JPH06146098A - Method for recovering and reproducing sn plating liquid - Google Patents

Abstract

PURPOSE:To efficiently recover and reproducing a tin plating liquid by desorbing the Sn adsorbed on a chelate resin by the recovered acid obtd. by removing harmful cations, by dialysis of a treating liquid which is obtd. by passing the tin plating liquid through the chelate resin and adsorbing the Sn ions thereon. CONSTITUTION:The tin plating liquid is passed to the chelate resin which selectively adsorbs the Sn ions, by which the Sn ions are adsorbed and removed away. The treating liquid from which the Sn ions are removed is treated by an electrodialysis method or diffusion dialysis method using plural exchange membranes, by which the Fe and other harmful cations are removed and the recovered acid is obtd. The recovered acid is passed to the resin on which the Sn is adsorbed, by which the Sn is desorbed to recover the Sn.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering and reusing a tin plating solution by removing Fe and other harmful cations accumulated in a tin plating solution and in a washing bath after tin plating.

[0002]

2. Description of the Related Art Conventionally, a halogen bath, a ferrostane bath, etc. have been often used as an electrotin plating bath. Particularly, in the latter case, plating with an insoluble anode is also performed. However, in recent years, environmental pollution has been highlighted and regulations on waste liquid treatment have become stricter. Therefore, it is necessary to close the plating line to reduce the waste liquid and replace the plating liquid itself with a less toxic one. For detoxifying the plating solution itself, a plating solution using methanesulfonic acid having no benzene ring as a conduction aid, which is not a specific chemical substance, has recently begun to be used as a tin plating bath. Particularly, since such plating agents are expensive, it is more important to recycle the plating solution. In addition, as a recent tendency, various expensive organic plating additives are often contained in the plating solution in order to improve current efficiency and plating appearance, but in order to prevent the loss of such effective additives, Recovery of plating solution has become indispensable.

However, when the waste liquid is recovered and returned to the plating tank by such a closed system, various impurities discharged from the system together with the waste liquid in the open system are accumulated in the plating liquid to improve the plating quality. It turned out to have an adverse effect. In particular, Fe ions are dissolved during the pre-dip from when the original plating plate (iron plate) enters the acidic tin plating tank until metal tin is electrodeposited on the surface by energization, or when the pickling water washing solution in the pretreatment process is used. It is accumulated in the plating solution when it is brought in. Furthermore, Fe in the plating solution
²⁺ ions undergo air oxidation or anodic oxidation on an insoluble anode to become Fe ³⁺ ions. _{^{Fe 2+ + 1 / 4O 2 +}} 1 / 2H 2 O → Fe 3+ + OH - a (1) However Sn ions occurs a reaction such as the Sn ions are present in the plating solution Fe ³⁺ ions two equations Oxidize. 2Fe ³⁺ + Sn ²⁺ → 2Fe ²⁺ + Sn ⁴⁺ (2) The Sn ⁴⁺ ions thus generated are sludge (Sn
It becomes O ₂ ) and precipitates.

Therefore, Fe ³⁺ ions are hardly present in the tin plating solution, and they are all present as Fe ²⁺ ions.
Also, there are few Sn ⁴⁺ ions, and most of them are Sn.
^It exists as a ²⁺ ion. Therefore, Fe ²⁺ is added to the tin plating solution.
The presence of ions causes Sn ²⁺ ions to oxidize to form sludge, resulting in a large loss of valuable tin. In addition, in the experiments conducted by the present inventors, it is known that the oxidation rate of Sn ²⁺ is proportional to the square of the Fe ²⁺ concentration. Therefore, when the Fe ion concentration in the plating solution is increased, the sludge generation amount is rapidly increased, If the Fe ²⁺ ion concentration in the plating solution exceeds 3 g / L, problems such as loss of tin due to sludge generation, deterioration of the plating surface shape due to dirt on the plating line and contact with sludge become significant. Therefore, F in the plating solution
It is necessary to remove and control Fe ions so that the e ²⁺ ion concentration does not exceed 3 g / L.

Up to now, Japanese Patent Publication Nos. 61-17920 and 57-53880 have been known as methods for removing Fe ions and regenerating a tin plating solution. Japanese Patent Publication 61-
No. 17920 is a regenerated acid solution in which Sn ions in a tin plating solution are recovered by electrolysis and then cations such as Fe ions are removed by a cation exchange resin. In this case, Sn ions are recovered by electrolysis, but since it is necessary to electrodeposit only Sn ions from the mixed solution of Fe ions and Sn ions, control by constant potential electrolysis is required. Further, it is necessary to dissolve the tin recovered as metallic tin in the regenerated acid solution by some method.

