JPH0892794A - Supplying of nickel material into nickel-base plating solution - Google Patents

Abstract

PURPOSE: To replenish the grain of metallic nickel directly into a plating soln. to dissolve the grain. CONSTITUTION: A plating soln. in a dissolution tank 1 is heated to 75-100 deg.C by a heat exchanger 5, a granular or powdery metallic nickel is charged into the plating soln. through a metallic nickel feeder 3, aq. hydrogen peroxide is continouosuly injected by an injector 9, and the mixture is agitated by an agitator 2 to dissolve the nickel.

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, high-speed plating method with high current density that enables high-efficiency production is adopted, but in the high-speed plating method, the anode replacement is more difficult than the soluble anode method which requires frequent anode replacement. Needless to say, a method of using an insoluble anode such as an iridium-based material that does not require the use of metal and continuously supplying 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 for replenishing metal ions such as nickel in the consumed plating solution, a method of dissolving the metal nickel by directly contacting the plating solution and a method of dissolving it in the form of a metal compound such as nickel hydroxide or nickel carbonate. There is a method of making the replenishment of metal ions 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. .

Conventionally, a method of dissolving a metal compound such as nickel carbonate is mainly used industrially, but these metal compounds are disclosed in JP-A-63-50328 and JP-A-1-15.
As described in Japanese Patent No. 3534, dissolution, precipitation separation,
Since it is a chemical that is manufactured through complicated steps such as thermal decomposition, it is expensive, which is one of the factors that prevent cost reduction.Because it is a powder, there are environmental problems such as dust generation. Impurities such as sodium, calcium, chlorine, and silicon that are usually contained cause various problems in terms of quality and equipment. Therefore, in the plating treatment equipment that uses a metal compound as the nickel ion source,
It is common to provide a dedicated facility for removing these impurities.

On the other hand, granular or massive metallic nickel has a unit price per nickel weight of 50 compared with metallic compounds.
It is cheap as ~ 60%, and there is no problem in the method of directly dissolving these in terms of cost and working environment, but the dissolution rate is low at the acid concentration of the usual plating solution, and some means for dissolving in large amounts is necessary. I need. In JP-A 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. It is described that the grains 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 the continuous supply of the metallic nickel particles into the basket-shaped anode are not satisfied. There are problems such as not being able to
Not a realistic method. Further, in JP-A-4-13900, in order to prevent passivation, metallic nickel used for the anode contains sulfur, and in order to promote dissolution, the metallic nickel is formed into a granular, plate-like or powder-like shape. It is described that a basket of corrosion resistant metal such as titanium is filled and electrolysis is performed while the plating solution is passed through to dissolve the metal nickel particles in the plating solution. According to this method, most of the problems in the method described in Japanese Patent Laid-Open No. 1-234598 are solved, but since such an electrolysis method cannot increase the electrolysis current, the electrolysis cell is 100 This is not a realistic method, considering the equipment cost and maintenance cost.

Further, JP-A-5-25700 describes 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. ing. When a nickel-zinc alloy is dissolved in an acidic bath, zinc is first dissolved preferentially, residual nickel is refined and the surface area is dramatically increased, so that the dissolution of nickel is also promoted. Nickel ions and zinc ions, which are expensive and consumed in nickel-zinc alloy plating, are replenished 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.

In addition to the above, the plating solution is, for example, 75-100.
It has also been studied to promote the direct dissolution of metallic nickel by raising the temperature to ℃ and setting the amount added to the plating solution to a certain value or more, but in this method there is a large amount of undissolved metallic nickel. It is necessary to take some measures to prevent the metal from mixing with the plating solution.

[0009]

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 of directly supplying nickel metal into a plating solution.

[0010]

[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. Characteristic nickel is charged, hydrogen peroxide solution is continuously injected, and the nickel metal is dissolved while stirring, more preferably, the concentration of hydrogen peroxide solution to be injected is 10 to 20%, And / or a method of supplying a nickel raw material into the above nickel-based plating solution in which the addition rate of hydrogen peroxide water to be injected is 30 to 100 l / hr per 1 m ³ of the plating solution.

[0011]

[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.

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 excess sulfate (SO ₄ ²⁻ ) in the plating bath interferes with the operation. It is necessary to remove excess sulfate by a dialysis method or the like, which causes a problem that equipment cost and running cost increase. In addition, a filter or the like is required to separate undissolved metallic nickel, but the presence of a large amount of metallic nickel causes a problem that the filter cloth is clogged and the filtration speed is reduced.

Therefore, in the present invention, no particular action is taken with respect to undissolved metallic nickel and hydrogen ion concentration, and hydrogen peroxide solution is used as a dissolution aid, and this is continuously added to the plating solution.
The hydrogen gas around the nickel particles is removed by continuously oxidizing the hydrogen gas (H ₂ ) generated by the equation (1) and converting it to water (H ₂ O), as shown schematically in FIG. , It is possible to eliminate the resistance layer against dissolution between nickel particles and hydrogen ions (H ⁺ ) and accelerate the reaction. FIG. 2A shows the case where no hydrogen peroxide solution is used, and FIG. 2B shows the case where hydrogen peroxide solution is added. Since the excess hydrogen peroxide solution is decomposed into water and oxygen, there is no adverse effect on the plating solution.

