JPH0967698A - Method for supplying nickel into nickel-base plating solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for supplying nickel into a nickel-base plating soln. by which the dissolving rate is increased when metallic nickel is dissolved in a tank, and the dissolving tank and its equipment are miniaturized. SOLUTION: A sulfuric acid-contg. nickel-base plating soln. is concentrated, metallic nickel is supplied to the concd. soln. and dissolved, the nickel-contg. concd. soln. is diluted with water, and nickel is supplied into the nickel-base plating soln. Otherwise, the concentration is conducted with an evaporator 2, the concd. soln. and metallic nickel are supplied to a metallic nickel dissolving tank 1 to dissolve the metallic nickel, the vapor from the evaporator 2 is condensed in a condenser 3, the concd. nickel-contg. soln. obtained in the dissolving tank 1 is diluted with the condensed water obtained in the condenser 3, and nickel is supplied into the nickel-base plating soln.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a nickel-based continuous electroplating equipment for metal strips such as steel strips using an insoluble anode, which is used to supply nickel ions to the plating solution to replenish consumed nickel ions. Regarding supply method.

[0002]

2. Description of the Related Art In recent years, the demand for improved corrosion resistance in automobiles, home appliances and the like has increased, and in addition to the galvanized steel sheets that have been conventionally used, the demand for alloy-plated steel sheets such as zinc-nickel alloy-plated steel sheets has significantly increased. ing. In order to cope with such an increase in demand, a high-speed plating method with a high current density that enables high-efficiency production is adopted.However, in the high-speed plating method, the anode replacement is more necessary than the soluble anode method, which requires frequent anode replacement. Needless to say, the method of using an insoluble anode such as an iridium-based material which is not necessary and continuously supplying the consumed metal ions to the plating solution is advantageous.

As a plating solution, a sulfuric acid-based electrolytic solution is usually used. Further, as a method of replenishing metal ions such as nickel into the plating solution, a method of directly dissolving the metal nickel or the like in the plating solution and a method of dissolving it in the form of a metal compound such as nickel oxide or nickel carbonate Such metal ion replenishment is performed in a metal dissolving tank such as a metal nickel dissolving tank provided separately from the plating solution circulating tank in the line, and the plating solution is supplied to the metal dissolving tank and the plating solution circulating tank by a circulation pump. The method of circulating between is adopted.

Metal compounds such as nickel carbonate are expensive, which is one of the factors that hinder the cost reduction, and because they are powders, they cause environmental problems such as dust generation. Further, sodium which is usually contained in these metal compounds, Calcium, chlorine,
Impurities such as silicon also cause the following problems. That is, since sodium improves the electric conductivity of the plating bath, if it exists in excess, it causes abnormal plating such as "plating burn".

Since calcium is not consumed in the plating operation, it accumulates in the plating bath and, when saturated, precipitates as gypsum, causing troubles such as pipe blockage. Chlorine reduces the plating adhesion when the concentration in the plating bath increases. When the concentration in the plating bath becomes high, silicon reacts with the iron content in the plating bath to form a highly adherent compound, which causes troubles such as pipe clogging.

For this reason, in the plating treatment equipment using a metal compound as a nickel ion source, it is general to provide a dedicated equipment for removing these impurities.
On the other hand, powdery, granular, or lumpy metallic nickel has a unit price per nickel weight of 50 to 60 compared to metallic compounds.
%, The method of directly dissolving these is not a problem in terms of cost and working environment, but is soluble in the acid concentration of the nickel-based plating solution used for the Zn—Ni alloy plating or the like which is the subject of the present invention. It is slow and requires some means to dissolve it in large quantities.

According to Japanese Patent Laid-Open No. 1-234598, an insoluble cathode and an insoluble basket-shaped anode are provided in a melting tank, metal nickel particles are filled in the basket-shaped anode, and a plating solution is passed through to perform electrolysis. Then, the metal nickel particles are dissolved in the plating solution. However, this method not only has a problem that the surface of the metallic nickel particles is oxidized and passivated, but also the durability of the basket-shaped anode and the inability to continuously supply the metallic nickel particles into the basket-shaped anode, etc. There are problems and it is not a realistic method.

Further, according to Japanese Patent Laid-Open No. 4-13900, the metallic nickel used for the anode contains sulfur in order to prevent passivation, and the metallic nickel has a granular or plate-like shape to promote dissolution. Alternatively, it is described that the powder is made into a powder, filled in a basket of a corrosion-resistant metal such as titanium, and electrolyzed while passing the plating solution to dissolve metallic nickel in the plating solution.

