JP2014214320A - Device and method for manufacturing chromium electroplated steel strip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for chromium electroplating of a steel strip, with adjustment of the concentration of metal impurities in a chromium plating tank; and a method of chromium electroplating.SOLUTION: The device for manufacturing a chromium electroplated steel strip includes: a plating tank in which a steel strip is chromium electroplated; a drag-out tank in which chromium plating solution dragged out of the plating tank by an associated flow along with the transfer of the steel strip is collected; a drag-out storage tank in which the chromium plating solution collected in the drag-out tank is stored; a device which is separately connected to the drag-out storage tank so as to remove metal impurities in the stored chromium plating solution; and a chromium plating solution buffer tank connected between the plating tank and the drag-out storage tank, which allows the chromium plating solution to be circulated into the plating tank and returns the chromium plating solution stored in the drag-out storage tank to the plating tank.

Description

  The present invention relates to an apparatus for producing an electrochromic steel strip and a method for producing an electrochrome steel strip.

  In recent years, when chromium plating is performed, the amount of penetration of metal impurities such as iron, nickel, copper, zinc, and aluminum increases in the plating solution as the operation time elapses. As the amount of penetration of these metal impurities has increased, there has been a problem of incurring quality defects such as a decrease in weldability of the steel strip.

  Therefore, when performing chromium plating, the upper limit value of the amount of metal impurities (particularly iron) contained in the plating solution is generally set to manage the plating solution (Non-patent Document 1). As a method for managing metal impurities contained in the plating solution, when the metal impurity concentration reaches the upper limit, the metal impurity concentration is managed by replacing part of the plating solution with a new solution and lowering the metal impurity concentration. (Patent Document 1). In addition, as disclosed in Patent Document 2, there is a method of managing the iron concentration (metal impurity concentration) using an iron removing device.

Japanese Patent Laid-Open No. 10-15882 JP 2008-45186 A

Shigei Shigeo, Plating Technology Handbook, (Showa 46), p218-219, Nikkan Kogyo Shimbun

  When the metal impurity concentration is reduced by the method of Patent Document 1, since a part of the plating solution is replaced, the chromic acid in the replaced plating solution is also a waste solution, and there is a problem that the chromic acid basic unit deteriorates. . In the method of Patent Document 2, the plating solution concentrating device and the iron removing device are arranged in series. This series method is effective for plating solution components such as methanesulfonic acid that are not highly corrosive like Patent Document 2. However, when this is applied to a chromic acid plating solution, the plating solution containing a high concentration of chromic acid is injected into the iron removing device by concentration of the plating solution. For this reason, a high concentration of chromic acid corrodes the iron content removing device and significantly reduces the life of the iron content removing device. As a result, there is a problem that the running cost of the apparatus is deteriorated.

  This invention is made | formed in view of this situation, Comprising: It aims at providing the apparatus and electrochrome plating method which adjust the metal impurity density | concentration in a chromium plating tank, and electrochrome-plating to a steel strip.

The gist of the present invention is as follows.
[1] A plating tank for performing electrochromic plating on a steel strip, a drag-out tank for recovering a chromium plating solution drawn out of the plating tank by an accompanying flow accompanying the movement of the steel strip, and chromium recovered in the drag-out tank A drag-out storage tank for storing a plating solution; a device for concentrating the stored chromium plating solution separately connected to the drag-out storage tank; and a separate connection to the drag-out storage tank for storing A device for removing metal impurities from the chrome plating solution, connected between the plating tank and the drag-out storage tank, circulates the chromium plating liquid between the plating tank and the drag-out storage tank. A plating solution buffer tank that returns the stored chromium plating solution to the plating tank. Apparatus for manufacturing an electrical chrome plated steel strip characterized by comprising.
[2] When electrochromic plating is performed on the steel strip moving in the plating tank while circulating the chromium plating solution between the plating tank and the plating solution buffer tank, the accompanying flow accompanying the movement of the steel strip causes the outside of the plating tank. In the manufacturing method of the electrochromic steel strip, the chromium plating solution drawn out in the drag-out tank is collected in the drag-out tank, the collected chromium plating solution is once stored in the drag-out storage tank, and then returned to the plating solution buffer tank. In the drag-out storage tank, the stored plating solution is concentrated and the metal impurities are individually removed.
[3] The method for producing an electrochromic steel strip according to [2], wherein the metal impurity removal is performed when a chromic acid concentration in the drag-out storage tank is a predetermined value or less.

  The present invention collects the plating solution drawn out of the chrome plating tank by the accompanying flow of the steel strip, stores it once, and then uses it again as the plating solution. The concentration of the plating solution and the metal removal are individually performed in the storage process. Thus, the plating solution drawn by the accompanying flow of the steel strip can be returned to the chromium plating tank and reused, and the metal impurity concentration in the plating tank can be adjusted. Moreover, since highly concentrated chromic acid with high corrosivity does not flow through the metal removing device, the life of the metal removing device can be maintained appropriately. Moreover, the chromic acid basic unit can be improved without using chromic acid in the chrome plating solution as a waste solution.