[0015]

EXAMPLE FIG. 1 shows the equipment configuration near the melting tank. 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, 7 is a plating solution circulation tank, and 9 is hydrogen peroxide water injection. It is a device. 1 m ³ of the plating solution was charged into the melting tank 1 and kept at a constant temperature by the heat exchangers 5 and 8, and metallic nickel was introduced into this by the metallic nickel introducing device 3 and, at the same time, peroxidation was carried out by the hydrogen peroxide water injection device 9. Hydrogen water is injected and the stirrer 2 is operated to dissolve it.

FIG. 3 shows a plating solution of 1 m ^{3 with} a solution temperature of 90 ° C. and a pH of 1.5.
In contrast, 10% of granular nickel with a particle size of 0.3 mm or less is injected, and 15% hydrogen peroxide solution is injected, and the injection rate is changed to measure the dissolution amount of metallic nickel in the dissolution time of 30 minutes. The result is shown. The solubility is improved when 15% hydrogen peroxide solution is added, compared with the case where hydrogen peroxide solution is not added, and the effect is particularly remarkable at 30 l / hr or more. Also, add 100 l of hydrogen peroxide solution
Even if added over / hr, the solubility does not change so much. Therefore, in the present invention, the upper limit of addition is set to 100 l / hr in consideration of the cost of hydrogen peroxide solution and the like.

Next, the influence of the concentration of the hydrogen peroxide solution to be injected was investigated. The commercially available hydrogen peroxide solution is usually 35%, but it was diluted to prepare 0-35%. Particle size for 1 m ³ of plating solution with a solution temperature of 90 ℃ and pH 1.5
FIG. 4 shows the results of measuring the amount of metallic nickel dissolved by adding granular nickel of 0.3 mm or less at a rate of 10 kg, adding hydrogen peroxide solution diluted with stirring, and dissolving the mixture for 30 minutes. From this result, it is more effective to add hydrogen peroxide solution after diluting it, and the effect is remarkable especially in the concentration range of 10 to 20%.

FIG. 5 shows the relationship between the temperature of the plating solution and the dissolved amount of metallic nickel. The amount of metallic nickel dissolved also increased with the increase of the plating solution temperature, and the increase was particularly remarkable at 75 ° C or higher. In the case of rubber linings that are commonly used in plating equipment, the heat resistance is 80
The temperature is up to about ℃, and if it exceeds this, 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 to be a very effective means, but in recent years FRP has been added to the plating tank.
The adoption of (fiber reinforced plastic) has made it possible to maintain temperatures up to about 100 ° C from a facility perspective.

Therefore, the temperature of the plating solution of the present invention is in the range of 75 to 100 ° C. When the dissolution is completed, the plating solution in the dissolution tank is cooled to the operating temperature by the heat exchanger 5 and then sent to the plating solution circulation tank 7 by the solution sending pump 6.

[0020]

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, annual removal costs of tens of millions of yen can be saved. Further, since the dissolution efficiency is improved, there is no need for equipment such as separation of undissolved metallic nickel, and there is an excellent effect that the dissolution tank can be downsized.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an equipment configuration near a melting tank according to the present invention.

FIG. 2 is a schematic view of the vicinity of nickel particles for explaining the operation of the present invention.

FIG. 3 is a graph showing the solubility of metallic nickel in Examples.

FIG. 4 is a graph showing the solubility of metallic nickel in the same example.

FIG. 5 is a graph showing the solubility of metallic nickel in the same example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Melting tank 2 Stirrer 3 Metal nickel input device 4 Liquid supply piping 5,8 Heat exchanger 6 Liquid supply pump 7 Plating solution circulation tank 9 Hydrogen peroxide water injection device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takao Ikenaga 1-chome, Mizushima Kawasaki-dori, Kurashiki-shi, Okayama Prefecture (no address) Inside Mizushima Works, Kawasaki Steel Co., Ltd. (72) Osamu Osamu, Kawashima-dori, Mizushima, Kurashiki-shi, Okayama Prefecture Chome (without street number) Inside the Mizushima Steel Works of Kawasaki Steel Co., Ltd. (72) Inventor Akio Sakurai 1-chome of Mizushima Kawasaki Street, Kurashiki City, Okayama Prefecture (without street) Inside the Mizushima Steel Works of Kawasaki Steel Co., Ltd.

Claims (3)

[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.
In the nickel-based plating solution, the temperature is raised to 1, the granular or powdery metallic nickel is charged into the plating solution, the hydrogen peroxide solution is continuously injected, and the metallic nickel is dissolved with stirring. Method of supplying nickel raw material to nickel. 2. The concentration of hydrogen peroxide water to be injected is 10 to 20%.
The method of supplying a nickel raw material into the nickel-based plating solution according to claim 1. 3. The addition rate of hydrogen peroxide water to be injected is 30 to 100 l / hr per 1 m ³ of plating solution.
The method for supplying a nickel raw material into the nickel-based plating solution according to.