JPH0247560B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preparing a zinc alloy plating solution, and in particular to a method for preparing a zinc alloy plating solution containing alloying elements such as nickel and cobalt used in zinc alloy plating of steel. Regarding the preparation method. A plating solution for plating zinc alloys on steel is produced by adding metallic zinc and alloy components to a sulfuric acid solution. During this dissolution, if an alloying element nobler than zinc and zinc exist in the same reaction system, the surface of the metallic zinc is covered with the alloying element nobler than zinc due to a substitution reaction, and the metallic zinc becomes passivated, making the dissolution stable. It is difficult to do it quickly and continuously.

The present invention solves the problems of the prior art as described above, and the first is a method for preparing a zinc alloy plating solution containing a first metal nobler than zinc.
Contacting a solid of a second metal more noble than a metal, a solid of metallic zinc, and a solid of a first metal with an acidic liquid,
A method for preparing a solution for zinc metal plating characterized by dissolving the metallic zinc solid and the first metal solid in the presence of a second metal solid; A solid consisting of a solid second metal, a solid metallic zinc, and a part of the first metal is brought into contact with an acidic liquid containing the remainder of the first metal as ions, and in the presence of the solid second metal, A method for preparing a zinc alloy plating solution characterized by dissolving the solid metallic zinc and the solid first metal; A method for preparing a solution for plating a zinc alloy, characterized in that the solid is brought into contact with an acidic liquid containing the first metal as an ion, and metallic zinc is dissolved in the presence of the solid second metal. be.

The configuration of the present invention will be explained in detail below.

In the present invention, metallic zinc includes the purest zinc (99.99% Zn) or dross generated from a hot-dip galvanizing bath. Dross is usually 91
Contains ~92% Zn, with the remainder being oxides consisting of Zn, Fe, and oxygen.

Metallic zinc has a shape of around 3 to 20 mmφ,
This is to ensure a dissolution rate as high as possible. Alloying elements other than zinc (first metal) include Fe,
There are Ni, Co, Mo, Cr, Mn, etc. These elements are added to improve the corrosion resistance and paintability of galvanizing. Metals nobler than zinc and alloying elements other than zinc (first metal) (secondary metal)
The metal) is, for example, copper when Co or Ni is used as the first metal. The second metal is usually in the form of powder or granules.

The plating solution is acidic and is usually a sulfuric acid solution.
The method of the present invention is carried out, for example, by showering an acidic liquid containing the first metal as ions into a column filled with metallic zinc and the second metal (third method).

Further, when all of the alloying elements are to be replenished by melting, a first method is used in which the first metal and the second metal are filled in the filling tower.

Furthermore, when replenishing a part of the alloying element by melting, the part of the first metal and second metal is filled in a packed tower, and the acidic liquid containing the remaining first metal as ions is flowed in a shower shape. A second method is performed.

In addition, metallic zinc, an alloying element other than zinc (first metal), and a metal nobler than zinc and the alloying element (secondary metal) are dissolved in an acidic solution and stirred. will be held.

When metallic zinc is dissolved by the first method and metallic zinc and the alloying element (first metal) are dissolved by the second method, the second metal exists as a solid in the same reaction system during dissolution, and the zinc and the first Since the dissolution of the metal is promoted, there is no passivation of metallic zinc unlike in conventional methods, and the dissolution rate is extremely high.

After the above dissolution is completed, unreacted solids (the second metal always remains as unreacted solids) are precipitated in a settling tank, and the supernatant is filtered or directly used as a plating solution without filtration.

By implementing the present invention as described above, the following effects can be obtained.

(1) When metallic zinc is dissolved in a liquid containing an alloying element, passivation of metallic zinc does not occur, and preferable dissolution is possible.

(2) Since melting is carried out in the presence of a metal more noble than the alloying element, the dissolution rate of zinc can be increased and the dissolution process can be carried out quickly.

(3) Operation becomes stable because the zinc concentration becomes a constant value.

Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 Metallic zinc (99.99%
Zn) with a diameter of 6 mm, the lumps (20Kg) and 200 mesh copper powder (20Kg) were added, stirred and mixed, zinc sulfate ion 150g/nickel ion 50g/
A sulfuric acid acidic (pH 1.2) plating solution containing . Dissolution was rapid, taking 30 minutes, and no passivation of metallic zinc occurred. It should be noted that the Cu content in the plating solution was 5 mg/, which was very low, so it was found that there was no risk of a large amount of Cu being incorporated into the plating film during alloy plating.

Example 2 Nickel ion 50g/, cobalt ion 10
A lump of metallic zinc (99.99% Zn) of 6 mm diameter (20 kg) is made of 100 g of sulfuric acid acidic solution containing g/
and 200 mesh copper grains (20Kg) are mixed and flowed down from the top of the tower filled with 150g/150g of zinc sulfate.
, Nickel ion 50g/, Cobalt ion 10
A sulfuric acid solution (pH=1.8) containing copper ions (pH=1.8) was obtained. In this case as well, preferable dissolution was possible without passivation of metallic zinc.

Furthermore, since passivation did not occur, the zinc concentration remained constant from the beginning to the end of the treatment, and electrogalvanizing in the subsequent process was carried out well, resulting in a desirable product.

Example 3 Into a tank containing 100 ml of sulfuric acid acid solution, 20 kg of metallic zinc (99.99% Zn) lumps of 6 mm diameter, 7 kg of nickel, and 200 mesh copper powder (20 kg) were put.
Stir and mix, sulfuric acid acidic (pH 1.2) containing 150 g of zinc sulfate ions and 50 g of nickel ions.
A Metsuki liquid was obtained.

Dissolution was rapid for 30 minutes and no passivation of metallic zinc occurred. The obtained plating solution was successfully used as a stock solution for zinc electroplating.

Example 4 Sulfuric acid acidic liquid containing nickel ion 20g/
Metallic zinc (99.99% Zn) in a tank containing 100%
20Kg of lump with 6mmφ, nickel 7Kg, 200
Add mesh copper powder (20Kg) and stir to mix.
Zinc sulfate ion 150g/, Nickel ion 50
A sulfuric acid acidic (pH 1.2) plating solution containing g/g was obtained.

Dissolution was rapid for 25 minutes and no passivation of metallic zinc occurred. The obtained plating solution was successfully used as a stock solution for zinc electroplating.

Claims (1)

[Scope of Claims] 1. A method for preparing a zinc alloy plating solution containing a first metal more noble than zinc, a solid of a second metal more noble than the first metal, a solid of metallic zinc, and a solid of the first metal. A method for preparing a solution for plating a zinc alloy, characterized in that the metallic zinc solid and the first metal solid are dissolved in the presence of the second metal solid by contacting the zinc alloy with an acidic liquid. 2. A method for preparing a zinc alloy plating solution containing a first metal nobler than zinc, a solid consisting of a second metal nobler than the first metal, a solid metallic zinc, and a part of the first metal; For zinc alloy plating, characterized in that the metallic zinc solid and the first metal solid are dissolved in the presence of the second metal solid by contacting with an acidic liquid containing the remainder of the first metal as ions. How to prepare the solution. 3 In a method for preparing a solution for zinc alloy plating containing a first metal nobler than zinc, a solid of a second metal nobler than the first metal and a solid metallic zinc, and an acidic liquid containing the first metal as an ion. 1. A method for preparing a solution for zinc alloy plating, which comprises dissolving metallic zinc in the presence of a solid second metal.