JPH073414A - Dross removal method and device - Google Patents

Abstract

(57) [Summary] [Purpose] The purpose is to centrifuge the top dross, molten metal, and bottom dross in the plating bath to remove top dross and bottom dross continuously to obtain clean molten metal. [Structure] Top dross removal processing for overflowing and removing top dross Dt having a light specific gravity after centrifugation, and bottom dross removal processing for overflowing and collecting clean molten metal K while leaving bottom dross Db having a heavy specific gravity after centrifugation And are continuously applied to the same plating bath M to remove both the top dross Dt and the bottom dross Db from the plating bath M.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention uses centrifugal separation 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 an apparatus for removing dross by separating molten metal and 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, the above-mentioned prior art only discloses the technology for removing the top dross, does not disclose the technology for removing the bottom dross, and the disclosed technology allows the bottom dross to be removed. However, there is a problem that bottom dross removal cannot be achieved.

Further, this prior art is a system for continuously and constantly separating and discharging molten zinc and top dross,
If the discharge amount is less than the minimum continuous discharge limit (the discharge flow rate that can be continuously discharged) specific to the equipment, it is not possible to select and discharge only the top dross, and mixing of molten metal into the discharge dross cannot be avoided. There was a problem called.

That is, when the content ratio of top dross is relatively high and exceeds the minimum continuous emission limit amount of top dross, it is possible to select and discharge only the top dross. When the ratio is relatively low and is below the minimum continuous discharge limit of top dross, it becomes difficult to select and discharge only the top dross, and mixing of molten metal cannot be avoided.

Therefore, in order to remove the bottom dross by utilizing the above-mentioned conventional technique, the centrifuge is periodically stopped, and the bottom dross accumulated in the separation tank is scraped out by some means and discharged. However, there is a problem in that bottom dross removal work involves great difficulty.

Further, in the above-mentioned prior art, a mixed liquid in which the molten zinc separated from the top dross and the bottom dross are mixed from the inside of the separation tank rotating at a high speed is provided on the side opposite to the top dross (in this case, the lower side). )) In an overflow state, the centrifugal force that acts on the mixed liquid of molten zinc and bottom dross is extremely strong. Therefore, it is technically extremely difficult to take out stably in an overflow state. In addition, since the molten zinc and the bottom dross have different specific gravities, there is a problem that it is physically impossible to take out uniformly in the overflow state.

Therefore, the present invention was devised to solve the above-mentioned problems in the prior art, and utilizes the difference in specific gravity of the molten metal with respect to the top dross and the bottom dross, and the good fluidity of the molten metal itself. At the same time, the technical issue is to flow-displace the bottom dross by adjusting the balance between the centrifugal force acting on the bottom dross and the gravity, so that clean molten metal is separated from the top dross and bottom dross from the plating bath. It is intended to be taken out.

[0012]

The method of the present invention for solving the above technical problems is to remove top dross from a molten metal by centrifuging the top dross from the molten metal in a mixed liquid of the top dross and the molten metal. To perform a top dross removal treatment, from the mixed liquid of the bottom dross and the molten metal, centrifuge the bottom dross from the molten metal, and perform a bottom dross removal treatment to remove the bottom dross, this top dross removal treatment and the bottom dross. The removal process
Applying consecutively to the same plating bath,
It is in.

In the top dross removal treatment, a mixed liquid of top dross and molten metal is supplied to a separation tank, and the high speed rotation operation of the separation tank centrifuges the top dross and molten metal to the top dross to the separation tank. Top dross is allowed to overflow and be removed from the separation tank by continuous supply of the mixed solution of the molten metal and the molten metal, and the bottom dross removal treatment is performed by supplying the mixed solution of the bottom dross and the molten metal to the separation tank. Centrifuge the bottom dross and molten metal by high-speed rotation, and store the separated bottom dross by continuous supply of the mixed liquid of bottom dross and molten metal to the separation tank, and collect the separated molten metal by overflowing. Then, when the amount of bottom dross accumulated reaches the set value, the rotation speed of the separation tank is reduced to make the bottom dross self-weight. Ri is good to shall be removed by falling emissions.

