JPH03197346A - Carbon-containing refractory - Google Patents

Abstract

PURPOSE:To improve the corrosion resistance and oxidation resistance of refractory by compounding a refractory material containing particles having specific particle diameter with a carbonaceous material and one or more materials selected from carbide material, nitride material, metallic material and vitreous material. CONSTITUTION:The objective carbon-containing refractory can be produced by compounding (A) 3-30wt.% of a carbonaceous material having particle diameter of about <0.5mm (e.g. pitch coke), (B) 0.1-20wt.% of one or more materials having particle diameter of about <=0.5mm and selected from carbide material (e.g. SiC), nitride material (e.g. Si3N4), metallic material (e.g. Al) and vitreous material (e.g. borax) and (C) a refractory oxide material (e.g. alumina) containing 10-30wt.% of particles having particle diameter of 1-0.5mm to obtain 100wt.% of a compounded composition, kneading the composition with a organic binder (e.g. phenolic resin) or an inorganic binder (e.g. sodium silicate), compression-molding the kneaded mixture and drying the molded product.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a carbon-containing refractory having excellent corrosion resistance and oxidation resistance.

(Conventional technology) Traditionally used as lining material for containers for hot metal and molten steel.

Refractories containing carbon, such as magnesia-carbonaceous or alumina-carbon-silicon carbide, are often used.

Carbon has the properties of not being easily wetted by slag and having excellent thermal shock resistance, and by combining it with refractory materials with high melting points such as alumina and magnesia, highly durable refractories can be obtained.

On the other hand, carbon has the disadvantage that it disappears by oxidation, and when a decarburized layer is formed in the above-mentioned refractory, erosion progresses significantly due to a decrease in strength or infiltration of the slab.

Therefore, various means have been studied to improve the corrosion resistance and oxidation resistance of carbon-containing refractories.

For example, JP-A No. 54-163913 proposes a method of adding metals, while JP-A No. 60-157857
The publication proposes a method of adding a vitreous component, and although each method is effective, the following problems have arisen, and a solution to these problems has been desired.

(Problem to be solved by the invention) In other words, in the method of adding metals, the effect of preventing oxidation can be obtained at high temperatures of 1000°C or higher, but at lower temperatures, the metal becomes a liquid phase that can block the passage of oxygen. Therefore, it has been difficult to completely prevent oxidation in this low temperature range.

In addition, the conventional method of adding glassy materials mainly composed of silicic acid and phosphoric acid can suppress oxidation because it forms a glass film on the brick surface in the low to high temperature range, but it is possible to suppress oxidation. Therefore, when a large amount of Ni was added, the corrosion resistance deteriorated significantly.

Therefore, although the method of using these additives is effective, it is not sufficient, and it has become necessary to simultaneously improve corrosion resistance and oxidation resistance by a method other than using additives.

(Means for solving the problem) Conventionally, carbon-containing refractory bricks generally have poor oxidation resistance,
Corrosion resistance is better when the porosity is smaller, so when blending coarse, medium, and fine particles in the particle size structure, the amount of medium particles added is reduced as much as possible to achieve close packing to reduce porosity.

However, as a result of microscopic observation of the operating surface of carbon-containing refractories after use, the inventors found that the wear and tear of refractories progresses with the aggregate protruding into the slag layer and the carbon-containing matrix taking precedence. Focusing on this, we also found that aggregates with a particle size of 1 mm or more are difficult to dissolve into slag, but gaps are created around the aggregate, allowing slag to enter. It has been found that aggregate easily dissolves into slag in the following cases. This is because grains of 11 or more have a large amount of thermal expansion and a large gap between the grains and the matrix when cooled, resulting in high air permeability and easy oxidation, as well as easy penetration of slag. Therefore, in order to suppress erosion loss, it is necessary to reduce the amount of aggregate of 1 m1 or more and/or less than 0.5 mm as much as possible, and to mix in more refractory aggregate particles with a particle size of 1 to 0.5 mm. We discovered that it is possible to increase the contact area between the particles and the matrix by reducing the gap between the particles and the matrix while maintaining a size that does not dissolve in the slag, which is effective in improving corrosion resistance and oxidation resistance. It has been completed.

