JPH06345549A - Castable refractory - Google Patents

Abstract

PURPOSE:To obtain a castable refractory excellent in slag permeability, thermal impact resistance and durability, etc., by mixing a specific composition of spinel raw material, alumina.zirconia raw material, alumina and a binder in a specific weight ratio. CONSTITUTION:(A) 10-40wt.% the spinel material, (B) 1-10wt.% the alumina.zirconia raw material and (C) the balance quantities of the alumina and the binder are mixed to produce the castable refractory. However, in the A component, electrofused spinel is essentially used for the product in the particle range from 0.05 to 2mm, and also an additional quantity of the electrofused spinel is >=50wt.% for the total spinel additional quantity. The B component also uses an electrofused product consisting of 50-80wt.% alumina and 50-20wt.% zirconia, and the particle range is from 0.125 to 1.5mm. A portion of the alumina in the C component is also composed of 2-5wt.% superfine powder containing >=50wt.% particles with <=3mum size, and also 2-10wt.% alumina cement is used as the binder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a castable refractory used for lining a ladle for steelmaking.

[0002]

2. Description of the Related Art As a refractory material for lining a ladle for steel making, wax stone bricks, high-alumina refractory materials, zircon-based refractory materials, etc. are generally used. However, in recent years, alumina / spinel castable refractories have come to be used due to demands such as improvement of useful life (JP-A-64).
-83575 publication).

[0003]

However, the conventional alumina-spinel castable refractories described above have the following problems, and therefore have stable service lives when used as lining refractory materials for steel ladle. Can't get (1) Since the sintered spinel is used, infiltration with slag is large. This is because spinel is a very excellent material with respect to slag resistance, but in sintered spinel particles, the crystals themselves do not react with the slag, but the slag component penetrates into the crystal grain boundaries and the particles collapse. It is easy to cause. Therefore, in the vicinity of the working surface of the refractory material, the sintered spinel particles are finely dispersed in the slag and flow out together with the slag by the molten steel flow. Therefore, infiltration of slag into the matrix portion becomes large, which causes structural spalling. (2) Cracks and peeling due to thermal shock are likely to occur. Therefore, an object of the present invention is to provide a castable refractory which can improve the slag infiltration resistance and the thermal shock resistance to further improve the service life.

[0004]

In order to solve the above-mentioned problems, the castable refractory material of the present invention is a spinel raw material 10
-40% by weight, 1-10% by weight of alumina / zirconia-based raw material, the balance consisting of alumina and a binder, and the particle size range of 0.05-2 mm of the spinel raw material mainly uses electrofused spinel, and If the amount of electrofused spinel added is 50 wt% or more of the total amount of spinel added, alumina.
The zirconia-based raw material is an electrofused product containing 50 to 80% by weight of alumina and 20 to 50% by weight of zirconia and having a particle size range of 0.
125-1.5 mm, part of the remaining alumina is 3
2 to 8% by weight of ultrafine powder containing 50% by weight or more of particles of μm or less, and alumina cement 2 to 10 as a binder.
% By weight is used. Silica contained in the castable refractory is preferably 0.3% by weight or less.

Here, the spinel raw material means particles of magnesium aluminate (MgO.Al ₂ O ₃ ), and
The electrofused spinel is an electrofused product composed of 70 to 80% by weight of alumina and 20 to 30% by weight of magnesia.

[0006]

In the above means, the electrospun spinel particles are dense and have few crystal grain boundaries, and the low melting point minerals containing silica (SiO ₂ ) and calcia (CaO) are isolated in the crystal grain boundaries. Slag is not present in the grain boundaries. Zirconia (ZrO ₂ ) in the alumina-zirconia-based raw material melts into the slag when it comes into contact with the slag. As a result, the slag composition changes and the viscosity rises sharply. In addition, minute cracks occur in the matrix inside or around the alumina-zirconia-based raw material that is not in contact with the slag. The addition of ultrafine alumina powder enables the matrix portion to form a dense structure. In addition, the ultrafine alumina powder in the matrix reacts with the alumina cement during heating, causing CaO-6
It produces acicular crystals of Al ₂ O ₃ . This CaO ・ 6Al
_Since there is volume expansion during the formation of ₂ O ₃ , the structure of the matrix portion is further densified. Alumina cement is
As described above, upon heating, it reacts with the alumina of the matrix portion to form needle-like crystals of CaO · 6Al ₂ O ₃ . Then, the structure of the matrix portion is densified by the volume expansion at the time of generation. On the other hand, by setting the amount of silica contained in the castable refractory to 0.3% by weight or less, the amount of low-melting minerals such as grenite and anorthite produced in the reaction phase with slag is reduced, and
Oversintering is prevented when spinel and silica coexist.

