JP3055707B2 - Automatic solution concentration control apparatus and method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for automatically controlling the concentration of a solution whose components decrease over time.

[0002]

2. Description of the Related Art For example, in a plating bath in operation, a specific component such as a plating component in a solution decreases as the plating progresses, and its concentration changes. However, in order for the plating operation to proceed properly, it is necessary to appropriately supply the reduced specific components and control the plating solution concentration to be within a predetermined range. Conventionally, the concentration of a plating bath is quantitatively titrated and analyzed at predetermined intervals to determine the difference between the analytical value and a predetermined standard value of a specific component, and a specific component having a reduced amount corresponding to the difference is supplied to the bath. I am trying to do it.

If such an operation is performed manually, it takes several hours to complete the replenishment operation of the necessary specific components after the analysis result is found, and the responsiveness is deteriorated and the reliability of management is reduced. There is a risk. It has also been proposed to automatically perform the above-mentioned management work.In the case of a known apparatus, an automatic titration analyzer performs quantitative titration analysis of specific components reduced by the progress of plating work for each component, and analyzes the analysis values and the analysis results. The amount corresponding to the difference from the standard value of the component is supplied using a variable capacity replenishing machine that replenishes each component.

Further, Japanese Patent Application Laid-Open No. Sho 56-72166 discloses an apparatus for managing a plating solution. In this disclosed apparatus, a quantitative analysis of the plating solution is not performed, and a specific component falls below a predetermined value. By detecting the fact, the specific component and other various amounts of change that change with the progress of the plating operation are estimated, and a predetermined replenishment operation is performed.

[0005]

However, an apparatus equipped with both an automatic quantitative titration analyzer and a variable-capacity replenisher has the disadvantage that the apparatus becomes large and expensive. In addition, there is also a problem that the number of chemical solutions used increases. The technique disclosed in Japanese Patent Application Laid-Open No. 56-72166 is simple in that quantitative analysis of the plating solution is not required, but cannot be applied when there are a plurality of specific components to be detected.

Accordingly, an object of the present invention is to provide a method for automatically controlling the concentration of a solution with a simple configuration even when there are a plurality of solution components to be monitored in controlling the concentration of the solution. It is to provide a management device.

[0007]

According to one aspect of the present invention, there is provided an automatic solution concentration management apparatus for solving the above-mentioned problems and achieving the object, the apparatus comprising: Sampling means for sampling a predetermined amount of a sample solution at predetermined time intervals from a solution in which the components of the components decrease over time, and a change over time in the content of the components in the solution provided for each of the components A determination agent that changes color in response to the above, a single detection unit that detects the color change of the sample liquid due to the determination agent, and a component that has a predetermined amount of the component related to the color change in the solution when the color change of the sample liquid is detected Means for replenishing, when the content of the plurality of components is determined based on one sampling of the sample liquid, and when the discoloration of the sample liquid is detected, it is determined that the replenishment of the components is necessary. Only supply of the necessary ingredients Characterized in that got to do.

In a preferred embodiment, the sample solution is introduced into a transparent container such as a transparent glass container, and the detecting means detects the color change of the sample solution by sensing a color in a predetermined wavelength region from outside the transparent container. Consists of a colorimeter.
The present invention can be suitably used in an automatic concentration control apparatus for a plating solution.For example, when the solution is a zinc plating solution, at least zinc and sodium hydroxide as components that decrease over time, It contains.

In this case, the determining agent for detecting the change in the amount of sodium hydroxide in the solution is a mixed solution of hydrochloric acid and sulfo orange, and the determining agent for detecting the change in the amount of zinc is a buffer, EDTA. And a mixed solution of xylenol orange and xylenol orange. The buffer is, for example,
Consist of an acetic acid-sodium acetate solution pH of about 5. The colorimeter for detecting the discoloration of the determination agent of sodium hydroxide and the discoloration of the determination agent corresponding to the change in the amount of zinc can be constituted by one having substantially the same sensitive wavelength region.
The thickness is preferably about 00 to 600 nm, more preferably about 520 to 540 nm.

