JP3090347B2 - Electroplating solution suspension treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a method for treating a suspension of an electroplating solution, which is performed in a process of returning a metal powder from a melting tank to the plating facility when circulating a plating solution from the plating facility to supply metal ions to the plating solution.

[0002]

2. Description of the Related Art In electroplating, plating is performed by a precipitation reaction of metal ions in a plating solution.
As the metal ions in the plating solution are consumed as the plating process progresses, it is necessary to supply the metal ions. Therefore, a part of the plating solution is sent from the plating facility to a dissolving tank, and metal ions are replenished by replenishing and dissolving the metal powder in the dissolving tank. Then, the plating solution is returned to the plating facility again, and in this process, the suspension is generally filtered and removed by a filtration device.

In this case, a filter using a filter cloth such as a leaf filter is used as a filter.
If used to some extent, filter resistance will increase due to filter cloth clogging, so stop operation and wash with plating solution.
A slurry containing the suspension and a slurry (hereinafter simply referred to as a washing drainage) is discharged. The washing waste liquid is separated into solid and liquid by a dehydrator, and the suspended cake is carried out of the system by a conveyor or the like and disposed of.

As a method for filtering the electroplating solution, Japanese Patent Application Laid-Open No. 57-108299 proposed by the applicant of the present invention has been proposed.
And JP-A-57-110700. In this technology, after the backwash liquid (washing waste liquid) discharged from the filtration device is once stored in a backwash liquid tank (storage tank), it is supplied to a dehydrator by a pump to perform solid-liquid separation, and plating after separation is performed. The liquid is used again for backwashing.

[0005]

The washing effluent stored in the storage tank immediately precipitates and solidifies the suspension, causing damage to the pump and clogging of the piping. As described above, since the filter is washed when the filter cloth is clogged as described above, it is intermittently performed at a considerably long interval (for example, every 7 hours). The plumbing is immediately clogged by the suspension.

If the flow rate of the washing and drainage during the pressure feeding is too low, the pipe cannot be made too large because the clogging occurs even during the feeding, and once it is clogged, the next operation cannot be started. there were. Also, the plating solution separated by the dehydrator is used again for backwashing. However, the plating solution after separation also contains extremely fine suspended solids (SS), which are gradually concentrated. Therefore, there is a problem that the removal processing is required after all.

[0007] The present invention provides a method for treating a suspension of an electroplating solution, which prevents precipitation of the suspension, thereby preventing damage to the pump and clogging of the piping, and preventing the progress of contamination of the cleaning solution. Aim.

[0008]

SUMMARY OF THE INVENTION The present invention relates to an electroplating method in a plating solution processing facility provided with a filtration device for removing suspended substances in a process of returning a plating solution from a metal powder dissolving tank to a plating facility side. A method for treating a suspension of a liquid, comprising: storing a slurry-like washing wastewater containing a suspension intermittently discharged from the filtration device in a storage tank having a stirrer; The washing waste liquid larger than the processing capacity of the machine is continuously pumped to the distribution tank by the pump, and the equivalent of the processing capacity of the dehydrator is supplied from the distribution tank to the dehydrator, and the remaining washing waste liquid is again discharged from the distribution tank. Returning to the storage tank, solving the problem in the above-described conventional technology by circulating the washing wastewater in the storage tank while stirring with the stirrer, Further, the plating solution that is continuously supplied to the dehydrator and separated by the dehydrator is mixed with the unfiltered plating solution on the inlet side of the filtration device, thereby avoiding concentration of the plating solution SS for cleaning the filtration device. It is.

[0009]

The slurry-like washing wastewater containing the suspended matter intermittently discharged from the filtration device is stored in a storage tank having a stirrer. Then, from the storage tank, the washing waste liquid larger than the processing capacity of the continuously operated dehydrator is continuously pumped to the distribution tank by the pump.

In this case, the amount of liquid to be sent is determined by the type of the dehydrator, the path of the piping, the concentration of suspended solids in the washing waste liquid, and the like, but is set to be about 2 to 7 times the processing capacity of the dehydrator. If this amount is less than twice, the suspended solids in the distribution tank settle violently, and in this tank, a stirrer is indispensable and clogging occurs depending on the piping route. If it exceeds seven times, not only the power of the pump will be wasted, but also the piping cost will increase significantly.

[0011] Of the washing and drainage that has been pressure-fed to the distribution tank in this way, a dewatering process is performed by supplying an amount corresponding to the processing capacity of the dehydrator to the dehydrator. In this case, since the dehydrator operates continuously, there is no clogging of the piping. On the other hand, the remaining washing waste liquid in the distribution tank is returned to the storage tank again. However, since the washing waste liquid in the storage tank is constantly stirred by the stirrer, the suspension does not precipitate.
The washing waste liquid is circulated through the distribution tank by the pump while being constantly stirred, and the flow rate is increased, so that no clogging occurs in the piping.

Further, the plating solution separated by the dehydrator is mixed into the unfiltered plating solution on the inlet side of the filtration device and is filtered again, and the filter is washed with a new plating solution. Therefore, the SS remaining in the plating solution in the washing drainage is not concentrated because it can be removed by filtration again. Since all of the plating solution in the cleaning and draining liquid is returned to the inlet side of the filtering device in this way, it is not discharged to the outside, and the burden of the draining process is eliminated.

[0013]

FIG. 1 shows an outline of a device configuration of a main part in a plating solution processing equipment for carrying out the present invention. The plating solution returned from the metal powder dissolving tank (not shown) to the plating equipment side by the pipe 20 is stored in the cushion tank 1, and the tank P 2 is filtered from the tank by the pump P ₁ through the pipe 21.
To be pumped. The filtering device in this example is a leaf filter, and washing when the filter cloth is clogged is performed by spraying a plating solution from a spray pipe 3.