When the addition amount of spinel raw material exceeds 40% by weight, alumina is insufficient in the reaction phase with slag and calcia becomes excessive, and low melting point minerals are easily generated, which is a cause of structural spalling. Become. On the other hand, if the addition amount is less than 10% by weight, the slag infiltration suppressing effect is small. Spinel has a small infiltration suppression effect for particles larger than 2 mm due to a small contact area with the slag, etc.
The following are preferred. For electrofused spinel, 0.05m
The particle size is preferably m or more, and in order to obtain a clear addition effect, the addition amount is preferably 50% by weight or more of the total spinel addition amount.

Alumina / zirconia-based raw materials have large melting loss when the addition amount exceeds 10% by weight. On the other hand, if the addition amount is less than 1% by weight, the effect of alleviating thermal shock is small. The eutectic point of alumina / zirconia is around 40% by weight, and in the composition before and after this, fine cracks generated inside the alumina / zirconia-based raw material are thin and most numerous. Therefore, a composition of 50 to 80% by weight of alumina and 20 to 50% by weight of zirconia is most suitable for thermal shock relaxation. Alumina / zirconia-based raw materials are 1.
With particles exceeding 5 mm, large cracks occur around the raw material. Therefore, the alumina-zirconia-based raw material is selectively corroded and locally melted. On the other hand, if the particle size is less than 0.125 mm, the effect of improving the thermal shock resistance is small.

If the amount of alumina ultrafine powder added exceeds 8% by weight, densification progresses, so that explosion tends to occur. On the other hand, if the addition amount is less than 2% by weight, the matrix portion becomes porous and the slag infiltration suppressing effect becomes small.

When the amount of alumina cement added exceeds 10% by weight, low-melting minerals such as grenite and anorthite tend to be produced in the reaction phase with slag, which causes structural spalling. On the other hand, if the addition amount is less than 2% by weight, the strength during construction becomes low.

[0011]

EXAMPLES Examples of the present invention will be described below. Examples 1 to 6 and Comparative Examples 1 to 5 The addition particle size of the electrofused spinel is set to 0.05 to 2 mm, and the addition particle size of the alumina / zirconia-based raw material is set to 0.5 to
1.5 mm, composition 60 wt% alumina, zirconia 4
0% by weight, and mixed with sintered spinel, alumina, and alumina cement in the proportions shown in Table 1, and 5 to 6% by weight of water was added to make the end faces fan-shaped as shown in FIG. Each of the test pieces 1 was obtained by casting in a curved plate-like shape and drying at a temperature of 110 ° C. for 24 hours.

The test piece 1 was set in the induction furnace 2 as shown in FIGS. 2 and 3, and an erosion test was conducted. As the erosion agent 3, SS41, 60 kg, and 500 g of steelmaking furnace slag are used and kept at a temperature of 1600 to 1620 ° C. for 3 hours,
After cooling, the amounts of melt loss and the infiltration thickness were compared. Further, a column-shaped test piece of 40 × 40 × 160 mm was prepared from the above material, and a repeated heating test was repeated 5 times at a temperature of 1400 ° C. to measure the dynamic elastic modulus. The infiltration thickness and the spalling resistance index after the erosion test using the induction furnace are shown in Table 1, respectively. Here, the spalling resistance index means the ratio of the dynamic elastic modulus after five repeated heating tests, where the dynamic elastic modulus before heating is 100.