According to this method, the above-mentioned Japanese Patent Laid-Open No. 1-234598 is used.
Although most of the problems in the method described in the publication have been solved for the time being, such an electrolysis method cannot increase the electrolysis current, so if it is attempted to implement it, 100 or more electrolyzers are required, and equipment cost, maintenance cost, etc. After all, it is not a realistic method. In addition, JP-A-5-25700
According to the publication, it is described that a nickel-zinc alloy having a particle size of 1 mm or less is melted in a melting tank according to the composition of nickel ions and zinc ions to be consumed.

When a nickel-zinc alloy is dissolved in an acidic bath, zinc is first preferentially dissolved, the residual nickel is finely divided, and the surface area is remarkably increased, whereby the dissolution of nickel is promoted and the dissolution rate is increased. Nickel ions and zinc ions, which are extremely high and consumed in nickel-zinc alloy plating, are supplied at the same time. However, the production conditions for producing a nickel-zinc alloy are extremely strict, mass production cannot be performed, and as a result, the unit price of the nickel-zinc alloy is extremely high, which is unrealistic.

[0011]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned problems of the prior art and to increase the dissolution rate when metal nickel is melted using a metal nickel melting tank.
It is possible to improve the productivity of nickel-based continuous electroplating and further downsize the metal nickel melting tank and its ancillary equipment.
It is intended to provide a method for supplying nickel into a nickel-based plating solution.

[0012]

A first aspect of the present invention is to concentrate a sulfuric acid-containing nickel-based plating solution, supply and dissolve metallic nickel into the concentrated solution, and dilute the obtained nickel-containing concentrated solution with water. And a method of supplying nickel into a nickel-based plating solution. As the concentration method in the first invention, an evaporation method by heating and / or reduced pressure can be used.

A second aspect of the invention is to concentrate a sulfuric acid-containing nickel-based plating solution using an evaporator, supply the concentrated solution and metallic nickel to a metallic nickel dissolving tank to dissolve metallic nickel, and obtain the resulting nickel-containing concentrated solution. Is a method for supplying nickel into a nickel-based plating solution, which comprises diluting the nickel with water. A third aspect of the present invention concentrates a sulfuric acid-containing nickel-based plating solution using an evaporator, supplies the concentrated solution and metallic nickel to a metallic nickel dissolving tank to dissolve metallic nickel, and at the same time, vapor from the evaporator is fed to a condenser. A method for supplying nickel into a nickel-based plating solution, which comprises condensing using a nickel-containing concentrate obtained in the dissolution tank and diluting the nickel-containing concentrate obtained using the condensed water obtained in the condenser. .

In the first invention, the second invention and the third invention, it is preferable that the temperature of the concentrated liquid in the metal nickel dissolving tank is 75 to 100 ° C. The maximum particle size of nickel metal is 0.3m
It is preferably m or less. In the present invention, the maximum particle size of 0.3 mm or less means that, when sieved with a JIS standard sieve having a sieve opening of 0.3 mm, 90 wt% or more thereof is under 0.3 mm or less.

In the second and third aspects of the invention, it is preferable that the vapor from the evaporator be heat-exchanged with the plating solution before flowing into the evaporator. Furthermore, the present invention provides a sulfuric acid-containing nickel-based plating solution containing Z
It is preferably used as a method of supplying nickel to a plating solution for Zn-Ni alloy electroplating such as n-Ni alloy electroplating and Zn-Ni-Cr alloy electroplating.

[0016]

Hereinafter, the present invention will be described in more detail. The present invention is preferably used as a method for supplying nickel to a sulfuric acid-containing nickel-based plating solution such as Zn-Ni alloy electroplating and Zn-Ni alloy electroplating such as Zn-Ni-Cr alloy electroplating, and more preferably Is the Zn-N
It is preferably used as a method of supplying nickel into the i-based alloy electroplating solution, more preferably into the Zn-Ni alloy electroplating solution.

The nickel-based plating solution (plating bath) currently used industrially has a pH of 1.5 to 2 and a solution temperature of 55 to 65 ° C.
Sulfuric acid solution (sulfuric acid bath). It is known that nickel ion sources such as metallic nickel and nickel oxide are hardly dissolved in a plating solution under such conditions. By the way, taking metallic nickel as an example, the dissolution reaction is as shown in the following formula (1).

Ni + 2H ⁺ → Ni ²⁺ + H ₂ ↑ (1) Further, the reaction rate (dissolution rate) r of this reaction is
It is indicated by (2). r = k · C _Ni ^a · C _{H +} ^b (2) where k = A · exp (−E / RT), C _Ni : metallic nickel concentration, C _{H +} : hydrogen ion concentration, T: plating solution temperature ,
a, b: constants Therefore, by increasing the metal nickel concentration, the hydrogen ion concentration, and the plating solution temperature, respectively, r in the equation (2)
It was thought that it could be expected to improve the value of, that is, the dissolution rate.

