JPH0749183A - Refractory lining structure of molten metal container - Google Patents

Abstract

(57) [Summary] [Purpose] To improve the corrosion resistance of the slag line part of a molten metal container lined with alumina-silicon carbide-carbonaceous unfired brick. [Constitution] In a molten metal container lined with alumina-silicon carbide-carbonaceous unfired brick, M is added to the slag line portion.
The refractory lining structure of a molten metal container is characterized in that gO · Al ₂ O ₃ -based spinel-silicon carbide-carbonaceous unfired bricks are arranged. [Effect] The spinel-silicon carbide-carbonaceous non-fired brick is excellent in slag erosion resistance, and there is little joint damage at the boundary with the alumina-silicon carbide-carbonaceous non-fired brick. As a result, the durability of the entire lining is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refractory lining structure for a molten metal container used in the iron making industry.

[0002]

2. Description of the Related Art Conventionally, alumina-silicon carbide-carbonaceous unfired brick has been known as a lining material for molten metal containers such as a pig iron car, a pig iron furnace, a hot metal ladle, a molten steel ladle and an electric furnace. For example, it is as disclosed in JP-A-58-84915. This alumina-silicon carbide-carbonaceous unfired brick exhibits excellent durability in combination with the volume stability / corrosion resistance of alumina, the effect of imparting carbon spalling resistance, and the antioxidation effect of silicon carbide. The corrosion resistance of the line part is not sufficient. Therefore, it can be considered to use magnesia-carbonaceous brick having excellent slag resistance as a slag line member material.

The term "slag line" as used herein refers to a portion of the lining of the molten metal container where the slag is in contact with the molten metal and has a greater melting loss than other portions. Since the slag floats on the molten metal, it is continuous in the circumferential direction of the container. The position, vertical width, etc., vary depending on the vertical movement of the molten metal, the amount of hot water received, the type of container, etc.

[0004]

[Problems to be Solved by the Invention] However, magnesia
The combined use of a carbonaceous brick and an alumina-silicon carbide-carbonaceous unfired brick has a phenomenon that the boundary portion thereof is greatly damaged. It is considered that this is due to the reaction between both materials and the difference in thermal expansion. An object of the present invention is to solve the above-mentioned conventional problems in the slag line portion in the lining made of alumina-silicon carbide-carbonaceous unfired brick.

[0005]

According to the present invention, in a molten metal container lined with alumina-silicon carbide-carbonaceous unfired brick, a MgO.Al ₂ O ₃ -based spinel-silicon carbide-carbonaceous material is provided in a slag line portion. It is a refractory lining structure of a molten metal container characterized by arranging fired bricks.

MgO.Al ₂ O ₃ System Spinel-Silicon Carbide-
In the carbonaceous unfired brick, MgO.Al ₂ O ₃ based spinel (hereinafter, simply referred to as spinel) dissolves FeO in the slag to prevent slag infiltration and improve corrosion resistance in the slag line portion. However, since spinel has a slightly higher thermal expansion property than alumina and has a high melting point, spinel does not form a liquid phase in the operating temperature range, and thus tends to cause thermal spooling. Therefore, in the present invention, the lower part of the slag line is lined with alumina-silicon carbide-carbonaceous unfired brick as in the conventional case.

Further, even if the spinel-silicon carbide-carbonaceous unfired brick is combined with the alumina-silicon carbide-carbonaceous unfired brick, the damage at the boundary between the two is small. This spinel - silicon carbide - partially exploded at a high temperature of the spinel is used in carbonaceous unfired bricks, MgO component is alumina caused by it - silicon carbide - Al ₂ O ₃ component of the carbonaceous unfired in brick It is considered that MgO.Al ₂ O ₃ system spinel is formed by reacting with the above, and volume expansion accompanying the formation prevents the joint from opening at the boundary.

Even if a magnesia-carbonaceous brick and an alumina-silicon carbide-carbonaceous unfired brick are combined, the formation of spinel is expected due to the reaction of the MgO component and the Al ₂ O ₃ component from both. However, since magnesia-carbonaceous bricks have extremely high coefficient of thermal expansion and thermal stress, cracking occurs inside the tissue due to the restraining force due to brickwork, and the thermal treatment with the alumina-silicon carbide-carbonaceous unfired brick of the lining Due to the difference in expansion, peeling damage occurs, and the effect of durability of the present invention cannot be obtained.

