JP3034958B2 - Method and apparatus for holding molten metal - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method and an apparatus for holding a molten metal and a hot-dip plating apparatus using the same.

BACKGROUND ART In equipment for plating a molten metal, such as zinc or aluminum, which is a conductive liquid, through a material to be plated, the molten metal is held, for example, by a method shown in Japanese Patent Application Laid-Open No. 4-356. According to this method, an opening provided at a lower portion of an aerial pot is formed of a molten metal and a material having poor wettability, and the molten metal in the aerial pot is held by utilizing the surface tension of the molten metal. In this method, there is a limit in increasing the height of the retained molten metal.

As a means to increase the height of the molten metal that can be held,
Japanese Patent Laid-Open Publication No. 63-109148 discloses a technique in which a pressure chamber is provided below a container for storing molten metal. In this method, a pressure chamber is provided so as to be connected to an opening at a lower portion of the container, and the pressure in the pressure chamber is increased to increase the holding height of the molten metal.

However, according to the disclosure in Japanese Patent Application Publication No. 63-109148, even if the pressure of the molten metal at the opening (by gravity) and the gas pressure in the pressure chamber are statically balanced, the gas and Due to the difference in density with the molten metal, a problem arises in that the gas enters the molten metal as bubbles and rises.

When plating a material by passing the material through the molten metal, in order to obtain good quality plating, it is desirable that the height of the molten metal be kept large and constant, and that no bubbles or the like be present in the molten metal. It is.

An object of the present invention is to enable a molten metal to be held at a predetermined height in a container having an open lower part.

Another object of the present invention is to prevent bubbles from being generated in the molten metal.

Another object of the present invention is to enable hot-dip plating with good quality.

DISCLOSURE OF THE INVENTION The present invention provides a magnetic field forming means for forming a horizontal magnetic field on the lower surface of the molten metal in order to hold the molten metal in a container by electromagnetic force, and a part of an eddy current generated in the molten metal is outside the molten metal. And a conductive block configured to pass through. The conductive block includes a block portion provided at a location where a horizontal magnetic field formed by the magnetic field forming means changes abruptly, and a connecting portion connecting the block portions outside the molten metal.

According to the present invention, the molten metal in the container is held by the electromagnetic force of the horizontal magnetic field formed by the magnetic field forming means. A part of the eddy current generated in the molten metal is guided to the conductive block and passes outside the molten metal. Therefore, the amount of current flowing in the molten metal is reduced, and the downward force acting on the molten metal can be reduced. Further, since the amount of current flowing in the molten metal is reduced, the temperature rise of the molten metal due to Joule heat can also be suppressed. Therefore, the height of the molten metal can be maintained higher than when there is no conductive block.

Further, the present invention is the molten metal holding device, further comprising a pressure chamber for holding a gas for applying pressure to a bottom surface of the molten metal, below the container.

The present invention also provides a container that accommodates a molten metal, and a lower portion provided with an opening for passing a material, and is disposed at a lower portion of the container, and forms a horizontal magnetic field on a lower surface of the molten metal. An electromagnet, a block provided near the end of the core of the electromagnet in the container, and a conductive block including a connecting portion connecting these blocks outside the molten metal; and the container. And a pressure chamber which is provided connected to a lower part of the molten metal and accommodates a gas for applying pressure to the bottom surface of the molten metal.

According to the molten metal holding device of the present invention, the molten metal in the container is held in the container by the electromagnetic force and the pressure applied to the bottom surface. Further, a Lorentz force in a direction opposite to the gravitational acceleration is generated in the vicinity of the bottom surface of the conductive liquid in the container by the magnetic field generating means, and the apparent gravitational acceleration can be directed upward. When the gas tries to enter the molten metal, the force due to the difference in density between the gas and the molten metal becomes downward, and the gas does not rise as bubbles in the molten metal. Therefore, a stable molten metal height can be maintained by increasing the gas pressure in the pressure chamber.

Further, the present invention provides a container provided with an opening at the bottom surface, in which molten metal is stored, and a horizontal portion below the molten metal to hold the molten metal by applying an electromagnetic force to the molten metal in the container. Magnetic field forming means for forming a magnetic field, in the container, a block portion is provided at a location where the horizontal magnetic field formed by the magnetic field forming means changes abruptly, and a conductive block for guiding an eddy current through outside the molten metal, A molten metal holding device comprising: a molten metal inlet and an outlet provided in the container outside the opening and inside the block of the conductive block.

