JPH07238400A - Method of supplying nickel raw material into nickel plating solution - Google Patents

Abstract

PURPOSE:To reduce the cost and eliminate the trouble of the equipment and operation due to use of a chemical such as nickel carbonate by introducing granular or powdery metallic nickel into a plating soln. in a heated dissolution tank to dissolve the nickel and supplying the soln. to a plating soln. circulating tank. CONSTITUTION:A nickelous plating soln. in a dissolution tank 1 is agitated by an agitator 2 and heated to 75-100 deg.C by a heat exchanger 5. A powdery or granular metallic nickel having <=0.3 mm grain diameter is supplied to the plating soln. from a feeder 3 and dissolved, the soln. is sent to a plating soln. circulating tank 7 through a pipeline 4 and a pump 6, and nickel is continuously supplied. Besides, a heat exchanger 8 is provided between the pump 6 and the tank 7 to cool the soln. to a plating temp. The dissolution temp. in the tank 1 is preferably kept as high as possible to increase the amt. of nickel dissolved, and the tank is made of FRP, etc., for the purpose.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for supplying a nickel raw material for replenishing a plating solution with consumed nickel ions in a nickel-based continuous electroplating equipment for metal strips such as steel strips using an insoluble anode.

[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 plated steel sheets has significantly increased. There is. 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 better 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 the plating solution, a sulfuric acid type 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 However, such replenishment of metal ions is performed in a dissolution tank provided separately from the circulation tank in the line, and the plating solution is usually circulated between the dissolution tank and the circulation tank by a circulation pump.

Since metal compounds such as nickel carbonate are chemicals, they are expensive, which is one of the factors that hinder the cost reduction, and because they are powders, they also cause environmental problems such as dust generation. Impurities such as sodium, calcium, chlorine, and silicon that are generated cause the following problems. 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.

[0006] Therefore, in a plating treatment facility using a metal compound as a nickel ion source, it is general to provide a dedicated facility for removing these impurities. On the other hand, granular or lumpy metallic nickel has a unit price per nickel weight of 50 to 60%, which is cheaper than metallic compounds, and the method of directly dissolving these is not a problem in terms of cost and working environment, The acid concentration of the plating solution has a low dissolution rate, and some means is required to dissolve it in a large amount.

According to Japanese Patent Application 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 electrolysis is performed while passing a plating solution. Then, the metal nickel particles are dissolved in the plating solution. However, this method not only has the problem that the surface of the metallic nickel particles is oxidized and passivated, but also the durability of the basket-shaped anode and
This is not a practical method because of problems such as the inability to continuously supply metallic nickel particles into the basket-shaped anode.

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 made of a corrosion-resistant metal such as titanium, and electrolyzed while passing the plating solution to dissolve the metal nickel particles in the plating solution. According to this method,
Although most of the problems in the method described in Japanese Patent 1-234598 have been solved for the time being, such an electrolysis method cannot increase the electrolysis current, so if an attempt is made, 100
This is not a realistic method, considering the equipment cost and maintenance cost.

Further, according to JP-A-5-25700, according to the composition of nickel ions and zinc ions consumed,
It is also described that a nickel-zinc alloy with a particle size of 1 mm or less is melted in a melting tank. Nickel-
When a zinc alloy is dissolved in an acidic bath, zinc is first preferentially dissolved, the residual nickel is refined and the surface area is dramatically increased, so that the dissolution of nickel is promoted and the dissolution rate is extremely high. -Nickel ions and zinc ions consumed in zinc-based alloy plating are supplied at the same time. However, the nickel-zinc alloy used has extremely strict manufacturing conditions, cannot be mass-produced, and as a result, the cost of the alloy becomes extremely high, which is impractical.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems in the prior art and to provide a method for directly supplying metallic nickel into a plating solution.

[0011]

[Means for Solving the Problems] A method for supplying a nickel raw material to a nickel-based plating solution of the present invention is to heat the plating solution in a melting bath to 75 to 100 ° C. -Shaped metallic nickel is charged and dissolved with stirring, and more preferably, in the above nickel-based plating solution, the amount of metallic nickel added is 30 kg / m ³ or more with respect to the plating solution in the melting tank. Is a method of supplying a nickel raw material to the.

[0012]

[Operation] At present, the plating solution (plating bath) used industrially is generally a sulfuric acid solution having a pH of 2 or less and a solution temperature of about 55 to 65 ° C. For plating solutions under these conditions,
It is known that nickel ion sources such as metallic nickel and nickel oxide are hardly dissolved.

Now, taking metallic nickel as an example, the dissolution reaction is as follows. Ni + 2H ⁺ → Ni ²⁺ + H ₂ ↑ (1) The reaction rate of this reaction is shown by the following equation. r = k · C _Ni ^a · C _{H +} ^b (2) k = A · exp (−E / RT) (3) where C _Ni : metallic nickel concentration, C _{H +} : hydrogen ion concentration, T: plating solution temperature, a, b: constant Therefore, by increasing the metal nickel concentration, the hydrogen ion concentration, and the plating solution temperature, the value of k in equation (3) increases and r in equation (2) increases. Value, that is, the dissolution rate can be improved.

By the way, if a large amount of sulfuric acid is added to increase the hydrogen ion concentration, the dissolution rate is improved, but the excess sulfuric acid in the plating bath interferes with the operation. Therefore, there is a problem that equipment cost and running cost increase. Therefore, in the present invention, no particular action is taken with respect to the hydrogen ion concentration, and the optimum condition is found by conducting an experiment with respect to the two conditions of the metallic nickel concentration, that is, the metallic nickel input amount and the plating solution temperature, and the dissolution capacity that can be used in an actual machine. Could be achieved.