It is a flowchart which shows the procedure which adjusts the metal impurity density | concentration in the chromium plating tank to which embodiment of this invention is applied. 10 is a flowchart showing a procedure for adjusting a metal impurity concentration in Patent Document 2. FIG.

  As shown in FIG. 1, the apparatus of the present invention comprises a chromium plating tank 1, a plating solution buffer tank 6, a dragout tank 2, a dragout storage tank 3, a chromium plating solution concentrating device 4, a metal impurity And a removal device 5. Note that the number of these devices is not limited to one and may be plural.

  The chrome plating tank 1 and the plating solution buffer tank 6 are connected by piping so that the chrome plating solution can be moved alternately. The chrome plating tank 1 is connected to a drag-out tank 2, the drag-out tank 2 is connected to a drag-out storage tank 3, and the drag-out storage tank 3 is connected to a plating solution buffer tank 6. Further, the chrome plating solution concentrating device 4 is individually connected to the drag-out storage tank 3 so that the chrome plating solution can be moved alternately. Further, the metal impurity removing device 5 is individually connected to the drag-out storage tank 3 so that the chromium plating solution can be moved alternately. The chromium plating solution concentrating device 4 and the metal impurity removing device 5 are individually connected to the drag-out storage tank 3, and the chromium plating solution is directly transferred from the chromium plating solution concentrating device 4 to the metal impurity removing device 5. It does not enter and always passes through the drag-out storage tank 3.

  In the chrome plating tank 1, electrochromic plating is performed on the steel strip, and a chrome plating solution used for the electrochrome plating is circulated between the chrome plating tank 1 and the plating solution buffer tank 6. Moreover, since the chromium plating solution is drawn out of the plating tank by the accompanying flow accompanying the movement of the steel strip to be chromium plated, the chromium plating solution is used together with the cleaning solution (using pure water) on the surface of the steel strip as the drag-out tank 2. It is diluted and collected. The collected chromium plating solution in the drag-out tank 2 is temporarily stored in the drag-out storage tank 3 connected to the tank 2. The chrome plating solution stored in the drag-out storage tank 3 is returned to the plating solution buffer tank 6 again, enters the chrome plating tank 1 in which the solution can move alternately with the plating solution buffer tank 6, and is again plated with steel strip. To be served. Therefore, the chromium plating solution drawn out by the accompanying flow of the steel strip can be returned to the plating tank and reused. The basic unit of chromic acid can be improved without making chromic acid in the chrome plating solution waste.

  Further, the metal impurity removal device 5 individually connected to the drag-out storage tank 3 removes metal impurities from the chromium plating solution stored in the drag-out storage tank 3. The chromium plating solution from which the metal impurities have been removed returns from the dragout storage tank 3 to the chromium plating tank 1 through the plating solution buffer tank 6. Therefore, the concentration of metal impurities in the chrome plating tank 1 can be adjusted.

  Further, the chromium plating solution diluted and recovered in the drag-out tank 2 is temporarily stored in the drag-out storage tank 3 and predetermined by the chromium plating solution concentrator 4 individually connected to the drag-out storage tank 3. Concentrated to a chromic acid concentration of In the present invention, the plating solution of the chromium plating solution concentrating device 4 is directly supplied to the metal impurity removing device 5 from the arrangement of the drag-out storage tank 3, the chromium plating solution concentrating device 4 and the metal impurity removing device 5. It will never be done. Therefore, since the high concentration chromium plating solution is not directly supplied to the metal impurity removing device 5, the life of the metal impurity removing device 5 can be maintained appropriately.

  As the chromium plating solution concentrating device 4, for example, a low temperature evaporation device or the like can be used. Further, as the metal impurity removing device 5, for example, a tank filled with an ion exchange resin or an apparatus in which ion exchange membranes are arranged in layers can be used.

  In the present invention, since the plating solution is concentrated in the chromium plating solution concentrating device 4 connected to the drag-out storage tank 3, the chromic acid concentration of the chromium plating solution stored in the drag-out storage tank 3 is increased. . As a result, the chromic acid concentration in the plating solution stored in the drag-out storage tank 3 can be concentrated and adjusted to the same level as the chromic acid concentration in the plating solution stored in the chrome plating tank 1. . Also, even if the chromic acid concentration of the chrome plating solution exceeds the predetermined value and excessively increases, the high concentration chromic acid is directly applied to the metal impurity removal device 5 by stopping the metal impurity removal device 5. Is not supplied, the life of the metal impurity removing device 5 can be maintained appropriately.

  In addition, since the drag-out storage tank 3 is provided separately from the drag-out tank 2 for collecting the plating solution, the chromic acid concentration of the chromium plating solution in the drag-out storage tank 3 is measured to obtain a new plating solution or pure water. It is also possible to appropriately adjust the concentration of the plating solution by supplying a diluent such as.

  Note that the plating solution concentrated to the target chromic acid concentration in the drag-out storage tank 3 may be returned directly to the chrome plating tank 1.

