JPH07268575A - Method for separating and discharging dross in bath and apparatus therefor - Google Patents

Abstract

PURPOSE:To surely and stably remove both of top dross Dt and bottom dross Db from the inside of a plating bath M. CONSTITUTION:The plating bath M is supplied into a separating chamber body 3 which rotates at a constant speed and is separated to the top dross Dt, clean metal K and the bottom dross Db by centrifugal force. The top dross Dt and the clean metal K are continuously discharged by centrifugal force. The bottom dross Db is intermittently discharged at the point of the time the specified accumulation quantity is attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method of melting in a plating bath by centrifuging to ensure the quality of molten metal such as molten zinc, molten aluminum, molten tin, molten copper and molten solder used for hot-dip galvanized steel sheets. The present invention relates to a method and apparatus for separating and discharging metal and dross to remove dross.

[0002]

2. Description of the Related Art As one of the methods for galvanizing the surface of a strip (steel plate), generally, the strip is continuously dipped in a plating bath containing molten zinc as a main component,
There is so-called hot dip galvanizing. In this plating bath,
Aluminum, which is an additive, and iron, which is leached from the strip, are contained, but these components become intermetallic compounds and produce particulate impurities called so-called dross.

This dross has a high specific gravity because it has a high aluminum content, and has a high specific gravity because it has a high iron content, and a bottom dross that has a high specific gravity because it has a high iron content. In the plating bath, the top dross is located in the upper part, the molten metal is located in the middle part, and the bottom dross is located in the lower part.

If the amount of dross in the plating bath increases, the quality of the plating will be significantly impaired, so it is necessary to remove the dross from the plating bath. Conventionally, as a method for removing this dross, Japanese Patent Laid-Open No. 63- There is means disclosed in Japanese Patent No. 219536.

In this prior art, the plating bath is separated into a top dross having a low specific gravity and a molten zinc having a high specific gravity by a centrifugal separator, and the top dross is discharged from a discharge port provided at the upper part of the molten zinc. The top dross is removed by discharging from the lower discharge port.

[0006]

However, in the above-mentioned conventional technique, the top dross floating on the bath surface is mainly collected and separated, so that the top dross is reliably collected from a wide bath surface. Is extremely difficult, and automation cannot be expected at all.

That is, in the above-mentioned conventional technique, the top dross is collected together with zinc and centrifuged, and the efficiency of the top dross recovery on the bath surface determines the practical use. I have tried to automate the collection of dross many times, but there are no cases where it exceeds human labor, and I still rely on human labor now. The reason for this is that dross remains between the complicated bath equipment, and the remaining dross accumulates and causes actual damage.Dross on the wide open surface of the bath is merely a spoiler. The dross between the devices does not behave with a certain regularity, and residual dross always accumulates during recovery work by a robot, which may cause unexpected damage, making automation difficult.

Furthermore, since dross and bottom dross suspended in the bath cannot be removed at all, removal of dross from the plating bath is extremely insufficient and cannot be put to practical use by itself.

Therefore, the present invention was devised to solve the above-mentioned problems in the prior art, and it is technically necessary to reliably and stably remove both top dross and bottom dross from the plating bath. It is an object to obtain a plating bath of high quality and to surely obtain wasteless dross removal.

[0010]

Therefore, in the method for separating and discharging dross in a bath according to the present invention, the separation is performed at a constant speed at a rotation speed capable of generating a centrifugal force sufficient to reach a liquid surface near a vertical surface. A plating bath is supplied into the tank main body from the upper part of the separation tank main body, and the plating bath is separated into bottom dross, clean metal and top dross from the side wall inner surface side of the separation tank main body in order by centrifugal force. The top dross stays in the upper part of the separation tank main body by the dross separation weir horizontally installed in the center of the inside, and the top dross is continuously discharged by centrifugal force from the top dross discharge pipe located above the dross separation weir and separated. The clean metal discharge pipe located at the bottom of the tank main body continuously discharges clean metal by centrifugal force, and the bottom dross discharge pipe located at the bottom of the separation tank main body provides bottom dross discharge. When it reaches a certain accumulation amount, by opening the bottom dross discharge pipe, it was decided to drain the bottom dross.

