JPH09166386A - Furnace bottom electrode repairing method of dc electric furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the need of welding and speed up repairing work when a furnace bottom electrode of a DC electric furnace is repaired by cooling a portion to be repaired and then disposing a construction frame so as to surround the furnace bottom electrode, and putting a conductive stamp material in the construction frame and lap piling them, and then applying a usual stamp material. SOLUTION: When a furnace bottom electrode is repaired, in which electrode positive electrode pins 1... protected by a trapezoidal refractory of a DC electric furnace are fixed to a pin mount plate 3 through a substrate 2, after the portion to be repaired is cooled between predetermined temperatures, an iron plate is rounded matched with the original size of a furnace bottom electrode block to form a ring-shaped construction frame 21. The construction frame 21 is lifted with a lifting tool, and is set so as to surround the upper part of the worn furnace bottom electrode up to a broken line A. Then, a proper amount of a conductive stamp material 20 is inserted into the construction work 21 and is stamped with an air hammer, and is filled between the original electrode thicknesses. Thereafter, a general stamp material is filled up to the thickness of the furnace bottom on the outside of the construction frame with a conventional method for completion of the repair.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for repairing a bottom electrode of a DC electric furnace used for refining molten metal.

[0002]

2. Description of the Related Art The present applicant has previously filed Japanese Patent Application No. 7-24275.
As No. 1, when the anode block that constitutes the bottom electrode of the DC electric furnace is damaged to a specified size, the bottom of the bottom of the furnace is removed to expose the damaged anode pin head and it is positioned with a grid-shaped iron frame. Then, add each anode pin, put iron powder, iron balls, steel balls, etc. in the seam part, then fill with an irregular shaped refractory,
We have already proposed a method in which the seams are completely joined by reenergization.

[0003]

By the way, it has been found that the above-mentioned proposal has the following problems. Anode pins are typically 120-140 mm apart, 1
Since 50 to 250 are also provided, by the above procedure,
Even if a new anode pin is welded to the head of the damaged anode pin, the temperature inside the furnace is generally higher than room temperature (80 to 250).
(° C), and because there are many places to be welded and the working environment is poor, the working time becomes long and the productivity drops. Even if a stamp material such as a dolomite material is filled between the anode pins, as described above, since the gap is narrow and the packing cannot be performed densely, it may be locally damaged during reuse. The present invention is intended to solve the above problems, and it is an object of the present invention to reduce the cost of repairs, speed up repair work, improve productivity, and improve the durability of repair parts.

[0004]

As a result of various observations and examinations of work procedures at the work site, the inventors of the present invention have used a stamp material having appropriate conductivity without welding the anode pins one by one and joining them. The inventors have completed the invention of the present application by discovering that they can be repaired quickly and surely. The gist of the invention is to set a circular construction frame on the bottom electrode of the furnace, in which the electrical resistivity is 2Ω · m. The repairing method of filling the following conductive stamp material is featured.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. First, the DC electric furnace will be described with reference to FIG. A DC electric furnace for refining molten metal is provided with a bottom electrode, which is an anode, and one electrode, which is a cathode, above the furnace. Scrap and auxiliary raw materials are put into the furnace, and discharge is made between the cathode and the anode. Electrical energy is applied to the scrap as heat energy to melt it. FIG. 2 is a cross-sectional view for explaining the structure of the bottom electrode of the DC electric furnace. 3 is fixed, and a fine-grained amorphous refractory (MgO) 7 is filled between the anode pin 1 and the regular refractory 12. When an irregular refractory material is used instead of the regular refractory material 12, it is not necessary to fill the fine grain irregular refractory material (MgO) 7. Anode pins are mounted and arranged on the anode pin mounting plate 3 so as to enhance the cooling effect of the cooling air blown through the cooling air wind box 4. Reference numeral 5 denotes a power cable support bracket, and reference numeral 6 denotes a power cable. A steel frame 8 is provided around the anode block, and is integrated with the substrate 2 and the anode pin mounting plate 3 so that the electrode can be easily mounted and removed in a cassette type when replacing electrodes. A certain refractory brick 9 forms a boundary with the furnace bottom refractory material 10.

