Dissolved metal precipitation device

Abstract

To provide a dissolved metal precipitation apparatus that enables easy maintenance and management of an electrode plate and a treatment tank for storing water to be treated, and that allows for easy introduction of equipment with a simple configuration. 【Solution means】In a dissolved metal precipitation apparatus 1 in which an electrode plate 10 composed of an anode plate 11 and a cathode plate 12 is arranged in a treatment tank 40 storing water to be treated after plating, and the electrode plate is supplied with direct current power to electrolyze the water to be treated and precipitate dissolved metal on the cathode plate 12, an interval holding means 20 is provided to hold a desired interval without fixing the electrode plate 10 to the treatment tank 40. Further, the electrode plate 10 is replaced while keeping the metal attached thereto without switching the polarity of the electrode plate. When the amount of deposited metal increases, it is only necessary to widen the interval between the non-fixed electrode plates, and the apparatus can be made into a dissolved metal precipitation apparatus with a simple structure that does not require much cleaning effort.

Description

Technical Field

[0001] The present invention relates to a dissolved metal precipitation device that electrolyzes treated water after plating, deposits dissolved metal on an electrode plate, and reduces the dissolved metal concentration in the treated water. More specifically, the present invention relates to a dissolved metal precipitation device that can easily maintain and manage a treatment tank storing treated water and an electrode plate, and can easily introduce equipment with a simple configuration.

[0002] More specifically, the electrode plates are arranged at a desired interval without being fixed to the treatment tank, so that an existing treatment tank can be used as it is to facilitate equipment introduction, and the electrode plates are exchanged while having metal attached thereto, so that the present invention relates to a dissolved metal precipitation device that eliminates the need for cleaning work in the treatment tank.

Background Art

[0003] In a plating product manufacturing factory, a base material forming a plating product is immersed in a plating solution, and a plating layer with a desired film thickness is deposited on the surface of the base material to manufacture a plating product. When moving from each plating process to the next process, the plating product is immersed in a cleaning tank, and the residual plating solution adhering to the product surface is washed with water, and management is carried out so that the plating solution in the previous process is not mixed into the surface activation treatment solution or plating solution in the next process.

[0004] The cleaning water stored in this cleaning tank is discharged as cleaning wastewater so that the dissolved metal concentration does not increase due to the washing of the residual plating solution, and the cleaning water is replaced. Specifically, in the case of zinc electroplating equipment, a huge amount of cleaning wastewater of 150 to 200 tons per day is discharged.

[0005] The wastewater treatment of electroplating facilities recovers dissolved metals such as chromium, zinc, cyanide, and copper contained in the washing water through chemical treatment, also known as the coagulation sedimentation method, and reduces the dissolved metal concentration until the wastewater standards are met. In the coagulation sedimentation method, by utilizing the difference in the pH values at which each metal ion is likely to precipitate, acidic agents and alkaline agents are added to the washing water to adjust the pH according to the type of metal to be recovered, while inorganic coagulants, liquid chelating agents, polymer coagulants, etc. are added to efficiently coagulate and recover the desired dissolved metals.

[0006] However, since zinc is an amphoteric metal that can dissolve in both acidic and alkaline pH regions, it is difficult to reliably recover the dissolved zinc contained in the washing wastewater only through chemical treatment. Therefore, 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 according to the Ministry of the Environment Ordinance No. 33 in 2006, the electroplating industry was exceptionally allowed to maintain the previous 5 mg / L as a provisional wastewater standard.

[0007] With the expiration of the application period of the above provisional wastewater standard in 2021, a legal amendment was implemented in the electroplating industry to newly strengthen the provisional wastewater standard to 4 mg / L and extend the application period of the provisional wastewater standard until the end of 2024. However, the provisional wastewater standard in 2021 is also expected to be abolished by the legal amendment in 2024, and the development of new wastewater treatment technologies has become an urgent issue in the electroplating industry to meet the general wastewater standard value of 2 mg / L for zinc.

[0008] Patent Document 1 discloses a technique of an electrolysis device that deposits and recovers inorganic salts contained in tap water on an electrode plate by electrolysis and suppresses the precipitation of inorganic salts in the pipes of a heat exchanger forming a water heater.

[0009] According to the technology described in this document, the anode plate and the cathode plate are alternately protruded from the side wall of the sealed container to form a flow path, and tap water supplied into the sealed container is electrolyzed to deposit inorganic salts on the electrode plates. Then, the inorganic salts deposited on the cathode plate are peeled off by the reversal of the polarity of the electrode plate, transported to the downstream side of the sealed container by the water flow, and suction-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 is applied to the washing wastewater of electroplating equipment, heavy metals such as zinc have a higher specific gravity than inorganic salts, so it is difficult to transport them by the water flow, and the heavy metals peeled off from the electrode plates will accumulate at the bottom of the flow path as they are.

[0011] Therefore, when the amount of deposited metal increases, there is a possibility that the anode plate and the cathode plate will short-circuit. When a short circuit occurs, there is a problem that the dissolved metal does not deposit on the cathode plate and the electrolysis device malfunctions. In particular, in a meandering flow path, since the flow path is long and thin, frequent deposition metal recovery operations are required to prevent short circuits in advance, which is not suitable for electroplating equipment that needs to treat a huge amount of washing wastewater.

[0012] Patent Document 2 discloses a water treatment device technology in which electrolysis is performed while passing the water to be treated between a positive electrode inclined plate and a negative electrode inclined plate, contaminants are deposited on the negative electrode inclined plate, the contaminants are peeled off by reversing the polarity of the electrode plate, and the contaminants are lowered along the inclined surface of the electrode plate and precipitated at the bottom of the treatment tank.

[0013] According to the technology described in this document, the entire electrode plate is immersed in the water to be treated, and the electrode plate is supported in a floating state from the bottom of the treatment tank. Specifically, a pair of opposing side surfaces forming the treatment water tank are provided with inclined guide grooves, and the electrode plate is inserted into the guide grooves for support.

[0014] However, depending on the technology described in this document, it is essential to dispose of the electrode plates at a position higher than the bottom of the treatment tank by means of guide grooves. Therefore, the portion where the electrode plates can be disposed becomes smaller with respect to the volume of the treatment tank. As a result, not only can an existing treatment tank without guide grooves not be diverted, but a large space is required for the installation of the treatment tank, and there has been a problem that it cannot be easily introduced into an electroplating factory with a huge amount of drainage. In addition, since contaminants are precipitated at the bottom of the treatment tank, it has been necessary to frequently clean the treatment tank.