According to the present invention, not only the molten metal can be held in the container by the electromagnetic force, and a part of the eddy current generated in the molten metal can be guided to the outside of the molten metal, but also the inlet for supplying the molten metal to the container. Since the outlet for discharging the molten metal from the container is provided outside the opening and inside the block of the conductive block, the molten metal flows without being hindered by the block, and the molten metal that has generated Joule heat is discharged. Can be circulated.

In the molten metal holding device having the above-described configuration, by disposing a conductive block at the end of the core where the magnetic flux density changes suddenly, it is possible to prevent generation of a flow (vortex) due to electromagnetic force when a liquid is present here. Can be. Further, by providing the opening of the container inside sufficiently away from the conductive block, the flow velocity component in the vertical direction at the opening can be reduced, and the molten metal can be stably held in the air. . By providing an entrance for molten metal inside the conductive block (opening side), the molten metal that has generated Joule heat at the expense of electromagnetic force is discharged to the outside of the core without obstructing the flow in the block, and cooled. After that, it can be circulated again from the inlet to the inside of the core.

Further, the present invention provides a container in which molten zinc is stored as molten metal, and a steel strip is continuously passed above a lower opening, and the molten zinc is held to hold the molten zinc in the container by electromagnetic force. A hot-dip galvanizing apparatus, comprising: a magnetic field forming means for forming a horizontal magnetic field below zinc; and a conductive block configured so that an eddy current generated in the molten zinc passes outside the molten zinc. is there.

The conductive block includes a block portion provided at a location where a horizontal magnetic field formed by the magnetic field forming means changes abruptly, and a connecting portion connecting the block portions outside the molten zinc. A pressure chamber for holding a gas for applying pressure to the bottom surface of the molten zinc in the container is provided below the container.

In order to hold the molten zinc of sufficient height (amount) required for plating in the container, the eddy current is applied to the position between the core ends of the electromagnets where the magnetic flux density changes suddenly and eddies flow in the molten zinc. A block portion of the conductive block for flowing is arranged.
Further, the opening of the container is provided inside the block of the conductive block away from the block to reduce the vertical component of the flow that hinders the stable holding of the molten zinc. Furthermore, in order to control the temperature of the molten metal within the control limits required for plating quality, and to forcibly circulate the molten zinc near the opening where the temperature rises due to Joule heat, the inlet pipe and the outlet pipe are connected to the conductive block. Provided on the inner container side wall.

According to the present invention, the height and temperature of the molten zinc in the container can be appropriately maintained, so that zinc plating of stable quality can be performed.

Further, the present invention provides a heat treatment apparatus for performing a heat treatment on a steel strip,
The coating apparatus includes a plating apparatus that performs hot-dip galvanizing on the steel strip that has passed through the heat treatment apparatus, and an alloying apparatus that performs an alloying process on the steel strip that has been plated by the plating apparatus. A container through which the steel strip is continuously passed above the lower opening, magnetic field forming means for forming a horizontal magnetic field below the molten zinc in the container, and eddy current generated in the molten zinc And a conductive block configured to pass outside the zinc.

Further, the present invention is a method of holding a molten metal in a container having an opening at a lower portion, wherein a horizontal magnetic field is formed below the molten metal to cause an electromagnetic force to act on the molten metal to form the molten metal. While holding in the air, a part of the eddy current generated in the molten metal is guided outside the molten metal to reduce the downward force acting on the molten metal and to suppress the generation of Joule heat. It is a feature.

The present invention also provides a horizontal magnetic field formed below the molten zinc in order to hold the molten zinc in which the steel strip passes continuously from below to above in the container, and reduces the eddy current generated in the molten zinc. A hot-dip galvanizing method, wherein the part is guided outside the hot-dip zinc.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a plating facility provided with a molten metal holding device.

FIG. 2 is a schematic view of a plating apparatus which is a holding apparatus for molten metal.

FIG. 3 is a side view, partially in section, of a molten metal holding device according to an embodiment of the present invention.