Japanese Patent Publication No. 57-53880 discloses a method in which a chelate resin having a property of selectively adsorbing Sn ions in a tin plating solution is used to recover cations such as Fe ions with a strongly acidic cation exchange resin. Is. The exchange reaction of the cation exchange resin is represented by the following formula (resin R-
H, the metal ion to be exchanged is M ^{n +} ). _{(R-H) n + M} n + → R n -M + nH + (3)

Therefore, the equilibrium must move to the right in order for the metal ions to be adsorbed by the resin, but when the pH of the treatment liquid is low, the equilibrium obviously goes to the left from the law of mass action. That is, if the pH of the plating solution is low, adsorption of Fe ions is unlikely to occur as it is, and it is necessary to raise the pH of the solution in an acidic bath such as a tin plating solution in order to effectively remove iron from the plating solution. . From the process, an extra operation of diluting the plating solution is required, and also when the recovered solution after iron removal is returned to the plating tank, it is necessary to concentrate the recovered solution, increasing process steps and energy costs due to concentration. This will result in an increase in the cost and the effect of improving the economic efficiency due to the closure will be offset. Moreover, since cations other than Fe ions are adsorbed, when a cation-based plating additive is used as a necessary plating additive, passing through a cation exchange resin causes a loss of expensive additive, which is a problem.

[0008]

DISCLOSURE OF THE INVENTION The present invention aims to improve environmental hygiene and economic efficiency of a tin plating solution. Particularly, Fe and other harmful cations accumulated in the tin plating solution are removed to recover the tin plating solution. The purpose is to provide a method for recycling.

[0009]

The present invention is a method for recovering and regenerating a tin plating solution by removing Fe and other harmful cations from a tin plating solution in which Fe and other harmful cations coexist. A step of removing Sn ions by passing through a chelate resin having a property of selectively adsorbing, a treatment solution from which Sn ions have been removed is treated by an electrodialysis method or a diffusion dialysis method using two or more ion exchange membranes. By removing Fe and other harmful cations to obtain a recovered acid, the recovered acid is passed through the chelate resin having the Sn ion adsorbed in the above step, and the adsorbed Sn ion is desorbed into the recovered acid. And a step of obtaining a Sn ion-containing recovered acid, and the steps are combined in this order to provide a method for recovering and regenerating a tin plating solution.

The present invention also provides a circulation system for returning a regenerated tin plating solution obtained by removing Fe and other harmful cations from a tin plating solution from a tin plating tank in which Fe and other harmful cations coexist, to a tin plating tank. A step of passing a plating solution from a tin plating tank through a chelating resin having a property of selectively adsorbing Sn ions to remove Sn ions, and a treatment solution from which Sn ions have been removed, in which two or more ion exchange membranes are used. F using electrodialysis or diffusion dialysis
e A step of removing other harmful cations to obtain a recovered acid, the recovered acid is passed through the chelate resin which has adsorbed Sn ions in the step (2), and the adsorbed Sn ions are desorbed into the recovered acid. , A step of obtaining a Sn-ion-containing recovered acid, and a step of circulating the Sn-ion-containing recovered acid obtained in the step in the plating tank, in a combination in this order. Is provided.

It is preferable to adjust the pH of the recovered acid obtained in the step before the Sn ion desorption step to a value suitable for desorption of tin ions. It is also possible to treat the Sn ion-containing recovered acid with activated carbon before circulating it to the plating tank, and then to adjust its components. Then, the Fe ²⁺ ion concentration in the recovered and regenerated tin plating solution is preferably 3 g / L or less.

The present invention will be described in detail below. The present invention utilizes the characteristics of a chelate resin to separate useful metal ions and unnecessary metal ions and effectively remove unnecessary metal ions.
The chelate resin has a property of selectively adsorbing a specific metal ion. In the present invention, a tin plating solution (in the present invention, a tin plating solution, a dragout after tin plating, a washing solution or a mixture thereof is generically referred to as a tin plating solution) has a property of selectively adsorbing tin ions. It is passed through the chelating resin that it has. If the tin plating solution is strongly acidic, the tin ion adsorbability will drop slightly, so it is desirable to mix it with dragout or a washing solution if possible in order to raise the pH of the passing solution. But it can be used. In addition, since the dragout or washing solution has a low Sn ion concentration or Fe ion concentration, the adsorption efficiency per unit time is poor even if it is passed through the resin as it is. Therefore, mix it with a tin plating solution that has not been iron-removed. It is desirable to remove iron.

