JP2022146594A - Repair structure and repair method for electric furnace tap hole brick - Google Patents

Abstract

To provide a repair structure and a repair method for an electric furnace tap hole brick by which a repair material for a tap hole brick is hard to peel.SOLUTION: A repair structure 2 comprises: an iron pipe 21 arranged so as to face an inner circumferential wall of a tap hole brick 14; and a castable construction body 22 arranged between an outer circumferential face of the iron pipe 21 and the inner circumferential wall of the tap hole brick 14. The castable construction body 22 comprises coarse particles and has a thickness of 30 mm or more. A repair method has a process in which the iron pipe 21 is inserted into an inner circumferential side of the tap hole brick 14, and a castable material comprising coarse particles is made to flow to a space between the inner circumferential wall of the tap hole brick 14 and the outer circumferential face of the iron pipe 21 with a gap of 30 mm or more secured.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to a repair structure and a repair method for tap hole bricks arranged on the inner periphery of a tap hole in the bottom of an electric furnace.

When the molten steel is transferred from the electric furnace to the ladle, the molten steel is tapped from the tap hole at the bottom of the electric furnace. A tap hole brick is arranged on the inner circumference of the tap hole, and the tap hole brick is eroded by contact with molten steel. Therefore, it was necessary to replace the tap hole brick every time it was used a predetermined number of times.
Since it takes time to replace taphole bricks, Patent Document 1 proposes repairing taphole bricks using mortar as a repairing material to extend the life of the taphole bricks.

JP 2001-215084 A

When tap hole bricks are repaired using mortar as a repair material as in Patent Document 1, there is a problem that the repair material peels off due to the friction and heat of molten steel during tapping.
The problem to be solved by the present invention is to provide a repair structure and a repair method for an electric arc furnace tap hole brick in which the tap hole brick repair material is less likely to peel off.

According to the present invention, the following electric furnace tap hole brick repair structure and repair method are provided.
1.
A repair structure for taphole bricks arranged on the inner periphery of a taphole in the bottom of an electric furnace,
an iron pipe arranged to face the inner peripheral wall of the tap hole brick;
A castable construction body arranged between the outer peripheral surface of the iron pipe and the inner peripheral wall of the taphole brick,
A repair structure for an electric arc furnace tap hole brick, wherein the castable body contains coarse grains and has a thickness of 30 mm or more.
2.
2. The electric arc furnace tap hole brick repair structure according to 1 above, wherein the castable body contains coarse particles of alumina and fine particles of magnesia, and the coarse particles of alumina have a maximum particle size of 5 mm or more.
3.
A method for repairing taphole bricks arranged on the inner circumference of a taphole in the bottom of an electric furnace, comprising:
a first step of installing a receiving jig at the lower end of the tap hole;
An iron pipe is inserted from the upper end side of the tap hole brick to the inner peripheral side of the tap hole brick, and a gap of 30 mm or more is provided between the inner peripheral wall of the tap hole brick and the outer peripheral surface of the iron pipe, and the supporting jig is installed. A second step of placing the iron pipe;
a third step of pouring a castable material containing coarse particles into the gap between the inner peripheral wall of the tap hole brick and the outer peripheral surface of the iron pipe;
a fourth step of removing the receiving jig after curing the castable material;
A method for repairing an electric arc furnace tap hole brick.
4.
The receiving jig has a positioning portion,
In the second step, by inserting the positioning part inside the iron pipe and placing the iron pipe on the receiving jig, the gap is formed between the inner peripheral wall of the tap hole brick and the outer peripheral surface of the iron pipe. 4. The method for repairing an electric furnace tap hole brick according to 3 above.
5.
Before the first step, cutting the inner peripheral wall of the tap hole brick so that a gap of 30 mm or more is formed between the inner peripheral wall of the tap hole brick and the outer peripheral surface of the iron pipe. 5. The method for repairing the electric furnace tap hole brick according to 4.
6.
After tapping the molten steel from the tap hole, it is inclined from the lower part of the castable construction body, which is the construction body of the castable material, toward the inner peripheral side of the tap hole so that the inclination angle θ is between 30 and 60°. A fifth step of cutting;
a sixth step of installing a receiving jig at the lower end of the tap hole;
An iron pipe is inserted from the upper end side of the castable construction body to the inner peripheral side of the castable construction body, and a gap of 30 mm or more is provided between the inner peripheral wall of the castable construction body and the outer peripheral surface of the iron pipe. A seventh step of placing the iron pipe;
an eighth step of pouring a castable material containing coarse particles into the gap between the inner peripheral wall of the castable construction body and the outer peripheral surface of the iron pipe;
6. The method for repairing an electric furnace tap hole brick according to any one of 3 to 5 above, including a ninth step of removing the receiving jig after the castable material is cured.