The present inventors have added sulfuric acid to the plating solution,
As a result of investigating the solubility of metallic nickel in the case of increasing the hydrogen ion concentration, it was found that the amount of metallic nickel dissolved largely depends on the contact probability between metallic nickel and hydrogen ions. Therefore, the plating solution was placed in a 1 m ³ metal nickel dissolution tank to carry out a dissolution experiment in which the metal nickel was dissolved. The metallic nickel is granular or powdery with a maximum particle size of 0.3 mm or less, and a melting tank having a stirring device was used as the melting tank, and the stirring blade rotation speed was 400 rpm.

First, as a first experiment, the supply amount of metallic nickel was 10 kg / m ³ -melting tank · h (the unit is hereinafter referred to as kg / m ³ · h), the sulfuric acid concentration of the plating solution was 1%, and the pH was 1.5. And the plating solution temperature was changed in the range of 50 to 100 ° C. The experimental results are shown in FIG. From FIG. 5, it can be seen that as the temperature of the plating solution is increased, the dissolution amount of metallic nickel also increases, and particularly in the temperature range of 75 ° C. or higher, the dissolution amount increases remarkably. However, even if the plating solution temperature is 100 ° C, the melting capacity required for actual equipment is 4 to 6 kg / m ³ − melting tank · h
Has not reached.

Next, the plating solution temperature is set to 60 ° C, 75 ° C, 90 ° C.
And, with each constant value, by adding sulfuric acid,
Sulfuric acid concentration of the plating solution in the metal nickel dissolution tank is 1 to 15%
The dissolution experiment was performed by changing the range. Figure 6 shows the experimental results.
Shown in From FIG. 6, the dissolution amount of metallic nickel increased as the sulfuric acid concentration in the plating solution increased regardless of the plating solution temperature, and the maximum dissolution amount was obtained when the plating solution temperature was 90 ° C. .

The following findings were obtained from the above experimental results. 1) When the temperature of the plating solution is raised, the amount of dissolution increases. In particular, 75
The increase is remarkable in the range of up to 100 ° C. 2) When sulfuric acid is added to increase the concentration of sulfuric acid in the plating solution, the amount of dissolution increases. Especially, the concentration of sulfuric acid in the plating solution is 10%
The effect is remarkable in the degree.

However, excessive mixing of sulfuric acid into the plating solution causes a decrease in current efficiency during plating in the plating bath, which is not preferable in operation. Therefore, it is necessary to remove excess sulfuric acid by electrodialysis or the like after dissolution of nickel,
There is a problem that equipment costs and running costs increase. Therefore, the present inventors concentrated the plating solution using the apparatus shown in FIG. 1 and conducted a dissolution test of metallic nickel using the concentrated plating solution obtained.

In FIG. 1, 1 is a metal nickel melting tank,
2 is an indirect heating type evaporator (evaporative concentrator), 3 is a condenser, 4 is a stirrer, 5a and 5b are indirect heating type heaters, 6 is a metallic nickel supply device including a hopper, a feeder, and the like, 7a, 7b is a pump, 8 is a plating solution circulation tank, 9 is an electroplating plating bath (hereinafter referred to as a plating bath), 10 is a liquid supply pipe between the evaporator 2 and the metal nickel dissolving tank 1, 12 is a steel strip, and 13 is a backup. Rolls, 14 are conductor rolls, and 15 is the traveling direction of the steel strip.

The metal nickel dissolving tank 1 and the liquid supply pipe 10
The pipes are kept warm with heat insulating materials such as glass wool heat insulating materials. The plating solution which is intermittently or continuously withdrawn from the plating bath 9 by the pump 7 b is sent to the plating solution circulation tank 8. The plating solution in the plating solution circulation tank 8 is sent to the evaporator 2 by the pump 7a, concentrated in the evaporator 2, and the concentrated plating solution having a large sulfuric acid concentration is sent to the metal nickel dissolving tank 1.

In the metallic nickel dissolving tank 1, powdery or granular metallic nickel is supplied, and the metallic nickel is dissolved in a concentrated plating solution which is heated and stirred. On the other hand, the vapor evaporated in the evaporator 2 is condensed in the condenser 3, and the condensed water is recirculated to the nickel-containing concentrated plating solution on the outlet side of the metal nickel dissolving tank 1 so that the plating solution having an appropriate sulfuric acid concentration is The solution is sent to the plating solution circulation tank 8.