In the present invention, the material and manufacturing method of the alumina-silicon carbide-carbonaceous unfired brick constituting the lower part of the slag line are the same as those of the conventional materials. Alumina raw material used in the production, synthetic or natural products, for example, sintered alumina, fused alumina, shale shale,
Alumina with an Al ₂ O ₃ content of at least 10 wt% or more, such as sillimanite, bauxite, and pyrophyllite, and / or
Alternatively, it is selected from alumina-silica.

Spinel-silicon carbide-carbonaceous non-fired bricks used in the production of spinel are not sufficiently supplied as natural products, so that they are either sintered products or electro-melted products produced by synthesizing magnesia and alumina. To do. MgO in spinel
The ratio of Al ₂ O ₃ to Al ₂ O ₃ is preferably close to the theoretical value of 28.3: 71.7, but MgO may be small, for example, around 10 wt%. The ratio is, for example, 40 to 90 wt
% Is preferred.

Silicon carbide serves as a carbon antioxidant. In order to make the effect remarkable, for example, 0.
It is preferable to use fine particles of 1 mm or less. The ratio is 1 for alumina-silicon carbide-carbonaceous unfired brick.
.About.25 wt%, and for spinel-silicon carbide-carbonaceous unfired brick, 1 to 20 wt% is preferable. If it is too small, there is no antioxidant effect, and if it is too large, the corrosion resistance decreases.

In the case of the spinel-silicon carbide-carbonaceous unfired brick, the reason why the upper limit ratio of silicon carbide is smaller than that of the alumina-silicon carbide-carbonaceous unfired brick is that a part of the spinel is decomposed during use of the brick. This is because the MgO component produced as a result and the SiO ₂ component produced by the decomposition of silicon carbide react with each other to produce forsterite (MgSiO ₄ ) having a low melting point, which lowers the corrosion resistance.

Carbon has the effect of imparting spalling resistance. Natural graphite, artificial graphite, pitch coke, anthracite, carbon black, electrode scrap, etc. can be used. The blending amount is preferably 3 to 40 wt%. If it is less than 3 wt%, the effect of carbon is small and the spall resistance is insufficient.
If it exceeds 40% by weight, the strength and wear resistance of the refractory material deteriorate. This is the same for both spinel-silicon carbide-carbonaceous non-fired bricks and alumina-silicon carbide-carbonaceous non-fired bricks.

In addition, spinel-silicon carbide-carbonaceous non-fired brick, alumina-silicon carbide-carbonaceous non-fired brick,
Silica, magnesia, calcia, zirconia, zircon, boron carbide, titanium carbide, chromium carbide, zirconium carbide, silicon nitride, boron nitride, magnesium boride, chromium oxide, cryolite, metal powder, glasses, fibers, etc. It is the same as that of the conventional carbon-containing refractory material in that an appropriate amount may be added. For example, addition of cryolite, metal powder, glasses, etc. is particularly effective in preventing oxidation.

Both spinel-silicon carbide-carbonaceous unfired bricks and alumina-silicon carbide-carbonaceous unfired bricks were kneaded by adding a binder such as phenol resin, furan resin, pitch or tar to the above mixture. After that, it is manufactured by molding with a friction press, an oil press or the like. After molding, it is common to give strength to the molded product and remove volatile components by heat treatment at about 300 ° C.

Since the upper part of the slag line is exposed to the atmosphere at a high temperature during use, carbon-containing products have a problem that the structure strength is deteriorated by the oxidation of carbon. Therefore, it is preferable to use a standard refractory or a non-standard refractory that does not contain carbon. Further, in a ladle, a mixed piggy car, etc., a refractory material having excellent resistance to an impact at the time of receiving hot water may be provided in the hot water contact portion of the furnace bottom.

[0017]

EXAMPLES Examples of the present invention and comparative examples will be described below. Table 1 shows the composition of the refractory used in each example and the test results. The symbols (1) to (4) are non-fired bricks, and after kneading the compounds shown in the table, pressure-molded into a normal size with a friction press was heat-treated at 300 ° C. for 24 hours to be manufactured. The reference numeral is a fired brick, and after the compounds shown in the table were kneaded, they were pressure-molded into a normal size with a friction press and further fired at 1350 ° C. for 24 hours. Is an irregular shaped refractory, and water was added at the time of construction, and after kneading, it was poured into a normal size and constructed.