According to the present invention, the castable construction body repairing the taphole brick becomes difficult to peel off.

FIG. 2 is a conceptual cross-sectional view showing the furnace bottom of the electric furnace; BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a conceptual cross-sectional view of a repair structure for an electric arc furnace tap hole brick that is one embodiment of the present invention. The conceptual sectional view which shows the electric furnace tap hole brick before repair. FIG. 4 is a conceptual cross-sectional view showing a first step and a second step of a method for repairing electric furnace tap hole bricks, which is another embodiment of the present invention. The perspective view which shows a receiving jig. The conceptual sectional view which shows the 3rd process of the repair method of an electric furnace tap hole brick. FIG. 5 is a conceptual cross-sectional view showing the fifth step of the electric furnace taphole brick repair method.

FIG. 1 conceptually shows a cross section of the furnace bottom of an electric furnace.
A furnace bottom electrode 12 is installed in the center of a furnace bottom portion 11 of the electric furnace 1 . A tap hole 13 is provided at one end of the furnace bottom 11 as a tapping port. A tap hole brick 14 is arranged in a cylindrical shape on the inner circumference of the tap hole 13 . A tap hole open/close lid 15 is installed at the lower end of the tap hole 13 . The tap hole opening/closing lid 15 is movable in horizontal and vertical directions. FIG. 1 shows a state in which the tap hole open/close lid 15 closes the lower end of the tap hole 13 . In addition, the code|symbol 16 is a furnace bottom refractory in FIG. 1, and the code|symbol 17 is an iron shell.
When transferring the molten steel from the electric furnace 1 to the ladle, the electric furnace 1 is tilted to one end side where the tap hole 13 is located. Also, the tap hole opening/closing lid 15 is moved vertically downward and then horizontally. Then, molten steel in the electric furnace 1 is tapped from the tap hole 13 . At this time, the tap hole brick 14 is eroded by contact with the molten steel. As the tap hole brick 14 melts, the tap hole 13 expands. Therefore, repair of the tap hole 13 is required.

FIG. 2 conceptually shows a cross section of an electric arc furnace tap hole brick repair structure (hereinafter simply referred to as "repair structure"), which is an embodiment of the present invention.
The repair structure 2 includes an iron pipe 21 arranged to face the inner peripheral wall of the taphole brick 14, and a castable construction body 22 arranged between the outer peripheral surface of the iron pipe 21 and the inner peripheral wall of the taphole brick 14. Prepare. The castable body 22 is obtained by pouring a castable material, and the castable material and the castable body 22 contain coarse grains. In this respect, it differs from the mortar used in Comparative Examples 4 and 5, which will be described later. Here, mortar does not contain coarse particles, 60 to 80% of the particles constituting the aggregate have a mass of 75 μm or less, and the maximum particle size is adjusted to a range of 0.3 to 0.5 mm. It is made by kneading an agent and a solvent such as water.
Here, in the specification, "coarse particles" refer to those having a particle size of 3 mm or more. The upper limit of the particle size of the coarse particles is not particularly limited and is based on common technical knowledge, but is generally 8 mm or less.