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

Problems to be Solved by the Invention

[0016] The problem to be solved by the present invention is to provide a dissolved metal precipitation device that requires less labor for the maintenance and management of a treatment tank for treated water and an electrode plate, and is easy to introduce equipment with a simple configuration.

Means for Solving the Problems

[0017] A first invention of the present invention is a dissolved metal precipitation device that immerses an electrode plate in treated water after plating, electrolyzes the treated water, and deposits dissolved metal on the electrode plate, including a plurality of sets of electrode plates having an anode plate and a cathode plate, a spacing holding means, and a power supply means. Each of the electrode plates is provided with a protruding portion that protrudes from the liquid surface of the treated water in a state of standing up from the bottom surface of a treatment tank that stores the treated water. Each of the anode plates and the cathode plates is immersed in the treatment tank so as to form a row with a desired interval, and each of the gaps formed by adjacent anode plates and cathode plates forms a flow path for the treated water. The spacing holding means is made of a non-conductive body that does not block each of the flow paths, and the non-conductive body is abutted from both sides of each electrode plate to fix the electrode plate to the treatment tank. while keeping the individual electrode plates separated,Maintain the desired interval, connect a power supply line extending from a DC power source to the protruding portion by the power supply means, and supply a DC current without changing the polarity of the electrode plate. depositing and adhering the dissolved metal onto the cathode plate, the electrode plates being arranged leaving a non-arrangement area in the treatment tank where the electrode plates are not arranged at the stage before the deposition of the dissolved metal, and when the adhesion of the dissolved metal progresses, narrowing the non-arrangement area according to the adhesion amount and re-arranging the electrode plates and the spacing holding means so as to widen the spacing between the electrode plates, enabling the continuation of the deposition of the dissolved metal without peeling off the metal adhered to the cathode plate It is characterized by this.

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

[0019] The electrode plates are composed of a plurality of sets of cathode plates and anode plates, and these are arranged in a standing state in the treatment tank at a desired interval. The gap formed between adjacent anode plates and cathode plates forms a flow path through which the water to be treated flows from the inflow side to the discharge side of the treatment tank. Since each electrode plate is not fixed to the treatment tank, the desired interval can be changed even after installation in the treatment tank. The number of electrode plates may be determined according to the size of the treatment tank and the desired interval.

[0020] When metal is deposited on the cathode plate and the flow path width narrows, by widening the desired interval according to the amount of metal adhesion, the flow path width can be maintained substantially equal to that before metal adhesion without peeling the metal. The anode plate and the cathode plate may be arranged in parallel, but if the anode plate and the cathode plate are arranged alternately and horizontally shifted so as to form a meandering flow path, the flow path length can be increased without changing the volume of the treatment tank, and the precipitation efficiency is also increased, which is preferable.

[0021] In addition, the anode plate and the cathode plate are provided with protruding portions that protrude to a position higher than the liquid level of the water to be treated. Since a power supply line can be connected to the protruding portion where no metal is deposited, no metal adheres to the connection terminal of the power supply line. Therefore, even when the deposited metal is scraped off from the electrode plate and the electrode plate is repeatedly used, since metal only adheres to the flat surface where the peeling operation is easy, the maintenance of the electrode plate is easy.

[0022] The spacing maintaining means is made of a non-conductor that does not block the flow path. The spacing maintaining means is not fixed to the treatment tank either. It is in contact with both surfaces of each electrode plate and is held so that a desired spacing can be changed according to the amount of metal deposition. Specifically, when the amount of metal deposition increases, the desired spacing can be widened by changing the dimension (hereinafter referred to as the protruding dimension) in which the non-conductor protrudes from the surface of the electrode plate.

[0023] Here, "not blocking the flow path" means that when a non-conductor is arranged in the flow path, the size of the non-conductor is smaller than the flow path and does not prevent the flow of the water to be treated. For example, shaft bodies with different diameters can be connected in multiple stages to serve as the spacing maintaining means. Only the thick-diameter shaft portion is brought into contact with the electrode plate, and gaps for the water to be treated to flow through are provided on both sides of the thin-diameter shaft portion (see Fig. 3). Since it is easier to deposit metal when the flow rate of the water to be treated is lower, it is preferable that the size of the non-conductor is as small as possible with respect to the flow path.

[0024] In addition to this, a rectangular parallelepiped-shaped non-conductor can be attached, adhered, or magnetically attached to the electrode plate to function as the spacing maintaining means (see Fig. 7(A)), or a frame body can function as the spacing maintaining means. Note that the non-conductor is not limited to being disposed in the flow path. It 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] The non-conductor only needs to be an object whose at least surface layer does not conduct electricity. For example, it may be an object entirely made of an insulator such as a shaft body or a frame body made of a resin such as vinyl chloride, or an object in which a lump of metal such as a magnet is rubber-coated so as not to conduct electricity.

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

[0027] In addition, after the operation of the dissolved metal deposition apparatus, the electrode supply means only allows a direct current to flow in one direction so as not to change the polarity of the electrode plate, and the attached metal is not peeled off and deposited on the bottom of the treatment tank. Therefore, no unintended short circuit occurs between the anode plate and the cathode plate due to the deposited metal, and there is no need to frequently clean the treatment tank to prevent short circuits.

[0028] According to the first invention of the present invention, each of the electrode plates arranged at a desired interval is held by the interval holding means brought into contact with both sides. As a result, without fixing the electrode plates to the treatment tank, it is possible to hold a desired interval so as to obtain a current density suitable for metal deposition according to the dissolved metal concentration, which has an unprecedented advantageous effect. Furthermore, since the electrode plates are not fixed, a flow path can be secured simply by widening the interval between the electrode plates without peeling off the attached metal, and the maintenance and management of the electrode plates can be simplified.

[0029] The second invention of the present invention is the first invention, wherein the interval holding means includes an interval changing means, and the interval changing means is made possible by the non-conductive body contacting and arranging it on the opposing surfaces of adjacent electrode plates, and when the adhesion amount increases, increasing the protruding dimension of the non-conductor protruding from the opposing surface characterized in that widening the spacing between the electrode plates when re-arranging the electrode plates it is made possible.

[0030] According to the second invention, the change in the protruding dimension may be, but is not limited to, the replacement of the non-conductive body. For example, when the non-conductive body consists of a magnet coated with rubber, the protruding dimension may be changed by magnetically attaching the non-conductive bodies so as to overlap each other. When the non-conductive body is a shaft body protruding in the surface direction of the electrode plate, a joint may be attached to the shaft body to increase the protruding dimension. In addition, when the horizontal length at which the non-conductive bodies intersect is different, the protruding dimension may be changed by rotating the non-conductive bodies in the horizontal direction.

