JP2001317880A - Refractory protecting sheet, refractory lining and refractory structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the back oxidation of a carbon-containing refractory used in a kiln and the like for treating molten metals or hot materials. SOLUTION: A refractory structure comprises a refractory protecting sheet 3 arranged between an iron shell 1 and a refractory 4, which sheet is a metal plate having the same shape as a part of the refractory structure and a bent-in portion extending from the side wall to the bottom thereof and divided into a plurality of pieces along the circumference of the refractory structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refractory structure such as a kiln or a holding vessel for handling molten metal or high-temperature material, a refractory lining for lining the refractory structure, and a protective sheet used for the refractory lining.

[0002]

2. Description of the Related Art For example, carbon-containing refractories have excellent slag resistance and can be expected to have high durability.
In recent years, steelmaking equipment has been widely used in refractory structures, such as converters (magnesia-carbon bricks), hot metal pretreatment equipment (alumina-SiC-carbon bricks), and secondary smelting furnaces (magnesia-carbon bricks). ing. However, when these refractories are used, the rear side, that is, the steel shell side may be oxidized and worn.
This phenomenon is particularly remarkable in secondary refining kilns. The cause of this backside oxidation is the air that has entered through the gaps in the steel shell or through the steam vent holes. The back surface of the refractory in use has a temperature of several hundred degrees Celsius, and carbon is oxidized in the presence of air, which causes oxidation of the back surface of the brick.

In order to solve this problem, for example, a metal case is attached to the back of magnesia-carbon brick, or as described in JP-A-62-255785, a flexible board is made of magnesia. A technique of disposing the back of a carbon brick is known.

[0004]

However, mounting the metal case is troublesome, reducing the production efficiency of the brick, and the cost of the metal case itself cannot be ignored. As a result, the cost of the brick increases. In addition, the air may enter through the gaps between the individual metal cases and oxidize the brick. On the other hand, JP-A-62-255
The flexible board described in Japanese Patent No. 785 has a problem in that when it is used and receives heat, the air permeability increases and the backside oxidation cannot be prevented.

The present invention prevents the backside oxidation of refractories of refractory structures such as kilns and holding vessels that handle molten metal and high-temperature substances, improves the life of refractory linings of kilns and the like,
An object of the present invention is to provide a refractory protective sheet, a refractory lining, and a refractory structure capable of reducing the production cost of molten metal and the like.

[0006]

Means for Solving the Problems As a result of continuing research for solving the problems, the present invention has been completed. That is, the gist of the present invention is as follows: (1) installed between a steel shell and a refractory, having the same shape as a part of the refractory structure, and having a folded portion from a side wall to a bottom; A refractory protection sheet comprising a metal plate divided into a plurality of pieces along the circumferential direction of the refractory structure, and (2) a flexible sheet is fixed to the metal plate. (1) The refractory protective sheet according to (1), (3) the refractory lining, wherein the periphery of the refractory is covered with the refractory protective sheet according to (1) or (2), (4) Iron The refractory structure according to (3), wherein the refractory lining according to (3) is disposed inside the skin.

[0007]

FIG. 1 shows an example of a refractory protection sheet according to the present invention. According to this embodiment, since the construction is simpler than the case where the metal case is attached to each brick and the number of joints is small, it is possible to effectively prevent the backside oxidation of the brick. The refractory protection sheet 3 is divided into a plurality of parts in the circumferential direction (three divisions in the figure) so that the distortion of the steel shell 1 and the distortion of the construction of the perm brick 2 can be absorbed. Also, the sheets 3 are slightly overlapped at their ends,
Prevent air intrusion as much as possible. This overlap width is at least 10mm
It is preferable to secure the above. In addition, the folding part 5
May be processed into an inward flange shape as shown in FIG. 1, may be cut and folded, or may be cut and folded as shown in FIG. The length of the folding part 5 is
It is desirable to set the length to 10 to 100% of the length of the brick to be covered (when a plurality of bricks are covered, the sum of the lengths).

It is desirable that the material of the metal plate forming the sheet has a melting point of not less than the operating temperature of the kiln minus 500 ° C. If the melting point is lower than that, there is a risk of melting and opening a hole. For steel refining kilns, ordinary steel,
Refractory steel, stainless steel, etc. can be recommended. The thickness is
It is about 0.1 mm or more from the viewpoint of strength and durability, and 5 mm or less, more preferably 1 mm or less from the viewpoint of workability at the time of installation.