The castable material contains coarse particles, so it is difficult for air to be included during pouring, making it easy to fill. In addition, since gas is easily released from the construction body during drying, the structure of the castable construction body 22 tends to be dense. Therefore, peeling is less likely to occur.
On the other hand, since mortar does not contain coarse particles, it is easy for air to be caught during pouring. Moreover, since gas is less likely to escape from the work during drying, the structure of the mortar work is less likely to become dense.

The castable material and the castable construction body 22 are preferably made of alumina-magnesia. Specifically, the castable material and the castable body 22 preferably contain alumina coarse particles and magnesia fine particles, and the maximum particle size of the alumina coarse particles is 5 mm or more. In this way, since coarse particles of alumina and fine particles of magnesia are included as main components, spinels are generated during drying or tapping, and the castable body 22 expands. Therefore, during drying or tapping, the castable body 22 is less likely to crack due to shrinkage and is less likely to peel off. For example, after drying at 1000° C., the alumina-magnesia castable body 22 has a porosity of 18 to 20%, and since the structure is denser, peeling hardly occurs. Here, in this specification, "fine particles" refer to those having a particle size of less than 1 mm.
On the other hand, the structure of the mortar-constructed body is difficult to become dense as described above. Moreover, the mortar-applied body shrinks during drying or tapping. Therefore, the mortar-applied body is likely to crack due to shrinkage during drying or tapping, and separation is likely to occur. The porosity of the mortar-applied body after drying at 1000° C. is 25 to 30%, and the texture is coarse, so peeling easily occurs.

The materials of the castable material and the castable body 22 are not limited to alumina-magnesia, and may be, for example, alumina-silica or magnesia. Moreover, in any material, in addition to the refractory raw material powder, a binder such as alumina cement may be appropriately contained, and a fibrous material such as organic fiber or metal fiber may also be contained.

The castable construction body 22 has a thickness of 30 mm or more. The thickness of the castable construction body 22 corresponds to the gap between the inner peripheral wall of the tap hole brick 14 and the outer peripheral surface of the iron pipe 21, which corresponds to the construction width when pouring the castable material. That is, the fact that at least a part of the castable construction body 22 has a thickness of 50 mm or more means that there is a construction width of 30 mm or more between the inner peripheral wall of the taphole brick 14 and the outer peripheral surface of the iron pipe 21. . By pouring the castable material while securing a construction width of 30 mm or more in this manner, the castable material is easily filled between the inner peripheral wall of the tap hole brick 14 and the outer peripheral surface of the iron pipe 21 . Also from this point, the structure of the castable body 22 tends to be dense. Therefore, peeling is less likely to occur.

The average construction width of the castable material, that is, the average thickness of the castable construction body 22 is preferably 30 mm or more. This is because when the average thickness of the castable construction body 22 is less than 30 mm, the strength of the castable construction body 22 is insufficient and peeling easily occurs. Here, in this specification, the average thickness of the castable construction 22 is calculated from the total volume V of the gap between the inner peripheral wall of the taphole brick 14 and the outer peripheral surface of the iron pipe 21 . Specifically, in a virtual cylindrical body having an inner diameter r as the outer diameter of the iron pipe 21 and h as the construction height, the outer diameter R is obtained when the volume of the cylindrical body is the total volume V of the gap. Then, (R−r)/2 is the average thickness of the castable construction body 22 .
Since the castable body 22 contains coarse particles, it is normal for irregularities to occur in the vicinity of the surface.
Note that the outer diameter of the iron pipe 21 is generally the initial diameter of the tap hole 13 . The initial diameter of the tap hole 13 is, for example, about 180 mm.

