JP2000169908A - Electric furnace provided with device for blowing gas to hearth - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a pipe for gas ejection from being clogged, and to easily and inexpensively recover a metal of low melting point by installing a metallic plate having a plurality of gas holes and provided with a plurality of hole to recover the metal of low melting point in its periphery on a hearth plate so as to cover an opening formed in the hearth of an electric furnace. SOLUTION: A hearth of an electric furnace is provided with an opening 10a for blowing the stirring gas and discharging the metal of low melting point such as lead contained in a molten metal. A stirring gas blowing device 12 provided with a gas inlet pipe 12a to be communicated with the opening, and a low melting point metallic trap 13 integrated therewith are fitted to the outside of the opening 10a, and a semi- spherical metallic plate 11 is installed on an electric furnace hearth plate 10 so as to cover the trap inside thereof. A plurality of gas holes 11a to eject the stirring gas is formed in the metallic plate 11, a plurality of holes 11b to recover the metal of low melting point are formed in the periphery thereof, and a stamp material 15 is filled between the metallic plate 11 and the hearth plate 10. The periphery of the gas holes 11a, and the periphery of the holes 11b are filled with a gas permeable stamp material, and a gas non-permeable and dense stamp material respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric furnace provided with a device for blowing a stirring gas into a molten metal through a furnace bottom and a hearth, and more particularly to a low melting point metal such as lead contained in the molten metal. The present invention relates to an electric furnace capable of recovering those alloys (hereinafter, low melting point metals) outside the furnace.

[0002]

2. Description of the Related Art In steelmaking by an electric furnace, an inert gas is blown into molten steel from a hearth or a gas inlet at the bottom of the furnace to stir the molten steel, remove impurities, homogenize the molten steel, and further promote a metallurgical reaction. Like that. The outline of the gas blowing device used in such an electric furnace will be described with reference to FIG. 5. As shown in FIG. 5A, a region where the permanent lining 3 forming the hearth 1 is not formed is formed. A spiral gas ejection pipe 6 is disposed directly above the furnace bottom plate 2, for example, and a consumable lining 4 is formed by filling a ramming material (stamp material) thereon. As shown in FIG. 5 (b), the gas ejection pipe 6 has a single diameter or a plurality of diameters having a predetermined diameter.
Is provided. This pipe is usually installed at a plurality of places in the furnace bottom. The gas supplied from the gas supply pipe 5 is spouted from the gas spout 6 a of the gas spouting pipe 6, passes through the consumable lining 4, rises in the molten steel in a foamy state, and stirs the molten steel.

However, in such a gas blowing device, a low-melting metal vapor floats at a high concentration around the pipe,
When this is cooled by touching the pipe, it solidifies, and the low melting point metal is clogged in the supply pipe, and the pipe is easily clogged. Therefore, the present applicant arranges cooling fins around the gas ejection pipe and supplies a cooling medium to solidify the low-melting-point metal, and also controls the flow rate of the cooling medium to raise the temperature and increase the temperature of the solidified metal. Is proposed to solve the problem (Japanese Patent Laid-Open No. 9-2363).
No. 87). FIG. 3 of JP-T-6-503873 discloses an embodiment using a box-shaped gas distribution device provided with a plurality of gas holes above an opening.

[0004]

However, in a conventional electric furnace equipped with a bottom gas injection device, the gas ejection pipe is liable to be clogged due to condensation of the low melting point metal,
In order to avoid this, a device provided with cooling fins has a problem in that the shape and structure are complicated, which increases the cost and makes it difficult to spread the device. In addition, Japanese Patent Translation No. Hei 6-50387
Also in the form of JP-A No. 3 (KOKAI), the low-melting point metal may be solidified on the distribution device and block the gas holes, and it is necessary to disassemble the furnace bottom refractory to remove and recover the low-melting point metal.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a furnace bottom gas blowing device capable of preventing blockage of a gas discharge pipe, having a simple structure and being inexpensive, and capable of recovering a low melting point metal. It is intended to provide an electric furnace.

[0006]

According to a first aspect of the present invention, there is provided an electric furnace having an opening for blowing a stirring gas and discharging a low-melting-point metal at the bottom of the furnace. The metal plate in which the low melting point metal hole is formed is set on the furnace bottom plate so as to cover the opening.
The invention according to claim 2 is characterized in that a deflection plate for changing the direction of the flow of the gas blown onto the opening is provided. The invention according to claim 3 is characterized in that a stamp material is filled between the metal plate and the furnace bottom plate. According to a fourth aspect of the present invention, in the stamp material filled on the outside of the metal plate, the periphery of the portion where the gas hole is formed is a stamp material having good gas permeability, and the periphery of the portion where the low melting point metal hole is formed is: It is characterized by being a dense stamp material that is difficult for gas to permeate.

[0007]

Embodiments of the present invention will be described below. FIG. 1 is a view for explaining a gas blowing portion at the bottom of an electric furnace according to the present invention. FIG. 1A is a sectional view, and FIG. 1B is a plan view of a hemispherical metal plate used in the present invention. FIG.
1A, an opening 10a through which gas is blown into a furnace bottom plate 10 and a low melting point metal such as lead is discharged.
A gas blowing device 12 having a gas introduction pipe 12a for introducing an inert gas is attached to the outside of the furnace bottom plate so as to surround the opening 10a. A low-melting-point metal trap 13 for capturing discharged low-melting-point metals such as lead is attached to the lower side of the gas blowing device 12.