[0015]

EXAMPLE FIG. 3 shows the equipment configuration near the melting tank. Reference numeral 1 is a dissolution tank, 2 is a stirrer, 3 is a metallic nickel charging device, 4 is a liquid supply pipe, 5 and 8 are heat exchangers, 6 is a liquid supply pump, and 7 is a plating solution circulation tank. First, as a preliminary experiment, using a metallic nickel charging device 3, 1% sulfuric acid was used for metallic nickel in the form of lumps (particle size 10 mm or more), granular and powdery (particle size 0.3 mm or less). (pH 1.
5) Dissolution tank 1 at a ratio of 10 kg to 1 m ^{3 of} plating solution
And keep the liquid temperature at 60 ° C using the heat exchanger 5,
Stirring was carried out with stirrer 2 and dissolved for 30 minutes, but in the case of lumpy form, the dissolution amount was 0.0001 kg / m ³ and practically no dissolution occurred, whereas in granular form and powdery form respectively 0.4, 0.6 kg / m ³ dissolved.

Therefore, the metallic nickel used in the present invention is in the form of particles or powder having a particle size of 0.3 mm or less. The plating solution temperature is usually 55
It is controlled at ~ 65 ℃, which is determined from both aspects of plating quality and heat resistance of plating equipment. In the case of rubber linings that are often used in plating equipment, the heat resistance is up to about 80 ° C, and above that temperature, the rubber will deteriorate and soften. Therefore, even though the temperature of the plating bath is raised to 70 to 75 ° C at most, it was not considered as a very effective means, but recently, FRP (fiber reinforced plastic) can be adopted in the plating tank. As a result, it has become possible to reach a temperature of around 100 ° C from the viewpoint of equipment.

Granular nickel of 0.3 mm or less is plated with 1 m ³
Fig. 1 shows the result of measuring the amount of dissolution by changing the temperature of the plating solution at a rate of 10 kg. As the plating solution temperature rises, the amount of metallic nickel dissolved also increases,
In particular, the increase is remarkable above 75 ° C. However, compared with the fact that at least 4 to 6 kg / m ^{3 is} required as the dissolution capacity in the actual machine, this value is still not sufficient,
From the tendency of this graph, it is desired to further raise the temperature, but the upper limit of the temperature range of the plating solution was set to 100 ° C in consideration of the upper limit temperature of FRP use.

Next, the temperature of the plating solution is adjusted to 60 ° C, 75 ° C, 90 ° C.
FIG. 2 shows the results of measuring the amount of dissolution by setting the temperature to ℃ and changing the input amount of metallic nickel within the range of 10 to 100 kg / m ³ . When the plating solution temperature is 90 ° C, the input amount of metallic nickel is 20 kg /
When it becomes m ³ or more, the dissolving capacity required as an actual machine is achieved. When the plating solution temperature is 75 ° C, the dissolution capacity required as an actual machine is achieved when the input amount of metallic nickel exceeds 30 kg / m ³ .

When the temperature of the plating solution is 60 ° C., no matter how much the amount of metallic nickel added is increased, the melting ability required as an actual machine cannot be achieved. From the above, the preferable temperature range of the plating solution is 75 to 100 ° C. In this temperature range, the amount of metallic nickel added is 30 kg /
It can be said that m ³ or more is more preferable.

When the dissolution is completed, the plating solution in the dissolution tank is cooled to the operating temperature by the heat exchanger 8 and is sent to the plating solution circulating tank 7 by the solution sending pump 6.

[0021]

According to the present invention, since metallic nickel can be directly dissolved in the plating solution, the cost for the plating treatment is greatly reduced as compared with the case of using expensive chemicals such as nickel carbonate. In addition, various equipment troubles caused by impurities such as manganese, sodium, calcium, chlorine, and silicon contained in nickel carbonate are eliminated, and the dedicated removal that was conventionally installed to remove these impurities is eliminated. By eliminating the need for equipment, it has the excellent effect of reducing tens of millions of yen in annual removal costs.

[Brief description of drawings]

FIG. 1 is a graph showing the solubility of metallic nickel in Examples.

FIG. 2 is a graph showing the solubility of metallic nickel in the same example.

FIG. 3 is a configuration diagram showing a facility configuration near a melting tank according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Melting tank 2 Stirrer 3 Metal nickel input device 4 Liquid feed pipe 5, 8 Heat exchanger 6 Liquid feed pump 7 Plating liquid circulation tank

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takao Ikenaga 1-chome, Mizushima Kawasaki-dori, Kurashiki-shi, Okayama Prefecture (no address) Inside the Mizushima Steel Works, Kawasaki Steel Co., Ltd. (72) Kaoru Mizumoto Mizushima-Kawasaki-dori, Kurashiki-shi, Okayama Prefecture 1 chome (without street number) Kawasaki Steel Works Mizushima Steel Works

Claims (2)

[Claims] 1. A method of supplying a nickel raw material into a nickel-based plating solution, wherein the plating solution in the melting tank is kept at 75 to 100 ° C.
A method for supplying a nickel raw material into a nickel-based plating solution, which is characterized in that the temperature is raised to 1, the granular or powdery metallic nickel is charged into this plating solution, and the nickel is dissolved with stirring. 2. The method for supplying a nickel raw material into a nickel-based plating solution according to claim 1, wherein the amount of metallic nickel added is 30 kg / m ³ or more with respect to the plating solution in the melting tank.