[0013]

[Table 1]

From Table 1, 10 to 40% by weight of the spinel raw material, 1 to 10% by weight of the alumina / zirconia-based raw material, and the balance alumina and alumina cement, and the particle size range of 0.05 to 2 mm of the spinel raw material is charged. Along with the molten spinel, the addition amount of the electrofused spinel is 5 to 25% of the total.
By adjusting the weight percentage, the infiltration thickness can be increased to 7 to 12 mm to enhance the slag infiltration resistance, while the spalling resistance index can be increased to 40 to 58% to enhance the thermal shock resistance, and cracks or peeling can occur. I know I won't.

Example 7, Comparative Examples 6 to 7 The addition particle size of the electrofused spinel was 0.05 to 2 mm, the addition amount was 15% by weight, the addition amount of the sintered spinel was 10% by weight, and the alumina-zirconia system was used. 5% by weight of raw material, 60% by weight of alumina, 40% by weight of zirconia
Then, the addition particle size was changed as shown in Table 2, and the amount of alumina and alumina cement added was 70% by weight and mixed to obtain each test piece as described above. The thickness of the infiltrated layer after the erosion test using the induction furnace of each test piece and the spalling resistance index after the repeated heating test are
The results of Example 4 are shown in Table 2 together.

[0016]

[Table 2]

From Table 2, the alumina / zirconia-based raw materials are
An electromelted product composed of 50 to 80% by weight of alumina and 20 to 50% by weight of zirconia, and having a particle size range of 0.125 to 1.5 mm, a refractory having excellent slag infiltration resistance and thermal shock resistance can be obtained. I understand. Further, it was found that the addition of the alumina / zirconia-based raw material having a particle size of less than 0.125 mm did not improve the thermal shock resistance, and the addition of the alumina-zirconia-based raw material having a particle size of more than 1.5 mm resulted in a large melt loss. .

Examples 8 to 12 and Comparative Examples 8 to 11 The addition particle size of the electrofused spinel was 0.05 to 2 mm, the addition amount was 15% by weight, and the addition amount of the sintered spinel was 10% by weight. The added particle size of the zirconia-based raw material is set to 0.
5 to 1.5 mm, the addition amount is 5% by weight, while the addition amount of alumina ultrafine powder containing 50% by weight or more of particles of 3 μm or less constituting the remaining alumina together with the alumina aggregate is shown in Table 3. Each test piece was obtained as described above. The thickness of the infiltrated layer after the erosion test using the induction furnace of each test piece and the spalling resistance index after the repeated heating test were as shown in Table 3 together with the results of Example 4.

[0019]

[Table 3]

From Table 3, 2 to 8% by weight of ultrafine alumina powder, which constitutes a part of the remaining alumina, and 2-1 to alumina cement are used.
It can be seen that when the content is 0% by weight, a refractory material having excellent slag infiltration resistance and thermal shock resistance can be obtained. It can be seen that when the addition amount of the alumina ultrafine powder is less than 2% by weight, the thickness of the infiltration layer becomes large, and when the addition amount exceeds 8% by weight, it tends to explode during drying. When the amount of alumina cement added is less than 2% by weight, cracking occurs during demolding due to insufficient strength, and when the amount added exceeds 10% by weight, thermal shock resistance decreases and cracks and peeling occur. It can be seen that occurs.

Example 13, Comparative Example 12 The addition particle size of the electrofused spinel was 0.05 to 2 mm, the addition amount was 15% by weight, the addition particle size of the sintered spinel was 10% by weight, and the alumina-zirconia-based raw material was used. The addition particle size is 0.125 to 1.5 mm, the addition amount is 10% by weight, the addition amount of alumina ultrafine powder is 5% by weight, and the addition amount of alumina cement is 5% by weight. The type was changed as shown in Table 4, and each test piece was obtained as described above. The thickness of the infiltrated layer after the erosion test using the induction furnace of each test piece and the spalling resistance index after the repeated heating test were as shown in Table 4 together with the results of Example 4.

[0022]

[Table 4]

From Table 4, when the content of silica in the castable refractory is 0.3% by weight or less, slag infiltration resistance,
It can be seen that a refractory having excellent thermal shock resistance can be obtained.

