Dissolved metal deposition device

Abstract

To provide a dissolved metal deposition device which is easy to maintain and manage electrode plates and a treatment tank storing treated water, and which has a simple structure and is easy to install.SOLUTION: There is provided a dissolved metal deposition device 1 in which electrode plates 10 consisting of anode plates 11 and cathode plates 12 are arranged in a treatment tank 40 storing treated water after plating, DC power is supplied to the electrode plates to electrolyze the treated water, and dissolved metals are deposited on the cathode plates 12, in which the electrode plates 10 are not fixed to the treatment tank 40, but are provided with spacing means 20 for maintaining a desired spacing. Further, polarity of the electrode plate 10 is not switched, and the electrode plate is replaced with metal attached thereto. When an amount of metal deposition increases, it is only necessary to widen a gap between non-fixed electrode plates, and the dissolved metal deposition device can be made with a simple structure without requiring any cleaning work.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a dissolved metal deposition device that electrolyzes plated water to deposit dissolved metals on electrode plates, thereby reducing the dissolved metal concentration in the water. More specifically, the present invention relates to a dissolved metal deposition device that is easy to maintain and manage the treatment tank containing the water to be treated and the electrode plates, and that has a simple configuration and is easy to install.

[0002] More specifically, the present invention relates to a dissolved metal deposition device in which the electrode plates are not fixed to the treatment tank but are arranged at desired intervals, thereby allowing existing treatment tanks to be used as they are and facilitating the installation of the equipment, and the electrode plates can be replaced with metal still attached, eliminating the need for cleaning the treatment tank. [Background technology]

[0003] In a manufacturing plant for plated products, the substrate that will become the plated product is immersed in a plating solution, and a plating layer of a desired thickness is deposited on the surface of the substrate to produce the plated product. When moving from each plating process to the next process, the plated product is immersed in a cleaning tank to wash off any remaining plating solution adhering to the product surface, and management is carried out to prevent the plating solution from the previous process from being mixed with the surface activation treatment solution or plating solution of the next process.

[0004] The cleaning water stored in this cleaning tank is replaced by discharging the wastewater from cleaning to prevent the concentration of dissolved metals from increasing as the residual plating solution is washed away. Specifically, in the case of zinc electroplating equipment, a huge amount of cleaning wastewater, between 150 and 200 tons, is discharged per day.

[0005] Wastewater treatment from electroplating facilities involves a chemical process known as coagulation and sedimentation, which recovers dissolved metals such as chromium, zinc, cyanide, and copper from the wash water and reduces the concentration of dissolved metals to a level that meets wastewater standards. The coagulation and sedimentation method utilizes the differences in pH values ​​at which different metal ions tend to precipitate, and adjusts the pH by adding acidic or alkaline agents to the wash water depending on the type of metal to be recovered. At the same time, inorganic coagulants, liquid chelating agents, polymer coagulants, etc. are added to efficiently coagulate and recover the desired dissolved metals.

[0006] However, because zinc is an amphoteric metal that can dissolve in both acidic and alkaline pH ranges, it is difficult to reliably recover dissolved zinc contained in cleaning wastewater using chemical treatment alone. Therefore, even when the general wastewater standard for zinc was strengthened from 5 mg per liter of water (hereinafter referred to as mg / L) to 2 mg / L by Environment Ministry Ordinance No. 33 of 2006, the electroplating industry was made an exception and allowed to maintain the previous provisional wastewater standard of 5 mg / L.

[0007] With the deadline for application of the above provisional effluent standards reaching 2021, the electroplating industry has also seen a new provisional effluent standard strengthened to 4 mg / L, and a legal amendment has been implemented to extend the application period of the provisional effluent standards until the end of 2024. However, the provisional effluent standards of 2021 are also expected to be abolished with the legal amendment of 2024, and the development of new effluent treatment technology has become an urgent issue for the electroplating industry as well, so that the general effluent standard for zinc of 2 mg / L can be met.

[0008] Patent Document 1 discloses a technology for an electrolysis device that recovers inorganic salts contained in tap water by depositing them on electrode plates through electrolysis, thereby preventing the deposition of inorganic salts inside the pipes of a water heat exchanger that constitutes a water heater.

[0009] According to the technology described in this document, a flow path is formed by alternately protruding anode and cathode plates from the side wall of a sealed container, tap water supplied into the sealed container is electrolyzed, and inorganic salts are precipitated on the electrode plates. The inorganic salts precipitated on the cathode plates are then peeled off by reversing the polarity of the electrode plates, carried by the water flow to the downstream side of the sealed container, and sucked and collected by a pump disposed on the bottom surface of the downstream side of the sealed container.

[0010] If the technology described in this document were to be applied to the washing wastewater from electroplating equipment, heavy metals such as zinc would have a higher specific gravity than inorganic salts and would therefore be difficult to transport in the water current, and the heavy metals that were peeled off from the electrode plates would simply accumulate at the bottom of the flow path.

[0011] Therefore, when the amount of deposited metal increased, there was a possibility of a short circuit between the anode and cathode plates. When a short circuit occurred, the dissolved metals would no longer deposit on the cathode plates, causing the electrolysis device to malfunction. In particular, because the serpentine flow path is long and narrow, frequent recovery of the deposited metals was necessary to prevent short circuits, making it unsuitable for electroplating facilities that require the treatment of large volumes of washing wastewater.

[0012] Patent Document 2 discloses a water treatment technology in which water to be treated is electrolyzed while passing between a positive electrode inclined plate and a negative electrode inclined plate, contaminants are precipitated on the negative electrode inclined plate, and the polarity of the electrode plate is reversed to separate the contaminants, which then descend along the inclined surface of the electrode plate and settle at the bottom of the treatment tank.

[0013] According to the technology described in this document, the electrode plates are entirely immersed in the water to be treated and are supported in a state where they are floating above the bottom of the treatment tank. Specifically, a pair of opposing side surfaces of the treatment tank are provided with inclined guide grooves, and the electrode plates are inserted into the guide grooves to be supported.

[0014] However, the technology described in this document requires that the electrode plate be positioned higher than the bottom of the treatment tank using a guide groove, which reduces the area available for arranging the electrode plate relative to the volume of the treatment tank. This not only precludes the use of existing treatment tanks without guide grooves, but also requires a large space for installation, making it difficult to easily introduce into electroplating plants with large wastewater volumes. Furthermore, because contaminants settle at the bottom of the treatment tank, the treatment tank needs to be cleaned frequently. [Prior art documents] [Patent documents]

[0015] Patent Document 1: Japanese Patent Application Laid-Open No. 2015-97988 Patent Document 2: Japanese Patent Application Laid-Open No. 2021-49523 Summary of the Invention [Problem to be solved by the invention]

[0016] The problem to be solved by the present invention is to provide a dissolved metal deposition device that requires less effort to maintain the treatment tank for the water to be treated and the electrode plates, has a simple configuration, and is easy to install. [Means for solving the problem]

