFF state of the bubble generator 16 and the amount of bubbles generated (directly the airflow rate of the blower pump 16a).

[0056] Furthermore, the controller 18 controls the opening and closing of the discharge port 10a of the storage tank 10 with instruction signal C EV It is controlled by the instruction signal C. MV It may also be controlled by an instruction signal C. PV It may be controlled by this method.

[0057] Furthermore, if a concentration meter 20, a water level meter 22, and a hydrogen peroxide concentration meter 30 are provided, the received signals S from these devices are also recorded. Q S L S H2O2 By receiving this data, it is possible to determine the metal ion concentration of the liquid to be treated in the storage tank 10, the liquid level of the liquid to be treated in the storage tank 10, and the concentration of hydrogen peroxide in the storage tank 10.

[0058] Furthermore, the controller 18 can output a notification signal SF when the metal ion concentration in the liquid being treated falls below a predetermined value, indicating that metal recovery is complete. The notification signal SF may also be used by the controller 18 itself.

[0059] <Concentration meter 20> The concentration meter 20 measures the metal ion concentration of the liquid to be treated in the storage tank 10. The measurement result is received as signal S Q This is transmitted to the controller 18. The concentration meter 20 can be of any type as long as it can measure the metal ion concentration. Figure 5 shows a concentration meter 20 consisting of a concentration meter body 20a, a first pipe 20b, a pump 20c, and a second pipe 20d. Alternatively, a concentration meter may be used in which a part of the storage tank 10 body is made of a transparent material, and the metal ion concentration is measured by obtaining information from the light absorption of the liquid through the transparent material using image processing or the like. This is because even if the metal ion concentration is not directly measured, if an index that can be used as a substitute for the metal ion concentration can be converted to the metal ion concentration, then it can be said that the metal ion concentration is being measured.

[0060] The first pipe 20b collects the liquid to be treated from the bottom of the storage tank 10 and sends it to the concentration meter body 20a via the pump 20c. After measurement, the liquid to be treated is returned to the top of the storage tank 10 via the second pipe 20d. Since the amount of liquid used by the concentration meter 20 is extremely small, the circulation of the liquid to be treated in the storage tank 10 by the pump 20c does not affect the formation of the sponge-like porous metal body.

[0061] <Water level gauge 22> The water level gauge 22 detects the liquid level of the liquid to be treated in the storage tank 10 and sends a received signal S to the controller 18. L Notification will be sent via [this method]. The water level gauge 22 can be suitably used when disposing of the treated liquid from the storage tank 10 after processing is complete, and when filling the empty storage tank 10 with new treated liquid. <Hydrogen peroxide concentration meter 30> The hydrogen peroxide concentration meter 30 measures the concentration of hydrogen peroxide in the liquid being treated and receives the measurement result as a signal S. H2O2 This notifies the controller 18. The liquid to be treated contains hydrogen peroxide at a relatively high concentration, which contributes to the dissolution of copper. If copper remains as a solid on the inner wall of the storage tank 10 or on the surface of the electrode plate 12, it can be removed from the storage tank 10 by being redissolved by the liquid to be treated. Therefore, the hydrogen peroxide concentration meter 30 is provided to measure the concentration of hydrogen peroxide in the liquid to be treated so that hydrogen peroxide can be added to the storage tank 10 if necessary.

[0062] <Rectifier Guide 24> The flow straightening guide 24 is provided between the electrode plate 12 and the inner wall of the storage tank 10. The lower end 24d has an opening that can take in all the bubbles from the aeration nozzle 16c. Therefore, it is large enough to completely surround the outlet 16d of the aeration nozzle 16c when viewed from above. The upper end 24u is positioned below the liquid surface of the liquid to be treated. With this configuration, bubbles generated from the aeration nozzle 16c float upward from the bottom of the storage tank 10. The upward flow generated at this time flows towards the inner wall surface of the storage tank 10 at the liquid surface, and circulates between the flow straightening guide 24 and the inner wall surface of the storage tank 10 as a flow from top to bottom.

[0063] The flow straightening guide 24 is a component whose purpose is to suppress the generation of in-plane swirling flow, as will be described later. Therefore, it does not have to be a shape that completely surrounds the electrode plate 12 as long as it can suppress in-plane swirling flow. For example, taking Figure 6 as an example, the flow straightening guide 24 may be provided as a flat plate-shaped component parallel to the electrode plate 12a and electrode plate 12e between the electrode plate 12a and the storage tank 10, and between the electrode plate 12e and the storage tank 10. Alternatively, it is preferable to arrange the electrode plate 12 parallel to the inner wall of the storage tank 10 and place the flow straightening guide 24 between the inner wall and the electrode plate 12.