The plating solution in the plating solution circulation tank 8 is intermittently or continuously sent to the plating bath 9 to perform nickel-based electroplating. FIG. 2 shows the relationship between the concentration rate of the plating solution in the evaporator 2 and the dissolved amount of metallic nickel, which was obtained in the examples described below. The concentration rate is defined as [(weight of water evaporated in evaporator 2 / weight of plating solution sent to evaporator 2) x 100%].

From these results, it is possible to improve the amount of nickel dissolved from 6 kg / m ³ · h to 10 kg / m ³ · h by 1.7 times by setting the concentration rate of the plating solution in the evaporator 2 to 50%. I understood. In the first aspect of the present invention, the concentration of sulfuric acid in the metal nickel dissolving tank is increased by concentration and the nickel-containing concentrated plating solution after the metal nickel is dissolved is diluted with water, so that the dissolution rate of metal nickel can be increased. Therefore, it is possible to achieve a significant reduction in the size of auxiliary equipment such as a metal nickel dissolving tank and a pump, and to eliminate the need for operations such as electrodialysis in the case of adding sulfuric acid.

Further, in the second aspect of the invention, since the concentration operation is performed by heating and evaporating the plating solution, the temperature of the concentrated plating solution supplied to the metal nickel dissolving tank is high, and at least the evaporator 2 and the metal nickel dissolving tank 1 are provided. Plumbing between
The temperature of the concentrated plating solution in the metal nickel dissolving tank 1 can be easily adjusted to 75 ~ by keeping the temperature of 10 using heat insulating material (: heat insulating material) such as fibrous heat insulating material, powdery heat insulating material, foamy heat insulating material.
It is possible to maintain the temperature within the range of 100 ° C.

As a result, as shown in Examples described later and FIGS. 5 and 6, the dissolution rate of metallic nickel was further increased, and the preferable plating bath temperature of Zn--Ni alloy electroplating was 55 to 65 ° C. It becomes easy to secure the amount of heat input, and the amount of heat input to the evaporator 2 can be effectively used. Next, FIG. 4 shows a schematic diagram of another nickel supplying apparatus for the other nickel-based plating solution according to the present invention.

In FIG. 4, reference numerals 1 to 10, 13, and 14 denote those in FIG.
11 shows the same member, 11 indicates an indirect heat exchanger, and 15 indicates the traveling direction of the steel strip 12. The apparatus of FIG. 4 is similar to the apparatus of FIG. 1, but the plating solution extracted from the plating solution circulation tank 8 is vaporized in the evaporator 2 and the indirect heat exchanger 11
In the above, the heat is exchanged, the temperature is raised, and then the liquid is sent to the evaporator 2.

Therefore, by using the apparatus of FIG. 4, the dissolution rate of metallic nickel is increased and the evaporator 2 is used.
It is possible to make the most effective use of the heat input at. The present invention is preferably used for continuous treatment in which concentrated plating solution and metallic nickel are continuously supplied to the metallic nickel dissolving tank, but the concentrated plating solution is charged into the metallic nickel dissolving tank in advance, and then metallic nickel is added. It can also be applied to a batch process for supplying, and is not limited to the method of supplying the concentrated plating solution and metallic nickel to the metallic nickel dissolving tank.

[0033]

EXAMPLES The present invention will be specifically described below based on examples. The amount of metallic nickel dissolved in this example was determined by sampling the plating solution in the metallic nickel dissolving tank and measuring the nickel ion concentration of the filtered plating solution by atomic absorption spectrometry.

Example 1 An experiment for dissolving metallic nickel in a plating solution was conducted using the apparatus shown in FIG. That is,
In order to supply nickel ions to the plating solution for Zn-Ni alloy electroplating, Ni powder having an average particle size of 5 μm was supplied to the plating solution in the metal nickel dissolving tank 1.

The temperature of the plating solution in the metal nickel dissolving tank 1 is
The temperature of the stirring blade of the stirrer 4 is 90 ° C, the supply rate of metallic nickel into the metallic nickel melting tank 1 is 30 kg / m ³ · h
It was set to 400 rpm. The pH of the plating solution at the inlet of the evaporator 2 was 1.5. FIG. 2 shows the experimental results when the concentration rate of the plating solution was changed by changing the amount of heat input to the evaporator 2. The concentration rate was changed within the range of 0 to 50% depending on the capacity of the evaporator and the like.