As the chelate resin having the property of selectively adsorbing tin ions used in the present invention, for example, a copolymer of styrene and divinylbenzene is used as a base, and a phosphoric acid group, an aminophosphoric acid group or an iminodiacetic acid group is used as a functional group. A chelating resin with is good. These chelating resins have a wide p
It has the property of adsorbing only tin ions in the H range, and it is easy to separate tin ions.

After removing the tin ions, the Fe ions are further removed by dialysis using two or more ion exchange membranes. Although there is an electrolytic method as another separation method using an ion exchange membrane, in a tin plating solution that often contains various additives and antioxidants, it is expensive due to the oxidative change of the additive due to the anodic oxidation of the plating solution. Such additives are lost, and the quality of the plating may be deteriorated by the modified product, which is not desirable.

As a dialysis method using an ion exchange membrane,
An electrodialysis method in which an ion-exchange membrane is placed between a pair of electrodes and an electric field is applied to move ions.
There are two types of diffusion dialysis method in which two or more ion exchange membranes are arranged, but an electric field is not applied, and ions are transferred by utilizing the concentration difference of the solution between the membranes. The electrodialysis method is characterized in that the size of the apparatus can be made compact and effective dialysis can be performed even when the concentration difference between the treatment liquid and the concentrated liquid is small. On the other hand, the diffusion dialysis method is used when the concentration of the treatment liquid is high to some extent, and is characterized by low running cost because it does not consume power.
These two methods may be used properly depending on the composition of the plating solution and the space of the equipment.

FIG. 1 shows a flow chart of a typical tin plating solution recovery and regeneration method of the present invention. Tin plating solution from tin plating tanks 1 and 2, or further dragout tank 3 and washing tank 4
The tin plating solution to which the solution from above is added is passed through the chelate resin tower 5 that selectively adsorbs Sn ions to remove Sn ions.

Then, the treatment solution from which Sn ions have been removed is passed through the electrodialysis tank 6. In the electrodialysis tank 5, a chamber 6a for introducing the treatment solution and a concentrating chamber 6b such as Fe are arranged via an ion exchange membrane 6c. Ions such as Fe in the treatment liquid are concentrated in the tank 6b through the ion exchange membrane 6c, and Fe ions in the treatment liquid are removed.

The treatment liquid from which Fe ions have been removed, that is, the recovered acid, is preferably concentrated through a concentrator 7 to a pH suitable for desorption of Sn ions, passed through a chelate resin tower 5, and adsorbed by this Sn. Ions are desorbed from the chelate resin tower 5 into the recovered acid. The tin plating solution thus regenerated by removing ions such as Fe is
Returned to 2 and used.

At this time, before returning to the tin plating tanks 1 and 2, the tin plating solution is preferably passed through the activated carbon treatment tower 8 in order to remove impurities and modified products (electrolytic products of additives) produced by continuous electrolysis. Moreover, it is preferable to pass through the component concentration adjusting tower 9 in order to adjust the component concentration of the tin plating solution. The space velocity (SV) is preferably 1 to 10 when passing through the chelate resin. Furthermore, a series of systems makes it possible to regenerate the plating solution and simultaneously close the tin plating line.

Next, referring to FIG.
A method of removing harmful ions by tin plating such as e-ions will be described. 2a and 2b are schematic diagrams of an electrodialysis cell, where KS is a proton-selective cation exchange membrane, K is a cation exchange membrane, and A is an anion exchange membrane.

The plating solution from which Sn ions have been removed by the chelate resin is placed in one chamber of a dialysis machine in which cation exchange membranes and proton-selective cation exchange membranes are alternately laminated, as shown in FIG. An electrolytic solution such as an acid that is harmless to the plating is put in to move Fe and other harmful cations into the electrolytic solution. After that, the remaining plating solution (acid and other additives) is recovered. When a phenol sulfonic acid bath or a methane sulfonic acid bath is used as the electrolyte solution that is harmless to plating, it does not affect the plating even if acid radicals are mixed in the plating solution side, and it is also cost effective. Therefore, it is better to use sulfuric acid.