The tests shown in Table 1 were measured by the following method. Thermal expansion coefficient: Measured based on "Test method for hot linear expansion coefficient of refractory bricks" according to JIS-R2207. Corrosion resistance: A mixture of hot metal slag and pig iron with a weight ratio of 1: 1 was used as a solvent, and rotary erosion was performed at 1600 ° C to obtain the melt loss dimension, which was indicated by an index with the melt loss dimension of the refractory code as 1. It was The smaller the value, the smaller the melt loss dimension.

[0019]

[Table 1]

In Table 2, a refractory material having the code shown in Table 1 was used to actually line a 600 ton mixed piggy car, and an actual machine test was conducted. FIG. 1 schematically shows a slag line upper portion (1), a slag line portion (2) and a slag line lower portion (3) of a mixed pig car. The width of the slag line portion (2) in the height direction is arbitrarily determined according to the type of container, the use conditions, etc., but here it was set to about 480 mm.

[0021]

[Table 2]

Joint damage dimension: The maximum damage depth was measured for the joint damage at the boundary between the slag line and the lower part of the slag line. Service life: The number of service times of the entire lining. Actually, the number of uses until the first repair of the lining is required.

As shown by the test results in Table 2, in all the examples of the present invention, the joint damage at the boundary between the slag line portion and the lower portion of the slag line is small. As a result, spinel-silicon carbide-corrosion resistance of the slag line portion that the carbonaceous non-fired brick has, and corrosion resistance at the bottom of the slag line of alumina-silicon carbide-carbonaceous non-fired brick is exhibited at all.
The durability of the entire lining is significantly improved. Further, in Examples 3 to 6 in which the carbon-free refractory without oxidative deterioration was used in the upper part of the slag line, the durability of the entire lining was further improved.

On the other hand, Comparative Example 1 in which the slag line portion and the lower portion of the slag line were made of alumina-silicon carbide-carbonaceous unfired brick, the slag line portion was made of magnesia-carbonaceous unfired brick, and the lower portion of the slag line was made of alumina-silicon carbide. −
In Comparative Example 2 in which the carbonaceous unfired brick was used, the slag line portion was greatly damaged and the durability was poor.

[0025]

INDUSTRIAL APPLICABILITY As described above, the refractory lining structure of the molten metal container according to the present invention does not impair the corrosion resistance of the lining made of alumina-silicon carbide-carbonaceous unfired brick, and its drawback is the slag line. This is a solution to the problem of reduced corrosion resistance of parts. As a result, as is apparent from the above-mentioned examples, the durability of the refractory lining as a whole is significantly improved as compared with the conventional structure. Although the lining structure of the embodiment has been described mainly for the mixed pig iron, the same effect can be obtained by a mixed pig furnace, a hot metal ladle, a molten steel ladle, and an electric furnace.

[Brief description of drawings]

FIG. 1 shows a refractory lining structure of a refractory lining for a mixed pig car.

[Explanation of symbols]

 1 Slug line upper part 2 Slug line part 3 Slag line lower part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Seiji Aso, 1st Nishinosu, Oita-shi, Oita, Oita-shi, Nippon Steel Co., Ltd., Oita Works (72) Inventor, Kimihiko Takeuchi 1-3-1, Niihama, Arai-cho, Takasago-shi, Hyogo Harima Ceramics Co., Ltd. (72) Inventor Toshiyuki Houki 1-3-1 Niihama, Arai-cho, Takasago-shi, Hyogo Prefecture Harima Ceramics Co., Ltd. (72) Noboru Okura 1-3-1 Niihama, Arai-cho, Takasago-shi, Hyogo Prefecture Harima Ceramics Co., Ltd.

Claims (2)

[Claims] 1. A molten metal container lined with alumina-silicon carbide-carbonaceous unfired brick, wherein MgO.Al ₂ O ₃ -based spinel-silicon carbide-carbonaceous unfired brick is arranged in the slag line portion. The refractory lining structure of the molten metal container. 2. The refractory lining structure for a molten metal container according to claim 1, wherein the upper portion of the slag line is a refractory material containing no carbon.