Example 2 An experiment for dissolving metallic nickel in a plating solution was carried out in the same manner as in Example 1. In this embodiment, the pH of the plating solution at the inlet of the evaporator 2 is 1.5,
The temperature of the plating solution in the metal nickel dissolving tank 1 is 90 ° C, and the supply amount of metal nickel into the metal nickel dissolving tank 1 is 10 to 70k.
g / m ³ · h and the concentration rate was 50%. In this case, the pH of the concentrated plating solution supplied to the metal nickel dissolving tank 1 is 1.
It was 09.

As a comparison, the case where no concentration treatment was performed was also examined. Experimental results are shown in FIG. From the results of this experiment, for example, when the supply amount of metallic nickel is 30 kg / m ³ h, the dissolution amount without concentration is 6.0 kg / m ³ h, whereas the dissolution amount with concentration is 10.0 kg / m ³ h. m ³ · h,
A 1.67-fold increase in dissolution was achieved.

From the above results, the required dissolution amount is 90 kg / h,
When the supply amount of metallic nickel is 30 kg / m ³ · h, the required volume of the dissolution tank is 90 / 6.0 = 15 m ³ without concentration and the concentration rate is 50
When concentrated to 90%, it becomes 90 / 10.0 = 9 m ³ , and it can be seen that the use of the method of the present invention makes it possible to make the metal nickel dissolution tank significantly compact.

[0039]

According to the present invention, metallic nickel can be directly and quickly dissolved in the plating solution.
Compared to the case of using expensive chemicals such as nickel carbonate,
Not only the cost of plating process is greatly reduced, but various equipment troubles caused by various impurities such as manganese, sodium, calcium, chlorine, and silicon contained in nickel carbonate are solved, and the conventional impurities are removed. This eliminates the need for the dedicated removal equipment that was installed to achieve this, and has made it possible to achieve a significant simplification of the equipment.

Further, as described above, the dissolution rate of metallic nickel is significantly higher than that of the conventional method, so that the metallic nickel dissolving tank can be greatly downsized. Further, according to the present invention, it becomes possible to effectively use the heat input to the evaporator to the maximum extent, and the required energy such as the required power of the agitator is significantly reduced with the reduction of the plating solution amount in the metal nickel dissolving tank. It also becomes possible to contribute to energy saving, and the industrial significance of the present invention is extremely great.

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram of a nickel supply device for a nickel-based plating solution according to the present invention.

FIG. 2 is a graph showing the relationship between the concentration of the plating solution and the amount of nickel dissolved.

FIG. 3 is a graph showing the relationship between the amount of metal nickel supplied and the amount of nickel dissolved.

FIG. 4 is a schematic explanatory view of a nickel supplying device for a nickel plating solution according to the present invention.

FIG. 5 is a graph showing the relationship between the temperature of the plating solution in the metal nickel dissolving tank and the amount of nickel dissolved.

FIG. 6 is a graph showing the relationship between the concentration of sulfuric acid and the amount of nickel dissolved in the plating solution in the metal nickel dissolution tank.

[Explanation of symbols]

 1 Metal Nickel Dissolution Tank 2 Evaporator 3 Condenser 4 Stirrer 5a, 5b Heater 6 Metal Nickel Supply Device 7a, 7b Pump 8 Plating Solution Circulation Tank 9 Electroplating Plating Bath 11 Indirect Heat Exchanger 12 Steel Strip 13 Backup Roll 14 Conductor Roll

Claims (5)

[Claims] 1. A sulfuric acid-containing nickel-based plating solution is concentrated,
A method for supplying nickel to a nickel-based plating solution, which comprises supplying metallic nickel to the concentrate, dissolving the nickel, and diluting the obtained nickel-containing concentrate with water. 2. A sulfuric acid-containing nickel-based plating solution is concentrated using an evaporator, the concentrated solution and metallic nickel are supplied to a metallic nickel dissolving tank to dissolve metallic nickel, and the resulting concentrated nickel-containing solution is used with water. A method for supplying nickel into a nickel-based plating solution, which comprises diluting with nickel. 3. A sulfuric acid-containing nickel-based plating solution is concentrated using an evaporator, the concentrated solution and metallic nickel are supplied to a metallic nickel dissolving tank to dissolve metallic nickel, and vapor from the evaporator is condensed using a condenser. And condensed,
A method for supplying nickel to a nickel-based plating solution, which comprises diluting the nickel-containing concentrated solution obtained in the dissolution tank with the condensed water obtained in the condenser. 4. The method for supplying nickel into a nickel-based plating solution according to claim 1, wherein the temperature of the concentrated solution in the metal nickel dissolving tank is 75 to 100 ° C. 5. The method for supplying nickel to a nickel-based plating solution according to claim 2, wherein the vapor from the evaporator and the plating solution before flowing into the evaporator are heat-exchanged.