 FIG. 4 is a view on arrow A in FIG.

FIG. 5 is a view of the molten metal holding device shown in FIG. 3 when viewed from the arrow B (from below) and from the arrow C (from above).

 FIG. 6 is a perspective view of an example of the conductive block.

FIG. 7 is an explanatory diagram showing the flow of current in the conductive block.

FIG. 8 is an explanatory diagram showing generation of eddy current when there is no conductive block.

FIG. 9 is a longitudinal sectional view of a molten metal holding device according to another embodiment of the present invention.

FIG. 10 is an explanatory diagram of the operation and effect of the device shown in FIG.

FIG. 11 is an explanatory diagram of the operation and effect of the device shown in FIG.

FIG. 12 is a longitudinal sectional view of a molten metal holding device according to still another embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment First, a continuous plating facility as an example to which the present invention is applied will be described. In FIG. 1, a steel strip 8 which is a material to be plated unreeled from a dispensing device (not shown).
First, pretreatment such as cleaning and degreasing is performed in a plating pretreatment facility 60, and then passes through an annealing furnace 61 composed of a heating zone, a soaking zone, and a cooling zone, and then is turned upward by a guide drum 35. Then, the plating enters the plating apparatus 70, where plating is performed.
The plated steel strip 8 is adjusted to a predetermined plating amount by a plating film thickness adjusting device 62, and then cooled by a cooling device 63.
After the direction is changed in the horizontal direction by the guide drum 36, it is taken up by a take-up device (not shown). In addition, this equipment
An alloying furnace is provided between the plating film thickness adjusting device 62 and the cooling device 63.
64 may be provided.

As shown in FIG. 2, the plating apparatus 70 stores a molten metal (molten zinc) 2 as a metal to be plated in a container 1. The molten metal 2 is supplied from a storage tank 53 for storing and controlling the temperature through a supply pipe 51 by an electromagnetic pump 54, and the molten metal 2 in the container 1 is returned to the storage tank 53 by gravity through a discharge pipe 52. Has become.

Next, a plating apparatus 70 to which the present invention is applied is shown in FIGS.
It will be described based on.

A central portion in the width direction of the bottom of the container 1 for holding the molten metal (conductive liquid) 2 constituting the plating bath is a downwardly projecting portion 1a, and the central portion of the projecting portion 1a A slit-shaped opening 3 for passing a steel strip 8 as a material is formed. Electromagnetic cores 11 are provided on both sides of the protrusion 1a so as to be in contact with the side surface of the protrusion 1a and the bottom surface of the container 1, respectively. In FIG. 5, a portion 11a indicated by a broken line is an end of the core 11. Although not shown, a coil is wound around the core 11, and an AC power supply is connected to the coil.

A conductive block 12 is provided in the container 1. The conductive block 12 is, as shown in FIG.
12a, and a connecting portion 12b that connects the block portions 12a to each other at an upper portion thereof. The reason why the connecting portion 12b is divided into two is that it is necessary to secure a space through which the steel strip 8 passes in the central portion. In this embodiment, the connecting portion 12b is formed not only in a frame shape but also as a lid of the container 1.

The conductive block 12 is arranged along the opposing inner wall surface of the container 1 so that the block portion 12a is located at a position where the horizontal magnetic field generated by the electromagnet suddenly changes, that is, between the end portions 11a of the core 11, and the lower end thereof. It is provided in a state fitted in the protruding portion 1a. The opening 3 at the bottom of the container 1 through which the steel strip 8 passes.
Is located inside the conductive block 12 away from the block portion 12a.

A connection part that also serves as a lid of the container 1 in the conductive block 12
An opening 13 for passing a steel strip 8 as a material to be plated is provided in a central portion (a portion corresponding to the opening 3) of 12b.

The block portion 12 of the conductive block 12 is
near the opening 3 and near the opening 3 of the molten metal 2.
And an outlet pipe 15 are provided. Inlet pipes 14 and outlet pipe 15
Are arranged substantially opposite to each other. The supply pipe 51 is connected to the inlet pipe 14, and the discharge pipe 52 is connected to the outlet pipe 15.
Is connected.