[0009] As for the method of arranging the sheet, if necessary, a perm brick is erected on an iron shell, and the sheet of the present invention is divided into two or more parts so that the iron shell or the perm brick is gradually overlapped along the surface. Arrange the seats without gaps, and build a wear brick inside. The perm brick may be arranged outside the sheet, inside, or on both sides.

Since a metal sheet lacks flexibility, there is a possibility that a gap may be formed between the metal sheet and the permanent brick or between the metal sheet and the wear brick. If the flexible sheet is fixed to the metal plate forming the sheet, the gap can be filled by its flexibility. Flexible sheets include carbides, borides, such as alumina, spinel, magnesia, dolomite, mullite, silica or silica, chromite, chromia, titania, zirconia, zircon, clay, chamotte, bauxite, clay shale, and silicon carbide. It can be obtained by kneading one or more kinds of refractory materials such as metal and glass and, if necessary, resin and molding. The fixing method is simple based on the adhesive force, an adhesive may be used, or the adhesive force of the flexible sheet itself may be used. Alternatively, the kneaded material of the flexible sheet raw material may be formed while being fixed to a metal sheet.

Although the case where the refractory structure to be protected is a carbon-containing brick has been described above, the same function and effect can be obtained by using a refractory other than bricks such as castables and other irregular shaped refractories.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An R of 300 t of capacitance having sidewalls of the structure of FIG.
The lower tank of the H degassing facility was used for actual operation. The metal plate that forms the refractory protection sheet is 0.7 mm thick ordinary steel (carbon steel)
The wear brick was a magnesia-carbon brick containing 8% by mass of carbon having a length (thickness) of 380 mm.
The perm brick was a magcro brick having a length (thickness) of 65 mm. The refractory protection sheet was divided into three parts in the circumferential direction so as to overlap each other by 100 mm. The length of the folded portion was one third of the entire length (380 mm) of the wear brick.

[0013] Perm brick is 65mm thick as usual
After building a magcro brick on the bottom of the lower tank,
The divided refractory protection sheets were placed along the perm brick without any gaps so that they overlapped each other. Next, a magnesia-carbon brick of wear brick was built inside. During the construction, care was taken to ensure that the back of the wear brick properly hit the refractory protection sheet without any gaps.

The completed lower tank was dried and heated as usual and used for actual use. The operation was stopped because the perm brick was exposed on a part of the side wall (5 pieces of wear bricks) after 567 times of use, and the refractory on the side wall was inspected after cooling after cooling. As a result, no back oxidation was observed on the magnesia-carbon brick of the wear. On the other hand, in the conventional lower tank without the refractory protection sheet, the perm is exposed to a wide area (several tens of pieces of wear bricks) after about 500 times, and an oxide layer having a thickness of 30 to 50 mm is formed on the back of the wear bricks. Thus, the contribution of the present invention to the prevention of backside oxidation and the improvement of the life of the wear brick was obvious.

[0015]

According to the present invention, the backside oxidation of refractories such as kilns handling molten metal and high-temperature substances can be prevented,
The life of the refractory lining of a kiln or the like can be improved, and the production cost of molten metal or the like can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing an example of a lower tank side wall of RH degassing equipment in which a metal refractory protection sheet according to the present invention is installed between the back of a wear brick and a permanent brick.

FIG. 2 is a perspective view showing another example of a refractory protection sheet in which a notch is cut into an end of a metal sheet to form a folded portion.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 steel shell 2 perm brick 3 refractory protection sheet 4 wear brick 5 refractory protection sheet fold

Claims (4)

[Claims] 1. A refractory structure which is installed between a steel shell and a refractory, has the same shape as a part of the refractory structure, has a folded portion from a side wall to a bottom, and extends along a circumferential direction of the refractory structure. A refractory protection sheet comprising a metal plate divided into a plurality of pieces. 2. The refractory protection sheet according to claim 1, wherein a flexible sheet is fixed to the metal plate. 3. A refractory lining, wherein the periphery of the refractory is covered with the refractory protection sheet according to claim 1. 4. A refractory structure, wherein the refractory lining according to claim 3 is provided inside a steel shell.