[0031] More specifically, while the amount of metal deposition is small, the two ends of the non-conductive body in the short side direction are brought into contact with the surfaces of adjacent electrode plates. After the amount of metal deposition increases, it may be rotated so that the two ends of the non-conductive body in the long side direction are brought into contact with the surfaces of adjacent electrode plates. According to the second invention of the present invention, according to the amount of metal deposition, a desired interval can be easily changed, and the advantage that the maintenance and management of the electrode plates can be made easier can be achieved.

[0032] The third invention of the present invention is the second invention, wherein the non-conductive body is a shaft body including a thin shaft portion and a side protruding portion that comes into contact with the electrode plate, and the thin shaft portion is such that when the tip of the shaft body is brought into contact with the bottom surface of the treatment tank, the rear end thereof protrudes from the liquid surface, and the side protruding portion protrudes horizontally from the thin shaft portion and has different protruding dimensions in two intersecting horizontal directions. at the stage before the deposition of the dissolved metal, arranging it in contact with the opposing surface of the electrode plate with the side protrusion facing so that its protruding dimension is short, and when the adhesion amount increases The side protruding portion is rotated around the thin shaft portion. by contacting it with the opposing surface in a state where its protruding dimension is increased To function as the interval changing means. and It is characterized by this.

[0033] The thin shaft portion and the side protruding portion forming the shaft body may be solid materials or hollow materials. Only the side protruding portion is brought into contact with adjacent electrode plates, and the thin shaft portion is separated from the electrode plates, and the water to be treated can flow between the thin shaft portion and the electrode plates. The number, protruding position, protruding length, etc. of the side protruding portions are not limited.

[0034] For example, if the thin shaft portion is a hollow tube made of vinyl chloride or the like, and the side protruding portion is an L-shaped joint, a T-shaped joint, a three-way joint, a five-way joint, etc. externally fitted to the end of the hollow tube, an interval holding means can be easily made with articles circulating in the market. It is preferable that the hollow tube forming the thin shaft portion has different diameters of hollow tubes connected in multiple stages to reduce the shaft diameter so as to widen the gap between the shaft body and the electrode plate.

[0035] According to the third invention, since the protruding dimensions of the side protrusions from the thin shaft portion are different in two intersecting horizontal directions, by simply rotating the thin shaft portion around its axis while the thin shaft portion is immersed in the water to be treated, the desired interval between the electrode plates can be changed. Thus, even when the amount of metal adhering to the electrode plates increases, it is only necessary to change the interval between the electrode plates, and since no cleaning work for the electrode plates is required, maintenance management becomes even easier, which has an advantageous effect.

[0036] According to a fourth invention of the present invention, in a dissolved metal precipitation device that immerses electrode plates in the water to be treated after plating, electrolyzes the water to be treated, and precipitates dissolved metal on the electrode plates, it includes a plurality of sets of electrode plates having an anode plate and a cathode plate, interval holding means, and power supply means. Each of the electrode plates has a protruding portion that protrudes from the liquid surface of the water to be treated in a state of standing up from the bottom surface of a treatment tank that stores the water to be treated. Each of the anode plates and the cathode plates is immersed in the treatment tank so as to form a row with a desired interval therebetween, and each gap formed between adjacent anode plates and cathode plates forms a flow path for the water to be treated. The interval holding means includes a support portion and a standing piece. The support portion outside the treatment tank, extending along the direction of the column together with a first support portion that supports the cathode plate and a second support portion that supports the anode plate. The standing piece outside the treatment tank each of the support portions along the extending direction of is vertically provided side by side with a desired interval therebetween, and by connecting the standing piece and the protruding portion, the electrode plates are fixed to the treatment tank while keeping the individual electrode plates separated and movable, to maintain the desired interval. The power supply means connects a power supply line extending from a DC power source to the protruding portion to supply a DC current without changing the polarity of the electrode plates depositing and adhering the dissolved metal onto the cathode plate, the electrode plates being connected to the standing pieces so as to be arranged leaving a non-arrangement area in the treatment tank where the electrode plates are not arranged at the stage before the deposition of the dissolved metal, and when the adhesion of the dissolved metal progresses, narrowing the non-arrangement area according to the adhesion amount and changing the position of the standing pieces to re-arrange the electrode plates so as to widen the spacing between the electrode plates, enabling the continuation of the deposition of the dissolved metal without peeling off the metal adhered to the cathode plate which is characterized in that.

[0037] According to the fourth invention, outside the flow path outside the treatment tank which is a treatment tankThe electrode plates are held at a desired interval by the interval holding means disposed thereon. Since the support portion that forms the interval holding means is divided into a first support portion and a second support portion, even if the support portion is a conductor, the cathode plate and the anode plate are not short-circuited. Each support portion may be divided into the same number as the standing pieces. The standing pieces may be vertically provided so as to protrude upward from the top surface side of the support portion, or may be vertically provided so as to protrude downward from the bottom surface side.

[0038] The protruding portion of any one of the electrode plates is connected to the standing piece. The electrode plate and the standing piece may be detachably connected by known fastening tools or clamping tools, or may be inseparably connected by welding. When it is detachable, by increasing the number of standing pieces more than the number of electrode plates and changing the position of the standing piece to which the electrode plate is connected, the interval between the electrode plates can be easily widened. Even in the case where it is non-detachable, if the support portion is divided into the same number as the standing pieces, the electrode plates can be moved integrally with the standing pieces to widen the interval between the electrode plates.

[0039] According to the fourth invention, since the interval holding means is outside the treatment tank disposed thereon, the desired interval can be easily widened according to the metal deposition state, and maintenance management is easy. Furthermore, since only the electrode plates can be replaced, the replacement work is easy and the maintenance cost can be kept low.

[0040] A fifth invention of the present invention is the fourth invention, wherein the interval holding means includes an interval changing means, and the interval changing means being the slide groove provided in the support portion, the slide groove being formed extending along the column direction is characterized in that the standing piece is slidably mounted along the slide groove, and by sliding the electrode plate connected to the standing piece along the slide groove, enabling the change of the spacing when re-arranging the electrode plates ...

[0041] According to the fifth invention, by simply sliding the standing piece connected to the electrode plate along the slide groove formed in the support portion, the desired interval can be changed. Thereby, according to the metal deposition situation, the desired interval can be changed steplessly, and there is an advantageous effect not found in the prior art in that the regular interval changing operation can be easily performed.