[0024]

As described above, according to the castable refractory of the present invention, the electromelting spinel particles are dense and have a small number of crystal grain boundaries, and also have a low melting point containing silica, calcia or the like in the crystal grain boundaries. Since the minerals exist independently, no penetration of the slag into the crystal grain boundaries is observed, so no collapse of the spinel crystal particles is observed, the initial shape is retained, and infiltration by the slag can be suppressed. . Also, zirconia melts into the slag when it comes into contact with it. As a result, the slag composition changes and the viscosity rapidly increases, so that the slag infiltration into the refractory is suppressed. In addition,
Since minute cracks are generated in the matrix inside or around the zirconia-based raw material, these minute cracks can reduce thermal shock. For this reason,
It is possible to prevent the occurrence of large cracks and peeling, and further improve the service life. Furthermore, the addition of ultrafine alumina powder forms a dense structure in the matrix part, and reacts with the alumina cement during heating to form needle-like crystals of CaO.6Al ₂ O ₃ and the volume expansion during this formation. Since it becomes more dense by this, the effect of suppressing the infiltration of slag can be enhanced. Therefore, the castable refractory of the present invention is remarkably excellent in slag infiltration resistance and thermal shock resistance as compared with the conventional one, and has a durability of 1.5 times or more. On the other hand, by setting the amount of silica contained in the castable refractory to 0.3% by weight or less,
Since the amount of low melting point minerals such as grenite and anorthite generated in the reaction phase with slag is reduced, and oversintering when spinel and silica coexist is prevented,
It is possible to suppress structural spalling, cracking, and peeling.

[Brief description of drawings]

FIG. 1 is a perspective view of a curved plate-shaped test piece whose end face is fan-shaped cast using a castable refractory material according to an embodiment of the present invention.

FIG. 2 is a sectional view of an induction furnace used for an erosion test of the test piece of FIG.

FIG. 3 is a plan view of an induction furnace used for an erosion test of the test piece of FIG.

[Explanation of symbols]

 1 Test piece 2 Induction furnace 3 Erosion agent

Front page continuation (72) Inventor Noboru Nakamura No. 1 Minamitou, Ogakie-cho, Kariya city, Aichi Toshiba Ceramics Co., Ltd. Kariya factory (72) Inventor Keisuke Yamazaki No. 1 Minamitou, Ogakie-cho, Kariya city, Aichi Toshiba Ceramics Co., Ltd. Company Kariya Plant (72) Inventor Keisuke Sumitomo 3-2-1 Asano, Kokurakita-ku, Kitakyushu City, Fukuoka Prefecture Waki Fireproof Industry Co., Ltd. (72) Inventor Masaki Tange 3-Asano, Kokurakita-ku, Kitakyushu City, Fukuoka Prefecture No. 2 No. 1 in Wake Fireproof Industry Co., Ltd. (72) Inventor Hiroshi Shiroguchi, 3rd, Hikari, Kashima-machi, Kashima-gun, Kashima-gun, Ibaraki Sumitomo Metal Industries, Ltd. Kashima Works (72) Inventor, Koichi Ura Kashima-gun, Kashima-gun, Kashima-gun 3 in Hikari-machi, Kashima Steel Works, Sumitomo Metal Industries, Ltd. (72) Inventor, Kiyoe Hirayama, in Kashima-machi, Kashima-gun, Ibaraki Prefecture, Sumitomo Metal Industries, Ltd. Kashima Steel Works, Ltd.

Claims (2)

[Claims] 1. A spinel raw material containing 10 to 40% by weight and an alumina-zirconia-based raw material 1 to 10% by weight, the balance being alumina and a binder.
In the particle size range of 05 to 2 mm, the electrospinning spinel is mainly used, and the addition amount of the electrospinning spinel is 5 of the total spinel addition amount.
0% by weight or more, the alumina-zirconia-based raw material is alumina 50 to 80% by weight, zirconia 20 to 50% by weight
Particle size range of 0.125 to 1.5 mm, and a part of the remaining alumina is 3 μm or less.
A castable refractory which is 2 to 8% by weight of ultrafine powder containing at least 2% by weight, and 2 to 10% by weight of alumina cement is used as a binder. 2. The castable refractory material according to claim 1, wherein the content of silica in the castable refractory material is 0.3% by weight or less.