JPH0734312Y2 - Bottom structure of DC arc furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a bottom structure of a DC arc furnace used for melting metal materials, refining molten metal, and the like.

[Prior Art] As an arc furnace for refining, a molten metal is refined by passing an electric current between an electrode placed above the molten metal charged in the furnace and a bottom electrode attached to the bottom of the furnace. DC arc furnaces are known. The bottom electrode in this type of DC arc furnace has a plurality of types of structure.
As disclosed in Japanese Patent Publication No. -152697, it is fixed to a furnace bottom plate 3 or an electrode mounting flange 10 shown in FIG. 5, and an electrical connection is provided between the furnace body and the furnace bottom electrode 1 via the electrode mounting flange 10. Insulating material 6 is installed between the bottom electrode of the furnace and the bottom plate of the furnace or an electrode mounting flange in order to cut the edge.

[Problems to be Solved by the Invention] However, in the case of a DC arc furnace having two independent rod-shaped bottom electrodes, the distance between adjacent rod-shaped bottom electrodes is short, and the following problems occur.

Lead contained in scrap solidifies and precipitates on the bottom of the furnace as it overwhelms the operation, gradually covering the insulating material between adjacent bottom electrodes, and conductivity is generated between the insulated bottom electrodes. It becomes inconvenient in control.

When electrical continuity occurs between multiple insulated bottom electrodes, the current for the electrodes that are in poor contact with scrap flows to the electrodes with good contact due to the contact state between scrap and bottom electrodes, and each bottom electrode There is a case where a current more than the allowable current that can flow through the furnace flows, which hinders the life of the bottom electrode.

The present invention is intended to solve the above problems and has an object to enable stable operation.

[Means for Solving the Problem] The bottom structure of the present invention has a plurality of electrically independent rod-shaped bottom electrodes, and the lower ends of the rod-shaped bottom electrodes are supported by cooling boxes. In the bottom structure of the DC arc furnace described above, an opening portion is provided in the bottom portion for penetrating two rod-shaped bottom electrodes having an appropriate interval, and the cooling box is provided in the penetration opening portion. Two flanges for mounting each are arranged so as to form a certain space without covering all the openings, and a fixed refractory having several grooves on the lower surface is arranged on the space. A bottom structure of a DC arc furnace characterized by the above.

[Operation] In the present invention, a hole is provided in the furnace bottom plate between the adjacent rod-shaped furnace bottom electrodes, and further, the rod-shaped furnace bottom electrode is supported and cooled in this hole. The cooling box is covered with a flange, but at this time, a constant space is formed between the two rod-shaped furnace bottom electrodes without covering all the openings. Therefore, the lead in the scrap that condenses at the center of the rod-shaped bottom electrode is discharged from the space of the opening to the outside of the furnace without impairing the insulation between adjacent rod-shaped bottom electrodes. A certain current can be reliably supplied to the rod-shaped bottom electrode, and stable operation becomes possible.

[Example] An example of the bottom structure of a DC arc furnace according to the present invention will be described with reference to FIGS. 1 and 2.

The rod-shaped bottom electrode 1 is fixed to the bottom plate 3 via a cooling box 2 for cooling the rod-shaped bottom electrode 1. The bottom plate 3 is provided with a through hole 4 which is integrally formed so as to collectively penetrate the adjacent rod-shaped bottom electrodes 1. The bottom plate 3 is provided with a flange 5 of the cooling box 2 and an insulating material 6. Is attached through.

The through hole portion 4 which is integrated in a plan view is not entirely covered by the flange portion 5 of the cooling box 2, and the space portion 11
Further, in order to prevent the outflow of the amorphous refractory 7 lined in the furnace to the outside of the furnace, the fixed refractory 8 is arranged in a portion not covered by the flange 5 of the cooling box 2. Note that standard refractories 8
By providing the lead discharge guide groove 9 as shown in FIG. 3, the lead discharge from the furnace becomes effective.

FIG. 4 shows an example of a bottom structure of another embodiment in which two rod-shaped bottom electrodes having the above-mentioned bottom structure are further provided via a rod-shaped bottom electrode mounting flange 10. This is a state in which the rod-shaped bottom electrode mounting flange 10 is cut off from the bottom plate 3, and two rod-shaped bottom electrodes 1 and a cooling box 2 are collectively attached by attaching and detaching the rod-shaped bottom electrode mounting flange 10. Can be maintained. For insulation, an insulating material 6a is provided between the rod-shaped bottom electrode attachment flange 10 and the bottom plate 3.

[Effect of the Invention] As described above, in the hearth bottom structure of the present invention,
While the rod-shaped bottom electrodes of the two books are close to each other and lead in scrap accumulates in the bottom of the furnace centering around the rod-shaped bottom electrodes while the operation continues, it does not impair the insulation with other rod-shaped bottom electrodes. Condensed / precipitated lead can be discharged from the furnace bottom plate, that is, from the space formed between the two rod-shaped furnace bottom electrodes to the outside of the furnace.
Stable operation is ensured and reliability of the life of the bottom electrode is improved, which greatly contributes to the improvement of operability and productivity.

[Brief description of drawings]

FIG. 1 shows a vertical sectional view of the bottom structure of a DC arc furnace according to the present invention, and FIG. 2 shows a partial sectional view of FIG. 1 taken along the line AA and omitting an amorphous refractory. FIG. 3 shows an example of the shape of a standard refractory material according to the present invention. FIG. 4 is a vertical sectional view of a bottom structure of a DC arc furnace according to another embodiment of the present invention. Fifth
FIG. 1 is a sectional view showing a conventional technique related to the present invention. DESCRIPTION OF SYMBOLS 1 ... Rod-shaped bottom electrode, 3 ... Furnace bottom plate, 4 ... Integrated through-hole part, 6, 6a ... Insulating material, 8 ... Regular refractory material, 10 ... Rod-shaped bottom electrode mounting flange, 11 ... Space part

Claims (1)

[Scope of utility model registration request] 1. A furnace bottom structure of a DC arc furnace having a plurality of electrically independent rod-shaped bottom electrodes, and the lower ends of the rod-shaped bottom electrodes being supported by a cooling box (2), respectively. An opening portion (4) for penetrating two rod-shaped furnace bottom electrodes (1) having an appropriate interval is provided in the furnace bottom portion, and the cooling box is attached to each of the penetration opening portions. A standard refractory material in which two flanges (5) are arranged so as to form a constant space portion (11) without covering all the opening portions, and having a plurality of grooves on the lower surface above the space portion. A furnace bottom structure of a DC arc furnace, wherein (8) is provided.