[0042] The sixth invention of the present invention is the first to fifth inventions, wherein the cathode plate and the anode plate forming the electrode plate are alternately horizontally displaced along the surface direction and arranged, and the flow path forms a meandering flow path. According to the sixth invention, even if the volume of the treatment tank is small, the flow path length can be lengthened, and even if the water to be treated has a low dissolved metal concentration, it is easy to deposit the metal.

[0043] The seventh invention of the present invention is the first to fifth inventions, wherein the electrode plate is made of a thin plate and is provided with a warping prevention means, the warping prevention means is made of a second non-conductive body that does not block the flow path, and both ends of the warping prevention means are in contact with the upper edge portions of the adjacent electrode plates, and it is characterized in that the electrode plate is prevented from warping convexly in a direction intersecting with its surface.

[0044] According to the seventh invention, the second non-conductive body is brought into contact with the upper edge portions of the adjacent electrode plates. Therefore, even if the electrode plate is a thin plate that is prone to warping, it is difficult to warp at the intermediate portion where the electrode plate extends horizontally, and it is difficult for the electrode plate to be convexly curved laterally. As a result, the electrode plate can be made into a thin plate, and even if the volume of the treatment tank is small, it is easy to arrange a large number of electrode plates, and the deposition efficiency can be increased.

[0045] The eighth invention of the present invention is the first to fifth inventions, 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 as described above.

[0046] The dissolved zinc concentration in the washing wastewater is controlled in the range of at least about 100 mg / L to about 500 mg / L so as not to easily affect the next process. It is more preferable to control it in the 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 2Since it is as described above, even from washing wastewater with a low dissolved zinc concentration, zinc can be sufficiently deposited without excessively increasing the power consumption.

[0047] The ninth invention of the present invention is the eighth invention, characterized in that the cathode plate is made of an iron plate with a thickness of 1 mm or less. According to the ninth invention, since the adhesion between iron and zinc is good, zinc is difficult to peel off naturally and can be reliably recovered. Also, since the electrode plate is inexpensive, it is possible to entrust the treatment to a resource recovery operator with zinc attached, and for an electroplating operator, the cleaning work of the treatment tank and the electrode plate becomes unnecessary, and labor saving can be achieved.

Advantages of the Invention

[0048] · According to the first invention of the present invention, even without fixing the electrode plate in the treatment tank, an unprecedented advantageous effect can be achieved in that a desired interval can be maintained so as to obtain a current density suitable for metal deposition according to the dissolved metal concentration. Furthermore, since the electrode plate is not fixed, a flow path can be secured simply by widening the interval between the electrode plates without peeling off the attached metal, and the maintenance and management of the electrode plates can be simplified. · According to the second invention of the present invention, an advantageous effect can be achieved in that a desired interval can be easily changed according to the amount of metal adhesion, and the maintenance and management of the electrode plates can be made even easier. · According to the third invention of the present invention, even when the amount of metal adhesion on the electrode plate increases, it is only necessary to change the interval between the electrode plates, and since the cleaning work of the electrode plates is unnecessary, the maintenance and management become even easier, which is an advantageous effect.

[0049] · According to the fourth invention of the present invention, since the interval holding means is outside the treatment tank disposed therein, a desired interval can be easily widened according to the deposition state of the metal, and the maintenance and management are easy. Furthermore, since only the electrode plate can be replaced, the replacement work is easy and the maintenance cost can be kept low. · According to the fifth invention of the present invention, there is an advantageous effect not found in the prior art in that the desired interval can be changed steplessly according to the deposition state of the metal, and the periodic interval change operation can be easily performed. · According to the sixth invention of the present invention, even if the volume of the treatment tank is small, the flow path length can be increased, and even if the water to be treated has a low dissolved metal concentration, it is easy to deposit the metal.

[0050] · According to the seventh invention of the present invention, the electrode plate can be made into a thin plate. Even if the volume of the treatment tank is small, a large number of electrode plates can be easily arranged, and the deposition efficiency can be increased. · According to the eighth invention of the present invention, since the current density of the DC power is at least 4.5 A / m 2 or more, even from the washing waste water with a low dissolved zinc concentration, zinc can be sufficiently deposited without excessively increasing the power consumption. · According to the ninth invention of the present invention, zinc is difficult to naturally peel off and can be reliably recovered. For electroplating operators, the cleaning work of the treatment tank and the electrode plate becomes unnecessary, and labor saving can be achieved.

Brief Description of the Drawings

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Mode for Carrying Out the Invention

[0052] In a dissolved metal precipitation apparatus in which electrode plates composed of an anode plate and a cathode plate are arranged in a treatment tank storing the treated water after plating, and direct current power is supplied to the electrode plates to electrolyze the treated water and deposit dissolved metal on the cathode plate, the electrode plates are not fixed to the treatment tank, and a spacing maintaining means for maintaining a desired spacing is provided. Further, without switching the polarity of the electrode plates, the electrode plates are exchanged while having metal adhered thereto. When the amount of metal precipitation increases, it is only necessary to widen the spacing between the non-fixed electrode plates, and a dissolved metal precipitation apparatus with a simple structure can be obtained.

Examples

[0053] In Example 1, a specific example of the dissolved metal precipitation apparatus 1 applied to an electroplating facility for zinc plating will be described with reference to FIGS. 1 to 6. FIG. 1 shows an overall schematic view of the electroplating facility. FIG. 2 shows a perspective view of the dissolved metal precipitation apparatus.

[0054] FIG. 3 shows an explanatory view of the spacing maintaining means. FIG. 3(A) shows a cross-sectional view taken at the A-A position of FIG. 3(B), and FIG. 3(B) shows a plan view seen from the B position of FIG. 3(A). FIG. 4 shows a specific example in which the spacing between the electrode plates is changed by the spacing changing means. FIG. 5 shows a modified example in which the spacing maintaining means is a three-way joint. FIG. 6 shows, in a graph, the measurement results of the dissolved zinc concentration in Precipitation Test 1. For ease of understanding, even in the plan views shown in each figure, the electrode plates are shown with hatching.

[0055] First, the outline of the wastewater treatment facility including the dissolved metal precipitation device 1 of the present invention will be briefly described with reference to FIG. 1. The wastewater treatment facility includes a conventional chemical treatment facility 100 (see the dashed line) and the dissolved metal precipitation device 1 of the present invention (see the broken line) provided between the chemical treatment facility and the electroplating facility 200 for zinc plating.

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

[0057] In the sedimentation tank 130, the dissolved metals coagulated in the coagulation reaction tank 120 are sedimented to separate the coagulated metals and the liquid. In the filtered water tank 140, the supernatant liquid of the sedimentation tank 130 is pumped up for filtration. Finally, in the second storage tank 150, it is inspected whether the dissolved metal concentration meets the wastewater standard value, and the treated liquid to be treated is adjusted to neutral before being discharged.