According to another feature of the present invention, a step of collecting a predetermined amount of a sample liquid at predetermined time intervals from a solution in which a plurality of contained components decreases over time; Adding a determining agent that changes color in response to a decrease in the content of the two components in the solution; detecting discoloration of the sample solution corresponding to the decrease in the one component; and A step of adding another determination agent that changes color in response to a decrease in the other components of the plurality of components, and a step of detecting the change in color of the sample solution corresponding to the decrease in the other components,
A step of replenishing only a component corresponding to the color change by a predetermined amount when the color change of the sample liquid is detected, is provided.

In a preferred embodiment, the one component is sodium hydroxide, the determination of which is a mixed solution of hydrochloric acid and sulfo orange for detecting a change in the amount of sodium hydroxide in the solution, and the other component is sodium hydroxide. Is a buffer, wherein the determination agent detects a change in the amount of zinc in the solution;
It may be a mixed solution of DTA and xylenol orange.

Before detecting a change in the color of the sample liquid due to the above-mentioned determination agent, it is desirable to stir the sample solution into which the determination agent has been added for about 3 minutes and then to stand still for about 3 minutes in order to improve the detection accuracy. .

[0013]

According to the present invention, instead of performing a quantitative analysis of a solution as in the prior art, it is determined whether or not each of a plurality of specific components in a decreasing solution is below a standard value, that is, a predetermined threshold value. At regular time intervals, a fixed amount of sample liquid is sampled to detect a change in color corresponding to a change in concentration.
According to this example, when the concentration of the specific component in the solution changes beyond a certain limit, each time a color change is detected using a concentration indicator that changes color, the replenisher only applies a fixed amount for the reduced component. Supply. This also eliminates the need to use a variable capacity replenisher. When there are a plurality of reduced specific components in the solution, it is determined by the color change whether or not the reduced amount of the component has exceeded the standard value of the component. A change in the amount of each component is detected using a different judgment agent or reagent, but the color change occurs in substantially the same wavelength region, so that it can be detected with a single colorimeter. When the detection of one component is completed, another component is detected using the same sample liquid.

In accordance with the result of the determination, no replenishment is carried out for the components which are considered to have no color change and therefore not degraded below the standard value, and the components for which a color change is detected and deemed to be deviated from the standard value are not performed. Replenish only a certain amount from the replenishing machine. In this case, a quantitative analysis of the solution is not required, and a replenisher is not required in a variable capacity type, so that an automatic concentration control device can be easily configured,
In addition, the solution concentration can be maintained in an appropriate range.

Incidentally, the replenishing amount can be set in advance to an appropriate amount in consideration of the rate of change of the solution concentration.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, there is shown a system diagram of an apparatus for automatically controlling a solution concentration according to an embodiment of the present invention.
This example is a case where the present invention is applied to an automatic concentration control apparatus for a zinc plating solution used in a running zincate bath.

The apparatus of this embodiment is provided with a plating tank 2 for containing a plating solution 1, and a zinc plate 3 as an anode is immersed in the plating solution 2 in the plating tank 2. A work to be galvanized, that is, an object to be plated 4 is immersed as a cathode opposite to the zinc plate 3. The plating solution 1 is a mixed solution of zinc and sodium hydroxide, and both are consumed with the progress of plating. Therefore, in order to continue proper plating work, the replenishment thereof is performed appropriately. The solution needs to be kept properly.

In the case of this embodiment, it is necessary to control both the consumption of zinc and the consumption of sodium hydroxide in order to secure an appropriate plating operation. For this purpose, a replenishing device for replenishing sodium hydroxide in the solution and a replenishing device for replenishing zinc are provided.
There is provided a sodium hydroxide supply tank 6 for containing an aqueous sodium hydroxide solution 5 and an electromagnetic valve 8 for opening and closing a pipe 7 constituting a supply passage of sodium hydroxide to the plating tank 2.

