JPH0687668A - Castable refractory - Google Patents

Abstract

PURPOSE:To ensure excellent slag wetting resistance and thermal shock resistance and to prolong useful life by incorporating a specified starting material for spinel, a specified starting material for alumina zirconia, alumina and a binder. CONSTITUTION:The castable refractories are obtd. by using a mixture consisting of 10-40wt.% starting material for spinel consisting of 70-80wt.% alumina and 30-20wt.% magnesia and contg. 5-25wt.% electromelted spinel having 0.05-2mm diameter, 1-10wt.% starting material for alumina-zirconia having 0.125-1.5mm diameter as an electromelted product consisting of 50-70wt.% alumina and 50-30wt.% zirconia and the balance alumina with a 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 service life (see JP-A-64-83575).

[0004]

However, the above-mentioned conventional alumina-spinel castable refractories 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 the sintered spinel particles, the crystal itself does not react with the slag, but the slag component easily enters the crystal grain boundaries. .

In the vicinity of the working surface of the refractory material, the sintered spinel particles become finely dispersed in the slag,
It is discharged 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 occur.

[0008] Therefore, an object of the present invention is to provide a castable refractory which can enhance the slag infiltration resistance and the thermal shock resistance to further improve the service life.

[0009]

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 binder, and the particle size range of 0.05-2 mm of the spinel raw material uses electrofused spinel and The total amount of molten spinel added is 5
It is set to 25% by weight.

The alumina-zirconia-based raw material is an electromelted product composed of 50 to 70% by weight of alumina and 30 to 50% by weight of zirconia, and preferably has a particle size range of 0.125 to 1.5 mm.

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.

[0012]

In the above means, the electrospun spinel particles are dense and have few crystal grain boundaries, and low melting point minerals such as silica (SiO ₂ ) and calcia (CaO) exist independently in the crystal grain boundaries. Therefore, no intrusion of slag into the crystal grain boundaries is observed.

On the other hand, zirconia (ZrO ₂ ) 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.

If the addition amount of spinel raw material exceeds 40% by weight, alumina will be insufficient in the reaction phase with slag and calcia will be in an excessive state, and low-melting minerals will be easily produced, 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.

If the amount of alumina-zirconia-based raw material added exceeds 10% by weight, the melting loss increases. On the other hand, if the addition amount is less than 1% by weight, the effect of alleviating thermal shock is small.

It is not necessary to use the electrofusion spinel for particles larger than 2 mm because the contact area with the slag is small for particles larger than 2 mm. No difference due to product is recognized.
Further, when the addition amount of the electrofused spinel exceeds 25% by weight of the whole, oversintering easily occurs, which causes cracks and peeling, and when the addition amount is less than 5% by weight of the total, the effect of suppressing infiltration of slag is obtained. Becomes smaller.

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 abundant. Therefore, 50 to 70% by weight of alumina,
A composition of 30-50 wt% zirconia is most suitable for thermal shock mitigation.

The alumina / zirconia-based raw materials are 1.
With particles exceeding 5 mm, large cracks occur around the raw material. Then, 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.

Alumina cement is used as the binder.

[0020]

EXAMPLES Examples of the present invention will be described below.

Addition particle size of electro-fused spinel is 0.05-2 mm
In addition, the added particle size of the alumina-zirconia-based raw material is 0.5 to 1.5 mm, the composition is 60% by weight of alumina, 40% by weight of zirconia, and these and sintered spinel, alumina and alumina cement are shown in Table 1, respectively. Mix in the proportions shown and add 5 to 6% by weight of water and cast into a curved plate whose end faces are fan-shaped as shown in FIG.
Various test pieces 1 were obtained by drying at the temperature of 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 were used, kept at a temperature of 1600 to 1620 ° C. for 3 hours, and after cooling, the amounts of erosion loss and infiltration thickness were compared.

Further, a columnar test piece of 40 × 40 × 160 mm was prepared from the above-mentioned 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 refers to the ratio of the dynamic elastic modulus after five repeated heating tests, where the dynamic elastic modulus before heating is 100.

