JPH08167474A - Furnace wall electrode of dc arc furnace - Google Patents

Abstract

PURPOSE: To provide a furnace wall electrode with an excellent durability which can suppress the fusing loss speed of rod form electrode by composition the rod from electrode at the bottom of an electric furnace by joining two sorts of materials, increasing the cooling operation, and making the fusing surface in the electrode generated stably at the upper side as high as possible. CONSTITUTION: Rod from electrodes 4a and 4b having a connecting surface 6 is installed to the bottom of a furnace by penetrating a furnace wall composed of an iron skin 3, a permanent brick 1, and an unsettled type refractor substance 2. A cooling sleeve 5 is arranged around the electrode 4b, a coolant 8 is delivered from a coolant piping 7 and the heat is removed from the electrode 4b while the coolant 8 passes through the sleeve 5. The upper side electrode 4a is made of a material same as a fusing metal to be rifined, (a steel billet, for example), while the electrode 4b out of the furnace is made of a material with a large heat conductivity as large as possible (copper, for example). The junction of the electrodes 4a and 4b is carried out by an explosion bonding, a brazing, a solid phase diffusion connecting, or hot equi-pressure pressurization. The form of the jointing surface is made in a fitting structure in order to increase the jointing area. Consequently, the fusing loss speed of the rod form electrodes 4a and 4b is suppressed, and a furnace electrode with an excellent durability can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wall electrode of a DC arc furnace used for melting metal materials, refining molten metal and the like.

[0002]

2. Description of the Related Art As an arc furnace for refining, an electric current is passed between an electrode arranged above a molten metal charged in the furnace and an electrode attached to a furnace wall such as a furnace bottom or a side wall to melt the molten metal. A DC arc furnace for refining is known. The bottom electrode in a DC arc furnace of this type is exposed to an extremely harsh working atmosphere due to heat received from the high-temperature molten metal in the furnace, Jewel heat generated when a supply current passes, and the like. Therefore, various proposals have been made to withstand this atmosphere and improve the durability of the furnace wall electrode. For example, in the furnace wall electrode of Japanese Patent Publication No. 63-43675, a cooling sleeve for a refrigerant passage is attached around the portion of the electrode projecting from the furnace wall (hereinafter referred to as the rear end), It is disclosed that the electrode is forcibly cooled by circulating a coolant such as water in the passage.

[0003]

However, since the cooling sleeve has an integral cylindrical shape, a gap is required between the rod-shaped electrode and the cooling sleeve, and even if the rear end of the electrode is cooled by the cooling sleeve. There is a case where the cooling effect becomes insufficient because there is a distance between the rod-shaped electrode and the rear end surface of the rod-shaped electrode. Although it is possible to directly cool the rod-shaped electrode in order to enhance the cooling, it is not preferable for safety if the position of the melting surface in the rod-shaped electrode is lowered during operation due to abnormal operation or the like. The present invention, the lower part of the rod-shaped electrode is composed of a material having a high thermal conductivity, the upper part is composed of a material of the same kind as the metal to be refined,
By joining the upper part and the lower part by a joining method that does not create a gap, cooling of the entire rod-shaped electrode is enhanced. As a result, the molten surface in the rod-shaped electrode is stably generated as high as possible. As a result, it is an object of the present invention to provide a furnace wall electrode having excellent durability, which suppresses the melting rate of the rod-shaped electrode.

[0004]

In order to solve the above problems, a furnace wall electrode of a DC arc furnace according to the present invention is a furnace wall electrode of a DC arc furnace in which a tip portion is embedded in a furnace wall refractory material. , The furnace wall electrode is formed in a rod shape, the buried portion inside the furnace wall and the portion located outside the furnace are made of two kinds of materials having different thermal conductivities, and the respective end portions are integrally formed. It is configured to be connected.

[0005]

In order to stabilize the position of the melting surface in the rod-shaped electrode at a position as high as possible, it is effective to circulate the refrigerant upward so that it is as close to the melting surface as possible, but the liquid refrigerant is circulated upward. This is not preferable for safety. Therefore, in order to cool only the portion outside the furnace of the rod-shaped electrode and to stabilize the melting surface upward, there is a method of improving heat transfer by configuring the rod-shaped electrode with a material having high thermal conductivity, for example, copper. However, the problem is that it is inadvertently eluted into the substance to be refined in the furnace. In the present invention, since the lower part of the rod-shaped electrode is made of a material having a high thermal conductivity and is integrally joined to the upper part, from the cooled part of the rear end of the electrode to the melting surface of the upper part of the rod-shaped electrode. Even if the distance is long, sufficient cooling is possible, and the position of the melting surface can be stabilized higher than in the conventional rod-shaped electrode made of one kind of substance.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in the drawings. FIG. 1 shows an example in which an electrode is attached to the bottom of a DC arc furnace. At the bottom of the DC arc furnace, an indeterminate refractory 2 is lined inside the perm brick 1, and the outside is supported by a steel shell 3. These iron skin 3, perm brick 1
Also, the rod-shaped electrode 4a and the rod-shaped electrode 4b having the joint surface 6 are attached to the furnace bottom by penetrating the furnace wall constituted by the amorphous refractory 2. A cooling sleeve 5 is arranged around the rod-shaped electrode 4b. The refrigerant 8 sent from the refrigerant pipe 7 to the cooling sleeve 5 takes heat from the rod-shaped electrode 4b while passing through the cooling sleeve 5.

The upper portion of the rod-shaped electrode, that is, the portion of the rod-shaped electrode 4a penetrating into the furnace is made of the same kind of material as the molten metal to be refined. For example, in the case of refining steel, a cylindrical billet made of steel is used. On the other hand, the lower portion of the rod-shaped electrode, that is, the rod-shaped electrode 4b outside the furnace is made of a material having the highest thermal conductivity, for example, copper. The upper rod-shaped electrode 4a and the lower rod-shaped electrode 4b are joined by a method such as explosive deposition, brazing, solid phase diffusion joining, hot isostatic pressing (HIP), etc., instead of mere crimping with bolts or the like. , Improve the inhibition of heat transfer at the joint surface. Further, in the embodiment, the shape of the joint surface is a hameai structure in order to increase the joint area as much as possible, but it may be a corrugated shape or any other shape as long as the joint area can be increased.

[0008]

As described above, in the furnace wall electrode of the present invention, the heat transfer capacity of the entire rod-shaped electrode is significantly improved as compared with the conventional method, so that the position of the melting surface in the rod-shaped electrode is increased. It is possible to stabilize. Therefore, the life of the electrode is significantly improved, and the frequency of maintenance work of the furnace wall electrode can be reduced, which contributes to the improvement of productivity.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example in which a furnace wall electrode of the present invention is applied to a furnace bottom of a DC arc furnace.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Permanent brick 2 Irregular refractory 3 Iron crust 4a Rod-shaped electrode (steel) 4b Rod-shaped electrode (copper) 5 Cooling sleeve 6 Joining surface 7 Piping 8 Refrigerant

Claims (1)

[Claims] Claim: What is claimed is: 1. A furnace wall electrode of a DC arc furnace, the tip of which is buried in a furnace wall refractory material, wherein the furnace wall electrode is formed in a rod shape, and the portion is located inside the furnace wall and outside the furnace. A furnace wall electrode for a DC arc furnace, characterized in that and are made of two kinds of materials having different thermal conductivities, and the respective end portions are connected so as to be integrally formed.