The zinc replenishing apparatus has a zinc supply tank 10 containing a zinc-containing sodium hydroxide aqueous solution 9 and a solenoid valve 12 for opening and closing a pipe 11 constituting a supply passage of zinc to the plating tank 2. Further, in order to monitor the concentration of the plating solution 1, in this example, the plating solution 1 is periodically sampled and its concentration is detected. The sampling device for the plating solution 1 is provided with a sampling pipe 13 whose leading end is immersed below the surface of the plating solution 1 and a device for sampling a fixed amount of the sample solution 14 of the plating solution 1 through the pipe. This device includes a metering pump 16 and an electromagnetic valve 16 that opens and closes a sampling passage formed by the pipe 13. The amount of liquid flowing through the pipe 13 is constant, and therefore the amount of liquid sampling can be managed only by controlling the period during which the solenoid valve 16 is open. The sample liquid sampled via the pipe 13 is introduced into a transparent glass cell 17. A rotor 18 for stirring the introduced sample solution 14 is provided inside the glass cell 17. Below the glass cell 17, a magnetic stirrer 19 for rotating the rotor 18 by magnetic force is arranged. Further, a colorimeter 20 for detecting discoloration of the sample liquid is arranged on the side of the glass cell 17.

A device for adding a determining agent 21 for detecting the concentration of sodium hydroxide in the solution to the sample liquid in the glass cell 17 is provided. A determining agent supply tank 22 containing the determining agent 21 is provided. A device for measuring and supplying a predetermined amount of the determination agent 21 through a pipe 23 is provided. This device includes a metering pump 24 and an electromagnetic valve 25 for opening and closing the pipe 23. Also in this device, the amount of liquid can be controlled only by controlling the period during which the solenoid valve 25 is open.

Further, there is provided a device for supplying a judging agent 26 for displaying a change in the amount of zinc as a color change. This supply device is also provided with a determination agent supply tank 27 containing a determination agent 26, and a device for measuring and supplying a predetermined amount of the determination agent via a pipe 28. This device includes a metering pump 29 and a pipe. And a solenoid valve 30 for opening and closing the supply passage of the determination agent 26 by the

Further, there is provided a device for discharging the sample solution 14 obtained by subjecting the sodium hydroxide to the color change inspection from the glass cell 17. The apparatus has a discharge pipe 31 extending to the bottom of the glass cell 17, and is attached to the pipe 31.
A device for discharging the sample liquid 14 is provided. The device has a pump 32 and an electromagnetic valve 33 for opening and closing the pipe 31.

An apparatus for cleaning the inside of the glass cell 17 after the sample liquid 14 is discharged from the glass cell 17 is provided. This apparatus uses distilled water 34 as a cleaning liquid.
An electromagnetic valve 37 is provided for controlling the opening and closing of the supply of the distilled water 34 to the glass cell 17 via the cleaning liquid supply tank 35 containing the water and the pipe 36. The control unit 38, which is provided with a control unit 38 for controlling the operation of these solenoid valves and the metering pump, receives a signal from the colorimeter 20 and receives the solenoid valve 8 for sodium hydroxide and the solenoid valve for zinc. A replenishment signal is output to the valve 12, and signals are output to the metering pumps 24, 29 and the solenoid valve 25 for the determination agents 21 and 26, the sampling metering pump 15, the solenoid valve 16, and the discharge pump 32 and the solenoid valve 33. It is supposed to.

The operation of the apparatus of this embodiment will be described. At an appropriate time during the operation of the zincate bath, the control unit 38 controls the sampling metering pump 15 at predetermined intervals.
Is driven and the electromagnetic valve 16 is opened to introduce a predetermined amount of the plating solution 1 in the plating tank 2, that is, the sample solution 14, into the glass cell 17. When a predetermined amount (3 ml in this example) of the sample liquid 14 is introduced into the glass cell 17 having a capacity of 200 ml, the control unit 38 closes the solenoid valve 16.

