JPH04163882A - Bottom electrode of dc arc furnace - Google Patents

Abstract

PURPOSE:To eliminate dangerous works and enhance the durability by furnishing a lower rod-shaped electrode whose foremost penetrates the iron sheath at the bottom of a DC arc furnace and which is embedded in blicks of the furnace and subjected to internal cooling, installing a plurality of upper rod-shaped electrodes whose oversurfaces are contacted with molten metal and which are coupled together by an upper electrode base board, and arranging these lower and upper electrodes over and below. CONSTITUTION:A DC electric furnace is so constructed that its bottom is lined with a fire resistant substance 11 and the outer side is supported by an iron sheath 1, and a lower rod- shaped electrode 4 made of steel or copper is installed while penetrating the furnace bottom. This lower electrode 4 is hollow, and a refrigerant 2 is supplied to the hollow part using a nozzle 3, and the heat conducted from the molten steel, which the lower electrode 4 receives, and Joule's heat due to current flow are carried away by this refrigerant 2. Each upper rod-shaped electrode 5 is composed of two or more electrode pins, upper electrode base board 6, iron plate frame 8, and stamping material 9, wherein the base board 6 has a recess to be fitted with a locational projection 7 on the lower electrode 4 so as to have easy location at the time of replacement of upper electrode 5. Thereby electrode replacement is made quickly without involving hazard, and the lifetimes of the electrodes and fire resistant substance are prolonged.

Description

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

[Prior art] A current is passed between a cathode placed above scrap charged in a furnace and an anode attached to the bottom of the furnace to melt metal materials, refine molten metal, etc. Direct current arc furnaces are known.

For example, in the furnace bottom electrode described in JP-A-57-1.52697, a hollow space is formed on the outer surface of the furnace using substrates protruding from the furnace wall of at least two electrodes, and a coolant such as air is injected into this hollow space. It is disclosed that the electrode neck, furnace outer surface, and substrate are cooled by flowing.

Furthermore, Japanese Patent Application Laid-Open No. 1-128392 discloses an electrode block in which electrode pins are stamped at a factory and the electrodes can be easily replaced on-site.

[Problem to be solved by the invention] However, such a hearth bottom electrode has the following problems.

■When replacing electrodes, each electrode block must be replaced, and it is necessary to remove the board, power cable, cooling medium piping, etc. Working under the furnace is both dangerous and time consuming.

■Since the electrodes are cooled from outside the furnace bottom, the cooling capacity is often insufficient due to the distance from the molten metal contact area, which is not effective in terms of the durability of the electrodes containing refractories.

The present invention is intended to solve the above-mentioned problems.In order to replace the electrodes, it is only necessary to replace the electrodes inside the furnace, which eliminates the need for dangerous work under the furnace, and improves the cooling capacity. The purpose of the present invention is to provide a furnace bottom electrode that can improve the durability of the electrode.

[Means for Solving the Problems] In order to achieve the object, the bottom electrode of the present invention has a tip portion that penetrates the bottom shell of a DC arc furnace and is buried in the brickwork of the furnace to provide internal cooling. The present invention is characterized in that a lower rod-shaped electrode and two or more upper rod-shaped electrodes whose upper surfaces are in contact with the molten metal and which are connected by an upper electrode substrate 6 are arranged one above the other.

[Operation] If the electrode needs to be replaced due to wear and tear on the refractory inside the furnace, the internally cooled lower rod-shaped electrode and the two or more upper rod-shaped electrodes connected by the electrode substrate are separated, and only the upper rod-shaped electrode is replaced. can be easily replaced without removing the under-furnace piping, etc., and can eliminate dangerous work under the furnace.

In addition, by flowing a coolant such as water into the lower rod-shaped electrode and carrying away heat directly from the rod-shaped electrode, it is possible to effectively cool the refractory and other components.

[Example] FIG. 1 is a vertical cross-sectional view of a bottom electrode of the present invention. The bottom of the DC electric furnace is lined with a refractory 11 and supported on the outside by an iron shell 1. A lower rod-shaped electrode 4 made of steel or copper is attached to the furnace bottom by penetrating the furnace bottom composed of the iron shell 1 and the refractory 11.