It is advantageous that the plating bath is first subjected to a top dross removing treatment for removing the top dross and then subjected to a bottom dross removing treatment for removing the bottom dross.

Further, according to the constituent means of the present invention for solving the above technical problem, the bottom plate is connected to the lower end of the cylindrical wall, and the inner flanged top plate is connected to the upper end of the cylinder wall. A take-out port for taking out the molten metal is opened at the peripheral end of the main body part, which is driven to rotate about the central axis of the cylinder wall as the axis of rotation and the outer opening of the take-out port. It has a separation tank for top dross removal consisting of a control member that controls the outflow of molten metal separated from the top dross by adjusting the gap with the opening edge of the outlet, and the bottom at the lower end of the cylindrical peripheral wall. Along with connecting the walls, an inner collar-shaped top wall is connected to the upper end of the peripheral wall, and the bottom dross removal part is located on the bottom wall portion located closer to the center than the opening edge of the opening formed by the top wall. The outlet is opened, and it is driven to rotate with the center axis of the peripheral wall as the rotation axis. In order to partition the inside of the main body into a lower end and other parts by forming an open portion between the main body and an outer diameter larger than the inner diameter of the top wall and forming an open portion between the inner peripheral surface of the peripheral wall, There is provided a bottom dross removing separation tank comprising a partition wall fixedly provided at a lower end of the main body portion, and combining the bottom dross removing separation tank and the top dross removing separation tank.

It is preferable that the inner peripheral surface of the cylindrical wall of the top dross removing separation tank is a tapered surface that expands downward, and the control member of the top dross removing separation tank is displaced along the axis of rotation. It should be possible.

The upper surface of the partition wall of the separation tank for removing bottom dross is an inclined surface which descends toward the peripheral wall at an inclination angle x, and the upper surface of the bottom wall descends toward the discharge port at an inclination angle y. An inclined surface is preferable, and an inclination angle x of the upper surface of the partition wall is set to 10 to 20 degrees, and an inclination angle y of the upper surface of the bottom wall is set to 30 to 60 degrees.

Above the partition wall in the main body of the bottom dross removing tank, a cylindrical inner tank having a bottom is provided for temporarily receiving the plating bath, and the central axis of the inner tank is aligned with the axis of rotation. It is effective to provide them.

The bottom dross removing separation tank is arranged below the top dross removing separation tank, and the mixed liquid of the molten metal and the bottom dross taken out from the top dross removing separation tank is directly transferred to the lower bottom dross removing separation tank. It is advantageous to supply.

[0020]

[Function] The liquid from which the top dross has been removed by the top dross removal treatment is a molten metal simple substance or a mixed liquid of molten metal and bottom dross, and the liquid from which the bottom dross has been removed by the bottom dross removal treatment is a molten metal simple substance or a molten metal. It is a mixed solution with top dross.

Therefore, when the top dross removing treatment and the bottom dross removing treatment are successively performed in succession on the same plating bath, when the top dross removing treatment is performed first, the next bottom dross removing treatment is performed. What is treated is a mixed liquid of molten metal and bottom dross, and after the bottom dross removal treatment, a clean molten metal simple substance can be obtained. What is treated by the top dross removal treatment is a mixed liquid of molten metal and top dross, and after the top dross removal treatment, the same molten metal simple substance is obtained, and complete removal of dross is achieved. .

In the top dross removing treatment, the top dross floating in the molten metal in the separation tank and centrifugally separated in a state of good fluidity is continuously supplied to the separation tank by continuously supplying the mixed liquid to an appropriate liquid level of the molten metal. By adjusting, it is achieved by overflowing from the inside of the separation tank.At this time, the amount of molten metal corresponding to the amount of the mixed liquid continuously supplied to the separation tank is continuously taken out from the separation tank, By keeping the liquid level position of the molten metal in the inside constant, the top dross removing process can be continuously performed.