It is possible to detect that the bottom dross has reached a certain amount accumulated in the main body of the separation tank by measuring the ratio of the bottom dross contained in the discharged clean metal, and also to the separation tank. It can also be detected by previously measuring the content ratio of bottom dross in the plating bath supplied into the main body.

The apparatus for separating and discharging dross in a bath according to the present invention comprises a separation tank body, a supply pipe and a rotating inner shaft.

The separation tank body is integrally assembled to a rotating outer shaft that rotates at a constant speed, has a top dross discharge pipe for discharging top dross in an intermediate portion, and a clean metal for discharging clean metal at a lower portion. It has a discharge pipe and a bottom dross discharge pipe for discharging bottom dross at the bottom.

The supply pipe communicates with the upper portion of the separation tank body so as to supply the plating bath into the separation tank body.

The rotating inner shaft penetrates through the inside of the separation tank main body and the inside of the rotating shaft and rotates at a constant speed in synchronization with the separation tank main body, and a supply weir that reaches just below the opening of the supply pipe is provided in the upper part. A dross separating weir that reaches directly below the top dross discharge pipe is horizontally provided in the middle part, and an extension plate having a discharge plug for opening and closing the bottom dross discharge pipe is horizontally provided at the lower part, and is vertically movable.

It is preferable that the lower part of the side wall of the separation tank main body is widened to form a bottom dross reservoir for accumulating bottom dross.

[0017]

The operation of the method of the present invention will be described below together with the operation of the apparatus of the present invention. First, a plating bath is supplied from the supply pipe into the main body of the separation tank that is rotating at a constant speed. The supplied plating bath is guided to the upper part of the inner surface of the side wall of the separation tank main body by hitting the supply weir located immediately below the supply pipe and receiving the centrifugal force of the separation tank main body rotating at a constant speed.

Next, due to the action of centrifugal force, the bottom dross having the highest specific gravity is located on the inner surface of the side wall of the separation tank body, the clean metal having the second highest specific gravity is inside thereof, and the top dross having the lowest specific gravity is present. It is located further inside.

In this state, the bottom dross and the clean metal gradually fall to the bottom of the separation tank main body due to their own weight,
The top dross is prevented from falling by the dross separation weir, stays above the separation tank body, and is continuously discharged from the top dross discharge pipe by centrifugal force.

Similarly, the clean metal accumulated in the lower part of the separation tank body is continuously discharged from the clean metal discharge pipe by centrifugal force.

Since the specific gravity is the highest, the bottom dross accumulated at the bottom of the separation tank body is discharged from the bottom dross discharge pipe. This discharge is achieved by moving the rotating inner shaft upward to move the discharging plug provided on the rotating inner shaft through the extension plate and opening the bottom dross discharge pipe.

The bottom dross is not continuously discharged by centrifugal force in the same manner as the top dross and the clean metal, since the amount of the bottom dross contained in the plating bath is usually smaller than that of the clean metal. This is because the clean metal is discharged from the bottom dross discharge pipe together with the bottom dross.

When the discharge of the bottom dross is completed, the inner shaft for rotation is moved downward to return the bottom dross discharge pipe to the closed state.

The bottom dross is carried out when it reaches a certain accumulated amount. Whether or not the certain accumulated amount is reached should be detected by the ratio of the bottom dross contained in the discharged clean metal. You can

When the bottom dross accumulates above a certain level, it is naturally discharged from the clean metal discharge pipe together with the clean metal by the action of centrifugal force. Therefore, by knowing that the proportion of bottom dross contained in the discharged clean metal has become higher than usual, it is judged that the accumulated amount of bottom dross has exceeded a certain level, and the bottom dross discharge pipe is opened to discharge bottom dross. Is.

Whether or not the bottom dross has reached a certain amount can be detected by measuring the content ratio of the bottom dross in the plating bath supplied into the separation tank body in advance.

