JP2895725B2 - Hot-dip dross removal method - 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 removing hot dross, which removes top dross floating on a bath surface in a hot dipping bath into which a material to be plated such as a steel plate is immersed by moving it to a predetermined place. is there.

[0002]

2. Description of the Related Art Generally, when a molten metal containing Zn-based, Al-based, and Pb-based metal ions is used as a plating solution and a steel plate to be plated is continuously plated, For example, as shown in FIG. 4, the end of the snout 3 is disposed in a bath, and the steel plate 4 continuously fed from the end is immersed in the molten metal 2. When the steel sheet 4 is immersed in a plating solution while the steel sheet 4 is being sent to the outside of the hot-dip plating bath 1 while the transport direction is changed upward, a plating process is performed. Precipitate.

At this time, when the steel plate 4 is immersed in the bath and a plating reaction occurs, a top dross 9 is generated, and the top dross 9 floats on the bath surface near the position where the steel plate 4 is immersed. If you leave this top dross 9 as it is,
A part of the top dross 9 is taken into the bath by convection of the molten metal 2 generated when the incoming steel plate 4 is immersed in the plating bath, and the top dross 9 is
It adheres to plating equipment such as rolls and rolls, or rises again due to the convection of the molten metal 2 and enters the snout 3, causing defects such as scratches on the steel plate 4.

In the prior art, as shown in FIG. 5, a worker draws the top dross 9 floating on the bath surface 2a by a scraping jig 20 to the end of the hot-dip plating tank 1, that is, the steel plate 4 to be immersed. Or snout 3 and then removed by a pump or the like. In addition, in FIG. 4, 21 is a bottom dross.

[0005]

However, in the method in which the worker rakes the top dross 9 floating on the bath surface 2a by the jig 20, the jig 20 is immersed in the bath from above when the worker gathers the top dross 9. A part of the top dross 9 floating on the bath surface 2a is caught in the bath due to the convection of the molten metal 2 due to the heat.

For this reason, the molten metal 2 in the hot-dip plating tank 1
Depending on the convection condition of the top dross 9
However, there is a problem that it may adhere to the steel plate 4 or the roll surface and cause a surface defect, or may enter the snout 3 and cause a flaw. The present invention
The present invention has been made by paying attention to the above-mentioned problems, and it is an object of the present invention to remove top dross in a hot-dip plating bath by moving it along a bath surface while suppressing the dross from being taken into the bath.

[0007]

Means for Solving the Problems To achieve the above object, a method for removing hot-dipped dross according to the present invention is directed to a top dross floating on a bath surface in a hot-dip bath or a bath surface in the vicinity thereof. , Melting of the molten metal in the hot-dip plating bath
By blowing a non-oxidizing gas at a temperature equal to or higher than the point , the top dross is moved to a predetermined location along the bath surface, and thereafter, the top dross is removed from the hot-dip plating tank. I have.

[0008]

[0009]

The gas is blown onto the top dross floating on the bath surface in the hot-dip bath or in the vicinity thereof, thereby causing a flow along the bath surface in the molten metal located near the bath surface. As a result, the top dross having a low specific gravity moves along with the flow. At this time, since only the flow along the bath surface is formed in the molten metal in the vicinity of the bath surface by spraying, the generation of convection such as involving the top dross in the molten metal is suppressed, and thus the top taken in the molten metal. The amount of dross is reduced.

In order to suppress the flow only near the bath surface as much as possible, it is preferable to blow the gas from obliquely above the bath surface and at a blowing speed that is not so strong that the top dross can move. . The place where the top dross is blown and collected is set to a place sufficiently distant from the immersion position of the plating apparatus such as a snout or a roll or a plating object such as a steel plate, as in the related art.

Then, at a position away from the steel plate or the like,
As in the past, the top dross is pumped up by a pump or the like and removed from the tank. At this time, since the top dross is separated from the steel plate or the like, even if the top dross is caught in the molten metal, the top dross is prevented from reaching the arrangement position of the snout or the like.

By using a non-oxidizing gas such as nitrogen or argon as the gas to be blown, it is possible to suppress the occurrence of an unnecessary redox reaction between the gas and the molten metal. Also, by setting the temperature of the gas to be equal to or higher than the melting point of the molten metal, the molten metal on the bath surface sprayed with the gas melts and the fluidity improves, and even if the gas blowing speed is low, the gas floats The top dross can be easily moved.

[0013]

An embodiment of the present invention will be described with reference to the drawings. First, the configuration will be described. As shown in FIGS. 1 to 3, a molten metal 2 such as a Zn-based metal is stored as a plating solution in a hot-dip plating bath 1, and the bath is heated from one end of a center line in the hot-dip plating bath 1. The end of the snout 3 is immersed in the
From the end of the snout 3, a steel plate 4 to be plated can be carried in along the line.