Next, a method for repairing electric furnace tap hole bricks (hereinafter simply referred to as "repair method"), which is another embodiment of the present invention, will be described.
FIG. 3 conceptually shows a cross section of an electric furnace tap hole brick before repair. In FIG. 3, the position of the initial diameter of the tap hole 13 is virtually indicated by a one-dot chain line. As shown in the figure, the tap hole bricks 14 arranged on the inner periphery of the tap hole 13 are eroded by contact with molten steel. The erosion is particularly large near the tap hole at the lower end of the tap hole brick 14 . As the tap hole brick 14 melts, the tap hole 13 expands. In this embodiment, the tap hole 13 is repaired when it becomes approximately 100 mm larger than the initial diameter. Each step of the repair method of this embodiment will be described below.

<First step>
A receiving jig is installed at the lower end of the tap hole 13 . Specifically, as conceptually shown in FIG. 4, the receiving jig 3 is sandwiched and supported between the tap hole opening/closing cover 15 and the lower end of the tap hole 13 .

<Second step>
An iron pipe 21 is inserted from the upper end side of the taphole brick 14 to the inner peripheral side of the taphole brick 14 . At this time, as conceptually shown in FIG. 4, the iron pipe 21 is placed on the receiving jig 3 with a gap of 30 mm or more between the inner peripheral wall of the tap hole brick 14 and the outer peripheral surface of the iron pipe 21.
In this embodiment, the receiving jig 3 has a substrate portion 31, a positioning portion 32 and a side wall portion 33, as shown in FIG. The positioning portion 32 is provided in a circular convex shape in the central portion of the substrate portion 31 . The outer diameter of the lower end of the circular convex positioning portion 32 is substantially the same as the inner diameter of the iron pipe 21 .
In the second step of the present embodiment, the iron pipe 21 is placed on the receiving jig 3 by inserting the positioning portion 32 inside the iron pipe 21 . As a result, the iron pipe 21 can be positioned at the center of the taphole 13, and a gap of 30 mm or more can be formed between the inner peripheral wall of the taphole brick 14 and the outer peripheral surface of the iron pipe 21. At this time, the receiving jig 3 can be positioned with respect to the tap hole 13 by bringing the inner peripheral surface of the side wall portion 33 into contact with the outer peripheral surface of the steel shell 17 of the tap hole 13 .
Three notches 331 are provided in the side wall portion 33 at equal intervals in the circumferential direction. These notches 331 are provided for checking whether there is a gap between the receiving jig 3 and the steel shell 17 .
In this embodiment, it is not possible to provide a gap of 30 mm or more between the inner peripheral wall of the taphole brick 14 and the outer peripheral surface of the iron pipe 21 only by inserting the iron pipe 21 into the inner peripheral side of the taphole brick 14. Before the first step, the inner peripheral wall of the tap hole brick 14 is cut so that a gap of 30 mm or more is formed between the inner peripheral wall of the tap hole brick 14 and the outer peripheral surface of the iron pipe 21 .

<Third step>
A castable material containing coarse particles is poured into the gap between the inner peripheral wall of the tap hole brick 14 and the outer peripheral surface of the iron pipe 21.例文帳に追加In this embodiment, since there is a gap of 30 mm or more between the inner peripheral wall of the taphole brick 14 and the outer peripheral surface of the iron pipe 21, the castable material is placed between the inner peripheral wall of the taphole brick 14 and the outer peripheral surface of the iron pipe 21. Easy to fill. In addition, since the castable material contains coarse particles, air is less likely to be included during pouring, making it easy to fill.
Furthermore, in this embodiment, since there is a gap of 30 mm or more between the inner peripheral wall of the taphole brick 14 and the outer peripheral surface of the iron pipe 21, as shown in FIG. The tip of the vibrator 4 can also be inserted into the gap between it and the outer peripheral surface. By inserting the tip of the vibrator 4 and pouring the castable material C while vibrating in this way, the castable material C can be more easily filled.
It should be noted that the upper end of the iron pipe 21 can be covered with a cap 5 as shown in FIG.

<Fourth step>
After hardening the castable material C, the receiving jig 3 and the cap 5 are removed. Thereby, a repair structure 2 as shown in FIG. 2 is obtained. That is, the first repair is completed up to the fourth step.