[0058] Now, the dissolved metal precipitation device 1 of the present invention is disposed between the electroplating facility 200 for zinc and the existing chemical treatment facility 100. The dissolved metal precipitation device 1 only needs to be provided in the electroplating facility 200 for zinc plating that is difficult to coagulate in chemical treatment, but it goes without saying that it may also be disposed in other electroplating facilities 210... for metal plating.

[0059] The dissolved metal precipitation device 1 includes a plurality of sets of electrode plates 10, a spacing maintaining means 20, and a power supply means 30, and is disposed in a treatment tank 40 for temporarily storing the washing waste water from the electroplating facility 200 (see Fig. 2). Each electrode plate 10 consists of an anode plate 11 and a cathode plate 12. For both the anode plate and the cathode plate, the spacing maintaining means 20 is in contact with both sides of the electrode plate, and they are in a state of standing upright from the bottom of the treatment tank 40. Also, since the spacing maintaining means 20 is sandwiched between the anode plate and the cathode plate, the electrode plates are arranged with a desired spacing between them, from the inflow pipe 41 on the upstream side to the drainage pump 42 on the downstream side of the treatment tank (see Fig. 3).

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

[0061] Also, each of the anode plate and the cathode plate is provided with a protruding portion 13 that protrudes from the liquid level of the water to be treated when standing upright from the bottom surface of the treatment tank (see Figs. 2 and 3(A)). Since the protruding portion 13 is not immersed in the water to be treated, by connecting the power supply line 31 of the DC power to the protruding portion, the dissolved metal is prevented from being deposited on the connection terminal 32 of the power supply line. Note that for ease of understanding, the power supply line 31 is shown at only one location in each figure, and the others are omitted.

[0062] The number of the electrode plates 10 is not limited and may be changed according to the volume of the treatment tank 40 and the value of the current density of the DC power. The electrode plates may be provided with a region 43 (see the dashed line in Fig. 3) where no electrode plates are arranged in a part of the treatment tank so that it is easy to widen the desired spacing according to the amount of metal adhesion. Note that according to the amount of metal adhesion, the number of the electrode plates may be reduced and the desired spacing may be widened. In this case, the value of the current density may be increased to maintain the precipitation efficiency.

[0063] The spacing maintaining means 20 is made of a non-conductive material and is a shaft body having a thin shaft portion 21 and a side protruding portion 22 (see Fig. 3). Only the side protruding 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 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, a hollow straight pipe made of vinyl chloride is used as the thin shaft portion 21, and an L-shaped joint made of vinyl chloride externally fitted to the tip of the thin shaft portion is used as the side protruding portion 22.

[0064] Also, the thin shaft portion 21 is formed by connecting two straight pipes with different diameters in series, widening the gap between the thin shaft portion through which the water to be treated flows and the electrode plate (see Fig. 3(A)). The length of the thin shaft portion 21 is such that, with the tip of the shaft body in contact with the bottom of the treatment tank, the rear end 23 of the thin shaft portion protrudes from the liquid level of the water to be treated. When widening the gap formed between the cathode plate and the anode plate as the amount of metal deposition increases, the rear end 23 of the thin shaft portion above the liquid level can be grasped and pulled out, and then replaced with the spacing maintaining means 24 composed of a shaft body with a diameter slightly larger and inserted into the gap (see Fig. 4(A) and Fig. 4(B)).

[0065] Note that since the L-shaped joint forming the side protruding portion 22 has two different horizontal protruding dimensions that intersect, the side protruding portion 22 may function as a gap changing means (see Fig. 4(C)). Specifically, at a stage where the amount of metal deposition is small, both ends in the short side direction of the L-shaped joint are brought into contact with the adjacent anode plate 11 and cathode plate 12 to maintain a desired gap (see Fig. 4(A)). The desired gap can be changed according to the current density supplied from the DC power source to the electrode plate and is not particularly limited. For example, in a state where no metal adheres to the electrode plate, if the desired gap is set to about 3 cm to 10 cm, the electrode plates can be arranged at a high density, which is suitable. If the electrode plates are arranged at an interval of about 5 cm to 7 cm, it is more suitable because it requires less effort to widen the gap and can also reduce the power consumption.

[0066] When metal deposition progresses and the cathode plate 12 bulges in the plane direction, the thin shaft portion 21 may be rotated around the axis to change the direction of the side protruding portion, and the arrangement interval between the anode plate 11 and the cathode plate 12 may be widened (see Fig. 4(C)). Here, the rotation angle of the thin shaft portion 21 does not have to be 90 degrees. The width for widening the desired interval is not limited, but it is preferable to be equal to the adhesion thickness of the metal.

[0067] In addition, instead of the L-shaped joint forming the side protruding portion 22, a three-way joint 25 in which pipes extend in three orthogonal axial directions may be used (see Fig. 5(A) and Fig. 5(B)). When the three-way joint 25 functions as an interval changing means, among the two joint pipes 26 and 27 extending in the horizontal direction, a short straight pipe 28 is attached to one joint pipe 26 to increase the protruding dimension of the side protruding portion 22 formed by the one joint pipe 26. Then, while the metal adhesion amount is small, the tip surface of the other joint pipe 27 with a short protruding dimension is brought into contact with the electrode plate (see Fig. 5(A)).

[0068] When the metal adhesion amount increases, the thin shaft portion 21 is rotated 90 degrees around the axis, the direction of the three-way joint 25 is changed by 90 degrees, the tip surface of the short straight pipe 28 attached to the joint pipe 26 is brought into contact with the electrode plate, and the desired interval may be widened. When the three-way joint is used as the side protruding portion 22, it may be rotated so that the tip surface of the joint pipe contacts the surface of the electrode plate, and adjustment of the desired interval for holding the electrode plate is easy.

[0069] The power supply means 30 includes 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 protruding portion 13 of the electrode plate via a connection terminal 32 and is not immersed in the water to be treated. Therefore, no metal adheres to the connection terminal 32, and even a connection terminal 32 having a simple structure without an insulating coating does not require much maintenance. For example, the electrode plate may be clamped by a known clamping terminal for 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 may be at least about 10 V or more, and the upper limit value is not limited. The current density may be at least 4.5 A / m 2 or more, and the upper limit value is not limited. Note that the voltage value and the current density are preferably maintained as low as possible so as not to excessively increase the power consumption. The power controller 34 may be controlled to maintain the above-described voltage value and current value, and the configuration is not limited.