A hemispherical metal plate 11 is provided in the furnace so as to cover the opening 10a. The hemispherical metal plate 11 has a predetermined curvature, and as shown in FIG. 1 (b), is provided with a plurality of gas holes 11a for ejecting a gas, and the surroundings are for collecting a low melting point metal. Is formed. This is because, for example, in the case of lead, the melting point is 327.4 ° C.,
It has a boiling point of 1750 ° C. and a specific gravity of 11.34, and floats at a high concentration in the furnace bottom as a vapor. When the vapor comes into contact with the gas-cooled hemispherical metal plate 11, it condenses, flows down the surface, and flows down. This is for the purpose of entering into the hemispherical metal plate 11 through 11b. Since the hemispherical metal plate 11 is used in a reducing atmosphere, a normal iron plate is sufficient even if it is not made of stainless steel. Therefore, cost can be reduced. The shape of the hemispherical metal plate 11 may be any shape as long as the low-melting-point metal can flow down the surface, but an electric furnace has an electric field. It is desirable to avoid concentration.

The outside of the hemispherical metal plate 11 is filled with a stamp material, but the periphery of the perforated hole 11b is formed as a dense stamp material 14 which is difficult for gas to permeate so that a stirring gas is not ejected through the perforated hole 11b. , On the other hand,
The periphery of a is filled with a stamp material 15 having relatively good gas permeability.

In such a configuration, the gas introduction pipe 12
a, A gas is introduced from the opening 10a and the gas is ejected into the stamp material 15 from the gas holes 11a of the hemispherical metal plate 11.
On the other hand, the low melting point metal such as lead and zinc in the molten steel touches the gas-cooled hemispherical metal plate 11, condenses, flows on the surface thereof, flows into the hemispherical metal plate 11 through the hole 11b, It is trapped in the low melting point metal trap 13 through the opening 10a.

FIG. 2 is a diagram showing another example of the present invention. In this example, a deflection plate 20 is attached to the apparatus shown in FIG. 1 at a predetermined interval between the furnace bottom plate 10 and a support 21 on the opening 10a. FIG. 2 (b)
As shown in (1), the deflection plate 20 is supported by the columns 21 at several places, and the introduced gas is blown out from between the deflection plate 20 and the furnace bottom plate 20 to the surroundings. Therefore, the gas flow can be directed in all directions. Although only one deflection plate is provided in the drawing, a plurality of openings may be opened in one hemispherical metal plate, and a deflection plate may be provided for each.

FIG. 3 is a diagram showing another example of the present invention. In this example, the stamp material 15 having good air permeability is filled in the hemispherical metal plate 11. Of course, instead of the stamp material 15, a porous sintered body or the like may be filled.

FIG. 4 is a diagram showing another example of the present invention. In this example, the gas blowing device 12 and the low melting point metal trap 13 are covered with a heat insulating material 30. By providing the heat insulating material 30 in this manner, the temperature of the furnace bottom plate 10 can be maintained at a temperature equal to or higher than the melting point of a low melting point metal such as lead, and the outflow thereof can be promoted. Glass wool as a heat insulator,
It is preferable to use heat-resistant wool such as ceramic wool.

In the above example, an example in which one hemispherical metal plate is provided has been described. However, the present invention is not limited to this. A plurality of hemispherical metal plates are provided, and each hemispherical metal plate is provided. One or more openings formed in the furnace bottom plate may be covered.

[0015]

As described above, according to the present invention, a metal plate having a plurality of gas holes formed so as to cover the opening of the furnace bottom plate and a plurality of low melting point metal holes formed around the metal plate is provided. By causing the gas to be ejected from the gas holes, the low-melting-point metal is precipitated on the surface of the metal plate and can be collected by flowing down the surface of the metal plate, so that the low-melting-point metal can be prevented from blocking the gas holes, Gas can be introduced continuously,
Thereby, secondary refining can be promoted immediately after primary melting, and it is possible to produce steel of stable quality. In addition, since a device for ejecting gas to recover a low-melting-point metal is easy to install with a simple configuration in which a metal plate is simply opened, it is expected that cost reduction and widespread use will be achieved. You.

[Brief description of the drawings]

FIG. 1 is a view for explaining gas introduction into the bottom of an electric furnace according to the present invention.

FIG. 2 is a diagram showing another example of the present invention.

FIG. 3 is a diagram showing another example of the present invention.

FIG. 4 is a diagram showing another example of the present invention.

FIG. 5 is a schematic view of a gas blowing device used in a conventional electric furnace.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Electric furnace bottom plate, 10a ... Opening, 11 ... Hemispherical metal plate, 11a ... Gas hole, 11b ... Punch hole, 12 ... Gas blowing device, 13 ... Low melting point metal trap, 14,15 ... Stamp material, 20 ... Deflection Board, 21 ... pillar, 30 ... insulation material.

Claims (4)

[Claims] 1. An electric furnace having an opening for blowing a stirring gas and discharging a low-melting-point metal in a furnace bottom, wherein a plurality of gas holes are formed and a plurality of low-melting-point metal holes are formed around the metal furnace. An electric furnace equipped with a furnace bottom gas blowing device, wherein a plate is placed on a furnace bottom plate so as to cover the opening. 2. The electric furnace according to claim 1, further comprising a deflection plate for changing a direction of a flow of gas blown onto the opening. 3. The electric furnace according to claim 1, wherein a stamp material is filled between the metal plate and the furnace bottom plate. 4. The stamp material filled on the outside of the metal plate is:
Around the portion where the gas hole is formed is a stamp material having good gas permeability, and around the portion where the low melting point metal hole is formed,
2. The electric furnace according to claim 1, wherein the electric furnace is a dense stamp material through which gas is hardly permeated.