<Fifth step>
After completion of the first repair, molten steel is tapped from the tap hole 13 . When molten steel is tapped from the repaired taphole 13, the iron pipe 21 melts and disappears in the repaired structure 2, after which the castable construction body 22 comes into contact with the molten steel. Then, the castable construction body 22 is eroded by contact with molten steel. Therefore, in this embodiment, the second repair is performed.
In the second repair, as shown in FIG. 7, the lower part of the castable construction body 22 is cut as a fifth step. Specifically, the castable construction body 22 located about 10 mm away from the originally arranged taphole brick 14 is obliquely cut from the lower end portion toward the inner peripheral side of the taphole 13 . An inclination angle θ of about 30 to 60° is suitable for oblique cutting.

<Sixth step>
In the sixth step, the receiving jig 3 is installed at the lower end of the tap hole 13 in the same manner as in the first step.

<Seventh step>
In the seventh step, as in the second step described above, the iron pipe 21 is inserted from the upper end side of the castable construction body 22 to the inner peripheral side of the castable construction body 22, and the inner peripheral wall of the castable construction body 22 and the outer peripheral surface of the iron pipe 21 are inserted. The iron pipe 21 is placed on the receiving jig 5 with a gap of 30 mm or more provided between. When performing this seventh step, since the castable construction body 22 from the first repair remains on at least a part of the inner circumference side of the taphole brick 14, the castable construction body 22 remains on the inner circumference side. An iron pipe 21 is inserted.

<Eighth step>
In the eighth step, the castable material containing the second coarse grains is poured into the gap between the inner peripheral wall of the castable construction body 22 and the outer peripheral surface of the iron pipe 21 in the same manner as the above-described third step. The second castable material used in the eighth step can be made of the same material as the castable material used in the third step.

<Ninth step>
In the ninth step, the receiving jig 3 and the cap 5 are removed after hardening the second castable material, similarly to the above-described fourth step. This completes the second repair. The third and subsequent repairs can be performed by repeating the fifth to ninth steps described above. By repeating the fifth to ninth steps in this way, the electric furnace can be continued to be used without replacing the tap hole bricks 14 .

In this embodiment, in the second and subsequent repairs, the lower portion of the castable construction body 22 is cut as the fifth step. If the lower part of the castable construction body 22 is not cut in the second and subsequent repairs, the phenomenon that the lower end of the castable construction body to be newly constructed in the eighth step tends to peel off easily occurs. In other words, by cutting the lower part of the castable construction body 22 in the fifth step, it is possible to suppress the peeling of the lower end of the castable construction body newly constructed in the eighth process. This is because cutting the lower part of the castable construction body 22 in the fifth step makes it possible to increase the thickness of the lower end of the castable construction body newly constructed in the eighth process.

Table 1 shows examples of the present invention and comparative examples.
In the examples and comparative examples, a gap corresponding to the "average thickness of the construction body" in Table 1 was provided between the inner peripheral wall of the taphole brick and the outer peripheral surface of the iron pipe, and the "refractory raw material" in Table 1 was provided. The first repair was carried out by pouring the material added with water corresponding to the "additional water amount". After performing the first repair, tapping was performed 50 to 60 times, and after tapping 50 to 60 times, the middle part and the lower end of the tap hole were visually observed to evaluate the degree of peeling of the work piece. . Specifically, the case where there was no peeling was evaluated as ⊚ (good), the case where there was small peeling was evaluated as ◯ (acceptable), and the case where there was large peeling was evaluated as × (improper).

In Examples 1 to 5, a castable material containing coarse grains was applied, and the average thickness of the castable applied body was 30 mm or more. The degree of detachment of the work piece after tapping 50 to 60 times was good, being ⊚ (good) or ◯ (fair). Among them, Examples 1 to 3 were castable materials containing coarse alumina particles and fine magnesia particles, and the maximum particle size of the coarse alumina particles was 5 mm or more. The degree of detachment of the body after steel was evaluated as ⊚ (good), which was particularly good.

