JPS6359074B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for stirring molten metal stored in a melting furnace.

A typical prior art is disclosed in Japanese Patent Application Laid-Open No. 56-23218. In this prior art, the lower end of a vertically extending refractory cylinder is immersed in molten metal stored in a ladle, and the gas pressure in the cylinder is varied to move the molten metal in the ladle into the cylinder. The ladle is configured to flow into and out of the ladle, thereby stirring the molten metal in the ladle.

In such prior art, since a refractory cylinder is provided directly above the molten metal stored in the ladle, after the molten metal flows into the cylinder, the molten metal inside the cylinder is When returning the metal to the ladle, there is a risk that the molten metal in the ladle may splash and scatter outside the ladle. Therefore, it is dangerous.

In addition, in this prior art, the upper end surface of the molten metal that has flowed into the cylinder comes into contact with the refractory cylinder near the upper end, and solidifies there, resulting in a small flow passage cross-sectional area near the upper end of the cylinder. This may eventually lead to blockage. Therefore, continuous operation becomes impossible.

An object of the present invention is to provide a molten metal stirring device that can smoothly stir the molten metal in a melting furnace and can be operated continuously for a long period of time.

The present invention extends vertically outside the melting furnace 1, is installed below the surface 8 of the molten metal 5 stored in the melting furnace 1, and rises upward from near a corner of the melting furnace 1. a riser pipe 10, a vacuum source 20, and an upper end of the riser pipe 10 connected to the vacuum source 20;
Alternatively, a switching valve 18 that sets the pressure to atmospheric pressure, and electric heaters 31 and 66 that heat the inner surface near the upper end of the riser pipe 10 to a temperature higher than the melting point of the molten metal. It is a stirring device.

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention,
FIG. 2 is a horizontal sectional view thereof. In the melting furnace 1,
Burner 2 is installed. As a result, the ingots or scraps charged from the input preheating chambers 3, 4 are melted as indicated by reference numeral 5. This molten metal 5 is taken out from the takeout port 6.

A riser pipe 10 is installed near a corner of the melting furnace 1 below the surface 8 of the molten metal 5 in the melting furnace 1 . This riser 10 extends vertically outside the melting furnace 1 . At the upper end 11 of the riser pipe 10,
An inspection window 62 is provided. This upper end portion 11 is connected to a protection tank 13 via a conduit 12 . Protective tank 13 is connected to filter 16 via duct 14 and valve 15 . The filter 16 is
It is connected to a three-way switching valve 18 via a conduit 17. The three-way switching valve 18 connects the pipe line 17 to the pipe line 19.
or connect line 17 to line 21 via a vacuum source 20 . Ducts 22 and 23 that guide exhaust gas from the melting furnace 1 are connected to the input preheating chambers 3 and 4. These ducts 22, 23 are led to a stack 25 via a duct 24 and vented to the atmosphere. Pipe line 21 is communicated with the atmosphere. protection tank 1
3 prevents a part of the molten metal 5 sucked into the riser 10 from flowing through the pipe 12 and erroneously flowing into the pipe 14 and beyond, thereby protecting subsequent equipment.

FIG. 3 is an enlarged sectional view of the riser 10. Molten metal inlet 68 to riser pipe 10 of melting furnace 1
is formed in a circular shape, but need not be limited to a circular shape; it may be an ellipse or other shape that is elongated in the horizontal direction (perpendicular to the plane of the paper of FIG. 3) and becomes circular at the bottom 69 of the riser 10. may be formed. The inner wall of this riser pipe 10 is lined with a silicon carbide refractory 65 containing silicon nitride bonds or silicon oxynitride bonds. The composition of the silicon carbide refractory 65 is, for example, 78.0% by weight of silicon carbide, 3.0% by weight of silicon dioxide, 0.4% by weight of ferric oxide, silicon nitride (Si ₃ N ₄ ), and silicon oxynitride (Si ₂ ON _{2 )} . ) total 18.0
Weight%. The outside of this silicon carbide refractory 65 is surrounded by a heat insulating material 28 made of ceramic, for example. A heat insulating material 2 is provided at the upper end of the riser pipe 10.
An electric heater 31 is provided surrounding 8. This electric heater 31 is energized with electric power, and the inner temperature of the portion of the heat insulating material 28 surrounded by the electric heater 31 is
Temperature higher than the melting point of molten metal, e.g. 650 ~
Heat to 750℃. As a result, the riser 10
This prevents the molten metal sucked in from solidifying near the surface 32 where it reaches. An electric heater 66 is also provided below the electric heater 13 and coaxially with the riser pipe 10 over its entire circumference and length. This electric heater 66 is also energized with electric power in the same way as the electric heater 31, and the electric heater 66
6 is heated to a temperature higher than the melting point of the molten metal. This prevents the molten metal in the riser 10 from solidifying. The outside of the electric heaters 31 and 66 is a heat insulating material 2.
9, and the outside thereof is further covered with an outer skin 30 made of iron or the like. The heat insulating material 29 is made of castable refractory material such as alumina cement.