[0064] <Filter 26> The filter 26 is installed below the outlet 10a of the storage tank 10. It filters out the fine powder deposited by electrolysis. Since the deposited metal from the outlet 10a is discharged as a sponge-like porous metal material, the filter does not need to be fine enough to filter out particles smaller than a few microns. For example, it is sufficient if it can capture particles of 10 μm or larger.

[0065] [Explanation of operating conditions] Figure 7 shows the processing flow (main flow) of the controller 18. See also Figures 5 and 6. The metal recovery method according to the present invention is carried out according to this processing flow. When the operation of the metal recovery device 1 starts (step S100), a termination determination is made (step S102). If processing is to continue (N branch in step S102), control proceeds to the next process. Note that in the termination determination, the device may enter a standby state based on signals from other devices.

[0066] If the process is to terminate (Y branch in step S102), the process is stopped (step S104). The termination conditions include stopping the device itself by the user, emergency stop, and the end of the liquid being processed. Of course, other conditions may also be used.

[0067] If the process is to continue (N branch in step S102), first pour the liquid to be treated into the storage tank 10 (step S106). Pour in enough liquid to completely submerge the electrode plate 12 and the connection terminal 14d between the electrode plate 12 and the power supply 14. This is because if the connection terminal 14d is submerged in the liquid, there is no risk of sparks flying from the connection terminal 14d, as this will not ignite the hydrogen present on the surface of the liquid to be treated.

[0068] The injection of the liquid to be processed is initiated by instruction signal C from controller 18. MV The process is initiated by opening the injection pipe valve 40a, and receiving the signal S from the water level gauge 22. L Based on this, the controller 18 determines that injection is complete and issues instruction signal C MV The process may be stopped by closing the injection tube opening / closing valve 40a. This process is a liquid injection process in which a solution containing a metal existing in an ionic state is injected into a container on which electrode plates are placed.

[0069] Next, the system is left to wait for a certain period of time (step S108). The solution to be processed here is assumed to be a copper etching solution. Copper etching solutions often contain a relatively large amount of hydrogen peroxide and are strong acids with a pH of approximately 1. Therefore, the purpose of holding the solution in the storage tank 10 for a while is to dissolve any copper components remaining on the electrode plate 12, the inner wall surface of the storage tank 10, the electrode terminals, etc. Therefore, this step may be skipped. Alternatively, this step may be replaced with a settling step in which the solution is allowed to settle in contact with the electrode plate.

[0070] Furthermore, Figure 8 shows the flow of the process in which hydrogen peroxide is added during step S108. Step S108 can be considered a waiting step to dissolve any remaining copper components. However, if the concentration of hydrogen peroxide in the solution being treated is low, the expected effect cannot be obtained. Therefore, when entering step S108, the hydrogen peroxide concentration M HO Measure (step S130). This is measured with a hydrogen peroxide concentration meter 30, and the result is received as signal S H2O2 This is done by notifying the controller 18.

[0071] Next, the hydrogen peroxide concentration M was measured. HO and threshold M THO Compare (step S132). Threshold M THO This can be preferably set to 1-20% by mass. Hydrogen peroxide concentration M HO The threshold M THO If the following conditions are met (Y branch in step S132), hydrogen peroxide is at least threshold M THO Further addition is made up to the above (step S134). This is because there is a risk that insufficient hydrogen peroxide may prevent the copper remaining in the storage tank 10 from being properly dissolved.

[0072] On the other hand, hydrogen peroxide concentration M HO The threshold M THO If the value is higher (N branch in step S132), do nothing and return to the main routine (step S136).

[0073] Refer to Figure 7 again. After step S108, current is passed between the electrode plates 12 (step S110). This is because the controller 18 sends an instruction signal C to the power supply 14. VI This is carried out by transmitting a current. When an electric current flows between two identical electrode plates 12A and 12B, copper is deposited while hydrogen is generated from the electrode plate that becomes the cathode. In Figure 6, for example, when electrode plate 12A is the anode and electrode plate 12B is the cathode, hydrogen is generated from electrode plates 12b and 12d, which are identical electrode plates 12B, and copper is deposited.

[0074] In this process, if there is flow of the treatment solution between the electrode plates 12, the deposited copper will become fixed to the electrode plates 12 as if it were plated. However, if the treatment solution between the electrode plates 12 is still, the deposited copper will undergo the electrolytic reaction while incorporating tiny hydrogen bubbles.