[0017] A first aspect of the present invention is a dissolved metal deposition device that immerses electrode plates in water to be treated after plating, electrolyzes the water to be treated, and deposits dissolved metals on the electrode plates. The device includes a plurality of sets of electrode plates each having an anode plate and a cathode plate, spacing means, and power supply means, wherein each of the electrode plates stands upright from the bottom of a treatment tank that stores the water to be treated and has a protruding portion that protrudes from the surface of the water to be treated, and the anode plates and cathode plates are immersed in the treatment tank in a row at desired intervals, and each of the gaps formed between adjacent anode plates and cathode plates forms a flow path for the water to be treated, and the spacing means is made of a non-conductor that does not block each of the flow paths, and the non-conductor is in contact with both sides of each electrode plate, fixing the electrode plates to the treatment tank. and the individual electrode plates are kept separate.The desired spacing is maintained, and the power supply means connects a power supply line extending from a DC power source to the protrusion, thereby supplying a DC current without changing the polarity of the electrode plates. The dissolved metal is deposited and attached to the cathode plate, and the electrode plates are arranged in the treatment tank in a state where no electrode plate is placed, leaving a non-placement area in which no electrode plate is placed, before the deposition of the dissolved metal, and when the deposition of the dissolved metal progresses, the non-placement area is narrowed according to the amount of deposition, and the electrode plates and the spacing maintaining means are rearranged so as to widen the gap between the electrode plates, so that the deposition of the dissolved metal can be continued without peeling off the metal attached to the cathode plate. It is characterized by the following.

[0018] The water to be treated is preferably washing wastewater discharged from electroplating equipment, but may also be washing wastewater discharged from electroless plating equipment or aged plating solution used for a long period of time, and is not limited thereto. The type of dissolved metal is preferably zinc, which is difficult to precipitate by chemical treatment, but is not limited thereto and may also be chromium, nickel, copper, etc.

[0019] The electrode plates consist of multiple pairs of cathode and anode plates, which are arranged upright in the treatment tank at a desired interval. The gaps between adjacent anode and cathode plates form a flow path through which the water to be treated flows from the inlet side to the outlet side of the treatment tank. Because the electrode plates are not fixed to the treatment tank, the desired spacing can be changed even after installation in the treatment tank. The number of electrode plates can be determined based on the size of the treatment tank and the desired spacing.

[0020] When metal is deposited on the cathode plate and the flow path width narrows, the distance between the plates can be increased as desired according to the amount of metal deposition, thereby maintaining the flow path width substantially equal to that before the metal deposition, without removing the metal. The anode and cathode plates may be arranged parallel to each other, but arranging the anode and cathode plates alternately and offset horizontally to form a serpentine flow path is preferable because it allows the flow path length to be increased without changing the volume of the treatment tank and also increases deposition efficiency.

[0021] The anode and cathode plates also have protruding portions that protrude above the liquid level of the water being treated. Because the power supply lines can be connected to the protruding portions, where metal does not deposit, metal does not adhere to the connection terminals of the power supply lines. Therefore, even if the deposited metal is scraped off the electrode plates and the electrode plates are used repeatedly, the metal only adheres to the flat surfaces, which are easy to peel off, making maintenance of the electrode plates easy.

[0022] The spacing means is made of a non-conductive material that does not block the flow path. The spacing means is also not fixed to the treatment tank, but is in contact with both sides of each electrode plate, and maintains a desired spacing that can be changed depending on the amount of metal adhesion. Specifically, when the amount of metal adhesion increases, the distance that the non-conductive material protrudes from the surface of the electrode plate (hereinafter referred to as the protrusion distance) can be changed to widen the desired spacing.

[0023] Here, "not blocking the flow path" means that, when a non-conductor is placed in the flow path, the size of the non-conductor is smaller than the flow path and does not obstruct the flow of the water to be treated. For example, a spacing means can be formed by connecting shafts of different diameters in multiple stages, with only the larger diameter shaft portions abutting the electrode plates and leaving gaps on both sides of the smaller diameter shaft portions to allow the water to flow through (see Figure 3). Note that, because a slower flow rate of the water to be treated facilitates metal deposition, it is preferable that the size of the non-conductor be as small as possible relative to the flow path.

[0024] Alternatively, a rectangular non-conductor may be attached, adhered, or magnetically attached to the electrode plate to function as the spacing means (see FIG. 7(A)), or a frame may function as the spacing means. Note that the non-conductor is not limited to being disposed within the flow path, and may be placed outside the flow path, for example, on the edge of the treatment tank, so as not to block the flow path (see FIG. 9).

[0025] A non-conductor is any object whose surface does not conduct electricity. For example, it may be an object whose entire body is made of an insulating material, such as a shaft or frame made of resin such as vinyl chloride, or it may be an object made of a metal mass such as a magnet that is covered with rubber to prevent it from conducting electricity.

[0026] The power supply means may be a known DC power source, a power supply line, and a voltage / current controller. The power supply line is connected to the protruding portion of the electrode plate, i.e., the portion that is not immersed in the water to be treated, so metal does not deposit on the connection terminal. Therefore, the connection terminal may have a simple structure such as a clip, and maintenance such as replacing the electrode plate can be reduced.

[0027] Furthermore, after the dissolved metal deposition device is put into operation, the electrode supply means passes a direct current only in one direction to prevent the polarity of the electrode plates from changing, and the deposited metal does not peel off and accumulate on the bottom of the treatment tank. As a result, there is no risk of unintentional short circuits between the anode and cathode plates due to deposited metal, and there is no need to frequently clean the treatment tank to prevent short circuits.

[0028] According to the first aspect of the present invention, the electrode plates are arranged at a desired interval and are held by spacing means abutting both sides. This provides an unprecedented advantage in that the desired spacing can be maintained so that the current density is suitable for metal deposition according to the dissolved metal concentration, even without fixing the electrode plates to the treatment tank. Furthermore, because the electrode plates are not fixed, a flow path can be secured simply by widening the spacing between the electrode plates without peeling off the adhered metal, simplifying the maintenance and management of the electrode plates.

[0029] A second aspect of the present invention is the first aspect of the present invention, wherein the spacing maintaining means comprises spacing changing means, and the spacing changing means is and when the amount of adhesion increases, the non-conductor is protruded from the opposing surface by a longer length. Therefore, When the electrode plates are rearranged, the spacing between the electrode plates is widened. It is characterized by making it possible.

[0030] According to the second aspect of the present invention, the protrusion dimension can be changed by replacing the non-conductor, but is not limited to this. For example, if the non-conductor is a rubber-coated magnet, the protrusion dimension can be changed by magnetically attaching the non-conductor so that it overlaps. If the non-conductor is a shaft that protrudes in the direction of the electrode plate surface, the protrusion dimension can be increased by attaching a joint to the shaft. In addition, if the horizontal lengths of the non-conductors intersecting are different, the protrusion dimension can be changed by rotating the non-conductor horizontally.

[0031] More specifically, while the amount of metal adhesion is small, both ends of the non-conductor in the short side direction are in contact with the surfaces of the adjacent electrode plates, and after the amount of metal adhesion increases, the electrode plates are rotated so that both ends of the non-conductor in the long side direction are in contact with the surfaces of the adjacent electrode plates. According to the second aspect of the present invention, the desired spacing can be easily changed depending on the amount of metal adhesion, which has the advantageous effect of further facilitating maintenance and management of the electrode plates.

