JPH07233500A - Method for removing metallic ion impurity - Google Patents

Abstract

PURPOSE:To simplify an equipment and to effectively utilize the electric power by making use of the advantage of a means for removing metallic impurities by electrolytic separation. CONSTITUTION:The inside of an electrolytic working tank A used in the pretreatment for plating is separated with a metal ion-permeable ion-exchange membrane 4 into a working chamber 5 filled with a working soln. and a precipitation chamber 6 filled with a processing soln. 7 on the electrode 8 side. The metallic ion impurities 10 contained in the working soln. 2 are permeated through the membrane 4 into the precipitation chamber 6 simultaneously with the electrolytic working in the chamber 5, allowed to react with the processing soln. 7 in the chamber 6 and precipitated. The soln. 7 contg. the precipitate is recirculated to the precipitation chamber 6 through a separator 11 from the chamber 6, and the precipitate is separated from the soln. 7 with the separator 11 and discharged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing metal ion impurities for preventing metal ion impurities harmful for plating processing from being mixed into a plating stock solution.

[0002]

2. Description of the Related Art In plating, not only the undiluted solution in the plating tank but also the object to be plated (hereinafter
Impurities such as dust, oil and fat, metal ions, etc., contained in the electrolytic pickling solution and etching solution (hereinafter referred to as processing solution including plating stock solution) in the electrolytic processing tank for pickling and etching It is desirable to remove it as much as possible because it is harmful because it causes deterioration of layer quality and processing speed.

Of the impurities contained in these working fluids,
Dust, oil and fat can be relatively easily removed by, for example, a filter, but metal ions cannot be easily removed by a filter because they are contained in the working liquid in a dissolved form.

Therefore, metal ion impurities gradually accumulate in these working liquids as the plating process is repeated.

For this reason, when the metal ion impurities in the working liquid reach a certain concentration, they have to be discarded or regenerated by neutralization in another process, resulting in pollution. Problems such as generation and soaring processing costs occur.

Therefore, in order to solve these problems, a method of removing metal ion impurities by electrolytic separation means, that is, an electrolytic separation method has hitherto been devised.

This electrolytic separation method is a method for continuously removing metal ion impurities contained in the working liquid. A processing facility consisting of an electrolytic separation tank is attached to the plating facility, and the inside of this electrolytic separation tank is attached. Is divided into a treatment chamber and a precipitation chamber by an ion-exchange membrane for permeation of metal ions, and an anode electrode on one side and a cathode electrode on the other side face each other with respect to the insides of these treatment and precipitation chambers. Arrange them together.

Then, while the processing liquid is filled in the precipitation chamber, the processing liquid in the plating tank or the electrolytic processing tank in the plating facility is circulated between the processing chamber and the processing liquid, and a direct current is applied between both electrodes.

As a result, the metal ion impurities contained in the processing liquid permeate into the processing liquid in the precipitation chamber through the ion exchange membrane, and react with the processing liquid to form metal hydroxide or metal oxide, and the metal ions in the precipitation chamber are discharged. Settle to the bottom.

In this way, harmful metal ion impurities are precipitated and taken out of the equipment to be removed.

[0011]

Therefore, this conventional electrolytic separation method requires an electrolytic separation tank, which is a treatment equipment for removing metal ion impurities, in addition to the plating equipment. It has the disadvantage of increasing equipment costs.

Not only that, but the current consumed in the electrolytic separation tank is used only for removing metal ion impurities, and not only the plating process but also the pickling of the processed product performed as a pretreatment. There is also a problem that it does not contribute to etching or the like at all, and that power consumption is newly required and the running cost becomes high accordingly.

Therefore, an object of the present invention is to utilize the advantages of the means for removing metal ion impurities by the electrolytic separation method, while at the same time simplifying the equipment and effectively utilizing the power consumption. It is to provide a removal method.