Next, the solenoid valve 25 is opened and the determination agent 21 for sodium hydroxide determination (hydrochloric acid (0.5N), an aqueous solution of sulfo orange (0.05 g / l) and distilled water are added in a ratio of 20: 5: 2.
5) is introduced into the glass cell 17 in a predetermined amount (50 ml). The control unit 38 stops the electromagnetic valve 25 and activates the magnetic stirrer 19 to rotate the rotor 18 to stir and mix the determination agent 21 and the sample liquid 14 for about 3 minutes.

After that, the magnetic stirrer 19 is stopped, and the liquid mixture inside the glass cell 17 is allowed to stand for about 3 minutes. Next, it is detected whether or not the amount of the collected sodium hydroxide is smaller than a predetermined standard value by a colorimeter 20 adjusted to respond to a wavelength of 400 to 600 nm, preferably 520 to 540 nm. In this case, when the amount of sodium hydroxide in the sample solution 14 is larger than the amount of hydrochloric acid in the added determination agent 21, the color is orange when the amount is small, and the color is yellow. Here, the reason why the solution is allowed to stand after stirring is to settle the generated precipitate. Therefore, it is determined whether or not the amount of sodium hydroxide has been consumed by the colorimeter 20 below the standard value.
It can be determined by the color of the solution inside. If the sodium hydroxide is below the standard value, that is, if the color of the solution in the glass cell 17 is yellow, the colorimeter 20 responds, and upon receiving this signal, the control unit 38 controls the electromagnetic unit. The valve 8 is opened, and a predetermined amount of 2 l of the sodium hydroxide replenisher (sodium hydroxide 500 g / l) in the sodium hydroxide supply tank 6 is replenished to the plating solution 1 in the plating tank 2.

Next, the control unit 38 includes a zinc determination agent 26 (acetic acid (30 g / l), sodium acetate (150 g / l) pH of about 5, and EDTA (1/10 mo).
l) and xylenol orange (0.01 g / l)
The metering pump 29 is driven to introduce a solution (mixed at a ratio of 0: 5: 25), and the solenoid valve 30 is opened. As a result, a predetermined amount (50 ml) of the judging agent 26 is
7 will be introduced. The control unit 38 stops the metering pump 29, closes the solenoid valve 30,
The magnetic stirrer 19 is operated for about 3 minutes, and the sample liquid 14 and the determination agent 2 in the glass cell 17 are rotated by the rotor 18.
Stir the mixture with 1 and 26. And colorimeter 2
A 0 detects the color of the solution.

When the amount of zinc exceeds the standard value, that is, when the amount of zinc in the collected sample solution 14 is added and ED
When the amount is larger than the TA amount, the color becomes reddish purple. Therefore, when the detected color is yellow, the colorimeter 20 responds, and the control unit 38 receives this result and opens the solenoid valve 12 when the color of the solution in the glass cell 17 is yellow. Zinc replenisher (Zinc 1
00 g / l, aqueous solution of sodium hydroxide 350 g / l)
Is replenished by a predetermined amount (1 l).

When the colorimeter 20 does not respond, that is, when the color of the solution in the glass cell 17 after the introduction of the sodium hydroxide determination agent 21 is orange, and when the solution after the introduction of the zinc determination agent 26 is reddish purple. In other words, the control unit 38 keeps the solenoid valves 8 and 12 closed even after the color detection operation is completed. A precipitate is formed after the addition of the sodium hydroxide determining agent 21. This precipitate is dissolved by a buffer solution (acetic acid-aqueous sodium acetate aqueous solution) of the determining agent 26 for zinc, and the pH of the buffer solution is about Since it is 5, the color of the determination agent 21 always becomes yellow, so that it does not hinder the color determination of zinc by EDTA and xylenol orange.

When the above determination operation is completed, the control unit 38 drives the pump 32, opens the solenoid valve 33, and performs a liquid mixture of the sample liquid 14 and the determination agents 21 and 26 for color detection in the glass cell 17. To discharge. Thereafter, the electromagnetic valve 37 is opened, and distilled water 34 is introduced to wash the inside of the glass cell 17. Then, the cleaning water in the glass cell 17 is discharged again by the pump 32 and the electromagnetic valve 33.