[0032] The third invention of the present invention is the second invention, wherein the non-conductor is a shaft body consisting of a thin shaft portion and a lateral protrusion portion that comes into contact with the electrode plate, the thin shaft portion has a length such that when the tip of the shaft body comes into contact with the bottom surface of the treatment tank, the rear end of the thin shaft portion protrudes above the liquid surface, the lateral protrusion portion protrudes horizontally from the thin shaft portion, and the protrusion dimensions in the two intersecting horizontal directions are different, Before the deposition of the dissolved metal, the lateral protrusions are arranged in contact with the opposing surfaces of the electrode plates so that the protrusion dimensions become shorter. When the amount of deposition increases, The lateral protrusion is rotated around the thin shaft portion, By making the protruding dimension longer and contacting the opposing surface, The distance change means R It is characterized by the following.

[0033] The thin shaft portion and the lateral protrusions that form the shaft body may be solid or hollow. Only the lateral protrusions abut against the adjacent electrode plates, and the thin shaft portion is spaced from the electrode plates, allowing the water to flow between the thin shaft portion and the electrode plates. The number, protruding position, protruding length, etc. of the lateral protrusions are not limited.

[0034] For example, if the thin shaft portion is a hollow tube made of vinyl chloride or the like and the lateral protrusion is an L-shaped joint, T-shaped joint, three-way joint, five-way joint, or the like that fits onto the end of the hollow tube, the gap maintaining means can be easily made using products available on the market. It is preferable that the hollow tube that makes up the thin shaft portion has a narrow shaft diameter by connecting hollow tubes of different diameters in multiple stages so that the gap between the shaft body and the electrode plate can be widened.

[0035] According to the third aspect of the present invention, the protrusion distance of the lateral protrusions from the thin shaft portion differs in the two intersecting horizontal directions, so that the desired spacing between the electrode plates can be changed simply by rotating the thin shaft portion around its axis while it is immersed in the water to be treated. This has the advantageous effect of further facilitating maintenance and management, since even if the amount of metal adhering to the electrode plates increases, it is only necessary to change the spacing between the electrode plates, and cleaning of the electrode plates is not required.

[0036] A fourth aspect of the present invention is a dissolved metal deposition device that immerses electrode plates in water to be treated after plating, electrolyzes the water to be treated, and deposits dissolved metals on the electrode plates. The device includes a plurality of sets of electrode plates each having an anode plate and a cathode plate, spacing means, and power supply means, wherein each of the electrode plates stands upright from the bottom of a treatment tank that stores the water to be treated and has a protruding portion that protrudes from the liquid surface of the water to be treated, and the anode plates and cathode plates are immersed in the treatment tank in a row at desired intervals, and each gap formed between adjacent anode plates and cathode plates forms a flow path for the water to be treated, and the spacing means has a support portion and an upright piece, and the support portion has Outside the treatment tank, extending along the direction of the rows and a first support portion that supports the cathode plate and a second support portion that supports the anode plate, and the upright piece is Outside the treatment tank, Each of the support parts Along the direction of extension, The electrode plates are arranged vertically at a desired interval, and the upright pieces and the protruding portions are connected to each other to fix the electrode plates to the treatment tank. and the individual electrode plates are separated and movable, The desired spacing is maintained, and the power supply means connects a power supply line extending from a DC power source to the protrusion, thereby supplying a DC current without changing the polarity of the electrode plates. The dissolved metal is deposited and attached to the cathode plate, and the electrode plate is connected to the upright piece so as to be arranged in the treatment tank while leaving a non-placement area where no electrode plate is placed, at a stage before the deposition of the dissolved metal, and when the deposition of the dissolved metal progresses, the non-placement area is narrowed according to the amount of deposition, and the positions of the upright piece are changed to widen the gap between the electrode plates, and the electrode plates are rearranged, so that the deposition of the dissolved metal can be continued without peeling off the metal attached to the cathode plate. It is characterized by the following.

[0037] According to the fourth aspect of the present invention, outside the flow path The outside of the treatment tankThe electrode plates are held at a desired distance by a spacing means disposed on the support member. The support member constituting the spacing means is divided into a first support member and a second support member, so that even if the support member is conductive, the cathode plate and the anode plate are not short-circuited. Each support member may be divided into the same number of upright pieces. The upright pieces may be provided so as to hang convexly upward from the top surface of the support member, or convexly downward from the bottom surface.

[0038] The upright piece is connected to a protruding portion of one of the electrode plates. The electrode plate and the upright piece may be detachably connected using a known fastening or clamping tool, or may be non-detachably connected by welding. When the upright pieces are detachable, the spacing between the electrode plates can be easily increased by increasing the number of upright pieces compared to the electrode plates and changing the position of the upright pieces to which the electrode plates are connected. Even when the electrode plates are non-detachable, if the support part is divided into the same number as the upright pieces, the electrode plates can be moved together with the upright pieces to increase the spacing between the electrode plates.

[0039] According to the fourth aspect of the present invention, the spacing means Outside the treatment tank Since the electrodes are arranged at regular intervals, the desired intervals can be easily widened according to the state of metal deposition, making maintenance easy. Furthermore, since only the electrode plates can be replaced, replacement work is easy and maintenance costs can be kept low.

[0040] A fifth aspect of the present invention is the fourth aspect of the present invention, wherein the spacing maintaining means includes spacing changing means, a slide groove provided in the support portion, the slide groove being formed to extend along the column direction; The upright piece is slidably mounted along the slide groove, and the electrode plate connected to the upright piece is slid along the slide groove, The spacing between the electrode plates can be changed when they are rearranged. It is characterized by the following.

[0041] According to the fifth aspect of the present invention, the desired spacing can be changed simply by sliding the upright pieces connected to the electrode plates along the slide grooves formed in the support parts. This provides advantageous effects not available in the prior art, such as the ability to change the desired spacing steplessly depending on the state of metal deposition and the ability to easily perform periodic spacing changes.

[0042] The sixth aspect of the present invention is the first to fifth aspects of the present invention, characterized in that the cathode plates and the anode plates constituting the electrode plates are alternately arranged with a horizontal offset along the surface direction, and the flow path is a serpentine flow path. According to the sixth aspect, even if the volume of the treatment tank is small, the flow path length can be long, and metals can be easily precipitated even in water to be treated with a low concentration of dissolved metals.

[0043] The seventh invention of the present invention is the first to fifth inventions, characterized in that the electrode plate is made of a thin plate and is provided with a curvature prevention means, the curvature prevention means is made of a second non-conductor that does not block the flow path, and both ends of the curvature prevention means contact the upper edge portions of the adjacent electrode plates, preventing the electrode plates from curving convexly in a direction intersecting their surfaces.

[0044] According to the seventh aspect of the present invention, the second non-conductor is in contact with the upper edge portions of adjacent electrode plates. Therefore, even if the electrode plates are thin plates that are prone to warping, they are less likely to warp in the horizontally extending intermediate portions, and the electrode plates are less likely to curve convexly to the side. This allows the electrode plates to be thin, making it easy to arrange a large number of electrode plates even in a small treatment tank, and improving deposition efficiency.