[0014]

In the present invention, the above object is to provide an ion exchange membrane for direct metal ion permeation in an electrolytic processing tank used as a pretreatment step of plating, and to perform the ion exchange. The membrane divides the inside of the electrolytic processing tank into a processing chamber filled with the processing liquid and a precipitation chamber on the electrode side filled with the processing liquid.

Simultaneously with the electrolytic processing step in the processing chamber, the metal ion impurities contained in the processing liquid are permeated to the precipitation chamber side through the ion exchange membrane and reacted with the processing liquid in the precipitation chamber to cause precipitation.

Thereafter, while circulating the treatment liquid containing the precipitate from the precipitation chamber through the separator to the precipitation chamber again,
This is achieved by separating and removing the precipitate from the treatment liquid by the separator.

[0017]

[Effects] That is, by taking the above means, metal ion impurities liberated in the working fluid during pickling or etching of the workpiece in the electrolytic processing tank, which is performed as a pretreatment step in plating. Permeates from the processing chamber to the precipitation chamber through the ion exchange membrane, and reacts with the processing liquid in the precipitation chamber to precipitate.

The treatment liquid containing this precipitate is circulated again from the precipitation chamber through the separator to the precipitation chamber, whereby the precipitate as metal ion impurities is separated from the treatment liquid by the separator and externally Taken out.

Therefore, the metal ion impurities are removed at the same time by utilizing the electric power at the time of pickling or etching which is a pretreatment step of the plating process.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The metal ion removing method according to the present invention will be described below with reference to an example of an actually applied apparatus.

As shown in FIG. 1, in a general process system for plating, in order to pretreat a workpiece in advance by pickling, etching, etc., first, the workpiece 1 is treated with an electrolytic acid as a pretreatment tank. It is placed in an electrolytic processing tank A filled with a processing liquid 2 such as a washing liquid or an etching liquid.

Then, the workpiece 1 is subjected to pretreatment such as pickling and etching with the processing liquid 2 in the electrolytic processing tank A, and then transferred to the plating tank B, and processed in the plating tank B filled with the plating stock solution 3. A plating layer is applied to the surface of the article 1.

Thereafter, the processed product 1 provided with this plating layer is successively passed through the primary water washing tank C and the secondary water washing tank D and rinsed with water twice to complete the plating process.

In the above plating process, particularly, when metal ion impurities are present in the plating stock solution 3 in the plating tank B, the metal ion impurities cause damage to the plating process as described above, and plating is performed. It causes deterioration of layer quality and processing speed.

Then, when considering the metal ion impurities, the metal ion impurities are mainly transferred to the workpiece 1 during pickling or etching in the electrolytic processing tank A which is a pretreatment step of the workpiece 1. Adhere to.

Then, as the plating process progresses,
The metal ion impurities are brought into the plating tank B from the electrolytic processing tank A together with the workpiece 1 and are accumulated in the plating stock solution 3.

From this, the machining liquid 2 in the electrolytic machining tank A is
It has been found that if the metal ion impurities contained in the solution are removed, the carry-in of the metal ion impurities into the plating bath B can be reduced and the metal ion impurities in the plating stock solution 3 can be reduced.

On the other hand, in the electrolytic processing tank A, which is a pretreatment process for plating, the electric power is originally used to perform electrolytic pickling and etching of the workpiece 1.

Therefore, based on these circumstances, in the present embodiment, the following means for removing metal ion impurities was adopted.

That is, as shown in FIG. 2, for example, the ion exchange membrane 4 for directly permeating metal ions is placed in the electrolytic processing tank A used as a pretreatment step for chromium plating.
And the inside of the electrolytic processing tank A is partitioned by the ion exchange membrane 4 into a processing chamber 5 and a precipitation chamber 6 on the electrode 8 side.

Inside the processing chamber 5, the processing liquid 2 such as an electrolytic pickling solution or an etching solution for pretreatment is put as it is, and inside the precipitation chamber 6 is a processing liquid 7 such as an aqueous solution of sodium carbonate. I'll meet you.