[0031]

As described above, in the present invention, instead of performing a quantitative analysis of a solution as in the prior art, a concentration indicator that changes color when a specific component in a solution that decreases decreases beyond a standard value is used. Each time a color change is detected, a fixed amount of the reduced component is supplied by the supply machine. This eliminates the need for complicated and time-consuming quantitative analysis of the solution, and also eliminates the need for a variable capacity replenisher. As described above, the detection of one component and the detection of the other component use different reagents, but the detection range can be performed in substantially the same wavelength range. Therefore, a single colorimeter can be configured. it can. The sample liquid is 1
Efficiency is high because the result of the detection operation of one component can be used without any problem in detecting the other components. As described above, the present invention is suitable for a case where it is necessary to detect changes in a plurality of components in order to perform appropriate solution concentration management.

In this method, it is not only necessary to perform the simple configuration operation as described above, but also it is possible to obtain the concentration detection result efficiently and early, and to carry out the replenishment operation quickly, so that high accuracy is achieved. Automatic concentration management can be performed.

[Brief description of the drawings]

FIG. 1 is a system diagram of an automatic concentration control device according to an embodiment of the present invention.

[Explanation of symbols]

 1 plating solution, 2 plating tank, 3 anode, 4 cathode, 5 sodium hydroxide replenisher, 9 zinc replenisher, 17 glass cell, 20 colorimeter.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-63-140944 (JP, A) JP-A-48-39871 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G05D 21/00 C23C 18/31 C25D 21/14 G05D 21/02

Claims (6)

(57) [Claims] 1. Sampling means for sampling a predetermined amount of a sample solution at predetermined time intervals from a solution in which a plurality of components contained decreases with time, and a sampling means provided for each of the components, wherein the solution of the component is provided. A determination agent that changes color in response to a temporal change in the content thereof, a single detection unit that detects the color change of the sample solution due to the determination agent, and a detection unit that detects the color change of the sample solution. Means for replenishing the components relating to discoloration by a predetermined amount, and determining the contents of the plurality of components based on one sampling of the sample liquid.
And a replenishing unit for replenishing the necessary components only when it is determined that the replenishment of the components is necessary by detecting the discoloration of the sample solution. 2. The colorimeter according to claim 1, wherein the sample liquid is introduced into a transparent container, and the detecting means detects a color change of the sample liquid by sensing a color in a predetermined wavelength region from outside the transparent container. The automatic solution concentration control device described in the above. 3. The apparatus according to claim 1, wherein the solution is a galvanizing solution, and contains at least zinc and sodium hydroxide as components that decrease over time. 4. The determining agent for detecting a change in the amount of sodium hydroxide in the solution is a mixed solution of hydrochloric acid and sulfo orange, and the determining agent for detecting a change in the amount of zinc is a buffer solution;
The solution concentration automatic management device according to claim 1 , wherein the solution concentration automatic management device is a mixed solution of DTA and xylenol orange. 5. A step of collecting a predetermined amount of a sample liquid at a predetermined time interval from a solution in which a plurality of contained components decrease with time; and containing one of the plurality of components in the solution. Adding a determination agent that changes color in response to a decrease in the amount; detecting a color change in the sample solution corresponding to the decrease in the one component; and another of the plurality of components in the sample solution. Adding another determining agent that changes color in response to the decrease in the component, detecting the color change of the sample solution corresponding to the decrease in the other component, and when the color change of the sample solution is detected, Replenishing only a component corresponding to discoloration by a predetermined amount. 6. The one component is sodium hydroxide, the determination of which is a mixed solution of hydrochloric acid and sulfo orange which detects a change in the amount of sodium hydroxide in the solution, and the other component is 6. The method according to claim 5, wherein zinc is zinc, and the determination agent is a mixed solution of a buffer for detecting a change in the amount of zinc in the solution, EDTA, and xylenol orange.