As the cation exchange membrane, for example, SERAMION CMV manufactured by Asahi Glass Co., Ltd., as the proton-selective cation exchange membrane, SERMION CMV special treatment film manufactured by Asahi Glass Co., Ltd., and the anion exchange membrane, SERAMION AAV manufactured by Asahi Glass Co., Ltd. You can use it. The electrode on the cathode side is not particularly limited, and steel, carbon, stainless steel or the like can be preferably used. The electrode on the anode side is not particularly limited as long as it is an insoluble anode in order to prevent the impurity metal from being dissolved in the solution. Carbon, platinum, titanium coated with iridium oxide, silicon, or the like may be used.

When the diffusion dialysis method is used, two or more anion exchange membranes are arranged and the plating solution is placed in every other chamber,
Water is admitted to the chamber adjacent to it through the anion exchange membrane. Thus, the acid in the plating solution moves to the adjacent chamber through the anion exchange membrane and the Fe ion-free acid is recovered.
By such electrodialysis or diffusion dialysis method, it is possible not only to recover and regenerate the drag-out solution of the tin plating solution, but also to actively remove Fe ions in the tin plating solution, thereby suppressing the reaction of the formula 2 Sludge formation due to the oxidation of ions can be effectively reduced. Particularly in a high-speed plating line, since the plating solution is often oxidized by the entrainment of air, the effect is further enhanced.

On the other hand, the solution from which tin ions have been removed by the chelate resin is placed in an electrodialyzer in which proton-selective cation exchange membranes and anion exchange membranes are alternately laminated, and the anions such as acids in the plating solution are moved to obtain this. A method of recovery is also conceivable (see Fig. 2b). Such a method may be used when all the plating additives are anionic.

The solution from which Fe ions have been removed can be added as a recovered acid to the tin plating solution. Further, by passing the solution through the chelate resin tower in which tin ions are adsorbed, it is possible to recover tin without mixing impurities. In this case, in order to desorb the adsorbed tin, it depends on the kind of the chelate resin, but it is usually necessary to make it strongly acidic. Therefore, in some cases, the pH may be adjusted by concentrating the recovered acid after removing Fe ions. After that, it is desirable to pass the solution through the chelate resin column in which tin ions are adsorbed.

[0026]

EXAMPLES Next, the present invention will be specifically described based on examples. (Example) Fe in a tin plating solution was prepared using the equipment shown in FIG.
Ions and other cations were removed. Methanesulfonic acid was used as the conduction aid of the tin plating solution. 0.5m ³ of a mixture of plating solution and dragout solution was added to resin 0.02
After passing through 5 m ³ with SV4 to remove tin ions, this solution was further charged into the treatment tank 6a of the electrodialysis tank 6 of FIG. 2 (a) and an electric field was applied to remove Fe ions and other cations. At this time, 2N was used as the electrode solution for the electrodialysis device.
2N sulfuric acid was put into the sulfuric acid / Fe concentration tank 6b. The liquid from which Fe ions and other cations were removed in this way was concentrated to a pH of 1.5 by the concentrator 7 and then passed through a resin tower in which tin ions were adsorbed to recover tin ions. Sn ions and F in the plating solution before and after removing Fe ions and other cations
Table 1 shows changes in the e-ion concentration. Table 2 shows the resins and ion exchange membranes used in this example.

Inventive Examples 1 and 3 were subjected to activated carbon treatment, and Inventive Examples 2 and 4 were subjected to activated carbon treatment without adjusting the concentration of each component, and then charged into a plating tank (1 and 2 in FIG. 1). The analysis of Sn ion concentration and Fe ion concentration was performed by an atomic absorption spectrometer. In the invention examples 1 to 4, only Sn ions were adsorbed by the resin. Further, Fe ions and other cations were efficiently removed by the electrodialyzer.

In Comparative Example 1, since no electrodialysis was performed, Fe ions and other cations were not removed. In Comparative Example 2, Fe ions and other cations were sufficiently removed as a result of removing Fe ions and other cations through a pair of cation exchange membranes between a pair of electrodes by diaphragm electrolysis, but addition in the plating solution by anodic reaction. The agent was oxidatively modified and lost, and it was necessary to replenish expensive additives. In Comparative Example 3, the Sn ion selectivity of the resin was poor, the Sn ions and the Fe ions could not be separated, and the Fe ions and other cations could not be removed from the plating solution.