Since the molten metal is taken out of the separation tank during the top dross removal treatment in a state where a strong centrifugal force acts on the molten metal, there is a risk that the molten metal will flow out in an excessive jet form. In order to prevent this, a control member is arranged at the opening of the molten metal outlet of the separation tank, and the outflow degree of the molten metal from this outlet is appropriately suppressed and controlled.

The bottom dross removal treatment is carried out by removing the bottom dross centrifugally separated while being pressed against the peripheral wall of the separation tank.
This can be achieved by continuously supplying the mixed liquid to the separation tank and storing it in order to overflow the molten metal separated from the bottom dross and collect it.However, the amount of bottom dross stored in the separation tank is set. When the value reaches the value, the rotation speed of the separation tank is reduced so that the effect of gravity acts more strongly on the accumulated bottom dross than the centrifugal force. It collapses and is dropped and discharged from the discharge port of the separation tank as it is.

In this bottom dross removing process, the upper surface of the partition wall and the upper surface of the bottom wall are formed as inclined surfaces, so that the falling discharge of the collapsed bottom dross from the discharge port is guided smoothly by the inclined surfaces. Will be.

When the bottom dross is accumulated in a state of being pressed against the peripheral wall of the separation tank, the bottom dross closes the opening formed between the partition wall and the peripheral wall, thereby discharging the bottom dross. Sometimes, the separated molten metal does not flow directly from the outlet through this opening, and if it flows out, it always flows out in the form of seeping through the bottom dross layer. Will contribute to the emission from

The inner tank is used for discharging the bottom dross by lowering the rotation speed of the separation tank, that is, when the centrifugal separation is not performed, until the discharge of the bottom dross is completed until the bottom dross discharge is completed. Store temporarily,
Prevents the liquid mixture from being wastefully discharged together with the bottom dross.

[0028]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show the basic configuration of the device of the present invention, in which the separation tank 1t for removing top dross in the separation tank 1 is placed on top and the separation tank 1b for removing bottom dross in the separation tank 1 is shown. For removing bottom dross from the separation bath 1t for removing top dross, that is, the plating bath M taken out by removing the top dross Dt from the separation tank 1t for removing bottom dross, that is, the mixed solution of the molten metal K and the bottom dross Db. The molten metal K is supplied to the separation tank 1b and continuously subjected to dross removal treatment to recover clean molten metal K from the bottom dross removal separation tank 1b.

In the separation tank 1t for removing top dross, a bottom plate 3t is connected to the lower end of a cylindrical wall 2t having a truncated cone shape whose inner peripheral surface is expanded downward, and an inner brim-shaped top plate 5t is provided at the upper end. An opening 6t is formed at the upper end portion in a continuous manner, and a constant gap is formed between the main body portion configured by opening a large number of outlets 4t at the peripheral edge of the bottom plate 3t and the opening end of the outlet 4t. And a control member 10 arranged to face each other.
Rotating shaft 9t having its center axis aligned with the center axis of the cylindrical wall 2t
The control member 10 is driven to rotate by the rotation shaft 9t with respect to the opening end of the outlet 4t of the main body that is driven to rotate.
It is possible to displace along the axis of.

In this top dross removing separation tank 1t,
The plating bath M, which is a mixed solution of the top dross Dt, the molten metal K, and the bottom dross Db, is continuously supplied from the opening 6t into the main body part that is being driven to rotate at high speed.
Is centrifuged from the molten metal K and the bottom dross Db,
As it is, it is overflowed and removed from the inside of the main body through the opening 6t.

On the other hand, the mixed liquid of the molten metal K and the bottom dross Db is taken out from the inside of the main body through the take-out port 4t, and the control member 10 is opposed to the take-out port 4t, and the control member 10 and the take-out port 4t. By forming a constant gap with the opening end, the flow passage area from the outlet 4t is regulated, so that the molten metal K and the bottom dross Db are removed.
The mixed solution of and is prevented from flowing out excessively by the action of centrifugal force.

