JP2825136B2 - How to extend the life of a hot-dip metal bath - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for extending the life of a hot-dip metal bath.

[0002]

2. Description of the Related Art In general, a molten metal plating bath is constructed by placing a refractory (brick or the like) inside a steel shell to form a container, and filling the molten metal therein with a material to be plated such as a steel strip. The refractory is cracked or partially missing after continuous operation for a long period of time, and the plated metal (molten metal) comes into contact with the steel shell.

[0003] When the plating metal comes into contact with the steel as described above, corrosion occurs, the iron is opened, and the plating metal leaks.

[0004]

However, such cracks and partial defects of the refractory occur, and even if the plated metal comes into contact with the steel, the opening due to erosion or the like is suppressed, and the bathtub is prevented from being opened. If the extension is not performed, the line will be frequently stopped for a long period of time for repairing the bathtub, etc., resulting in disadvantages such as a significant decrease in productivity.

[0005]

According to the present invention, a refractory is disposed inside a steel shell, and in a molten metal plating bath configured in a container shape, a plating metal is formed in a crack portion and a partially missing portion of the refractory. This is a method for extending the life of a molten metal plating bath characterized by cooling an iron shell to a temperature of from 200 ° C. to less than the melting point of a plating metal when infiltrating to solidify a plating metal at a contact portion of the iron shell.

As described above, by cooling, the plating metal invades cracks and partially missing portions of the refractory, and when it comes into contact with the steel shell, the plating metal at the contact site is cooled and solidified. A solidified layer of thin plated metal is generated on the skin surface, and by continuing cooling, the solidified layer is maintained,
By preventing contact between the hot-dip galvanized metal and the iron shell, corrosion of the iron shell is prevented, opening of the iron shell is avoided, and the life of the bathtub is extended.

[0007] As such a cooling method, for example, a cooling medium such as a gas, a water-water mixture, or a liquid such as water can be sprayed and cooled from the outside of the steel shell. , The iron temperature is 200 to less than the melting point of molten zinc (about 420 ° C.);
0 to less than the melting point of aluminum (about 700 ° C.) or less than the melting point of the plated metal to 200 ° C. to solidify the steel contact portion of the plated metal that has penetrated into cracks of the refractory inside the steel. be able to.

Although the temperature may be lower, it is not preferable in that the temperature of the bath as a whole is kept at a temperature suitable for plating and energy consumption is increased.

[0009] The cooling of the steel shell as described above is performed by, for example, arranging a temperature sensor on the entire steel shell and cooling the portion where the steel shell temperature has risen so as to maintain the bath temperature and reduce costs. It is preferable from the point.

Next, an example of the present invention will be described with reference to the drawings.

In the drawing, a refractory 2 is arranged inside a steel shell 1 to form a container, which is filled with a molten metal plating bath 3 to form a molten metal plating bath 4, and a surface of the steel shell 1 is heated to a temperature. A sensor 5 is provided, and the temperature measurement result of the iron shell 1 of the sensor 5 is guided to a temperature monitoring device 6, and when the device 6 detects a portion at which a temperature required for cooling is reached, a signal is transmitted to a cooling valve opening / closing device 7. Then, the nozzles 8 to 8C and the valve 9 directed to the portion are opened, and the cooling medium is sprayed on the surface of the steel shell 1 for cooling.

In the figure, reference numeral 10 denotes a cooling medium holder.

Next, examples of the present invention will be described together with comparative examples.

[0014]

EXAMPLE The test was carried out as follows in a galvanizing bath of a continuous galvanizing facility. 1) Plating bath capacity: 2.30t 2) Plating bath iron thickness: 20mm (Material SS41) 3) 〃 Refractory thickness: 250mm (castable) 4) Zinc plating bath temperature: 460 ℃

A temperature sensor was arranged outside the side wall of such a bathtub, and as a result of measurement, the temperature fluctuated at 115 to 121 ° C.
Since the temperature was measured in the high temperature range of 450 to 458 ° C, air at room temperature
The operation was continued while spraying 40 Nm ³ / min and maintaining the high-temperature part at 400 ° C., and after about 12 months of continuous operation and regular repairs were conducted, the part was investigated. 600
A crack reaching up to the steel shell of mm was generated, and the erosion of the steel shell was limited to 3 mm.

[0016]

[Comparative Example] In the same zinc plating bath layer as described above, the same operation was performed for 12 months without cooling the high temperature part.
The erosion of the iron skin was as large as 15 mm and was substantially open.

[0017]

As described above, the life of the bath for hot-dip metal plating can be remarkably prolonged, there is no need to stop the line for repair, and the productivity can be greatly improved.

Also, excellent effects such as a reduction in the cost of the bathtub can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Iron shell 2 Refractory 3 Hot-dip metal plating bath 4 Hot-dip metal plating bath 5 Temperature sensor 6 Temperature monitoring device 7 Cooling valve opening / closing device 8 Nozzle 9 Valve 10 Cooling medium holder

Claims (1)

(57) [Claims] A refractory is arranged inside a steel shell, and when a plating metal enters a cracked part or a partially missing part of the refractory in a molten metal plating bath tub formed in a container shape, the steel shell is removed. A method for extending the life of a hot-dip metal plating bath, comprising cooling the metal to a temperature lower than the melting point of the plating metal to a temperature of less than the melting point of the plating metal.