JPH06116049A - Spinel monolithic refractory - Google Patents

Abstract

PURPOSE:To control rate of linear change after sintering to 0 to +2% regardless of the ratio of magnesia and alumina to spinel in a raw material by restricting the particle diameter of alumina in a monolithic refractory containing magnesia, alumina and spinel as a main component. CONSTITUTION:This monolithic refractory contains (A) 100 pts.wt. sum consisting of 5-95 pts.wt. magnesia and 95-5 pts.wt. alumina with a small quantity of a binder and a slaking preventive by external multiplication or (B) 100 pts.wt. sum consisting of 5-95 pts.wt. magnesia, 95-5 pts.wt. alumina and 0.1-90 pts.wt. spinel with a small quantity of the binder and the slaking preventive by external multiplication, where the alumina used for both (A) and (B) contains 3-10 pts.wt. alumina having <=0.2mm particle diameter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an amorphous refractory used for a molten metal container.

[0002]

2. Description of the Related Art An amorphous refractory containing magnesia, alumina and spinel as main components is widely used especially in a steelmaking process because it has excellent heat resistance, corrosion resistance and spalling resistance. In order to improve the corrosion resistance and spalling resistance of these refractories, it is necessary to add magnesia fine powder and alumina ultrafine powder having a particle diameter of 1 μm or less to the matrix portion (JP-A-63-218586). 3 to 30% by weight of magnesia having a particle size of 0.5 mm or more, 1 to 5% by weight of magnesia having a particle size of less than 0.5 mm, or 1 to 20% by weight of spinel having a particle size of less than 0.5 mm, and alumina cement 0. It is known that the content is 5 to 5% by weight and the balance is alumina (Japanese Patent Laid-Open No. 3-109273).

[0003]

However, these amorphous refractories have a problem in that during use, Svinel is formed from magnesia and alumina, which causes volume expansion. In order to maintain the stability of the refractory structure, it is desired that the linear change rate after firing at 1500 ° C. is a positive value, preferably within the range of 0 to + 2.0%. This is because when the linear change rate is a negative value, a gap is generated in the refractory structure, and when the linear change rate is + 2% or more, a large stress due to restraint is generated inside the structure.

Conventionally, in order to keep the linear change rate within the range of 0 to + 2.0%, adjustment is made by changing the ratio of magnesia, alumina and spinel in the raw material. However, the range of the composition that has the best properties such as corrosion resistance and spalling resistance required for the material does not necessarily match the range of the composition that is limited in terms of linear change rate, and it is necessary to demonstrate sufficient properties. I can't. An object of the present invention is to provide a spinel amorphous refractory in which the linear change rate after firing is controlled within the range of 0 to + 2% regardless of the ratio of magnesia, alumina and spinel in the raw material.

[0005]

In order to solve the above problems, the present invention contains magnesia as a main component in an amount of 5 to 95 parts by weight and alumina in an amount of 95 to 5 parts by weight in total of 100 parts by weight. The amorphous refractory containing a binder and an anti-digestion agent is characterized in that the alumina contains 3 to 10 parts by weight of alumina having a particle diameter of 0.2 mm or less.

Further, the present invention contains as a main component 5 to 95 parts by weight of magnesia, 95 to 5 parts by weight of alumina, and 0.1 to 90 parts by weight of spinel, which is 100 parts by weight in total. An amorphous refractory material containing a digestion inhibitor and the above-mentioned alumina is characterized in that the alumina is 3 to 10 parts by weight of alumina having a particle diameter of 0.2 mm or less.

[0007]

[Function] Oxides such as magnesia, alumina, and spinel have high fire resistance and excellent corrosion resistance to molten steel or slag, and are therefore used as main raw materials for refractories. Magnesia has excellent corrosion resistance to slags having a high CaO content, and alumina and spinel have excellent corrosion resistance to slags having a low CaO content. Also,
Alumina has a property of improving thermal shock resistance because of its low coefficient of thermal expansion. Furthermore, when magnesia and alumina are used at the same time, the residual expansivity can be imparted by the spinel formation reaction.

As described above, magnesia, alumina and spinel have different characteristics, and can be blended in a combination according to the application. However, in order to adjust the rate of change in the residual line by the reaction of spinel formation from magnesia and alumina, it is necessary to contain magnesia and alumina in an amount of 5 parts by weight or more each. In addition, spinel can be used for the purpose of reducing residual expansion.