The plating solution that has been filtered and cleaned is supplied to a pipe 22.
Is returned to the plating equipment side. Reference numeral 23 denotes a pipe for supplying the plating solution for cleaning the leaf filter. The cleaning liquid after the leaf filter cleaning is stored in the storage tank 4 by the pipe 24. The pipe 24 has a considerably large downward slope and a large pipe diameter so that clogging does not occur even if the washing wastewater is intermittently discharged.
Then, the washing drainage S ₁ stored in the storage tank 4
It is pumped to the distribution tank 6 through the pipe 25 by the processing capacity more than the amount that pump P ₂ of the dehydrator 11 in continuous operation while preventing the precipitation hardening constantly stirred with a suspension by a stirrer 5. Note that the distribution tank 6 is installed at a position higher than the storage tank 4, preferably immediately above the storage tank.

A part of the washing waste liquid S ₂ fed to the distribution tank 6 overflows from a V notch (not shown) of the weir 7 and is supplied to the dehydrator 11 by a pipe 27. Machine
The liquid level is controlled and adjusted by the liquid level control cylinder 8 so as to correspond to 11 continuous processing amounts. Although to prevent precipitation of suspension was placed a stirrer 9 for distribution tank of this example, the capacity of the pump P ₂ is sufficient enough, agitation in the wash effluent S ₂ itself is sufficiently If performed, this stirrer 9 is not necessary.
BR> 10 is for stabilizing the liquid level L with a baffle plate.

The remaining washing drainage S after being supplied to the dehydrator 11
₂ is returned to the storage tank 4 again via the liquid level control cylinder 8 and the pipe 26, and circulates through the above-described path while being constantly stirred. On the other hand, the washing wastewater supplied to the dehydrator 11 is separated into solid and liquid by the dehydrator 11, and the suspended cake is carried out of the system by the conveyor 12 and discarded. The separated plating liquid is returned to the cushion tank 1 via the pipe 28 by the pump P _3, it is mixed into the unfiltered plating solution of the filter 2 entry side.

Here, a centrifugal type capable of continuously dehydrating the water is preferably used as the dehydrator 11, and its installation location is located immediately below the distribution tank 6, and the pipe 27 is formed with a descending gradient as large as possible for washing and discharging. It is desirable to be able to gravity feed the liquid. If the metal powder is mixed with the undissolved metal powder in the plating solution sent from the dissolving tank through the pipe 20, the metal powder is mixed with the washing effluent while still undissolved, and is filtered. , It can be almost completely dissolved by stirring in the storage tank 4 and stirring in the middle of circulation between the storage tank 4 and the distribution tank 6.

At the time of iron-based electroplating, a leaf filter was used as a filtration device, and a centrifugal dehydrator was used as a dehydrator, and a suspension of a plating solution was treated with the equipment configuration shown in FIG. In this case, two leaf filters were operated alternately every 7 hours, but the amount of washing drainage at one time was 14 m ³ ,
The continuous processing capacity of the centrifugal dehydrator was set to 2 m ³ / H, and the amount of liquid sent from the storage tank to the distribution tank was set to 10 m ³ / H. The suspended cake after the solid-liquid separation by the dehydrator was discarded, and the plating solution was returned to the cushion tank.

As a result, troubles such as clogging of the piping did not occur at all, the suspended matter could be removed smoothly, and a clean plating solution could be returned to the plating equipment side. Although fine iron powder of from about 12 g / m ³ during the washing waste liquid discharged from the leaf filter was mixed, no evidence that there remains iron powder discharged suspension cake washed It was also confirmed that the iron powder in the discharged liquid was almost completely dissolved by the stirring during circulation between the storage tank and the distribution tank, and was returned to the cushion tank together with the plating solution.

[0020]

According to the method for treating a suspension of an electroplating solution according to the present invention, the suspension can be prevented from settling in each pipe after the filtration device to cause clogging, thereby improving the operation rate of the equipment. Further, a clean plating solution can be returned to the plating facility without the SS in the plating solution being concentrated, and there is no need to discharge the plating solution out of the system, so that a waste liquid treatment facility is not required.

Further, since the metal powder can be completely dissolved by stirring during the circulation of the washing wastewater, there is an advantage that a part of the function of the melting tank can be shared.

[Brief description of the drawings]

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic explanatory view of a main part of a plating solution processing facility for carrying out the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cushion tank 2 Filtration device 3 Spray piping 4 Storage tank 5 Stirrer 6 Distribution tank 7 Weir 8 Liquid level control cylinder 9 Stirrer 10 Baffle plate 11 Dehydrator 12 Conveyor 20-28 Piping S Cleaning drainage

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C25D 21/14, 21/18

Claims (2)

(57) [Claims] 1. A method for treating a suspension of an electroplating solution in a plating solution treatment facility provided with a filtration device for removing suspended matter in a process of returning a plating solution from a metal powder dissolving tank to a plating facility side. The slurry-like washing wastewater containing the suspended matter intermittently discharged from the filtration device is accommodated in a storage tank having a stirrer, and the washing wastewater larger than the processing capacity of the dehydrator continuously operated from the storage tank. The liquid is continuously pumped to the distribution tank by a pump, and the processing capacity of the dehydrator is supplied from the distribution tank to the dehydrator, and the remaining washing waste liquid is returned from the distribution tank to the storage tank again. A method for treating a suspension of an electroplating solution, comprising circulating washing wastewater in a tank while stirring with the stirrer. 2. The electroplating solution according to claim 1, wherein the plating solution continuously supplied to the dehydrator and separated by the dehydrator is mixed into the unfiltered plating solution on the inlet side of the filtration device. Suspension treatment method.