Thus, the separation tank 1 for removing top dross
The amount of the mixed solution of the molten metal K and the bottom dross Db taken out from t is determined by adjusting the position of the control member 10 with respect to the opening end of the taking-out port 4t according to the amount of the plating bath M supplied and the composition of the plating bath M. Although properly achieved, the control member 10 not only controls the amount of take-out, but also rubs its surface with the bottom dross Db coming out together with the molten metal K from the take-out port 4t. The bottom dross Db is prevented from clogging the outlet 4t.

The fluidity of the bottom dross Db is far inferior to that of the molten metal K. However, the inner peripheral surface of the cylindrical wall 2t of the top dross removing separation tank 1t has a bottom plate 3t.
Since the taper surface is expanded toward the outlet 4t of the bottom dross Dt, the outlet 4t of the separated bottom dross Db is removed.
The move to is accomplished smoothly.

The lower bottom dross removing separation tank 1b for receiving the plating bath M, which is the mixed liquid of the molten metal K and the bottom dross Db taken out from the top dross removing separation tank 1t, has a bottomed linear cylindrical main body. And partition wall 7b
The main body is fixed to the rotating shaft 9b by the bottom wall 3b with the center axis of the peripheral wall 2b aligned with the center axis of the rotating shaft 9b, and is also a flat disk-shaped partition. Wall 7
b is fixed to the rotary shaft 9b while being located at the lower end of the main body.

The opening 6b formed by the inner flange-shaped top wall 5b provides an outlet for the separated clean molten metal K from the main body and an inlet for the plating bath M. In addition, the clean molten metal K formed with a relatively large diameter passes through the peripheral edge of the opening 6b,
In a state where the top wall 5b overflows, it is discharged and collected from the main body.

A large number of outlets 4b formed in the bottom wall 3b
Is located closer to the center side than the opening edge of the opening 6b so that the molten metal K does not flow unnecessarily from the discharge port 4b, and the bottom dross collapses when the rotation speed of the main body is reduced. In order to smoothly achieve the discharge of Db, the opening area is as large as possible.

On the contrary, the open portion 8b minimizes the amount of the molten metal K entering the lower end portion of the bottom dross removing separation tank 1b partitioned by the partition wall 7b.
It is made as small as possible within a range where the falling bottom dross Db can smoothly pass.

In the state shown in FIG. 1 in which the bottom dross removing separation tank 1b is rotated at a high speed to separate and collect clean molten metal K, the bottom dross Db is pressed against the inner peripheral surface of the peripheral wall 2b in a deposited state. However, as shown in FIG. 2, when the rotation speed of the bottom dross removing separation tank 1b is reduced, the effect of gravity becomes large, so the molten metal K contained in the separation tank 1b slightly reduces the effect. The bottom dross Db, which has fluidity, is in the form of flowing down and directly flows into the bottom wall 3
b, or from the partition wall 7b through the opening 8b, it collapses onto the bottom wall 3b, and is discharged from the discharge port 4b.

FIG. 3 shows a preferred embodiment of the bottom dross removing separation tank 1b, in which the upper surface of the partition wall 7b is an inclined surface having an inclination angle x, and the upper surface of the bottom wall 3b is an inclined surface having an inclination angle y. In addition, the bottom wall 3b has an inner flange shape, the entire central portion thereof is opened as a discharge port 4b, and the top wall 5b has a truncated conical trapezoid shape having a diameter reduced upward.

By making the upper surface of the partition wall 7b into an inclined surface, the bottom dross D collapsed on the partition wall 7b.
b rapidly moves to the open portion 8b, drops from the open portion 8b onto the bottom wall 3b, and by making the upper surface of the bottom wall 3b an inclined surface, the bottom dross Db that has dropped onto the bottom wall 3b is By the action of gravity, the bottom dross Db is smoothly moved toward the discharge port 4b, so that the discharge of the bottom dross Db from the main body portion is smoothly achieved.