  Further, in the present invention, when the concentration of metal impurities is high due to the arrangement of the drag-out storage tank 3, the chromium plating solution concentrating device 4 and the metal impurity removing device 5, the chromium plating solution concentrating device 4 is stopped. The operating time of the metal impurity removing device 5 can be lengthened appropriately. Moreover, when the density | concentration of chromium plating solution is low, the removal apparatus 5 of a metal impurity can be stopped and the operation time of the concentration apparatus 4 of chromium plating solution can be lengthened suitably.

  In the present invention, the chromic acid concentration that corrodes the metal impurity removing device 5 varies depending on the material of the metal impurity removing device, and therefore may be set as appropriate depending on the material of the metal irregular material removing device 5.

  An example is shown in FIG. With the method of the present invention, the steel strip was chromium plated while adjusting the metal impurity concentration in the plating solution drawn by the accompanying flow of the steel strip. On the other hand, as a comparative example, the metal impurity concentration in the plating solution was adjusted by the method described in Patent Document 2. FIG. 2 is a flowchart of a comparative example showing a procedure for adjusting the metal impurity concentration described in Patent Document 2. In FIG. 2, the plating solution stored in the chrome plating tank 1 is temporarily stored in the plating solution circulation tank 12, and the stored plating solution is supplied from the plating solution circulation tank 12 to the sludge removing device 7. After the sludge in the plating solution is removed by the sludge removing device 7, the plating solution is concentrated in the concentrating device 4. The concentrated plating solution is directly supplied in the order of the iron analyzing and extracting device 8, the iron compound separating device 9, the remelting device 10, and the iron content removing device 11. The plating solution from which the iron compound is separated by the iron compound separation device 9 is returned to the circulation tank 12. On the other hand, the iron compound is supplied to the redissolving device 10 and redissolved in water, and then the iron component is removed by the iron content removing device 11 and then returned to the plating solution circulation tank 12. Returned and reused.

  About the example of this invention and the comparative example, the production line of the electrochromic steel strip was operated for 12 months, respectively.

  In the example of the present invention (FIG. 1), when the chromic acid concentration in the plating solution exceeded 150 g / L, which is the corrosion limit of the metal impurity removal device 5, the metal impurity removal device 5 was stopped. At this time, the concentrating device 4 was continuously operated. As a result, the metal impurity removing device 5 could be operated without any trouble. And it could concentrate to the target chromic acid density | concentration and was able to adjust the metal impurity density | concentration in a plating tank.

  In the comparative example (FIG. 2), the corrosion from the iron analyzing and extracting device 8 to the iron compound separating device 9 corresponding to the metal impurity removing device of the present invention is severe, and the metal impurities in the plating solution are used for 12 months. In the middle of the process, a part of the plating solution must be renewed with a new solution of chromic acid, the chromic acid basic unit deteriorates and the amount of chromic acid used is 1.5 compared to the present invention example. Doubled.

  Therefore, compared with the comparative example, the present invention example can return the plating solution drawn out by the accompanying flow of the steel strip to the plating tank and reuse it, and can adjust the metal impurity concentration in the plating tank, thereby extending the life of the metal removing device. It was possible to maintain it properly, and the chromic acid basic unit of the plating solution could be greatly improved.

DESCRIPTION OF SYMBOLS 1 Chromium plating tank 2 Drag out tank 3 Drag out storage tank 4 Chromium plating solution concentration device 5 Metal impurity removal device 6 Plating solution buffer tank 7 Sludge removal device 8 Iron analyzer 9 Iron compound separation device 10 Remelting device 11 Iron removal equipment 12 Plating solution circulation tank

Claims (3)

A plating tank for electrochrome plating on the steel strip;
A drag-out tank that collects the chromium plating solution drawn out of the plating tank by the accompanying flow accompanying the movement of the steel strip;
A drag-out storage tank for storing the chromium plating solution collected in the drag-out tank;
A device individually connected to the drag-out storage tank and concentrating the stored chromium plating solution;
An apparatus for individually removing metal impurities from the stored chromium plating solution, connected to the drag-out storage tank;
Connected between the plating tank and the drag-out storage tank to circulate the chromium plating solution between the plating tank and return the chromium plating solution stored in the drag-out storage tank to the plating tank. An electrochromic steel strip production apparatus comprising a plating solution buffer tank. In carrying out electrochromic plating on the steel strip moving in the plating tank while circulating the chromium plating solution between the plating tank and the plating solution buffer tank,
The chromium plating solution drawn out of the plating tank due to the accompanying flow accompanying the movement of the steel strip is collected in the drag-out tank, and the collected chromium plating solution is once stored in the drag-out storage tank, and then again the plating solution buffer. A method for producing an electrochromic steel strip that is returned to a tank,
In the drag-out storage tank, concentration of the stored plating solution and removal of metal impurities are individually performed.   The method for producing an electrochromic steel strip according to claim 2, wherein the metal impurity removal is performed when the chromic acid concentration in the drag-out storage tank is a predetermined value or less.

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