In this way, the heating means includes electric heaters 31 and 66 coaxially with the riser pipe 10 over its entire circumference and length.
However, the heating means includes an electric heater 3 at the upper end of the riser pipe 10 as described above.
1, and instead of the electric heater 66 below the riser 10, it may be configured to supply high-temperature gas higher than the melting point of the molten metal coaxially with the riser 10 over its entire circumference and length.

When the pipes 17 and 19 are connected through the three-way switching valve 18, the pressure in the pipe 12 is low and the molten metal 5 in the melting furnace 1 is sucked into the riser pipe 10. The surface of this sucked molten metal 5 in the riser 10 is near the reference numeral 32, as clearly shown in FIG. Thereafter, the three-way switching valve 18 is operated to connect the pipe line 17 to the pipe line 21. Therefore, air at atmospheric pressure and room temperature is introduced into the pipe line 12 via the pipe line 21 that communicates with the atmosphere. This ambient temperature air at atmospheric pressure is guided into the riser 10 as the molten metal in the riser returns to the melting furnace 1 under its own weight. Since the molten metal falls under its own weight in this way, the structure is simple. As the molten metal in the riser 10 returns to the melting furnace 1, the molten metal in the melting furnace 1 is rotated and stirred as shown by the arrow 33 in FIG. Although the riser pipes 10 are provided near the corners of the melting furnace 1, they may be provided at other positions.

FIG. 4 is a sectional view showing a specific configuration of the three-way switching valve 18. A valve body 35 is housed in the valve box 34 . Valve rod 3 fixed to this valve body 35
6 is driven to reciprocate in its axial direction (vertical direction in FIG. 4) by a pneumatic cylinder 37 controlled by a control device 40 shown in FIG. When the pneumatic cylinder 37 is extended and the valve body 35 is in the state shown in the fourth figure, the pipe line 17 is connected to the valve chamber 60.
The molten metal 5 is communicated with the pipe line 19 through the riser pipe 10, and the molten metal 5 is sucked into the riser pipe 10. When the pneumatic cylinder 37 is contracted, thereby keeping the valve body 35 in the position indicated by the phantom line 38, the line 17 is communicated with the line 21 via the valve chamber 60 and connected to the riser 10. Air at atmospheric pressure and room temperature is supplied. Of course, this three-way switching valve 18 may be realized by other configurations.

In the embodiments described above, the upper end of the riser pipe 10 was configured to be supplied with air at atmospheric pressure and at room temperature, but in other embodiments of the present invention, the riser pipe 10 may be supplied with heated air or air. The exhaust gas from the duct 24 may be supplied at atmospheric pressure. By supplying exhaust gas, oxidation of the molten metal is suppressed and blockage of the riser pipe is prevented.

As described above, according to the present invention, when the molten metal sucked into the riser pipe is returned to the melting furnace, gas is supplied to the upper end of the riser pipe at atmospheric pressure, so that the molten metal falls under its own weight. This makes it possible to stir the inside of the melting furnace, and the melting furnace can be stirred with a simple configuration.

In particular, according to the present invention, the riser pipe 10 extending vertically outside the melting furnace 1 is located below the surface 8 of the molten metal 5 stored in the melting furnace 1 and from near the corner of the melting furnace 1. It is installed upwards.
Therefore, when the molten metal that has flowed into the riser pipe 10 is returned to the melting furnace 1, the molten metal flowing out from the riser pipe 10 flows from the corner of the melting furnace 1 into the melting furnace 1.
It flows inside under its own weight. Therefore, the molten metal in the melting furnace 1 is stirred by rotating in a horizontal plane. Therefore, the molten metal is prevented from scattering, the molten metal can be stirred smoothly, and safety is improved.

Furthermore, in the present invention, the inner surface near the upper end of the riser 10 is heated by the electric heaters 31 and 66 to a temperature higher than the melting point of the molten metal, so that the molten metal flows into the riser 10. This prevents the upper end of the molten metal from solidifying and adhering to the inner surface near the upper end of the riser pipe 10. This makes it possible to continue continuous operation for a long period of time.

[Brief explanation of drawings]

1 is a longitudinal cross-sectional view of one embodiment of the present invention, FIG. 2 is a cross-sectional view thereof, FIG. 3 is an enlarged cross-sectional view of the riser pipe 10, and FIG. 4 is a cross-sectional view of the three-way switching valve 18. 1... Melting furnace, 5... Molten metal, 10... Rise pipe, 18... Three-way switching valve, 20... Vacuum source,
31, 66...electric heater, 37...pneumatic cylinder.

Claims (1)

[Scope of Claims] 1. Extending vertically outside the melting furnace 1 and rising from the vicinity of a corner of the melting furnace 1 below the surface 8 of the molten metal 5 stored in the melting furnace 1. a riser pipe 10, a vacuum source 20, and an upper end of the riser pipe 10 connected to the vacuum source 20;
Alternatively, a switching valve 18 that sets the pressure to atmospheric pressure, and electric heaters 31 and 66 that heat the inner surface near the upper end of the riser pipe 10 to a temperature higher than the melting point of the molten metal. Stirring device.