[0045] The eighth aspect of the present invention is the first to fifth aspects of the present invention, wherein the water to be treated is washing wastewater from a washing tank for washing a zinc plating solution, the dissolved zinc concentration is at least 100 mg / L or more, and the current density of the DC power supplied by the power supply means is at least 4.5 A / m 2 It is characterized by the above.

[0046] The dissolved zinc concentration in the washing wastewater is controlled within a range of about 100 mg / L to about 500 mg / L at most so as to minimize the influence on the subsequent process. It is more preferable to control it within a range of 300 mg / L to 400 mg / L. According to the eighth invention, the current density of the DC power is at least 4.5 A / m 2As a result, even if the washing wastewater has a low concentration of dissolved zinc, zinc can be sufficiently precipitated without excessively increasing the amount of power consumption.

[0047] The ninth aspect of the present invention is the eighth aspect, characterized in that the cathode plate is made of an iron plate having a thickness of 1 mm or less. According to the ninth aspect, iron and zinc have good adhesion, so the zinc is less likely to peel off naturally and can be reliably recovered. In addition, because the electrode plate is inexpensive, it can be entrusted to a resource recovery company for treatment with the zinc still attached, and electroplating companies can eliminate the need for cleaning the treatment tank and electrode plate, thereby reducing labor. [Effects of the Invention]

[0048] The first aspect of the present invention has the unprecedented advantage that the desired spacing can be maintained to achieve a current density suitable for metal deposition according to the dissolved metal concentration, even without fixing the electrode plates to the treatment tank. Furthermore, because the electrode plates are not fixed, a flow path can be secured simply by widening the spacing between the electrode plates without peeling off the adhered metal, simplifying the maintenance and management of the electrode plates. According to the second aspect of the present invention, the desired spacing can be easily changed depending on the amount of metal attached, which has the advantageous effect of further facilitating maintenance and management of the electrode plates. According to the third aspect of the present invention, even if the amount of metal adhering to the electrode plates becomes large, it is only necessary to change the spacing between the electrode plates, and there is no need to clean the electrode plates, which has the advantageous effect of making maintenance even easier.

[0049] According to the fourth aspect of the present invention, the spacing means Outside the treatment tank Since the electrodes are arranged at regular intervals, the desired intervals can be easily widened according to the state of metal deposition, making maintenance easy. Furthermore, since only the electrode plates can be replaced, replacement work is easy and maintenance costs can be kept low. According to the fifth aspect of the present invention, the desired interval can be changed steplessly depending on the state of metal deposition, and the interval can be easily changed periodically, which is an advantageous effect not available in the prior art. According to the sixth aspect of the present invention, even if the volume of the treatment tank is small, the flow path length can be increased, and metals can be easily precipitated even in water to be treated that has a low concentration of dissolved metals.

[0050] According to the seventh aspect of the present invention, the electrode plates can be made thin, and even if the volume of the treatment tank is small, it is easy to arrange a large number of electrode plates, thereby increasing the deposition efficiency. According to the eighth aspect of the present invention, the current density of the DC power is at least 4.5 A / m 2 As a result, even if the washing wastewater has a low concentration of dissolved zinc, zinc can be sufficiently precipitated without excessively increasing the amount of power consumption. According to the ninth aspect of the present invention, zinc is less likely to peel off naturally and can be reliably recovered. This eliminates the need for electroplating companies to clean the treatment tank and electrode plates, thereby reducing the number of workers required. [Brief explanation of the drawings]

[0051] [Figure 1] 1 is a schematic diagram of a dissolved metal deposition device applied to electroplating equipment (Example 1). [Figure 2] FIG. 1 is an explanatory diagram of a dissolved metal deposition apparatus (Example 1). [Figure 3] FIG. 2 is an explanatory diagram of a spacing means (first embodiment). [Figure 4] 10 shows a specific example (first embodiment) of changing a desired interval by an interval changing means. [Figure 5] 10 is a modified example (embodiment 1) in which the spacing means is a three-way joint. [Figure 6] Graph showing dissolved zinc concentration (Example 1). [Figure 7] Another specific example of the spacing means (Example 2). [Figure 8] FIG. 10 is an explanatory diagram of a bending prevention means (Example 3). [Figure 9]Specific example (Example 4) in which the spacing means is disposed outside the treatment tank. [Figure 10] A modified example (Embodiment 4) in which the spacing means is slidably disposed outside the treatment tank. [Figure 11] 10 is a graph showing the concentration of dissolved zinc when the electrode plate is made of iron (Example 4). [Figure 12] A photograph showing the cathode plate after 10 days of operation and the amount of zinc that had peeled off from the cathode plate. DETAILED DESCRIPTION OF THE INVENTION

[0052] In a dissolved metal deposition device, electrode plates consisting of anode and cathode plates are arranged in a treatment tank storing post-plating water to be treated, and DC power is supplied to the electrode plates to electrolyze the water to be treated and precipitate dissolved metals on the cathode plates.The device is equipped with a spacing maintaining means for maintaining a desired spacing between the electrode plates without fixing them to the treatment tank.Furthermore, the electrode plates can be replaced without switching their polarity, with metals still attached to them.When the amount of metal precipitated becomes large, it is only necessary to widen the spacing between the free electrode plates, resulting in a dissolved metal deposition device with a simple structure. [Example]

[0053] In Example 1, a specific example of a dissolved metal deposition apparatus 1 applied to electroplating equipment for zinc plating will be described with reference to Figs. 1 to 6. Fig. 1 shows a schematic diagram of the entire electroplating equipment. Fig. 2 shows a perspective view of the dissolved metal deposition apparatus.

[0054] FIG. 3 shows an explanatory diagram of the spacing means. FIG. 3(A) shows a cross-sectional view taken along line AA in FIG. 3(B), and FIG. 3(B) shows a plan view taken from line B in FIG. 3(A). FIG. 4 shows a specific example in which the spacing between the electrode plates is changed using a spacing change means. FIG. 5 shows a modified example in which the spacing means is a three-way joint. FIG. 6 shows a graph of the measurement results of the dissolved zinc concentration in Deposition Test 1. For ease of understanding, the electrode plates are shown with diagonal lines in the plan views shown in each figure.

[0055] First, an outline of a wastewater treatment facility including a dissolved metal deposition apparatus 1 of the present invention will be briefly described with reference to Fig. 1. The wastewater treatment facility comprises a conventional chemical treatment facility 100 (see dashed line) and a dissolved metal deposition apparatus 1 of the present invention (see broken line) installed between the chemical treatment facility and an electroplating facility 200 for zinc plating.

[0056] The chemical treatment facility 100 comprises, from the upstream side, a first storage tank 110, a coagulation reaction tank 120, a sedimentation tank 130, a filtered water tank 140, and a second storage tank 150 before final release. The first storage tank 110 collects and temporarily stores the washing wastewater discharged from each electroplating facility 200, 210, etc. In the coagulation reaction tank 120, chemicals such as a pH adjuster, inorganic coagulant, liquid chelating agent, and polymer coagulant are added to the washing wastewater pumped up from the first storage tank 110 to coagulate the dissolved metals.