[0075] Figure 9 shows a conceptual diagram of the progression of this state. Figure 9 shows a cross-section of the cathode plate. For the sake of explanation, let's assume that copper and hydrogen are generated on only one side. Copper is represented by black circles and hydrogen by white circles. Referring to Figure 9(a), copper fine powder Cu1 is initially deposited on the surface of the cathode plate. After copper has been deposited by electrolysis for a while, as mentioned above, the liquid is still, so microscopically, the cathode surface becomes deficient in copper ions, creating conditions where hydrogen is easily generated. The hydrogen H1 generated from the surface of the cathode plate becomes tiny bubbles, which prevent the deposited copper Cu1 from adhering to the electrode (Figure 9(b)). It can also be said that the copper Cu1 is pushed away from the electrode. Therefore, the deposited copper Cu1 cannot form large granular clumps and is kept away from the cathode plate surface as fine powder. At this time, a force is acting to attract the copper Cu1 fine powder towards the cathode.

[0076] Meanwhile, the hydrogen microbubbles H1 are pushed away from the cathode plate along with the copper fine powder Cu1 by the next generated copper fine powder Cu2 (Figure 9(c)). The hydrogen microbubbles H1 maintain their shape without breaking due to surface tension and trap the copper fine powder Cu1 on their surface. The copper Cu2 is then pushed away from the cathode plate surface by the next generated hydrogen microbubbles H2 (Figure 9(d)).

[0077] In this way, the metal fine powder is attracted to the cathode plate, and the hydrogen microbubbles that are successively generated push it back from the cathode plate. Furthermore, the metal fine powder separates the hydrogen microbubbles from the cathode plate. This reaction continues, and a collection of structures is formed on the cathode plate that appear as if the copper fine powder has embraced the hydrogen microbubbles. This is called a "sponge-like metal porous body." Since the metal here is copper, it can also be called a "sponge-like copper porous body" or "sponge-like copper porous body."

[0078] Figure 10 shows a conceptual diagram of a sponge-like porous metal body (reference numeral 60) growing on the cathode plate. The sponge-like porous metal body 60 maintains a unified shape in the liquid because the metal fine powder is only held together by the surface tension of the hydrogen microbubbles. However, the bonds themselves are very weak and it shakes even with slight vibrations. Furthermore, since it is not fixed to the electrode plate 12, it can easily detach and fall off if the electrode plate 12 is subjected to slight physical vibrations.

[0079] Furthermore, the sponge-like porous metal (copper) body 60 grows on the cathode plate because the deposited copper fine powder is attracted to the cathode plate. However, when the polarity of the electrode plate 12 is reversed, the force attracting it towards the cathode plate disappears and it falls. If the sponge-like porous metal body 60 that has fallen in the liquid is poked with a rod or the like, tiny hydrogen bubbles separate and bubble. Therefore, if bubbles appear when pressed in the liquid, it can be determined that a sponge-like porous metal body 60 has been formed.

[0080] It is believed that the sponge-like porous metal body 60 is formed by the mechanism described above. Therefore, when the current flowing between the electrode plates 12 increases, the amount of hydrogen microbubbles generated increases, making it possible to form a more unstable sponge-like porous metal body 60. This means that the metal is deposited in a state that is easy to detach from the electrode plates 12, i.e., easy to recover. In the current experiment, the cathode side is 10 A / dm 2 ~200A / dm 2 It has been confirmed that a sponge-like metal porous body 60 suitable for recovery can be obtained within this range. If the current density is too low, the sponge-like metal porous body 60 will not form, and metal will be deposited and fixed on the cathode. If the current density is too high, the efficiency of copper generation (deposition) may be poor.

[0081] Furthermore, this reaction is a phenomenon that occurs depending on the current density of the cathode electrode plate 12. Therefore, if the area of ​​the cathode electrode plate 12 is smaller than the area of ​​the anode electrode plate 12, the formation of the sponge-like metal porous body 60 on the cathode plate can be actively promoted even when the same current is applied.

[0082] In the configuration shown in Figure 6, the same electrode plate 12A is composed of three electrode plates 12, and the same electrode plate 12B is composed of two electrode plates 12. If the same electrode plate 12B is used as the cathode, the number of electrode plates 12 that act as the cathode is less than the number of electrode plates 12 that act as the anode. Therefore, the current density of the same electrode plate 12B can be higher than that of the same electrode plate 12A, and the sponge-like porous metal body 60 can be formed more efficiently. Of course, the area of ​​the cathode electrode plate 12 can be reduced while maintaining the same number of plates. As described above, this process can be described as a sponge-like porous metal body formation process in which current is passed between electrode plates to form a sponge-like porous metal body 60 on the electrode plate that acts as the cathode.