[0071] (Deposition Test 1) The above-described dissolved metal deposition apparatus 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. For Deposition Test 1, it was conducted by the applicant himself / herself in accordance with the "Frame Atomic Absorption Method for Zinc" specified in Japanese Industrial Standard "JIS K 0102 53.1". The measuring instrument used was an "Atomic Absorption Spectrophotometer" manufactured by Shimadzu Corporation.

[0072] The test period was from January 30, 2023 to February 10, 2023, and the dissolved zinc concentration was measured for 7 days out of this period. During the test period, the volume of the washing wastewater was about 150 to 200 tons per day. Also, the dissolved zinc concentration in the surprise inspection conducted by an external inspection agency commissioned by the applicant was used as a comparative example. In the comparative example as well, the treated water in the second storage tank was sampled and the test was conducted. The test days of the comparative example were a total of 5 days on September 8, October 26, November 24, December 23, 2022 and January 27, 2023 before the installation of the present invention.

[0073] The electrode plates were made of stainless steel plates with a thickness of 2 mm. The cathode plates and the anode plates were arranged in a meandering flow path from the upstream side to the downstream side of the treatment tank at intervals of about 3 cm to 4 cm, with 10 plates each (see FIGS. 2 and 3). The voltage value was about 10 V, and the current density was 4.5 A / m 2 The volume of the treatment tank is not limited, but here, a treatment tank with 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.

[0074] FIG. 6(A) shows the measurement results of the spot check in the comparative example, and FIG. 6(B) shows the measurement results when the present invention is applied. Before installing the dissolved metal precipitation device 1, the dissolved zinc concentration exceeded the general wastewater standard value of 2.0 mg / L on all inspection days, and the average value on 5 inspection days was about 2.38 mg / L (see FIG. 6(A)).

[0075] On the other hand, as shown in FIG. 6(B), when the dissolved metal precipitation device 1 was operated, good results were obtained in that the dissolved zinc concentration was below the general wastewater standard value on all operating days. The difference in the dissolved zinc concentration on each test day is presumably because the production volume of zinc-plated products differed on each test day, resulting in variations in the dissolved zinc concentration in the washing wastewater.

[0076] Note that even on the day with the highest product production volume, the dissolved zinc concentration in the second storage tank was below the general wastewater standard value. Also, the average value of the dissolved zinc concentration over 10 days was about 1.5 mg / L. This is 40% or less of the current provisional wastewater standard value (4.0 mg / L), and even when the electrode plate is made of stainless steel, good results below the general wastewater standard value were obtained.

[0077] After the completion of precipitation test 1, the cathode plate was taken out and the amount of zinc deposition was confirmed. Even with only 10 days of operation, zinc was deposited on substantially the entire surface of the cathode plate (see the photograph in FIG. 12(A)). When the deposited zinc was scraped off and weighed, about 6 kg of zinc was deposited in total on 10 cathode plates (see the photograph in FIG. 12(B)). According to the present invention, if the zinc plating equipment is continuously operated in the same manner, it is expected that about 100 kg or more of dissolved zinc that had to be discharged heretofore can be recovered annually and recycled as a valuable metal.

Example

[0078] In Example 2, another specific example of the interval holding means will be described with reference to FIG. 7. FIG. 7(A) shows an example in which an attachment member forming the interval holding means 50 is magnetically attached to the surface of the electrode plate. FIG. 7(B) shows an example in which side protrusions are provided at two locations, namely the lower end and the middle of the shaft body forming the interval holding means 60. In the following of Example 2, for the configurations already described in Example 1, the same reference numerals will be used and the description will be omitted.

[0079] The attachment member 51 (see FIG. 7(A)) forming the interval holding means 50 is made of a non-conductor obtained by rubber-coating a neodymium magnet. The thickness of the rubber coating may be any thickness that allows magnetic attachment to the electrode plate by the magnetic force of the neodymium magnet. The position where the attachment member is magnetically attached is not limited, but it is preferable to magnetically attach it near the four corners on the surface of each electrode plate because it is difficult for the electrode plate 10 to tilt.

[0080] Also, the outer shape of the attachment member 51 is cylindrical or polygonal prism-shaped, and the contact surface with the electrode plate 10 and the protruding end surface are flat surfaces. The attachment member 51 can also function as an interval changing means by stacking and magnetically attaching a similar attachment member 51 to the protruding end surface 52 of the attachment member that has already been magnetically attached. In this case, by changing the number of stacked layers of the plurality of attachment members, the desired interval can be changed in multiple steps.

[0081] The shaft body (see FIG. 7(B)) forming the interval holding means 60 includes two split thin shaft portions 61 and side protrusions 62 and 63 provided at two locations, namely the lower end and the middle of the shaft body. The two thin shaft portions 61, 61 are made of a square tube made of vinyl chloride. The side protrusion 62 provided at the lower end of the shaft body is a T-shaped joint made of a square tube made of vinyl chloride, and the side protrusion 63 provided between the two thin shaft portions 61, 61 is a cross joint made of a square tube made of vinyl chloride. Each joint is externally fitted to the end of the thin shaft portion 61.

[0082] The shaft body forming the interval maintaining means 60 can also function as an interval changing means by bringing the short side direction or the long side direction of the side protrusions 62 and 63 into contact with the electrode plate. Specifically, when the adhesion amount of the variable metal is small, the T-shaped side surface of the T-joint forming the side protrusion 62 and the cross-shaped side surface of the cross-joint forming the side protrusion 63 are brought into contact with the electrode plate.

[0083] On the other hand, when the adhesion amount of the metal increases, the thin shaft portion 61 is rotated 90 degrees along the horizontal plane, and both ends of the angle pipes extending in the horizontal direction of each joint are brought into contact with the electrode plate. In this case, it is only necessary to rotate the shaft body, and it is easy to change the desired interval. Further, since the side protrusions 62 and 63 are provided at two locations, the lower end portion and the middle portion of the thin shaft portion 61, the electrode plate is less likely to tilt.

Example

[0084] In Example 3, the electrode plate is made of a thin iron plate 14 with a thickness of 1 mm or less, and the dissolved metal precipitation device 2 provided with the bending prevention means 70 will be described with reference to FIG. 8. FIG. 8(A) shows a perspective view of the bending prevention means. FIG. 8(B) shows a state in which the bending prevention means is brought into contact with the upper edge portion of the iron plate to prevent the iron plate from bending.