A sink roll 5 around which the steel plate 4 is wound is disposed at a central portion in the hot-dip plating bath 1 so that the transport direction of the immersed steel plate 4 can be changed upward. Further, two blowout headers 6 are installed above the hot-dip plating tank 1 along the line center, and a plurality of nozzles 6 a are provided on the side surface of each blowout header 6. The blowing direction of the nozzle 6a is set slightly downward in the width direction of the conveyed steel plate 4 (direction orthogonal to the center line).

The blowout header 6 is connected via a pipe 7 to a gas tank 8 in which nitrogen gas is sealed, and nitrogen gas is supplied from the gas tank 8. In the plating equipment equipped with the above-described top dross removing function, by constantly or intermittently blowing nitrogen gas from each nozzle 6a of the blowing header 6,
On the bath surface 2a, a flow of the molten metal 2 along the bath surface 2a is formed toward both ends 1a, 1b of the hot-dip plating bath 1 orthogonal to the center line.

On the other hand, the steel sheet 4 continuously fed from the snout 3 is immersed in the molten metal 2, subjected to a plating treatment, and carried out of the molten plating tank 1 via the sink roll 5. During the plating reaction, dross 9 is generated and floats on the bath surface 2a. The top dross 9 floating on the bath surface 2a is blown to both ends of the hot-dip plating bath 1 along the flow on the bath surface 2a formed by blowing the nitrogen gas.

The top dross 9 blown and collected at the end of the hot dip coating tank 1 is appropriately removed from the hot dip coating tank 1 by a suction pump device or the like. Each end 1a, 1b of the hot-dip plating tank 1 into which the top dross 9 has been blown is located at a position sufficiently distant from the steel plate 4, the sink roll 5, and the snout 3 to be plated. When removing the top dross 9, even if a part of the top dross 9 is taken into the molten metal 2, the top dross 9 does not adhere to the steel plate 4, the roll 5, or the like.

Further, by using nitrogen gas as the gas to be blown out, the gas is prevented from causing an unnecessary oxidation-reduction reaction with the molten metal 2. Further, as the temperature of the nitrogen gas is increased, the temperature of the sprayed bath surface 2a rises and melts, and the viscosity decreases. Therefore, only the molten metal 2 near the bath surface 2a increases its fluidity, and The top dross 9 floating on the surface 2a is easily moved. For this reason, the frictional resistance between the Dop dross 9 and the molten metal 2 is reduced, and the velocity of the blown gas can be suppressed to a low level, so that the incorporation of the top dross 9 into the molten metal 2 is further suppressed.

Although nitrogen gas is used as the non-oxidizing gas in the above embodiment, other non-oxidizing gas such as argon gas may be used. However, nitrogen gas is advantageous in terms of cost. In the above embodiment, the blowing header 6 for blowing out nitrogen gas is fixed, but may be movable along the bath surface 2a.

[0020]

As described above, according to the hot-dip dross removing method of the present invention, the top dross can be collected at a specific place while suppressing the incorporation of the top dross into the molten metal. Thereby, there is an effect that adhesion of dross to a plating object such as a steel plate or a roll or a plating facility such as a roll is reduced and a yield is improved.

At this time, by using a non-oxidizing gas as the gas to be blown, useless redox reaction between the gas and the molten metal does not occur. Also, by raising the temperature of the gas, the fluidity of only the molten metal near the bath surface sprayed with the gas is improved, the top dross becomes easy to move, and the wind speed of the blown gas can be suppressed small,
Furthermore, it is possible to suppress the incorporation of the top dross into the molten metal.

[Brief description of the drawings]

FIG. 1 is a side view showing a hot-dip plating facility according to an embodiment of the present invention.

FIG. 2 is a plan view showing a hot-dip plating facility of an example according to the present invention.

FIG. 3 is a front view showing a hot-dip plating facility according to an embodiment of the present invention.

FIG. 4 is a side view showing a general hot-dip plating facility.

FIG. 5 is a side view showing a conventional approach of a top dross.

[Explanation of symbols]

 Reference Signs List 1 hot-dip plating tank 2 hot-dip metal 2a bath surface 4 steel plate 6 blow-out header 6a nozzle 9 top dross

Claims (1)

(57) [Claims] 1. A toward the bath surface of the top dross or near floating on a bath of molten plating tank, the molten
Non-oxidizing at temperatures above the melting point of the molten metal in the plating tank
A top dross is moved to a predetermined location along a bath surface by spraying said gas, and thereafter said top dross is removed from said hot dipping bath.