[0083] Furthermore, in the configuration shown in Figure 6, if the same electrode plate 12B is used as the cathode, then an anode plate will always be present on both sides of every cathode plate. This configuration is preferable because it can mitigate the flow of the solution on the surface of the cathode plate.

[0084] Refer to Figure 7 again. After a current is passed between the electrode plates 12 for a certain period of time (step S110), the current is then stopped and the bubble generator 16 is activated (step S112). This is done when the controller 18 receives instruction signal C B This is done by sending the air to the bubble generator 16 (more specifically, the blower pump 16a).

[0085] Figure 11 shows a conceptual diagram of this process. The bubble generator 16 generates bubbles from below the electrode plate 12. The generated bubbles collide with the electrode plate 12 or the sponge-like porous body 60, causing the electrode plate 12 to vibrate. They also float upwards along the surface of the electrode plate 12. The vibration of the electrode plate 12 at this time, along with the stimulation caused by the bubbles sweeping across the surface of the electrode plate 12, causes the sponge-like metal porous body 60 to detach from the electrode plate 12 and fall.

[0086] Therefore, this process can be described as a peeling process that separates the sponge-like porous material from the electrode. Furthermore, since the sponge-like porous material is peeled away from the electrode plate by air bubbles, it is a peeling process that separates the sponge-like porous material from the electrode, and is a process that brings air bubbles into contact with the electrode plate.

[0087] In this case, a flow from bottom to top is generated within the storage tank 10. If a flow straightening guide 24 is provided between the electrode plate 12 and the inner wall of the storage tank 10, the flow from bottom to top will pass between the electrode plate 12 and the inner wall of the storage tank 10 and flow from top to bottom. In this way, the generation of a swirling flow (called an "in-plane swirling flow") where both a flow from bottom to top and a flow from top to bottom occur simultaneously between the electrode plate 12 can be suppressed.

[0088] The in-plane swirling flow pulverizes the sponge-like porous metal body 60 into tiny hydrogen bubbles and metal powder. This is undesirable because the metal powder may float in the treated liquid, making recovery difficult.

[0089] The step of generating these bubbles (step S112) is a step of peeling the sponge-like porous metal body 60 from the electrode plate 12. In the metal recovery apparatus 1 targeted by the present invention, a sponge-like porous metal body 60 is generated in which fine metal powder is loosely bound together, and the bond with the electrode plate 12 is also loose, so it can be peeled from the electrode plate 12 by means other than bubbles.

[0090] For example, by providing an electrode plate vibrator to directly vibrate the electrode plate 12, the sponge-like porous metal body 60 can be detached from the electrode plate 12. Figure 12 shows a state in which electrode plate vibrators 50A and 50B are provided, which can vibrate the same electrode plate 12A and the same electrode plate 12B, respectively. These electrode plate vibrators 50 can be controlled by instruction signals from the controller 18. The process using the electrode plate vibrator is a detachment process in which the sponge-like porous body is pulled away from the electrode, and is a process in which vibration is applied to the electrode plate.

[0091] Furthermore, the sponge-like metal porous material 60 can also be detached from the electrode plate 12 by reversing the polarity of identical electrode plates 12A and 12B. As already explained, the sponge-like metal porous material 60 is attracted to the cathode plate. Therefore, by reversing the polarity of the opposing electrode plate 12, the cathode to which the sponge-like metal porous material 60 was attracted changes to the anode, and a repulsive force acts on the sponge-like metal porous material 60. On the other hand, the opposing electrode plate 12 changes to the cathode, and an attractive force acts towards the opposing electrode plate 12. As a result, the sponge-like metal porous material 60 can be detached from the electrode plate 12. Thus, the process of reversing polarity is a detachment process that separates the sponge-like porous material from the electrode, and is a process of reversing the polarity of the electrode plates.

[0092] Furthermore, if the power supply 14 is of the bipolar type, the polarity of the electrode plate 12 is reversed by an instruction signal C from the controller 18. VI This can be done by [method].

[0093] As described above, step S110 is a peeling step in which the sponge-like porous body is separated from the electrode, and the means of peeling may be replaced with a step of applying air bubbles to the electrode plate 12, a step of vibrating the electrode plate 12, or a step of reversing the poles of the electrode plate 12.