[0057] In the settling tank 130, the dissolved metals that have been coagulated in the coagulation reaction tank 120 are allowed to settle, separating the coagulated metals from the liquid. In the filtered water tank 140, the supernatant liquid from the settling tank 130 is pumped up and filtered. Finally, in the second storage tank 150, the dissolved metal concentration is inspected to see if it meets the wastewater standard, and the treated liquid is adjusted to neutral before being released.

[0058] The dissolved metal deposition apparatus 1 of the present invention is disposed between a zinc electroplating facility 200 and an existing chemical treatment facility 100. It is sufficient to provide the dissolved metal deposition apparatus 1 only in the zinc electroplating facility 200, which is difficult to coagulate by chemical treatment, but it goes without saying that it may also be provided in electroplating facilities 210, etc., for plating other metals.

[0059] The dissolved metal deposition device 1 includes multiple sets of electrode plates 10, spacing means 20, and power supply means 30, and is disposed in a treatment tank 40 that temporarily stores washing wastewater from an electroplating facility 200 (see FIG. 2). Each electrode plate 10 consists of an anode plate 11 and a cathode plate 12. Both the anode plate and the cathode plate are abutted by spacing means 20 on both sides of the electrode plate, and are in a state of standing upright from the bottom of the treatment tank 40. Furthermore, because the spacing means 20 is sandwiched between the anode plate and the cathode plate, the electrode plates are arranged at a desired interval between an inlet pipe 41 on the upstream side of the treatment tank and a drainage pump 42 on the downstream side (see FIG. 3).

[0060] Furthermore, the anode plates 11 and cathode plates 12 are alternately shifted horizontally along the surface direction so that the gap between them forms a serpentine flow path, with one side end of the electrode plate abutting against the side of the treatment tank and the other side end being spaced apart from the side of the treatment tank (see Figures 2 and 3(B)). Note that the anode plates and cathode plates may also be arranged without shifting to form parallel flow paths.

[0061] Each of the anode and cathode plates has a protrusion 13 that protrudes above the surface of the water to be treated when it is raised from the bottom of the treatment tank (see Figures 2 and 3(A)). Because the protrusion 13 is not immersed in the water to be treated, a DC power supply line 31 is connected to the protrusion to prevent dissolved metals from depositing on the power supply line connection terminal 32. For ease of understanding, only one power supply line 31 is shown in each figure, and the others are omitted.

[0062] The number of electrode plates 10 is not limited and may be changed depending on the volume of the treatment tank 40 and the current density of the DC power. The electrode plates may be provided with a region 43 (see dashed lines in FIG. 3) in which no electrode plates are arranged in part of the treatment tank, so that the desired spacing can be easily increased depending on the amount of metal deposited. Note that the number of electrode plates may be reduced and the desired spacing increased depending on the amount of metal deposited. In this case, the current density may be increased to maintain deposition efficiency.

[0063] The spacing means 20 is made of a non-conductive material and is a shaft body having a thin shaft portion 21 and a lateral protrusion portion 22 (see FIG. 3). Only the lateral protrusion portion 22 of the shaft body abuts against the adjacent anode plate 11 and cathode plate 12, respectively, and the thin shaft portion 21 is spaced apart from the surface of the electrode plate. The water to be treated flows through the gap between the thin shaft portion 11 and the surface of the electrode plate. In Example 1, the thin shaft portion 21 is a hollow straight pipe made of vinyl chloride, and the lateral protrusion portion 22 is an L-shaped vinyl chloride joint fitted onto the tip of the thin shaft portion.

[0064] Furthermore, thin shaft portion 21 is made up of two connected straight pipes of different diameters, widening the gap between the thin shaft portion through which the water to be treated flows and the electrode plate (see Figure 3(A)). The length of thin shaft portion 21 is set so that rear end 23 of the thin shaft portion protrudes above the liquid surface of the water to be treated when the tip of the shaft is in contact with the bottom of the treatment tank. To widen the gap between the cathode plate and the anode plate as the amount of metal adhesion increases, simply grasp and pull out rear end 23 of the thin shaft portion above the liquid surface, replace it with spacing means 24 consisting of a shaft with a larger pipe diameter, and insert it into the gap (see Figures 4(A) and 4(B)).

[0065] Since the L-shaped joints forming the lateral protrusions 22 have different protrusion dimensions in the two intersecting horizontal directions, the lateral protrusions 22 may function as a spacing adjustment device (see FIG. 4(C)). Specifically, when the amount of metal adhesion is low, both ends of the short side of the L-shaped joint are brought into contact with the adjacent anode plate 11 and cathode plate 12 to maintain a desired spacing (see FIG. 4(A)). The desired spacing is not limited and can be adjusted according to the current density supplied to the electrode plates from the DC power source. For example, when no metal is attached to the electrode plates, a desired spacing of approximately 3 cm to 10 cm is preferable because it allows for a high-density arrangement of the electrode plates. Arranging the electrode plates at intervals of approximately 5 cm to 7 cm is more preferable because it reduces the effort required to increase the spacing and also reduces power consumption.

[0066] When metal deposition progresses and the cathode plate 12 expands in the planar direction, the thin shaft portion 21 can be rotated around its axis to change the orientation of the lateral protrusions and widen the arrangement gap between the anode plate 11 and the cathode plate 12 (see FIG. 4(C)). Here, the rotation angle of the thin shaft portion 21 does not have to be 90 degrees. The width by which the desired gap is widened is not limited, but it is preferable to set it to the same width as the thickness of the deposited metal.

[0067] Instead of the L-shaped joint forming the lateral protrusion 22, a three-way joint 25 in which the pipe extends in three orthogonal axial directions may be used (see Figures 5(A) and 5(B)). When the three-way joint 25 is used as a spacing changer, a short straight pipe 28 is attached to one joint pipe 26 of two horizontally extending joint pipes 26, 27, thereby lengthening the protruding dimension of the lateral protrusion 22 formed by one joint pipe 26. Then, while the amount of metal adhesion is small, the tip end face of the other joint pipe 27, which has a shorter protruding dimension, is brought into contact with the electrode plate (see Figure 5(A)).

[0068] When the amount of metal adhesion becomes large, the thin shaft portion 21 can be rotated 90 degrees around the axis, the orientation of the three-way joint 25 can be changed 90 degrees, and the tip surface of the short straight pipe 28 attached to the joint pipe 26 can be brought into contact with the electrode plate, thereby widening the desired gap. When the three-way joint is formed as the lateral protrusion 22, the tip surface of the joint pipe can be rotated so as to contact the surface of the electrode plate, making it easy to adjust the desired gap for holding the electrode plate.

[0069] The power supply means 30 comprises a known power supply line 31, a DC power supply 33, and a power controller 34 (see FIG. 2). The power supply line 31 extends from the DC power supply 33 and is connected to the protrusion 13 of the electrode plate via a connection terminal 32, and is not immersed in the water to be treated. Therefore, metal does not adhere to the connection terminal 32, and even a connection terminal 32 with a simple structure without an insulating coating does not require much maintenance. For example, the electrode plate may be clamped with a known clamping terminal to establish an electrical connection.