According to many experiments, the tilt angle x is 10-2.
About 0 degrees is suitable, and the inclination angle y is about 30 to 60 degrees. The difference between the inclination angle x and the inclination angle y is that the main portion of the bottom dross removing separation tank 1b is slow,
Since it is rotating, a centrifugal force acts on the bottom dross Db, which is caused by the influence of this centrifugal force.

FIG. 4 shows another preferred embodiment of the bottom dross removing separation tank 1b, in which an internal tank 11 is provided above the partition wall 7b in the main body portion and continuously supplied during the bottom dross removing process. The incoming plating bath M is temporarily received so as not to mix with the molten metal K and the bottom dross Db that have already been separated, and the efficiency of centrifugal separation between the molten metal K and the bottom dross Db is prevented from decreasing. At the same time, the supplied plating bath M is prevented from being wastefully discharged together with the separated bottom dross Db.

Needless to say, it is necessary to keep the entire apparatus in the non-oxidizing atmosphere and keep the atmosphere at a temperature equal to or higher than the melting point of the molten metal.

[0044]

Since the present invention has the above-mentioned structure, it has the following effects. Since the centrifugally separated ones with a low specific gravity are removed or collected by using the overflow operation, it is possible to easily and reliably achieve the operation of separately taking out the centrifuged ones. Since this is done, the recovery of clean molten metal can be achieved easily, reliably and efficiently.

Removal of the top dross and recovery of the molten metal from the plating bath is accomplished by an overflow which can inevitably occur during the centrifugation operation.
All of the processing can be accomplished without requiring human labor, and thus, clean molten metal recovery and dross separation / removal can be safely achieved.

[Brief description of drawings]

FIG. 1 is an overall front view of a right half section of an embodiment of the present invention during a centrifugal separation operation, which is cut vertically.

FIG. 2 is an overall front view of the embodiment shown in FIG. 1 when bottom dross is discharged.

FIG. 3 is a front view in which the right half is longitudinally sectioned, showing another embodiment of the bottom dross removing separation tank in the present invention.

FIG. 4 is a front view in which the right half is longitudinally sectioned, showing still another embodiment of the bottom dross removing separation tank of the present invention.

[Explanation of symbols]

 1; Separation tank 1t; Separation tank for top dross removal 2t; Cylinder wall 3t; Bottom plate 4t; Outlet port 5t; Top plate 6t; Opening 9t; Rotating shaft 10; Control member 1b; Bottom dross removal separation tank 2b; Peripheral wall 3b; Bottom Wall 4b; Discharge port 5b; Top wall 6b; Opening portion 7b; Partition wall 8b; Opening portion 9b; Rotating shaft 11; Inner tank x; Partition wall upper surface inclination angle y; Bottom wall upper surface inclination angle M; Plating bath K; Molten metal Dt; Top dross Db; Bottom dross

Claims (11)