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

[0086] Since the bending prevention means 70 is inserted into the gap of the iron plate 14, even if the electrode plate is a thin plate of 1 mm or less, the electrode plate is less likely to be convexly bent laterally. When the bending prevention means is provided, it was possible to prevent the occurrence of bending even for iron plates with any of the plate thicknesses of 0.2 mm, 0.3 mm, and 0.5 mm.

[0087] Since the bending prevention means 70 prevents the electrode plate from bending, the distance between the electrode plates does not partially narrow, and the metal is likely to be evenly deposited over the entire surface of the electrode plate. As a result, even when the thin iron plate 14 is used as the electrode plate, the deposition efficiency of the dissolved metal can be maintained over a long period, and the period until the electrode plate is replaced can be extended.

Example

[0088] In Example 4, the dissolved metal precipitation device 3 in which the distance holding means is outside the treatment tank arranged will be described with reference to FIGS. 9 to 11. FIG. 9(A) shows a plan view of the dissolved metal precipitation device 3, and FIG. 9(B) shows a perspective view of the portion surrounded by the broken line A in FIG. 9(A). FIG. 10 shows a modified example of the distance holding means in a perspective view in the same manner as FIG. 9(B). FIG. 11 shows a graph of the dissolved zinc concentration in the precipitation test 2 using the dissolved metal precipitation device 3 shown in FIG. 9.

[0089] In the dissolved metal precipitation device 3, the distance holding means 80 is placed on the top of the side wall forming the treatment tank 40 through which the water to be treated flows (see FIG. 9). The distance holding means 80 includes a first support portion 81 that supports the cathode plate, a second support portion 82 that supports the anode plate, a plurality of standing pieces 83, and a plurality of connecting means 84. Both the first support portion 81 and the second support portion 82 are formed by a flat metal plate extending long. outside the treatment tank Each of the standing pieces 83 is also made of a flat metal plate and stands side by side with a desired interval on the top surface of the continuously extending support portions 81 and 82. The number of standing pieces 83 is more than that of the electrode plates 10. When widening the desired interval, any position of the unused standing piece 85 can be selected and the electrode plate 10 (see the broken line in FIG. 9(B)) can be moved. Further, the entire surface of the metal plate forming the standing piece 83 forms a contact portion with the electrode plate 10 so that DC power can be efficiently transmitted.

[0090]

[0091] ​The electrode plate 10 is composed of thin iron plates with a thickness of 0.2 mm for both the anode plate and the cathode plate. The protruding portion 13 forming the electrode plate is provided with a side extension portion 15 extending outward from the treatment tank (see FIGS. 9(B)). By connecting this side extension portion 15 to any one of the standing pieces 83, the electrode plate is supported in a standing state and arranged at a desired interval. Instead of providing a side extension portion on the protruding portion of the electrode plate, the standing piece may protrude inward from the treatment tank.

[0092] The connecting means 84 between the electrode plate 10 and the standing piece 83 is a fastener composed of a known bolt and nut. With the through hole 86 formed in the standing piece and the through hole 16 formed in the side extension portion of the electrode plate overlapped, the shaft of the bolt forming the connecting means 84 is inserted and the nut is tightened, thereby detachably connecting the standing piece and the electrode plate.

[0093] The power supply line 31 is connected to the first support portion 81 on the negative side and the second support portion 82 on the positive side of the power supply line so as to supply DC power to the protruding portion 13 of each electrode plate via the standing piece 83. Thereby, it is not necessary to directly connect the power supply line to each individual electrode plate, and the wiring work is easy. Note that the support portion and the standing piece may be made of a non-conductive material. In this case, the power supply line may be directly connected to the protruding portion of the electrode plate.

[0094] Next, a modified example of the dissolved metal deposition apparatus 3 will be described with reference to FIG. 10. In this case, the support portion forming the interval holding means 90 is composed of a rail member 91 having a slide groove, a flat plate portion 92 provided with a standing piece 83, and a fixture 93 for fixing the flat plate portion at a desired position in the slide groove. The fixture is a known bolt and nut. The rail member 91 is provided with a slide groove 94. The slide groove 94 is composed of a wide groove 95 for accommodating the head of the bolt and a narrow slit groove 96 for protruding only the shaft portion of the bolt from the slide groove. The flat plate portion 93 has a through hole 97 for inserting the shaft portion of the bolt.

[0095] By screwing a nut onto the shaft portion of the bolt protruding from the through hole 97, both side portions of the slit groove 96 and the flat plate portion 93 are tightened, and the flat plate portion 93 is fixed in position. As a result, the electrode plate 10 connected to the standing piece 83 integral with the flat plate portion 93 is positioned at a desired position. When changing the desired interval between the electrode plates, the fastening of the nut may be loosened to make the flat plate portion 93 movable along the slide groove 94.

[0096] In addition, since the electrode plate 10 is provided with a rib 17 formed by bending the upper edge portion, even if the electrode plate is a thin plate of 1 mm or less, it is difficult to be bent. As a result, even with a simple configuration in which the side extension portion 15 is only connected to the standing piece 83, the adjacent electrode plates 10 can be made to stand upright neatly with a desired interval therebetween. The rib 17 may be provided at any position on the peripheral edge portion of the electrode plate, and ribs may be provided at a plurality of locations on the peripheral edge portion, for example, at two locations on the upper edge portion and the lower edge portion.

[0097] (Precipitation Test 2) In Precipitation Test 2, the dissolved metal precipitation device 3 shown in FIG. 9 was applied to a zinc plating facility, and the electrode plate was an iron plate with a thickness of 0.2 mm. The test period was approximately 7 months from July 20, 2023 to March 4, 2024. In Precipitation Test 2, a random inspection of the dissolved zinc concentration was carried out irregularly by an external inspection agency commissioned by the applicant of this application.

[0098] The test days by the random inspection were a total of 8 times on July 20, August 21, October 20, December 6, December 25, 2023, January 11, February 15, and March 4, 2024. The dissolved zinc concentration on each test day is shown in FIG. 11. During the test period, the volume of the washing wastewater was approximately 150 to 200 tons per day, which was substantially the same as that in Precipitation Test 1.

[0099] In addition, the number and spacing of the electrode plates, the voltage value and current density of the DC voltage, and the volume of the treatment tank were also set to the same conditions as in Deposition Test 1. In the measurement results of Deposition Test 2, the dissolved zinc concentration was about 0.26 mg / L at the minimum and about 1.3 mg / L at the maximum. The average value of the dissolved zinc concentration by 8 spot checks was about 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, even when the provisional effluent standard for zinc, which was only permitted in the electroplating industry, was abolished and shifted to the general effluent standard, it was confirmed that it was not necessary to increase the amount of service water used immediately before discharge. In particular, when the electrode plate was made of an iron plate as in Deposition Test 2, the dissolved zinc concentration could be reduced to about one-third of the general effluent standard value.