By doing so, the discharge amount of the clean metal and the top dross can be measured, and the amount of the bottom dross accumulated in the separation tank body can be estimated from the discharge amount in relation to the above content ratio. .

By forming the bottom dross reservoir by making the lower part of the side wall of the separation tank main body diverge, it is possible to prevent the bottom dross from being discharged from the clean metal discharge pipe, and to accumulate a large amount of bottom dross. You can

[0029]

FIG. 1 shows an embodiment of the device of the present invention. This is a device for separating the clean zinc K, the top dross Dt and the bottom dross Db from the zinc bath M and discharging them. This device is in a box-type electric furnace and is constantly heated and kept at 450 ° C. In addition, the inside of the furnace is replaced with nitrogen gas as an antioxidant measure.

The separation tank main body 3 has a top dross discharge pipe 7, a clean metal discharge pipe 8 and a bottom dross discharge pipe 9, each of which is provided with four pipes. The separation tank main body 3 is fixed to the rotating outer shaft 2 and rotates at a constant speed of about 800 rpm.

The plating bath M passes through the supply pipe 5 and is supplied to the upper part of the separation tank main body 3 by the supply weir 4 fixed to the rotating inner shaft 1. The plating bath M that has entered the separation tank main body 3 begins to separate the top dross Dt and the bottom dross Db by centrifugal force, and the top dross Dt is dammed and collected by the top dross separation weir 6 fixed to the rotating inner shaft 1. The bottom dross Db precipitates so as to stick to the inner surface of the separation tank body 3, and is collected in the bottom dross reservoir 12.

The top dross Dt is a top dross separating weir 6
It is dammed up and accumulated, and when the liquid level rises, it is continuously discharged from the top dross discharge pipe 7 to the outside of the separation tank body 3.

FIG. 2 shows an operating state in which the bottom dross Db is collected and accumulated. In this embodiment, the bottom portion of the side wall of the separation tank body 3 is enlarged in a divergent manner to provide a bottom dross reservoir 12. In the bottom dross reservoir 12, the bottom dross discharge pipe 9 is closed by a discharge plug 10 provided at the tip of the extension plate 13 to accumulate the bottom dross Db.

A receiving seat 11 is provided at the tip of the bottom dross discharge pipe 9 in order to maintain a tightly closed state by the discharge plug 10.

FIG. 3 shows an operating state while discharging the bottom dross Db. When the bottom dross Db is sufficiently accumulated in the bottom dross reservoir 12, the bottom dross discharge plug 10 solidified on the rotary inner shaft 1 is opened and closed by moving the rotary inner shaft 1 up and down in the axial direction to discharge the bottom dross Db from the bottom dross discharge pipe 9. .

A molten zinc bath M (top dross: about 0.4 wt%, bottom dross: about 0.2 wt%) whose dross amount was measured in advance by a dross amount measuring device using the device shown in this embodiment.
%), The top dross Dt and the bottom dross Db were separated.

Table 1 shows the results of the separation experiment using this apparatus, and Table 2 shows the results of the component measurement. From this result, molten zinc bath M
From this, it was confirmed that the top dross Dt and the bottom dross Db can be separated at the same time. That is, it can be seen from Table 1 that the supplied molten zinc bath contained about 0.4 wt% top dross Dt and about 0.2 wt% bottom dross Db. It can be seen that K does not include either the top dross Dt or the bottom dross Db.

Further, it can be seen from Table 2 that the aluminum concentration and the iron concentration in the separated clean zinc are much lower than those of the supplied zinc bath M.

[0039]

[0040]

[0041]

Since the present invention has the above-mentioned structure, it has the following effects. Since the entire dross can be separately separated from the molten metal, top dross and bottom dross, and discharged, it is not necessary to combine with other treatment methods and equipment for dross removal, and thus dross removal can be performed in a single operation. Can be achieved continuously.

Since not only the top dross but also the bottom dross can be removed, it is not necessary to suspend the operation for removing the bottom dross from the inside of the main body of the apparatus or to remove the bottom dross from the inside of the main body of the apparatus by a dedicated work. It can be achieved smoothly and safely.