[Claims] 1. The top dross (Dt) is mixed with the molten metal (K) from a mixed liquid of the top dross (Dt) and the molten metal (K).
From the mixed solution of the top dross removing treatment for removing the top dross (Dt) by centrifugation from the bottom dross (Db) and the molten metal (K), the bottom dross (Db) is mixed with the molten metal (K ) From the bottom dross (Db)
Bottom dross removal treatment to remove the same plating bath
A dross removal method for removing dross (D) from a plating bath (M) by continuously applying it to (M). 2. A top dross removing treatment
Supply the mixed solution of (Dt) and molten metal (K) to the separation tank (1),
By the high-speed rotation operation of the separation tank (1), the top dross
(Dt) and molten metal (K) are centrifuged, and the top dross (Dt) is continuously supplied to the separation tank (1) by a mixed liquid of the top dross (Dt) and molten metal (K). The separation tank (1)
The method of claim 1 wherein the material is overflowed and removed.
The dross removal method described in. 3. A bottom dross removing process is performed.
Supply the mixed solution of (Db) and molten metal (K) to the separation tank (1),
The bottom dross is generated by the high speed rotation operation of the separation tank (1).
(Db) and molten metal (K) are separated by centrifugation, and the separated bottom dross (Db) is continuously fed to the separation tank (1) by a mixed liquid of the bottom dross (Db) and molten metal (K). ), The separated molten metal (K) is overflowed and collected, and if the amount of the bottom dross (Db) accumulated reaches the set value, the rotation speed of the separation tank (1) is reduced. The dross removing method according to claim 1, wherein the bottom dross (Db) is dropped and discharged by its own weight to be removed. 4. The top dross (D) is added to the plating bath (M).
The dross removing method according to claim 1, 2 or 3, wherein after performing a top dross removing process for removing t), a bottom dross removing process for removing bottom dross (Db) is performed. 5. A bottom plate (3t) is connected to the lower end of a cylindrical wall (2t), and an inner collar-shaped top plate (5t) is connected to the upper end of the cylinder wall (2t).
And a take-out port (4t) for taking out molten metal (K) is opened at the peripheral edge of the bottom plate (3t), and is driven to rotate with the central axis of the cylindrical wall (2t) as the axis of rotation. Melted separated from the top dross (Dt) by adjusting the gap between the main body part and the outside opening of the outlet (4t), and adjusting the gap between the opening edge of the outlet (4t). Separation tank for removing top dross consisting of a control member (10) for controlling the outflow amount of metal (K)
(1t), the bottom wall (3b) is connected to the lower end of the cylindrical peripheral wall (2b), and the inner flange-shaped top wall (5b) is connected to the upper end of the peripheral wall (2b). In the bottom wall (3b) portion located closer to the center than the opening edge of the opening (6b) formed by the wall (5b), the bottom dross (Db)
A discharge port (4b) for removal is opened, and a main part that is driven to rotate with the central axis of the peripheral wall (2b) as the axis of rotation and the top wall (5
It has an outer diameter larger than the inner diameter of b) and forms an open part (8b) between the inner peripheral surface of the peripheral wall (2b) and divides the inside of the main body into a lower end and other parts vertically. In order to do so, a dross removing device in combination with a bottom dross removing separation tank (1b) comprising a partition wall (7b) fixed to the lower end of the main body. 6. A cylindrical wall (2) of a separation tank (1t) for removing top dross.
The inner peripheral surface of t) is a tapered surface that expands downward.
The dross removing device described in 1. 7. The dross removing device according to claim 5, wherein the control member (10) of the top dross removing separation tank (1t) is displaceable along the axis of rotation. 8. An upper surface of the partition wall (7b) of the bottom dross removing separation tank (1b) is an inclined surface which is inclined downward toward the peripheral wall (2b) at an inclination angle (x), and the bottom wall (3b) is also formed. 8. The dross removing device according to claim 5, 6 or 7, wherein an upper surface of the dross is an inclined surface which is inclined downward toward the discharge port (4b) at an inclination angle (y). 9. The inclination angle (x) of the upper surface of the partition wall (7b) is 10
The angle of inclination of the upper surface of the bottom wall (3b) as well as from 20 to 20 degrees
The dross removing device according to claim 8, wherein (y) is set to 30 to 60 degrees. 10. A bottomed cylindrical inner tank (11) for temporarily receiving the plating bath (M) is provided above the partition wall (7b) in the main body of the bottom dross removing separation tank (1b). 7. The center axis of the internal tank (11) is provided so as to match the axis of rotation.
Alternatively, the dross removing device according to 7 or 8. 11. A molten metal (K) taken out from the top dross removing separation tank (1t), wherein a bottom dross removing separation tank (1b) is arranged below the top dross removing separation tank (1t).
The dross removing device according to claim 5, 6 or 7 or 8 or 10, wherein a mixed liquid of the water and the bottom dross (Db) is directly supplied to the lower separation tank (1b) for removing bottom dross.