[0070] The DC power supply 33 may be obtained by rectifying a commercial power supply (not shown). The voltage value of the DC power supply is at least about 10 V or more, and there is no upper limit. The current density is at least 4.5 A / m 2 The upper limit is not limited as long as it is equal to or greater than the above. It is preferable to maintain the voltage value and current density as low as possible so as not to cause excessive power consumption. The power controller 34 is not limited in configuration as long as it can control the voltage and current values ​​to be maintained within the above ranges.

[0071] (Deposition test 1) The above-described dissolved metal deposition device was applied to a zinc plating facility to conduct a deposition test, and the dissolved zinc concentration in the second storage tank 150 immediately before ocean discharge was measured. Deposition Test 1 was conducted by the applicant himself in accordance with the "flame atomic absorption method for zinc" specified in the Japanese Industrial Standard "JIS K 0102 53.1." The measuring device used was an "atomic absorption spectrophotometer" manufactured by Shimadzu Corporation.

[0072] The test period was from January 30 to February 10, 2023, and dissolved zinc concentrations were measured for seven of those days. The volume of wastewater discharged during the test period was approximately 150 to 200 tons per day. The comparative example was the dissolved zinc concentration measured in a surprise inspection conducted by an external testing organization commissioned by the applicant. In the comparative example, the treated water from the second storage tank was also sampled and tested. The comparative example was tested on five days: September 8, October 26, November 24, and December 23, 2022, before the installation of the present invention, and January 27, 2023.

[0073] The electrode plates were stainless steel plates with a thickness of 2 mm, and 10 cathode and 10 anode plates were arranged at intervals of approximately 3 to 4 cm, forming a serpentine flow path from the upstream to downstream sides of the treatment tank (see Figures 2 and 3). The voltage was approximately 10 V, and the current density was 4.5 A / m. 2 Although the volume of the treatment tank is not limited, a treatment tank having a length of about 0.95 m, a width of about 0.85 m, a height of about 0.4 m, and a volume of about 300 liters was used here.

[0074] Figure 6(A) shows the measurement results of the surprise inspection in the comparative example, and Figure 6(B) shows the measurement results when the present invention is applied. Before the installation of the dissolved metal deposition device 1, the dissolved zinc concentration exceeded the general wastewater standard value of 2.0 mg / L on every inspection day, and the average value over the five inspection days was approximately 2.38 mg / L (see Figure 6(A)).

[0075] In contrast, as shown in Figure 6(B), when the dissolved metal deposition device 1 was operated, good results were obtained, with the dissolved zinc concentration being below the general wastewater standard value on all operating days. The reason for the difference in the dissolved zinc concentration on each test day is presumed to be due to the fact that the production volume of zinc-plated products differed on each test day, which resulted in variations in the dissolved zinc concentration in the cleaning wastewater.

[0076] Even on the day when production volume was at its highest, the dissolved zinc concentration in the second storage tank was below the general wastewater standard. The average dissolved zinc concentration over the 10-day period was approximately 1.5 mg / L. This is less than 40% of the current provisional wastewater standard (4.0 mg / L), and even when stainless steel plates were used for the electrode plates, good results were obtained, below the general wastewater standard.

[0077] After completion of Deposition Test 1, the cathode plates were removed and the amount of zinc deposited was confirmed. Even after only 10 days of operation, zinc was found to be deposited on almost the entire surface of the cathode plates (see the photograph in Figure 12(A)). When the deposited zinc was scraped off and weighed, it was found that a total of approximately 6 kg of zinc had been deposited on the 10 cathode plates (see the photograph in Figure 12(B)). According to the present invention, if the zinc plating equipment is continued to be operated in the same manner, it is expected that more than approximately 100 kg of dissolved zinc, which previously had to be discharged, can be recovered per year and recycled as a valuable metal. [Example]

[0078] In Example 2, another specific example of the spacing means will be described with reference to Fig. 7. Fig. 7(A) shows an example in which an attachment member constituting spacing means 50 is magnetically attached to the surface of an electrode plate. Fig. 7(B) shows an example in which lateral protrusions are provided at two locations, the lower end and the middle portion, of the shaft constituting spacing means 60. In Example 2 and subsequent examples, the same reference numerals will be used to designate components already described in Example 1, and descriptions thereof will be omitted.

[0079] The attachment member 51 (see FIG. 7(A)) that constitutes the spacing means 50 is made of a non-conductive material in which a neodymium magnet is rubber-coated. The thickness of the rubber coating need only be thick enough to allow the neodymium magnet to be magnetically attached to the electrode plate. There are no restrictions on the position where the attachment member is magnetically attached, but it is preferable to magnetically attach it near the four corners on the surface of each electrode plate, as this makes it less likely that the electrode plate 10 will tilt.

[0080] The outer shape of the attachment member 51 is cylindrical or polygonal, with the surface that comes into contact with the electrode plate 10 and the protruding end surface being flat. The attachment member 51 can also function as a gap changing means by magnetically attaching an attachment member 51 of the same shape to the protruding end surface 52 of an attachment member that has already been magnetically attached. In this case, the desired gap can be changed in multiple stages by changing the number of layers of multiple attachment members.

[0081] The shaft body (see Figure 7(B)) that constitutes the spacing means 60 is equipped with a thin shaft portion 61 that is divided into two, and lateral protrusions 62, 63 at two locations, at the bottom end and middle portion of the shaft body. The two thin shaft portions 61, 61 are made of square tubes made of vinyl chloride. The lateral protrusion 62 provided at the bottom end of the shaft body is a T-joint made of square pipe made of vinyl chloride, and the lateral protrusion 63 provided between the two thin shaft portions 61, 61 is a cross joint made of square pipe made of vinyl chloride. Each joint is fitted onto the end of the thin shaft portion 61.

[0082] The shaft forming the spacing maintaining means 60 can also function as spacing changing means by abutting the electrode plate with the short side or the long side of the lateral protrusions 62, 63. Specifically, when the amount of metal deposit is small, the T-shaped side surface of the T-shaped joint forming the lateral protrusion 62 and the cross-shaped side surface of the cross joint forming the lateral protrusion 63 are abutted against the electrode plate.

[0083] On the other hand, when the amount of metal adhesion becomes large, the thin shaft portion 61 is rotated 90 degrees along the horizontal plane so that both ends of the horizontally extending square tubes of each joint abut against the electrode plate. In this case, the desired spacing can be easily changed simply by rotating the shaft body. In addition, since the lateral protrusions 62, 63 are provided in two locations, the lower end and the middle portion of the thin shaft portion 61, the electrode plate is less likely to tilt. [Example]

[0084] In Example 3, a dissolved metal deposition apparatus 2 using a thin iron plate 14 with a thickness of 1 mm or less as the electrode plate and equipped with a curvature prevention means 70 will be described with reference to Figure 8. Figure 8(A) shows a perspective view of the curvature prevention means. Figure 8(B) shows the state in which the curvature prevention means is in contact with the upper edge of the iron plate to prevent the iron plate from curving.