The inside of the lower rod-shaped electrode 4 is hollow, and the nozzle 3
The refrigerant 2 is supplied to the hollow portion, and the Joule heat due to the heat transfer from the molten steel and the electric current received by the lower rod-shaped electrode 4 is carried away by the refrigerant 2. For example, water is used as the refrigerant.

The upper rod-shaped electrode 5 is composed of two or more electrode pins, an upper electrode substrate 6, a steel plate frame 8, and a stamp material 9, and the upper electrode substrate 6 fits into a positioning protrusion 7 provided on the lower rod-shaped electrode 4. It has a concave part. The positioning protrusion 7 and the four parts provided at the center of the first electrode substrate 6 facilitate positioning when replacing the upper electrode. In this case, protrusion 7
Even if there is no one, there is no problem with installing it separately. At this time, the upper electrode substrate 6 and the lower rod-shaped chamber 8i4 are connected only by metal touch.

FIG. 2 shows a separate male side of the present invention, in which the iron plate frame 8 is tapered and the upper electrode substrate 6 is
An example is shown in which the prevention of floating during operation is strengthened.

The connection between the upper electrode substrate 6, which connects the upper rod-shaped electrode 5, and the lower rod-shaped electrode 4 is only by metal touch, as in FIG. 5 serves to constantly press the upper electrode substrate 6 downward, thereby strengthening the metal touch connection and preventing the upper electrode substrate 6 from floating due to vibrations during operation.

FIG. 3 shows yet another embodiment, which shows a fixture 12a for bringing the upper electrode substrate 6 and the lower rod-shaped electrode 4 into close contact.

12b is a partially enlarged view of a connecting portion in an example in which the connector 12b is used. In this embodiment, the upper electrode substrate 6 is replaced with the lower rod-shaped electrode 4.
By placing it on the board and rotating it, it is possible to make a close contact.
To remove it, just rotate it in the opposite direction. In FIG. 3, the fixture 12a is fixed to the lower rod-shaped electrode 4, and the fixture 12b is fixed to the upper electrode substrate 6. Since the contact surfaces of the fixtures +2a and 12b are tapered, when the upper electrode substrate 6 is rotated, a wedge effect is produced and the upper electrode substrate 6 and the lower rod-shaped electrode 4 are brought into close contact with each other.

In this way, by dividing the bottom electrode of the DC arc furnace into the upper electrode and the lower electrode, it is possible to replace only the upper electrode, and the lower rod-shaped electrode 4 has a structure that allows strong cooling close to the molten metal. Therefore, the electrode replacement work can be easily carried out in a short time and without dangerous work, and the life of the electrode including the refractory can be extended.

[Effects of the Invention] As described above, according to the present invention, electrode replacement work can be easily carried out in a short time and without dangerous work, and operability is also dramatically improved. Furthermore, by cooling the electrode from a position close to the contact area between the molten metal and the electrode, not only the electrode but also large objects can be effectively cooled, extending the life of the electrode including the refractory.

[Brief explanation of drawings]

FIG. 1 shows a vertical cross-sectional view of the bottom electrode of the DC arc furnace of the present invention. FIG. 2 shows a separate male side in which the prevention of lifting of the upper electrode substrate is strengthened in the present invention. Figure 3 shows
FIG. 7 shows a partially enlarged view of a connecting portion in yet another embodiment in which a fixture is used to bring the upper electrode substrate and the lower electrode into close contact with each other. 1... Iron skin, 2... Refrigerant, 3... Nozzle, 4...
・Lower rod-shaped electrode, 5... Upper rod-shaped electrode, 6... Upper electrode substrate, 7... Positioning protrusion, 8... Iron plate frame, 9
... Stamp material, 10... Electrode lifting prevention brick, 11... Refractory material, 12a, 12b... Fixing metal fittings, 13... Insulator, 14... Power supply cable.

Claims (1)

[Claims] 1. An internally cooled lower rod-shaped electrode whose tip penetrates the furnace bottom shell and is buried in the brickwork of the furnace, and two or more upper rod-shaped electrodes whose upper surfaces are in contact with the molten metal and connected by an electrode substrate. A bottom electrode for a DC arc furnace characterized by having electrodes arranged above and below.