[0026]

[Table 1]

From Table 1, 10-40% by weight of the spinel raw material, 1-10% by weight of the alumina / zirconia-based raw material, and the balance alumina and alumina cement, and the particle size range of 0.05-2 mm of the spinel raw material is charged. Along with the molten spinel, the addition amount of the electrofused spinel is 5 to 25% by weight of the whole, so that the slag infiltration resistance can be enhanced by setting the infiltration thickness to 7 to 12 mm and the spalling resistance index to 40%. It can be seen that the thermal shock resistance can be increased and the melting loss does not increase when the content is set to 58%.

Further, the addition particle size of the electrofused spinel is 0.05 to
2 mm, addition amount 15% by weight, addition amount of sintered spinel 1
In addition to 0% by weight, the addition amount of the alumina-zirconia-based raw material was 5% by weight, the composition was 60% by weight of alumina and 40% by weight of zirconia, and the addition particle size was changed as shown in Table 2. Add 7
The test pieces of Example 7 and Comparative Examples 6 and 7 were obtained in the same manner as described above by mixing them as 0% by weight.

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 shown in Table 2 together with the results of Example 4.
It came to be shown in.

[0030]

[Table 2]

From Table 2, the alumina-zirconia-based raw materials are
It is understood that the melting loss does not increase when the particle size range is 0.125 to 1.5 mm in the electromelted product composed of 50 to 70% by weight of alumina and 30 to 50% by weight of zirconia.

[0032]

As described above, according to the castable refractory of the present invention, the electrofused spinel particles are dense and have few crystal grain boundaries, and the crystal grain boundaries are made of a low melting point mineral such as silica or calcia. Since they exist independently, no intrusion of slag into the crystal grain boundaries is observed, so that collapse of spinel crystal particles is not observed, their initial shape is retained, and infiltration by slag can be suppressed.

When zirconia comes into contact with the slag, it dissolves in the slag. 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 of the alumina / zirconia-based raw material or in the periphery thereof, these minute cracks can alleviate thermal shock. Therefore, the occurrence of large cracks and peeling can be prevented, and the service life can be further improved.

[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

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideo Uemoto 1st Nanto, Ogakie-cho, Kariya city, Aichi Toshiba Ceramics Co., Ltd. Kariya factory (72) Inventor Keisuke Yamazaki 1st-nanto, Ogakie-cho, Kariya city, Aichi prefecture Toshiba Ceramics Co., Ltd. Kariya Plant (72) Inventor Keisuke Sumitomo 3-2-1 Asano, Ogurakita-ku, Kitakyushu, Fukuoka Prefecture Waki Fire Resistant Industry Co., Ltd. (72) Inventor Masaki Tange, Kokurakita, Kitakyushu, Fukuoka 3-2-1 Asano, Waki Fireproof Industry Co., Ltd. (72) Inventor Hiroshi Shiroguchi, 3rd light, Kashima-cho, Kashima-cho, Kashima-gun, Ibaraki Sumitomo Metal Industries, Ltd. Kashima Works (72) Inventor Koichi Ura, Ibaraki Sumitomo Metal Industries, Ltd. Kashima-cho, Kashima-cho, Kashima-gun, Kashima Prefecture (72) Inventor, Kiyoe Hirayama, Kashima-gun, Kashima-gun, Ibaraki Gumi 3rd Sumitomo Metal Industry Co., Ltd. Kashima Works

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.
A castable refractory material characterized in that an electrofused spinel is used in the particle size range of 05 to 2 mm, and the addition amount of the electrofused spinel is 5 to 25% by weight of the whole. 2. The castable refractory according to claim 1, wherein the alumina-zirconia-based raw material is 50 to 50 alumina.
A castable refractory material, which is an electromelted product composed of 70% by weight and 30 to 50% by weight of zirconia and has a particle size range of 0.125 to 1.5 mm.