In the molten metal holding device having such a configuration, the inlet pipe 14
The molten metal flowing into the vessel 1 from the container is stably held in the opening 3 by the horizontal magnetic field and the electromagnetic force generated by the induced eddy current I, and the molten metal 2 that has generated Joule heat passes through the outlet pipe 15 without leaking. It is discharged outside. The molten metal 2 cooled outside the system is again supplied from the inlet pipe 14 to the vessel 1.
Supplied within. 3 and 4, a portion indicated by 17 is a portion where Joule heat is generated.

As shown in FIG. 8, when an alternating magnetic field is applied to the molten metal 2 in the container 1, an eddy current I is generated, and forces F ₁ and F ₂ are generated from the eddy current I and the alternating magnetic field according to Fleming's law. At this time, the force F ₂ is a force directed downward due to the direction of the eddy current is reversed. Therefore, the force F for holding the molten metal 2
Becomes F ₁ −F ₂ , and it is necessary to apply an extra current, that is, an alternating magnetic field, to supplement the force corresponding to F ₂ . The molten metal 2 is further heated by Joule heat due to the extra current.

However, in the present invention, as shown in FIG. 7, the conductive block 12 is disposed in the container 1 to form a closed circuit that passes outside the molten metal 2, so that a part of the eddy current flows outside the molten metal 2. to flow, it does not occur downward force F _2. Therefore, it is possible to reduce the current flowing through the molten metal 2 by a current amount corresponding to F _2, heating is also reduced due to Joule heat. That is, the rise in the temperature of the molten metal 2 can be suppressed, and the molten metal 2 having a sufficient height can be held.

Further, since the inlet pipe 14 and the outlet pipe 15 of the molten metal 2 are provided inside the block section 12a of the conductive block 12 and outside the opening section 3, the core section 11 is not hindered by the block section 12a. The molten metal 2 that has generated Joule can be circulated. As a result, the molten metal 2 can be maintained outside the core 11 without disturbing the stable maintenance of the molten metal 2.
Can be cooled, and the temperature of the molten metal 2 can be maintained at an optimum temperature for maintaining plating quality.

Further, as described above, the block portion of the conductive block 12
By arranging 12a between the ends 11a of the core 11 where the magnetic flux density changes greatly, it is possible to prevent the generation of a vortex that hinders the stable holding of the molten metal 2, and to generate the molten metal 2 with Joule heat. Since it can be cooled outside, even if the eddy current I due to the core 11 is increased, the temperature of the molten metal 2 is kept within the control limit required for plating quality, and the height of the molten metal 2 is maintained as required for plating. Can be.

Second Embodiment In FIG. 9, a rectangular opening 20 for passing a steel strip 8 to be plated is formed at the bottom of a container 1 for storing a molten metal 2 such as zinc or aluminum as a molten metal. The opening 20 is extended downward by an opening forming portion 20a integrally connected to the container 1. Opening forming part 2
The cross-sectional shape (shape viewed from a plane) of 0a is a rectangle. A pressure chamber 21 is connected to a lower end of the opening forming part 20a. At the lower end of the pressure chamber 21, a slit 22 for passing the steel strip 8 is formed. The pressure chamber 21 is provided with piping and gas supply means for supplying gas,
The gas pressure in 21 is to be regulated. Note that gas supply means and the like are the same as those in the related art, and are omitted in the drawings.

A coil 23 is provided outside the opening forming part 20a as a magnetic field generating means. Power supply means (not shown) is connected to the coil 23. That is, an electromagnet is configured using the opening forming portion 20a as an iron core.

In such an apparatus, when an electric current is applied to the coil 23 and an alternating magnetic field is applied to the opening 20a near the bottom of the molten metal 2, an electromagnetic force (Lorentz force) F is applied to the molten metal 2 in a direction opposite to the direction of gravity G. Occurs. The pressure distribution inside the molten metal 2 at this time is as shown in FIG. 10, and the bottom surface of the molten metal ₂ is balanced with the gas pressure p ₂ in the pressure chamber 21.
p ₁ is a pressure acting on the liquid surface of the molten metal 2.

In this state, even if the gas bubbles 24 try to enter the molten metal 2, a downward force acts on the gas bubbles 24 as shown in FIG. Obviously you can't. Therefore, by increasing the gas pressure, the position of the lower surface 2a of the molten metal 2 is raised, and the height of the molten metal 2 can be increased.