As the furnace bottom electrode refractory, a magnesia / carbonaceous regular refractory, magnesia, dolomite irregular irregular stamp material, etc. are used.

In such an anode block structure, when the number of uses (operations) reaches about 200 to 300 ch (charge), the furnace bottom is eroded as shown by the broken line A in FIG.
Worn. Therefore, it is necessary to replace the entire anode block when the remaining dimension becomes equal to or smaller than the predetermined dimension.

Next, the repairing method of the present invention will be described with reference to FIG. First, the repaired part is cooled down to a desired temperature, and an iron plate having a thickness of 3 to 5 mm is rolled according to the original size (diameter) of the furnace bottom electrode block in advance to form a ring-shaped construction frame. 21 (the height is adjusted to the depth of the worn portion) is prepared, and is hung by a suspending tool (not shown) and set so as to surround the worn furnace bottom electrode up to the broken line A. At this time, if there is a gap between the lower portion of the construction frame 21 and the worn furnace bottom electrode head, thermosetting mortar is filled to prevent the stamp material described later from leaking. .

The stamp material (ramming material) used in the method of the present invention is a known material, for example, a natural / synthetic refractory material of alumina-silica type, a basic refractory material such as magnesia, calcia, dolomite, alumina magnesia or chromium. -Refractory materials such as synthetic spinel materials such as magnesia can be used,
The electrical resistivity, which is one of the important characteristics, must be 2Ω · m or less. This is because if it is larger than 2 Ω · m, the current will be insufficient and the arc will not be generated to start.

An appropriate amount (generally about 2000 to 3000 kg) of such a conductive stamp material 20 is put into the construction frame 21 so as to have a uniform thickness, and a thickness of 150 mm / 1 time is given by an air rammer. Stamp on. At this time, the support rod 22 may be provided obliquely downward to the outside so that the construction frame does not deform or move.

In particular, if the inside of the construction frame is carefully stamped with a high packing density to remove the frame, the construction frame 20 may be removed and used again. However, when the so-called "tightness" of the stamp material is bad and there is a risk that the inner portion of the construction frame may be broken when the frame is removed, the stamp material may be left as it is, and so-called "burn-out" may be performed.

In this way, when the stamping is performed to fill the original thickness (height) of the electrode and then to remove the frame, the stamp material and the surrounding depressions are filled. The outside of the frame is filled with a conventional stamp material, for example, magnesia dolomite, up to the original thickness of the furnace bottom by a conventional method.

In the case of stacking layers in stamping, the upper surface of the lower layer is zigzag or parallel, so-called soaking is performed, and the next stamp material is put on the stamping material. Then, there is a great effect in improving conductivity and preventing the bottom of the furnace from rising.

[0014]

As described above, according to the present invention, compared with the method of welding the anode pins one by one, no labor is required for welding (anode pins are not used). The work can be speeded up, and as a result, the downtime of the electric furnace can be shortened (about 30% of the conventional one), so that the productivity can be improved. Further, since the stamp material can be densely filled without being disturbed by the contact pin, the durability of the repaired portion can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a furnace bottom electrode repairing method of the present invention.

FIG. 2 is a diagram illustrating a furnace bottom electrode structure. DESCRIPTION OF SYMBOLS 1 ... Anode pin, 2 ... Substrate, 3 ... Pin mounting plate, 7 ... Fine-grained amorphous refractory, 8 ... Steel frame, 9 ... Refractory brick, 10 ... Furnace bottom refractory material, 11 ... Coating material, 12 ... Standard refractory, 20 ... Conductive stamp material, 21 ... Construction frame, 22 ... Support rod.

Claims (1)

[Claims] 1. A method of repairing a bottom electrode of a direct current electric furnace having an anode pin using a fixed refractory or an irregular refractory, cooling a repair required portion to a desired temperature, and then repairing the bottom electrode. The step of installing the construction frame so as to surround it, the step of putting a conductive stamp material with an electrical resistivity value of 2 Ω · m or less inside the construction frame and repeatedly striking the required number of times, without removing or removing the construction frame, A method for repairing a bottom electrode of a DC electric furnace, comprising the step of applying a conventional stamp material between the conductive stamp material and its surroundings or outside the construction frame.