Both the top dross and the bottom dross can be removed while the constant speed operation is maintained, and can be continuously achieved without loss of power due to acceleration / deceleration.

Both the dilute top dross and bottom dross can be reliably and stably removed from the plating bath, a high quality plating bath can be obtained, and wasteless dross removal can be achieved.

[Brief description of drawings]

FIG. 1 is a front sectional view showing an embodiment of the device of the present invention.

FIG. 2 is a semi-front sectional view showing a bottom dross accumulation operation state in the embodiment of FIG.

FIG. 3 is a front sectional view showing a bottom dross discharging operation state in the embodiment of FIG.

[Explanation of symbols]

 1; inner rotating shaft 2; outer rotating shaft 3; separation tank body 4; supply weir 5; supply pipe 6; dross separation weir 7; top dross discharge pipe 8; clean metal discharge pipe 9; bottom dross discharge pipe 10; discharge plug 11 Receiving seat 12; Bottom dross reservoir 13; Extending plate M; Plating bath K; Clean metal Dt; Top dross Db; Bottom dross

Claims (5)

[Claims] 1. A separation tank main body (3) which rotates at a constant speed at a rotation speed capable of generating a centrifugal force sufficient to reach a liquid surface near a vertical surface.
A plating bath (M) is supplied to the inside of the separation tank main body (3) from above, and the plating bath (M) is separated by centrifugal force into the separation tank main body.
Bottom dross (Db), clean metal in order from the inner surface of the side wall of (3)
(K) and top dross (Dt), and a dross separation weir that is horizontally installed in the center of the separation tank body (3).
(6) The top dross (Dt) is removed by the separation tank body
(3) The top dross (Dt) is continuously discharged by centrifugal force from a top dross discharge pipe (7) located above the dross separation weir (6) inside the separation tank body (3). The clean metal (K) is continuously discharged by centrifugal force from the clean metal discharge pipe (8) located at the bottom of (3), and the bottom dross discharge pipe is located at the bottom of the separation tank body (3).
According to (9), when the bottom dross (Db) reaches a certain amount of accumulation, the bottom dross discharge pipe (9) is opened to discharge the bottom dross (Db) to separate and discharge the bath dross. 2. Bottom dross in the separation tank body (3)
The separation discharge of dross in the bath according to claim 1, wherein the fact that (Db) has reached a certain accumulated amount is detected by measuring the proportion of bottom dross (Db) contained in the discharged clean metal (K). Method. 3. Bottom dross inside the separation tank body (3)
The fact that (Db) has reached a certain amount of accumulation is detected by previously measuring the content ratio of bottom dross (Db) in the plating bath (M) supplied to the separation tank body (3). The method for separating and discharging dross in the bath as described. 4. A top dross discharge pipe (7), which is integrally assembled to a rotating outer shaft (2) which rotates at a constant speed, discharges top dross (Dt) at an intermediate portion, and has a clean metal at a lower portion. A separation tank body (3) having a clean metal discharge pipe (8) for discharging (K) and a bottom dross discharge pipe (9) for discharging bottom dross (Db) at the bottom, and the separation tank body (3). 3) Inside plating bath (M)
In order to supply the above, the supply pipe (5) communicating with the upper part of the separation tank body (3) and the separation tank body (3) penetrating the inside of the separation tank body (3) and the rotation shaft are synchronized with the separation tank body (3). Then, the supply weir (4) is rotated at a constant speed and reaches the upper part just below the opening of the supply pipe (5).
A dross separating weir (6) that reaches directly below the top dross discharge pipe (7) is installed horizontally, and a discharge plug (10) that opens and closes the bottom dross discharge pipe (9) is installed in the lower part. A rotating inner shaft (1) that has an extension plate (13) and has a vertical movement.
And a device for separating and discharging dross in the bath. 5. A bottom dross reservoir in which bottom dross (Db) accumulates by making the lower part of the side wall of the separation tank body (3) divergent.
The device for separating and discharging dross in a bath according to claim 4, which comprises forming (12).