In Comparative Examples 1 to 3, a castable material containing coarse grains was applied, and the average thickness of the castable applied body was 10 to 20 mm. The degree of peeling of the work piece after tapping 50 to 60 times was x (impossible).
In Comparative Examples 4 and 5, mortar containing no coarse particles was applied. The average thickness of the work piece was 50 to 60 mm, but the degree of peeling of the work piece after tapping 50 to 60 times was x (impossible).

1 Electric Furnace 11 Furnace Bottom 12 Furnace Bottom Electrode 13 Tap Hole 14 Tap Hole Brick 15 Tap Hole Opening/Closing Lid 16 Furnace Bottom Refractory 17 Steel Shell 2 Repair Structure 21 Iron Pipe 22 Castable Constructed Body 3 Receiving Tool 31 Substrate Part 32 Positioning Part 33 Side wall portion 331 Notch 4 Vibrator 5 Cap C Castable material

Claims (6)

A repair structure for taphole bricks arranged on the inner periphery of a taphole in the bottom of an electric furnace,
an iron pipe arranged to face the inner peripheral wall of the tap hole brick;
A castable construction body arranged between the outer peripheral surface of the iron pipe and the inner peripheral wall of the taphole brick,
A repair structure for an electric arc furnace tap hole brick, wherein the castable body contains coarse grains and has a thickness of 30 mm or more. 2. The structure for repairing an electric arc furnace tap-hole brick according to claim 1, wherein said castable body contains coarse particles of alumina and fine particles of magnesia, and said coarse particles of alumina have a maximum particle size of 5 mm or more. A method for repairing taphole bricks arranged on the inner circumference of a taphole in the bottom of an electric furnace, comprising:
a first step of installing a receiving jig at the lower end of the tap hole;
An iron pipe is inserted from the upper end side of the tap hole brick to the inner peripheral side of the tap hole brick, and a gap of 30 mm or more is provided between the inner peripheral wall of the tap hole brick and the outer peripheral surface of the iron pipe, and the supporting jig is installed. A second step of placing the iron pipe;
a third step of pouring a castable material containing coarse particles into the gap between the inner peripheral wall of the tap hole brick and the outer peripheral surface of the iron pipe;
a fourth step of removing the receiving jig after curing the castable material;
A method for repairing an electric arc furnace tap hole brick. The receiving jig has a positioning portion,
In the second step, by inserting the positioning part inside the iron pipe and placing the iron pipe on the receiving jig, the gap is formed between the inner peripheral wall of the tap hole brick and the outer peripheral surface of the iron pipe. The method for repairing electric arc furnace tap hole bricks according to claim 3, wherein Before the first step, cutting the inner peripheral wall of the tap hole brick so that a gap of 50 mm or more is formed at least partially between the inner peripheral wall of the tap hole brick and the outer peripheral surface of the iron pipe. The method for repairing an electric furnace tap hole brick according to claim 3 or 4. After tapping the molten steel from the tap hole, it is inclined from the lower part of the castable construction body, which is the construction body of the castable material, toward the inner peripheral side of the tap hole so that the inclination angle θ is between 30 and 60°. A fifth step of cutting;
a sixth step of installing a receiving jig at the lower end of the tap hole;
An iron pipe is inserted from the upper end side of the castable construction body to the inner peripheral side of the castable construction body, and a gap of 30 mm or more is provided between the inner peripheral wall of the castable construction body and the outer peripheral surface of the iron pipe. A seventh step of placing the iron pipe;
an eighth step of pouring a castable material containing coarse particles into the gap between the inner peripheral wall of the castable construction body and the outer peripheral surface of the iron pipe;
6. The method for repairing an electric arc furnace tap hole brick according to any one of claims 3 to 5, further comprising a ninth step of removing the receiving jig after the castable material has hardened.

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