In this case, if the amount of spinel used is 0.1 parts by weight or less, the effect of reducing the residual expansion cannot be obtained. Therefore, the amount of spinel used must be 0.1 parts by weight or more. Further, since the spinel-shaped amorphous refractory material of the present invention contains magnesia and alumina in an amount of 5 parts by weight or more, the upper limit of the amount of spinel used is 90 parts by weight.

The spinel formation reaction proceeds due to the diffusion of magnesia into the alumina particles, and the smaller the alumina particle size, the larger the spinel formation reaction. When the particle size of alumina is 1 mm or less, the alumina particles are almost completely spinelized. Further, when the particle diameter of alumina is 1 mm or more, a part of the alumina particles becomes spinel. As a result, there is an effect of expanding the volume.

On the other hand, the generated spinel crystal shrinks due to sintering, but when the particle size is 0.2 mm or less, the shrinking effect is particularly great. In order to control the residual line change rate within the range of 0 to + 2%, it is necessary to balance the expansion due to spinel formation and the contraction due to sintering. Of these, expansion associated with spinel formation is unavoidable.

Therefore, it is necessary to control the shrinkage of the produced spinel due to sintering by controlling the amount of alumina having a particle diameter of 0.2 mm or less. That is, when the amount of alumina having a particle diameter of 0.2 mm or less is less than 3 parts by weight, the rate of change in residual line becomes negative, and when it exceeds 10 parts by weight, it is +2.
%, So the amount is 3 to 10 parts by weight. As the binder and anti-digestion agent, those used for ordinary irregular-shaped refractory may be used.

[0013]

EXAMPLE As an example, Table 1 shows the characteristics of the spinel amorphous refractory material of the present invention. The line change rate after firing is 40 ×
Test piece molded in the shape of 40 x 160 mm at 1500 ° C
Calculated from the amount of dimensional change after firing for 12 hours. In addition, as a comparative example, an amorphous refractory having a composition in which the amount of alumina or magnesia used is less than 5 parts by weight, a particle size of 0.2
The amount of alumina used is less than 3 parts by weight or 10
Table 1 also shows the properties of the irregular refractory materials that are more than parts by weight.

[0014]

[Table 1]

In each of Examples 1 to 6 of the present invention, the linear change rate after firing is in the range of 0 to + 2%, and shows excellent structural stability. On the other hand, the amount of alumina or magnesia used is 5
In Comparative Examples 7 and 8 in which the amount was less than parts by weight, the linear change rate after firing was negative. Further, in Comparative Example 9 in which the amount of alumina having a particle diameter of 0.2 mm or less is less than 3 parts by weight, the linear change rate after firing exceeds + 2%, and the particle diameter is 0.2 mm.
Comparative Example 1 in which the amount of alumina used below was more than 10 parts by weight
At 0, the line change rate was negative. As described above, in the comparative example, the linear change rate after firing does not fall within the range of 0 to + 2%, and the structural stability is inferior to the examples.

[0016]

As described above, since the spinel amorphous refractory material of the present invention can control the linear change rate associated with firing, it has both heat resistance, corrosion resistance, spalling resistance and structural stability. Therefore, the durability of the molten metal container can be improved.

Front page continuation (72) Inventor Junji Yamada 1-1 Tobahata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka Inside the Nippon Steel Corporation Yawata Works (72) Inventor Kouji Kono 1-Hibata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka No. 1 New Nippon Steel Co., Ltd. Yawata Works (72) Inventor Jun Egami 1-1 Kurosaki Ceramics Co., Ltd., Higashihama-cho, Hachimansai-ku, Kitakyushu, Fukuoka

Claims (2)

[Claims] 1. An amorphous refractory material containing magnesia as a main component in an amount of 5 to 95 parts by weight and alumina in an amount of 100 parts by weight in total of 95 to 5 parts by weight. Alumina contains 3 to 10 parts by weight of alumina having a particle diameter of 0.2 mm or less, which is an amorphous refractory material. 2. Magnesia as a main component is 5 to 95 parts by weight, alumina is 95 to 5 parts by weight, and spinel is 0.1 to 9 parts.
0 parts by weight, 100 parts by weight in total, in an irregular shaped refractory containing a small amount of a binder and an anti-digestion agent on the outside, the alumina contains 3 to 10 parts by weight of alumina having a particle diameter of 0.2 mm or less. Atypical refractory.