[0085] The second non-conductor forming the bending prevention means 70 is a hollow vinyl chloride tube having an approximately U-shape. The downward bent portions 71 forming the hollow tube may be formed by bending both ends of a single hollow tube downward, or by connecting L-shaped tubes to both ends of a straight tube. The diameter of the downward bent portions 71 is approximately the same as the spacing between the iron plates 14 forming the electrode plates. Each downward bent portion 71, 71 is inserted into the gap formed by adjacent iron plates 14, 14 and abuts against the upper edges of the iron plates on both sides.

[0086] Because the curvature prevention means 70 is inserted into the gaps in the iron plate 14, the electrode plate is less likely to bend convexly to the side, even if the electrode plate is a thin plate of 1 mm or less. When the curvature prevention means is provided, it is possible to prevent curvature from occurring in iron plates of any thickness, 0.2 mm, 0.3 mm, or 0.5 mm.

[0087] Because the curvature prevention means 70 prevents the electrode plates from curving, the gap between the electrode plates does not narrow in parts, and metals tend to deposit evenly across the entire surface of the electrode plates. This makes it possible to maintain the deposition efficiency of dissolved metals over a long period of time, even when thin iron plates 14 are used as electrode plates, and lengthen the period until the electrode plates need to be replaced. [Example]

[0088] In the fourth embodiment, the spacing means is Outside the treatment tank The dissolved metal deposition device 3 installed in the above-mentioned manner will be described with reference to Figs. 9 to 11. Fig. 9(A) shows a plan view of the dissolved metal deposition device 3, and Fig. 9(B) shows a perspective view of the area surrounded by dashed line A in Fig. 9(A). Fig. 10 shows a perspective view of a modified spacing means, similar to Fig. 9(B). Fig. 11 is a graph showing the dissolved zinc concentration in deposition test 2 using the dissolved metal deposition device 3 shown in Fig. 9.

[0089] In the dissolved metal deposition device 3, the water to be treated flows through the spacing means 80. Outside the treatment tank Specifically, it is placed on the top of the side wall that forms the treatment tank 40 (see Figure 9). The spacing means 80 consists of a first support part 81 that supports the cathode plate, a second support part 82 that supports the anode plate, a plurality of upright pieces 83, and a plurality of connecting means 84. The first support part 81 and the second support part 82 are both made of elongated flat metal plates.

[0090] Each of the upright pieces 83 is also made of a flat metal plate, and stands upright in a row at a desired interval on the top surface of the continuously extending support parts 81, 82. The number of upright pieces 83 is greater than the number of electrode plates 10, and to widen the desired spacing, the position of any unused upright piece 85 can be selected and the electrode plate 10 (see the dashed line in Figure 9(B)) can be moved. In addition, the entire surface of the metal plate forming the upright piece 83 forms a contact portion with the electrode plate 10, enabling efficient transmission of DC power.

[0091] Both the anode and cathode electrodes 10 are made of thin iron plates with a thickness of 0.2 mm. The protruding portions 13 of the electrode plates are provided with lateral extensions 15 extending outward from the treatment tank (see FIG. 9(B)). By connecting these lateral extensions 15 to one of the upright pieces 83, the electrode plates are supported in an upright position and are arranged at a desired interval. Note that instead of providing lateral extensions on the protruding portions of the electrode plates, the upright pieces may protrude inward from the treatment tank.

[0092] The connecting means 84 between the electrode plate 10 and the upright piece 83 is a fastener consisting of a known bolt and nut. With the through-hole 86 formed in the upright piece and the through-hole 16 formed in the lateral extension of the electrode plate overlapping, the shaft of the bolt constituting the connecting means 84 is inserted and the nut is fastened, thereby detachably connecting the upright piece and the electrode plate.

[0093] The negative side of the power supply line 31 is connected to the first support portion 81 and the positive side to the second support portion 82 via the upright piece 83 so that DC power is supplied to the protrusion 13 of each electrode plate. This eliminates the need to directly connect the power supply line to each electrode plate, making wiring work easier. The support portion and the upright piece may be non-conductive. In this case, the power supply line may be directly connected to the protrusion of the electrode plate.

[0094] Next, a modified example of the dissolved metal deposition apparatus 3 will be described with reference to Figure 10. In this case, the support portion constituting the spacing means 90 comprises a rail member 91 having a slide groove, a flat plate portion 92 having an upright piece 83, and a fastener 93 for fixing the flat plate portion at a desired position in the slide groove. The fastener is a known bolt and nut. The rail member 91 has a slide groove 94. The slide groove 94 comprises a wide groove 95 for accommodating the head of the bolt, and a narrow slit groove 96 for allowing only the shank of the bolt to protrude from the slide groove. The flat plate portion 93 has a through hole 97 for inserting the shank of the bolt.

[0095] By screwing a nut onto the shank of the bolt protruding from the through-hole 97, both side portions of the slit groove 96 and the flat plate portion 93 are fastened together, fixing the position of the flat plate portion 93. This positions the electrode plate 10 connected to the upright piece 83 integral with the flat plate portion 93 at the desired position. To change the desired spacing between the electrode plates, the nut can be loosened to allow the flat plate portion 93 to move along the slide groove 94.

[0096] Furthermore, because the electrode plate 10 is provided with a rib 17 formed by bending the upper edge, it is difficult for the electrode plate to bend even if it is a thin plate of 1 mm or less. As a result, even with a simple configuration in which the lateral extensions 15 are simply connected to the standing pieces 83, adjacent electrode plates 10 can be made to stand up neatly with a desired spacing. The rib 17 may be provided anywhere on the periphery of the electrode plate, or ribs may be provided in multiple locations on the periphery, for example, at two locations on the upper and lower edges.

[0097] (Deposition test 2) In Deposition Test 2, the dissolved metal deposition device 3 shown in Figure 9 was applied to a zinc plating facility, and the electrode plate was an iron plate with a plate thickness of 0.2 mm. The test period was approximately seven months from July 20, 2023 to March 4, 2024. In Deposition Test 2, random inspections of the dissolved zinc concentration were carried out at irregular intervals by an external inspection agency commissioned by the applicant.

[0098] The surprise inspections were conducted eight times in total on July 20, August 21, October 20, December 6, and December 25 in 2023, and January 11, February 15, and March 4 in 2024. The dissolved zinc concentrations on each test date are shown in Figure 11. The volume of washing wastewater during the test period was approximately 150 to 200 tons per day, which was roughly the same as in Deposition Test 1.

[0099] The number and spacing of electrode plates, the voltage value and current density of the DC voltage, and the volume of the treatment tank were also the same as in Deposition Test 1. The measurement results for Deposition Test 2 showed that the dissolved zinc concentration was approximately 0.26 mg / L at minimum and approximately 1.3 mg / L at maximum. The average dissolved zinc concentration from eight surprise inspections was approximately 0.60 mg / L.

[0100] (Summary of Deposition Tests 1 and 2) According to Deposition Test 1 shown in Example 1 and Deposition Test 2 shown in Example 4, it was confirmed that even if the provisional effluent standards for zinc, which are only permitted for the electroplating industry, are abolished and replaced by general effluent standards, it will not be necessary to increase the amount of clean water used immediately before discharge. In particular, when the electrode plate was made of iron, as in Deposition Test 2, the dissolved zinc concentration could be reduced to approximately one-third of the general effluent standard value.