In the above embodiment, the coil 23 is employed as the magnetic field generating means to generate a horizontal magnetic field.However, a facing linear motor may be employed to generate a moving magnetic field so that the Lorentz force acts. Good.

Third Embodiment In FIG. 12, a central portion in the width direction of the bottom of a container 1 holding a molten metal (molten zinc) 2 constituting a plating bath is a projection 1a projecting downward, and the projection 1a is formed. An opening 3 for passing a steel strip 8 as a material to be plated is formed in the central portion of the opening 3. Electromagnetic cores 11 are provided on both sides of the protrusion 1a so as to be in contact with the side surface of the protrusion 1a and the bottom surface of the container 1, respectively. A coil is wound around the core 11, and an AC power supply is connected to the coil.

A conductive block 12 is provided in the container 1 similarly to the embodiment shown in FIGS. As shown in FIG. 6, the conductive block 12 is composed of opposing block portions 12a and a connecting portion 12b that connects the block portions 12a to each other at an upper portion thereof. The reason why the connecting portion 12b is divided into two portions is that it is necessary to secure a space through which the steel strip 8 passes in the central portion. In this embodiment, the connecting portion 12b is formed not only in a frame shape but also as a lid of the container 1.

Further, the conductive block 12 is arranged along the opposed inner wall surface of the container 1 so that the block portion 12a is located between the ends of the core 11 where the horizontal magnetic field by the electromagnet suddenly changes, and the lower end is formed in the projecting portion. It is provided in a state fitted in 1a.
Connecting part 12 also serving as lid of container 1 in conductive block 12
An opening 13 for passing a steel strip 8 as a material to be plated is provided in a central portion of b (a portion corresponding to the opening 3). Block portion of the conductive block 12 on the side of the container 1
In the vicinity of the opening 12a and near the opening 3, an inlet pipe 1 for the molten metal 2 is provided.
4 and an outlet pipe 15 are provided. Inlet pipes 14 and outlet pipe 1
5 are arranged substantially facing each other. Other configurations are the same as those shown in FIGS.

A pressure chamber 21 is formed by connecting to the protruding portion 1a at the bottom of the container 1. At the lower end of the pressure chamber 21, a slit 22 for passing the steel strip 8 is formed. In the pressure chamber 21,
Piping and gas supply means for supplying gas are provided,
The gas pressure in the pressure chamber 21 is adjusted.
Note that gas supply means and the like are the same as those in the related art, and are omitted in the drawings.

In this molten metal holding device, the molten metal 2
Is maintained by both the horizontal magnetic field generated by applying a current to the coil, the electromagnetic force generated by the induced eddy current, and the pressure applied from the inside of the pressure chamber 21 to the bottom surface. And
Since a part of the generated eddy current flows through the conductive block 12, the force acting downward on the molten metal 2 is reduced (see FIGS. 7 and 8), and the amount of current holding the molten metal 2 is reduced. In addition, heat generation of the molten metal 2 due to Joule heat can be suppressed. Further, gas can be prevented from entering the molten metal 2 as bubbles.

──────────────────────────────────────────────────続 き Continued on the front page (72) Noriyuki Kawada, Inventor 4-62-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd. Hiroshima Research Laboratory (72) Inventor Yasuo Fukada 4-chome, Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture No. 6-22 Mitsubishi Heavy Industries, Ltd.Hiroshima Works (72) Inventor Chiaki Kato 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Engineering Co., Ltd.Technical Research Laboratory (72) Inventor Toshitane Matsukawa Kawasaki, Chuo-ku, Chiba-shi No. 1, Kawasaki Steel Corporation Chiba Works (56) References JP-A-7-145940 (JP, A) JP-A-63-317656 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , (DB name) C23C 2/00-2/40

Claims (9)