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

The present invention provides an efficient method for removing and recovering Fe ions and other cations in a tin plating solution. Therefore, the present invention greatly contributes to resource saving and energy saving, can further close the tin plating equipment, and has an extremely high effect of protecting environmental hygiene.

[Brief description of drawings]

[Fig. 1] Fe for closing the tin plating facility
FIG. 3 is a typical flow chart of the present invention in which ions and other cations are removed and a plating solution is recovered and regenerated.

2A is a schematic diagram of electrolytic dialysis using a proton-selective cation exchange membrane and a cation exchange membrane, and FIG. 2B is a schematic diagram of electrolytic dialysis using a proton-selective cation exchange membrane and an anion exchange membrane. is there.

[Explanation of symbols]

 1, 2 Tin plating tank 3 Drag-out tank 4 Water washing tank 5 Chelating resin tower 6 Electrodialysis tank 6a Treatment chamber (plating solution input chamber) 6b Fe enrichment chamber 6c Ion exchange membrane 7 Concentrator 8 Activated carbon treatment tower 9 Component concentration adjustment tower

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Hajime Ogata, 1 Kawasaki-cho, Chuo-ku, Chiba, Chiba Pref., Technical Research Division, Kawasaki Steel Co., Ltd. (72) Keiko Hamahara, Kawasaki, Chuo-ku, Chiba, Chiba Town No. 1 Kawasaki Iron & Steel Co., Ltd. Technical Research Division (72) Inventor Toshihiro Kikuchi No. 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Kawasaki Steel Co., Ltd. Technical Research Division (72) Inventor Mori Tonobu Chiba Kawasaki Steel Co., Ltd., Chuo-ku, Chiba City, Chiba Prefecture, Japan Technical Research Division (72) Inventor, Yukio Matsumura 10 Goi Kaigan, Ichihara City, Chiba Asahi Glass Co., Ltd. Chiba Factory

Claims (5)

[Claims] 1. A method for recovering and regenerating a tin plating solution by removing Fe and other harmful cations from a tin plating solution in which Fe and other harmful cations coexist, wherein the tin plating solution has a property of selectively adsorbing Sn ions. Removal of Sn ions by passing through a chelating resin that has, Fe and other harmful substances by treating the treatment solution from which Sn ions have been removed by electrodialysis or diffusion dialysis using two or more ion exchange membranes A step of removing a cation to obtain a recovered acid, and passing the recovered acid through the chelate resin having the Sn ion adsorbed in the above step, desorbing the adsorbed Sn ion into the recovered acid to recover the Sn ion-containing recovered acid. The method for recovering and regenerating a tin plating solution, which is characterized in that the steps for obtaining the above are performed in combination in this order. 2. A tin plating tank in which a regenerated tin plating solution obtained by removing Fe and other harmful cations from a tin plating solution from a tin plating tank in which Fe and other harmful cations coexist is returned to the tin plating tank. A step of passing the plating solution from No. 1 through a chelating resin having a property of selectively adsorbing Sn ions to remove Sn ions, the treatment solution from which Sn ions have been removed using two or more ion exchange membranes F using electrodialysis or diffusion dialysis
e A step of removing other harmful cations to obtain a recovered acid, the recovered acid is passed through a chelate resin which has adsorbed Sn ions in the above step, and the adsorbed Sn ions are desorbed in the recovered acid to contain Sn ions. A method of recovering and regenerating a tin plating solution, which comprises performing the step of obtaining a recovered acid, and the step of circulating the Sn ion-containing recovered acid obtained in the step in the plating bath in this order. 3. The pH of the recovered acid obtained in the step before the step of desorbing Sn ions is adjusted to a pH suitable for desorption of Sn ions.
The method for recovering and regenerating a tin plating solution according to claim 1, wherein 4. The tin-plating solution according to claim 2, wherein the Sn ion-containing recovered acid is treated with activated carbon before being circulated in the plating tank before the component adjusting step of claim 4 and then the components are adjusted. Recovery method. 5. The method according to claim 1, wherein the Fe ²⁺ ion concentration in the Sn ion-recovering acid is 3 or ^less.
Recovery method of tin plating solution below g / L.