[0101] Furthermore, in Precipitation Test 2, the dissolved metal deposition device was used continuously for more than six months, but the deposited zinc only adhered to the electrode plates, and almost no zinc accumulated on the bottom of the treatment tank, so there was no need to perform periodic cleaning of the treatment tank. Therefore, according to the present invention, it is possible to reduce the labor required for cleaning the treatment tank and electrode plates, and the deposited zinc can be recovered while still attached to the electrode plates, making it easy to recycle zinc.

[0102] (others) In this embodiment, the electrode plates are arranged at equal intervals, but the intervals between the electrode plates may be different between the upstream and downstream sides. For example, since the dissolved metal concentration decreases toward the downstream side of the flow path, it is preferable to gradually narrow the intervals between the electrode plates from the upstream side to the downstream side so that metals can be efficiently deposited downstream. In Example 4, for ease of understanding, Outside the treatment tank However, it goes without saying that the spacing means shown in Examples 1 and 2 and the bending prevention means shown in Example 3 may be combined with Example 4. The embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The technical scope of the present invention is not limited to the above description, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0103] 1, 2, 3... Dissolved metal precipitation equipment, 100... Chemical treatment equipment, 10...electrode plate, 11...anode plate, 12...cathode plate, 13...projection part, 14...Iron plate, 15...Side extension portion, 16...Through hole, 17...Rib, 20, 24... Spacing holding means, 21... Thin shaft portion, 22... Lateral protrusion, 23... Rear end, 25... Three-way joint, 26, 27... Joint pipe, 28... Short straight pipe, 30...power supply means, 31...power supply line, 32...connection terminal, 40... treatment tank, 41... inlet pipe, 42... drainage pump, 43... area where electrode plates are not arranged, 50... spacing means, 51... attachment member, 52... protruding end surface, 60... Spacing holding means, 61... Thin shaft part, 62,63... Lateral protrusion part, 70...bending prevention means, 71...downward bending portion, 80... Spacing holding means, 81... (first) support part, 82... (second) support part, 83...standing piece, 84...connecting means, 85...(unused) standing piece, 86...through hole, 90... Spacing means, 91... Rail member, 92... Flat plate portion, 93... Fixing device, 94...slide groove, 95...wide groove, 96...slit groove, 97...through hole, 110...first storage tank, 120...flocculation reaction tank, 130...sedimentation tank, 140... Filtration tank, 150... Second storage tank, 200...Electroplating equipment (for zinc plating), 210...Electroplating equipment (for plating other metals)

Claims

1. A dissolved metal deposition device that immerses electrode plates in plated water to be treated, electrolyzes the water to be treated, and deposits dissolved metals on the electrode plates, The electrode plate includes a plurality of sets of electrode plates each having an anode plate and a cathode plate, a spacing means, and a power supply means; Each of the electrode plates has a protrusion that protrudes from the liquid surface of the water to be treated when it is upright on the bottom surface of the treatment tank in which the water to be treated is stored, The anode plates and the cathode plates are immersed in the treatment tank so as to form a row at a desired interval, and each gap formed between adjacent anode plates and cathode plates forms a flow path for the water to be treated, the spacing means is made of a non-conductive material that does not block any of the flow paths; the non-conductors are brought into contact with both sides of each electrode plate, and the electrode plates are maintained at the desired interval without being fixed to the treatment tank; the power supply means connects a power supply line extending from a DC power source to the protrusion, and supplies DC current without changing the polarity of the electrode plate; A dissolved metal deposition device characterized by:

2. the spacing maintaining means includes spacing changing means, the spacing change means makes it possible to change the desired spacing by changing the protruding dimension of the non-conductor; 2. The dissolved metal deposition apparatus according to claim 1 .

3. the non-conductor is a shaft body having a thin shaft portion and a lateral protruding portion that comes into contact with the electrode plate, the thin shaft portion has a length such that the rear end thereof protrudes above the liquid surface when the tip of the shaft body is brought into contact with the bottom surface of the treatment tank, the lateral protrusions protrude horizontally from the thin shaft portion, and the protrusion dimensions in the two intersecting horizontal directions are different; The lateral protrusion can be rotated around the thin shaft portion to change the state of contact between the lateral protrusion and the electrode plate, thereby functioning as the gap changing means.

3. The dissolved metal deposition apparatus according to claim 2, wherein:

4. A dissolved metal deposition device that immerses electrode plates in plated water to be treated, electrolyzes the water to be treated, and deposits dissolved metals on the electrode plates, The electrode plate includes a plurality of sets of electrode plates each having an anode plate and a cathode plate, a spacing means, and a power supply means; Each of the electrode plates has a protrusion that protrudes from the liquid surface of the water to be treated when it is upright on the bottom surface of the treatment tank in which the water to be treated is stored, The anode plates and the cathode plates are immersed in the treatment tank so as to form a row at a desired interval, and each gap formed between adjacent anode plates and cathode plates forms a flow path for the water to be treated, the spacing means includes a support portion and an upright piece, the support portion is disposed outside the flow path and includes a first support portion that supports the cathode plate and a second support portion that supports the anode plate, The upright pieces are hung down from the respective support portions at desired intervals, By connecting the upright piece and the protrusion, the electrode plate is not fixed to the treatment tank, and the desired interval is maintained; the power supply means connects a power supply line extending from a DC power source to the protrusion, and supplies DC current without changing the polarity of the electrode plate; A dissolved metal deposition device characterized by:

5. the spacing maintaining means includes spacing changing means, the spacing change means is a slide groove formed in the support portion and extending along the arrangement direction of the electrode plates, The upright pieces are slidably mounted along the slide grooves, and the electrode plates connected to the upright pieces are slid along the slide grooves, thereby making it possible to change the desired interval.

5. The dissolved metal deposition apparatus according to claim 4.

6. The cathode plates and the anode plates constituting the electrode plates are alternately arranged so as to be horizontally shifted along a surface direction, The flow path forms a serpentine flow path.

6. The dissolved metal deposition apparatus according to claim 1, wherein the dissolved metal deposition apparatus comprises:

7. the electrode plate is made of a thin plate and has a bending prevention means; the bending prevention means is a second non-conductive body that does not block the flow path, Both ends of the curvature prevention means are in contact with the upper edge portions of the adjacent electrode plates, thereby preventing the electrode plates from curving convexly in a direction intersecting the surfaces of the electrode plates.

6. The dissolved metal deposition apparatus according to claim 1, wherein the dissolved metal deposition apparatus comprises:

8. the water to be treated is washing wastewater from a washing tank for washing a zinc plating solution, The dissolved zinc concentration is at least 100 mg / L or more, The current density of the DC power supplied by the power supply means is at least 4.5 A / m ２ It is said that 6. The dissolved metal deposition apparatus according to claim 1, wherein the dissolved metal deposition apparatus comprises:

9. The cathode plate is made of an iron plate with a plate thickness of 1 mm or less.

9. The dissolved metal deposition apparatus according to claim 8.

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