[0101] In addition, in Deposition Test 2, the dissolved metal deposition apparatus was continuously used for more than half a year, but the deposited zinc only adhered to the electrode plate, and there was almost no zinc deposited on the bottom of the treatment tank, so it was not necessary to perform regular cleaning work on the treatment tank. From this, according to the present invention, the labor of cleaning the treatment tank and the electrode plate can be reduced, and the deposited zinc can be recovered while adhering to the electrode plate, and the recycling of zinc is also easy.

[0102] (Others) · In this example, an example in which the electrode plates are arranged at equal intervals has been described, but the interval between the electrode plates may be changed between the upstream side and the downstream side. For example, since the dissolved metal concentration decreases as it goes downstream in the flow path, it is preferable to gradually narrow the interval between the electrode plates from the upstream side to the downstream side so that the metal can be efficiently deposited on the downstream side. · In Example 4, for ease of understanding, outside the treatment tank only the interval holding means to be disposed has been described, but it goes without saying that in Example 4, the interval holding means shown in Examples 1 and 2 and the curvature preventing means shown in Example 3 may be combined. ·The embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The technical scope of the present invention is not limited to the above description but is shown by the scope of the claims, and it is intended that all modifications within the meaning and scope equivalent to the scope of the claims be included.

Explanation of Signs

[0103] 1, 2, 3... Dissolved metal precipitation device, 100... Chemical treatment equipment, 10... Electrode plate, 11... Anode plate, 12... Cathode plate, 13... Protrusion, 14... Iron plate, 15... Side extension part, 16... Through hole, 17... Rib, 20, 24... Spacing holding means, 21... Thin shaft part, 22... Side 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... Inflow pipe, 42... Drainage pump, 43... Region where electrode plates are not arranged, 50... Spacing holding means, 51... Attached member, 52... Protruding end face, 60... Spacing holding means, 61... Thin shaft part, 62, 63... Side protrusions, 70... Bending prevention means, 71... Lower bending part, 80... Spacing holding means, 81... (First) support part, 82... (Second) support part, 83... Upright piece, 84... Connecting means, 85... (Unused) upright piece, 86... Through hole, 90... Spacing holding means, 91... Rail member, 92... Flat plate part, 93... Fixture, 94... Slide groove, 95... Wide groove, 96... Slit groove, 97... Through hole, 110... First storage tank, 120... Coagulation reaction tank, 130... Sedimentation tank, 140... Filter water tank, 150... Second storage tank, 200... Electroplating equipment (for zinc plating), 210... Electroplating equipment (for other metal plating)

Claims

1. A dissolved metal precipitating device for precipitating dissolved metals on an electrode plate by immersing an electrode plate in water to be treated after plating and electrolyzing the water to be treated, comprising: 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 protruding portion protruding from the liquid surface of the water to be treated in a state where the electrode plate stands up from 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 be arranged in a row at a desired interval, and each gap 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-conductive body is brought into contact with both sides of each of the electrode plates, and the electrode plates are not fixed to the treatment tank, and the desired interval is maintained while the individual electrode plates are kept separated from each other; the power supply means connects a power supply line extending from a DC power source to the protruding portion, supplies a DC current without changing the polarity of the electrode plate, and deposits and attaches the dissolved metal to the cathode plate; the electrode plates are arranged in the treatment tank in such a manner that, before the precipitation of the dissolved metal, a non-placement area is left in which no electrode plate is placed, and when adhesion of the dissolved metal progresses, the non-placement area is narrowed in accordance with the amount of adhesion, and the electrode plates and the spacing retaining means are rearranged so as to widen the gap between the electrode plates, thereby making it possible to continue the precipitation of the dissolved metal without peeling off the metal adhered to the cathode plate. A dissolved metal deposition apparatus comprising:

2. The space maintaining means includes a space changing means, the spacing change means disposes the non-conductor in contact with the opposing surfaces of adjacent electrode plates, and when the amount of adhesion increases, increases a protruding dimension of the non-conductor from the opposing surfaces, thereby making it possible to widen the spacing between the electrode plates when rearranging the electrode plates.

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 a rear end of the thin shaft portion protrudes above a liquid surface when a tip of the shaft body is abutted against a bottom surface of the treatment tank, the lateral protrusions protrude horizontally from the thin shaft portion, and the protruding dimensions in the two intersecting horizontal directions are different; Before the precipitation of the dissolved metal, the lateral protrusion is arranged in contact with the opposing surface of the electrode plate so that the protruding dimension of the lateral protrusion is shortened, When the amount of adhesion increases, the lateral protrusion is rotated around the thin shaft portion to contact the opposing surface with its protruding dimension increased, thereby functioning as the interval changing means.

3. The dissolved metals deposition apparatus according to claim 2 .

4. A dissolved metal precipitating device for precipitating dissolved metals on an electrode plate by immersing an electrode plate in water to be treated after plating and electrolyzing the water to be treated, comprising: 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 protruding portion protruding from the liquid surface of the water to be treated in a state where the electrode plate stands up from 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 be arranged in a row at a desired interval, and each gap 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 a standing piece, the support portion extends along the row direction outside the treatment tank 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 vertically arranged at desired intervals outside the treatment tank along the extending direction of each of the support parts, By connecting the upright pieces and the protruding portions, the electrode plates are not fixed to the treatment tank, and the desired intervals are maintained while the individual electrode plates are movable separately; the power supply means connects a power supply line extending from a DC power source to the protruding portion, supplies a DC current without changing the polarity of the electrode plate, and deposits and adheres a dissolved metal to the cathode plate; Prior to precipitation of the dissolved metal, the electrode plates are connected to the upright pieces so as to be arranged in the treatment tank while leaving a non-placement area in which no electrode plate is placed, and when adhesion of the dissolved metal progresses, the non-placement area is narrowed according to the amount of adhesion, and the electrode plates are rearranged by changing the positions of the upright pieces so as to widen the gap between the electrode plates, thereby making it possible to continue precipitation of the dissolved metal without peeling off the metal adhered to the cathode plate. A dissolved metal deposition apparatus comprising:

5. The space maintaining means includes a space changing means, The gap change means is a slide groove provided in the support portion, The slide groove is formed to extend along the column direction, The standing piece is slidably attached along the slide groove, and the electrode plate connected to the standing piece is slid along the slide groove, thereby making it possible to change the interval when rearranging the electrode plate.

5. The dissolved metals 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 surface 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 having a thickness of 1 mm or less.

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

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