JPH05301772A - Carbon-containing brick - Google Patents

Abstract

PURPOSE:To improve spalling resistance by including expanded graphite as a carbonaceous material in carbon-containing brick. CONSTITUTION:The objective carbon-containing brick is produced by inserting H2SO4, etc., into spaces between layers of graphite, rapidly heating the resultant graphite intercalation compound at 800-1000 deg.C, providing expanded graphite, kneading 0.1-10wt.% resultant expanded graphite with a basic refractory material such as magnesia and a neutral refractory material such as alumina, forming the obtained kneaded mixture and then heat-treating the formed compact at about 300 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a hot metal wheel, a hot metal ladle, a converter,
The present invention relates to a carbon-containing brick used for lining various molten metal containers such as molten steel pots and electric furnaces.

[0002]

2. Description of the Related Art In recent years, carbon-containing bricks have been widely used as lining bricks for various molten metal containers such as converters. This carbon-containing brick uses a carbonaceous material mainly composed of scaly graphite as a constituent element, and has a property of being hard to be wetted by the slag, high corrosion resistance due to high thermal conductivity, and high spooling resistance.

[0003]

Recently, various treatments have been carried out in these molten metal containers, so that operations at high temperatures have become normal, and higher corrosion resistance and sponging resistance than before have been desired. It is like this. Furthermore, refractory materials containing carbonaceous materials tend to shift to low carbon due to the problem of carbon pickup into steel, such as in the melting of ultra-low carbon steel in the direction of high grade steel. Such low carbon carbon-containing bricks are particularly required to have a sparkling resistance.

[0004]

As a result of various studies on the method of improving the spalling resistance of the carbon-containing brick, the inventors of the present invention have found that the sponging resistance of the brick is simpler than the method of adding an additive. It has been found that sex can be improved. That is, the present invention is characterized in that expanded graphite is used for the scaly graphite of the carbon-containing brick.

The carbon-containing brick of the present invention is mainly composed of a basic and neutral refractory material in addition to expanded graphite.
The basic refractory material is magnesia, dolomite, calcia, magcalcia, etc., and the neutral refractory material is alumina, spinel, etc. These may be used alone or as a mixture. It is also possible to use these refractory materials as a main component, and also use other known oxide refractory materials, non-oxide refractory materials, and the like. Especially magnesia car
Bon bricks, magcalcia carbon bricks, alumina carbon bricks, alumina silicon carbide carbon bricks, spinel carbon bricks, spinel alumina alumina
Carbon bricks are preferably magnesia, spinel, carbon bricks and the like, but use of magnesia carbon bricks is more preferable because it suppresses the magnesia-carbon reaction at high temperatures.

Expanded graphite as a carbonaceous material, which is a feature of the present invention, expands graphite layers by rapidly heating a graphite intercalation compound in which sulfuric acid or the like is inserted between graphite layers to a temperature of 800 to 1000 ° C. It is a thing. This expanded graphite is used together with the basic and neutral refractory materials, but it is also possible to use expanded graphite and scaly graphite together. The amount used is 3 to 40% by weight of the total carbonaceous material in the brick, and is particularly suitable for the carbon-containing brick in the low carbon region of 3 to 10% by weight. The amount of expanded graphite used is preferably in the range of 0.1 to 10% by weight in production, and it is desirable in terms of characteristics that the total amount of expanded graphite is low carbon.

In the present invention, the above-mentioned basic and neutral refractory materials and expanded graphite are used. In addition to these, metal powder, antioxidant materials such as vitreous materials, and materials for improving anti-spooling properties such as various fibers. It is acceptable to use known additives such as. A binder such as a phenol resin is added to these materials, and the mixture is used as an unfired refractory brick which is kneaded and molded by a usual method and then heat treated, or a fired refractory brick which is reduced and fired at a high temperature.

[0008]

[Function] Expanded graphite is a bulky mass that has a honeycomb structure in which graphite crystallization is intertwined with each other and has excellent elasticity. Therefore, when used as a carbon-containing brick, thermal expansion and contraction of refractory materials, especially magnesia, etc. As a result, it becomes a brick with high resistance to sporing. Therefore, in the low carbon brick, since the carbon content is small, the spalling resistance is lowered, but the use of expanded graphite can compensate for the drop in the spalling resistance.

Furthermore, since it is bulky and excellent in airtightness, it prevents slag from entering the brick and contributes to corrosion resistance. This property is remarkable in a low carbon brick in which the amount of carbon material used is small. In addition, since expanded graphite is excellent in shape retention so that it can be molded into a sheet without using a binder, when a large amount is used, the binder phenol
It is also possible to reduce the amount of resin.

[0010]

EXAMPLE Magnesia carbon bricks having the composition shown in Table 1 were kneaded, press-molded, and then heat-treated at 300 ° C. for 10 hours. The results of various tests on the brick are also shown in Table 1. The anti-spooling index is expressed by the maintenance ratio of the elastic modulus before and after repeating the operation of immersing in molten steel at 1650 ° C. three times. Corrosion resistance index is converter slag (C / S = 3.4)
Was used and the reciprocal of the amount of erosion after treatment at 1750 ° C. for 5 hours was represented by an index with Comparative Example 3 being 100. The breaking energy was measured by the work-of-fracture method with a chevron notch.

[0011]

[Table 1]

The results for magnesia-carbon bricks, which showed the greatest effect, were shown as examples, but the same tendency was observed for other carbon-containing bricks such as alumina-silicon carbide-carbon bricks. From the results of Table 1, when expanded graphite is used instead of conventional scaly graphite,
What is considered to be the effect of the expanded graphite absorbing the thermal expansion of magnesia appears as an improvement of the spooling resistance (maintenance of elastic modulus). This effect is remarkable especially in the low carbon region. Further, the thermal shock damage resistance, which is another measure of the spooling resistance, is almost doubled due to the introduction of expanded graphite. This effect is more effective as the carbon becomes lower. On the other hand, regarding the corrosion resistance, even if expanded graphite is used in the high carbon region, it is almost the same as the conventional one, and the corrosion resistance is improved in the low carbon region.

[0013]

INDUSTRIAL APPLICABILITY In the present invention, the sponging resistance of bricks can be improved by replacing the conventional scaly graphite with expansive graphite as the carbonaceous material used for the carbon-containing bricks, and in particular, the low-coloring can be achieved. The effect of using expanded graphite is remarkable in the carbon-containing brick of Bonn.

[0014]

[Table 1]

Claims (1)

[Claims] 1. A carbon-containing brick characterized by containing expanded graphite as a carbonaceous material.