Then, the workpiece 1 is processed into the processing liquid 2 in the processing chamber 5.
The processed material 1 is used as an anode electrode and the electrode 8 in the precipitation chamber 6 is used as a cathode, and a DC current is passed through a rectifier 9 between them.

As a result, the workpiece 1 is subjected to electrolytic processing, which is a pretreatment step, and at the same time, the metal impurities 10 contained in the processing liquid 2 become cations and pass through the ion exchange membrane 4 to settle in the precipitation chamber 6. Permeate into the treatment liquid 7.

The metal ion impurities 10 that have permeated the ion exchange membrane 4 react with the treatment liquid 7 in the precipitation chamber 6 to form metal hydroxides, which precipitate on the bottom of the precipitation chamber 6.

Therefore, while the treatment liquid 7 containing the precipitate is circulated from the precipitation chamber 6 through the separator 11 to the precipitation chamber 6 again, the separator 11 separates the precipitate from the treatment liquid 7 and takes it out.

The metal hydroxide taken out is treated as sludge, or if it can be effectively used, it is sold as a raw material.

Thus, the metal ion impurities harmful to the plating process are removed at the same time by utilizing the electric power at the time of pickling or etching which is a pretreatment process of the plating process.

However, even with the above means, most of the metal ion impurities that have permeated into the precipitation chamber 6 through the ion exchange membrane 4 are precipitated as metal hydroxides, but some of them remain as they are. Thus, the concentration of the metal ion impurities remaining in the treatment liquid 7 gradually increases.

Therefore, it is necessary to renew the processing liquid 7 at a stage where the concentration becomes constant, but the increasing rate of this concentration is extremely low, and therefore it can be used for a long period of time.

Even so, the treatment liquid 7 will eventually need to be renewed. In that case, the treatment liquid 7 is detoxified and discharged by neutralization ion exchange treatment or the like.

In the above-mentioned embodiments, the case of chromium plating or the like in which the workpiece 1 is used as an anode for pretreatment has been described as an example.

However, in the case of galvanizing or the like, the pretreatment can be carried out using the work piece 1 as an anode or a cathode.

Therefore, even in this case, the workpiece 1
Is used as the anode and a sodium sulfate aqueous solution or the like is used as the treatment liquid 7 in the precipitation chamber 6, in the same manner, the metal ion impurities can be removed while being precipitated as metal oxides.

[0044]

As described above, according to the present invention, the electrolytic processing tank used as the pretreatment step of plating is used, and the electric power at the time of the pretreatment is utilized to simultaneously remove the metal ion impurities. Since it can be removed, there is an advantage that the plating facility can be simplified and the power consumption can be effectively utilized.

Further, in addition to the above, it is possible to suppress the deterioration of the pretreatment processing liquid and extend the life thereof.

[Brief description of drawings]

FIG. 1 is a system diagram showing an example of a general process of a plating facility.

FIG. 2 is a schematic diagram showing a structural example of an electrolytic processing tank for carrying out the present invention in the system diagram of FIG.

[Explanation of symbols]

 A Electrolytic processing tank 2 Processing liquid 4 Ion exchange membrane 5 Processing chamber 6 Precipitation chamber 7 Processing liquid 8 Electrode 10 Metal ion impurity 11 Separator

Claims (1)

[Claims] 1. An ion exchange membrane for directly permeating metal ions is stretched in an electrolytic processing tank used as a pretreatment step for plating, and the inside of the electrolytic processing tank is filled with the processing liquid by the ion exchange membrane. It is divided into a processing chamber and a precipitation chamber on the electrode side filled with the processing liquid, and at the same time as the electrolytic processing step in this processing chamber, metal ion impurities contained in the processing liquid are permeated to the precipitation chamber side through an ion exchange membrane, After the metal ion impurities are reacted with the treatment liquid in the precipitation chamber to cause precipitation, the treatment liquid is circulated from the precipitation chamber through the separator to the precipitation chamber again, while the separator separates the precipitate from the treatment liquid. A method for removing metal ion impurities, characterized in that