(57) [Claims] A magnetic field forming means for forming a horizontal magnetic field on a lower surface of the molten metal so as to hold the molten metal in the container by an electromagnetic force; and a magnetic field forming means provided at a location where the horizontal magnetic field formed by the magnetic field forming means changes abruptly. And a conductive block including a connecting portion that connects the block portion outside the molten metal, wherein an eddy current generated in the molten metal passes through the block portion and the connecting portion of the conductive block. A molten metal holding device, wherein the molten metal passes through the outside of the molten metal. 2. The molten metal holding device according to claim 1, further comprising a pressure chamber connected below the container and holding a gas that applies pressure to a bottom surface of the molten metal in the container. 3. A container for accommodating a molten metal, and a lower portion provided with an opening for letting a material pass therethrough, and disposed at a lower portion of the container to form a horizontal magnetic field on a lower surface of the molten metal. An electromagnet, a block provided in the vicinity of the end of the core of the electromagnet in the container, and a conductive block including a connecting portion that couples these blocks outside the molten metal; and A pressure chamber which is provided connected to a lower portion and accommodates a gas for applying pressure to a bottom surface of the molten metal; 4. A container in which an opening is provided in the bottom surface and in which molten metal is stored, and a horizontal magnetic field is provided below the molten metal to hold the molten metal by applying an electromagnetic force to the molten metal in the container. Magnetic field forming means for forming a; a block portion is provided at a location in the container where the horizontal magnetic field formed by the magnetic field forming means changes abruptly; and a conductive block for guiding an eddy current through outside the molten metal; A molten metal holding device, comprising: an inlet and an outlet for the molten metal provided in the container outside the opening and inside the block of the conductive block. 5. A container in which molten zinc is stored as molten metal, and a steel strip is continuously passed above a lower slit, and said molten zinc is retained in said container by an electromagnetic force. A magnetic field forming means for forming a horizontal magnetic field at a lower portion, a block portion provided at a location where the horizontal magnetic field formed by the magnetic field forming portion changes suddenly, and a conductive portion comprising a connecting portion for joining the block portions outside the molten metal A hot-dip galvanizing apparatus, comprising: a conductive block; and an eddy current generated in the hot-dip zinc passes outside the hot-dip zinc by passing through the conductive block. 6. The hot-dip galvanizing apparatus according to claim 5, further comprising a pressure chamber connected below the container and holding a gas for applying pressure to a bottom surface of the molten metal in the container. 7. A heat treatment apparatus for performing heat treatment on a steel strip, a plating apparatus for performing hot-dip galvanizing on a steel strip passed through the heat treatment apparatus, and an alloy for performing alloying treatment on the steel strip plated by the plating apparatus. And a plating apparatus, wherein the plating apparatus stores molten zinc, and a container through which a steel strip is continuously passed above an opening in the lower part, and forms a horizontal magnetic field below the molten zinc in the container. Magnetic field forming means, and a conductive block provided at a location where a horizontal magnetic field formed by the magnetic field forming means changes suddenly, and configured so that an eddy current generated in the molten zinc passes outside the different molten zinc. Continuous galvanizing equipment characterized by the following. 8. A method for holding a molten metal in a container having an opening at a lower portion, wherein a horizontal magnetic field is formed below the molten metal to cause an electromagnetic force to act on the molten metal so that the molten metal is held in the air. And a part of the eddy current generated in the molten metal is provided at a location where the horizontal magnetic field changes suddenly,
In addition, a method of holding a molten metal, in which a block portion connected outside the molten metal passes through the outside of the molten metal to reduce a downward force acting on the molten metal and suppress generation of Joule heat. 9. A horizontal magnetic field is formed below the molten zinc in a container having an opening at the bottom to apply an electromagnetic force to the molten zinc to hold the molten zinc without leaking from the opening of the container. A hot-dip galvanizing apparatus in which a steel strip is continuously passed from below to above the container via the opening, wherein a coil to which an AC power supply is connected to form a horizontal magnetic field below the molten zinc is provided. The container has a wound core, and the container has a central portion in the width direction serving as a protruding portion that protrudes downward over the length direction of the container. A block formed with a slit-like opening through which the horizontal magnetic field formed by the core is fitted to both ends of the projecting portion of the container corresponding to the end of the core where the horizontal magnetic field suddenly changes. Department and these A galvanizing block comprising a conductive block formed of a connecting portion for joining the outer portions of the molten zinc to the outside of the molten zinc, and a device for circulating the molten zinc in the container outside the container. apparatus.