[0094] Refer to Figure 7 again. After operating the bubble generator 16 for a certain period of time, the bubble generator 16 is stopped and the system is left waiting for a certain period of time (step S114). The purpose of this waiting period is to allow the flow of the liquid to be treated between the electrode plates 12 generated by the bubble generator 16 to subside.

[0095] Next, the metal ion concentration Mq in the liquid to be treated is measured and compared with the threshold Mth (step S116). The controller 18 receives the signal S from the concentration meter 20. Q The metal ion concentration Mq can be determined by this. If the metal ion concentration Mq is below the threshold Mth (Y branch in step S116), the recovery of metal from the current treatment liquid is considered complete, and the process proceeds to the drainage step (step S118). Note that the measurement of the metal ion concentration may be performed continuously.

[0096] In this case, the controller 18 may internally generate and transmit a processing completion notification signal SF (see Figure 5). If the metal ion concentration Mq is not below the threshold Mth (N branch in step S116), control is returned to the process of passing current between the electrode plates 12 again (step S110). In other words, the standing process, the sponge-like porous formation process, and the peeling process are repeated until the metal ion concentration in the liquid being processed falls below a predetermined value.

[0097] Once the process moves to step S118, it can be determined that the processing of the liquid to be processed is complete, and the liquid to be processed is discarded. This is done when the controller 18 receives instruction signal C V This can be done by opening the discharge port 10a of the storage tank 10.

[0098] From the outlet 10a, the recovered metal as a sponge-like porous metal body 60 and the treated liquid are discharged. By filtering this with a suitable filter 26, the precipitated metal can be recovered. This step involves filtering the treated liquid and recovering the sponge-like porous body.

[0099] As described above, the metal recovery apparatus targeted by the present invention can recover metal ions in the liquid to be treated as clumps bound together by loose bonds. [Industrial applicability]

[0100] This invention can be suitably used not only as a device for recovering copper from etching solution wastewater, but also as a cleaning device for a device for recovering dissolved metals from wastewater containing other metals. [Explanation of Symbols]

[0101] 100 Washing device 110 Collection containers 110a Drain outlet 112 Return piping 114 Circulation pump 116 pH meter 118 Alkaline agent additive 118a Alkaline agent tank 118b Alkaline agent valve 120 spray nozzles 122 Cleaning controller 130 Washing water source 130a Wash water valve 130b Flushing water pipe C DV instruction signal C WP instruction signal C WV instruction signal C AV instruction signal S pH Received signal SE Cleaning complete signal 1. Metal recovery device 10 Storage tanks 10a outlet 10b Through hole 12 Electrode plate 12a, 12b, 12c, 12d, 12e electrode plate 12A same electrode plate 12B Same electrode plate 14 Power supply 14a, 14b terminals 14c power line 14d Connection terminal 16. Bubble generator 16a Blower pump 16b Air pipe 16c Aeration nozzle 16d spout 18 Controller 20 Densitometer 20a Concentration meter main unit 20b 1st piping 20c pump 20d Second piping 22 Water level gauge 24 Rectifier Guide 24u (upper end of the rectifier guide) 24d (Lower end of the flow guide) 26 filters 28 Additional tanks 28a Additional on / off valve 30 Hydrogen peroxide concentration meter 40 Injection tube 40a Injection pipe on / off valve 50 Electrode plate exciter 60 Sponge-like porous metal body C EV instruction signal C VI instruction signal C B instruction signal C MV instruction signal C PV instruction signal S Q S L S H2O2 Received signal S VI Received signal SF notification signal M HO hydrogen peroxide concentration M THO threshold Mq Metal ion concentration Mth threshold

Claims

1. A cleaning apparatus for a metal recovery apparatus having a storage tank in which electrode plates for electrolyzing a solution containing a metal existing in an ionic state are arranged, and a filter for recovering the metal deposited by electrolysis, A recovery device for collecting the washing water below the aforementioned filter, A spray nozzle for spraying the cleaning water into the storage tank and toward the electrode plate, A return pipe that returns the cleaning water in the recovery device to the spray nozzle, A circulation pump is provided in the return piping, A pH meter is installed in the return piping, A cleaning device for a metal recovery apparatus, having a controller that stops the supply of cleaning water when the pH of the cleaning water flowing through the return pipe, as measured by the pH meter, reaches a predetermined value.

2. A cleaning device for a metal recovery apparatus according to claim 1, further comprising an alkaline agent additive provided in the return piping.

3. A cleaning device for a metal recovery device according to claim 1 or 2, wherein the recovery device is provided with a drain outlet that opens and closes based on instructions from the controller.

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