That is, in 100% by weight of a blend consisting of 3% to 30% by weight of carbonaceous material and the remainder being a refractory oxide material, 10% to 30% by weight
A carbon-containing refractory characterized in that 30% by weight is the refractory oxide material having a particle size of 1 to 0.5 mm.

The carbonaceous materials used in the present invention include natural graphite, artificial graphite, pitch coke, anthracite, carbon black, etc. The addition amount is limited to 3 to 30% by weight. This is because the effect is not obtained and the spall resistance is insufficient, and if it exceeds 30% by weight, the strength and abrasion resistance as a refractory decrease. Although the particle size of the carbonaceous material is not particularly limited, a material having a particle size of less than 0.5 m is usually used.

Refractory oxide materials include single components such as alumina, silica, magnesia, calcia, zirconia, and chromium, or spinel, alumina-silica,
One or more types of dolomite, zircon, etc. can be used. The reason for limiting the particle size of the refractory oxide material to 10 to 30% by weight is that if it is less than 10% by weight, the particle size of the refractory material is 11 or more and less than 0.5%. Aggregates with a particle size of 1 kaku or larger are difficult to dissolve into the slag, but if slag gets into the surroundings of the aggregate, it easily flows out into the slag and wear and tear progresses all at once. This is because if the distance is less than 5 m, the dissolution of the aggregate into slag progresses rapidly and the wear and tear of the brick matrix progresses significantly. 30% by weight of particle size of 1 to 0.5-
This is because if it exceeds this, the filling properties will be reduced and good corrosion resistance and strength will not be obtained.

The binder is an organic binder such as phenol resin, sodium silicate,
Inorganic binders such as aluminum phosphate can be used.

Further, in order to prevent carbon oxidation, 0.1 to 20% by weight of one or more of carbide materials, nitride materials, metal materials, and glass materials can be used.

As the carbide material, silicon carbide, boron carbide, titanium carbide, chromium carbide, zirconium carbide, etc. are used, and as the nitride material, silicon nitride, boron nitride, titanium nitride, chromium nitride, zirconium nitride, etc. are used as appropriate. As the metal material, silicon, aluminum, magnesium, calcium, chromium, zirconium, iron, etc. can be used alone or in combination or alloys.

As the glassy material, borax, sodium silicate, sodium phosphate, sodium borosilicate, sodium borophosphate, sodium borophosphate containing F, Li, and 0 and having a low separation point can be used.

Limiting the amount added to 0.1 to 20% by weight is 0.1%
This is because if the amount is less than 20% by weight, the effect of addition will not be obtained, and if it exceeds 20% by weight, the corrosion resistance will decrease.

The particle size of carbides, nitrides, metals, and glassy materials is not limited, but is added for the purpose of preventing oxidation of carbonaceous materials.
．． Fine particles of 5011 or less are preferred.

(Function) As mentioned above, in 100% by weight of a mixture consisting of 3 to 30% by weight of carbonaceous material and the remainder being a refractory oxide material,
The carbon-containing refractory is characterized in that ~30% by weight is the refractory oxide material having a particle size of 1 to 0.5 m, and the carbon-containing refractory has a large proportion of the refractory material with a particle size of 1 to 0.5 m. Therefore, the refractory material does not flow out into the slag all at once, and the particles are less likely to dissolve in the slag, resulting in improved corrosion resistance.

The carbon-containing refractory of the present invention is normally used as an unfired brick, but since the effects of the invention do not change even if it is fired, it can also be used as a fired brick. It goes without saying that it can also be applied to monolithic refractories since the same effects as unfired bricks can be obtained as monolithic refractories.

(Example) Examples will be described below.

Example 1 After mixing and kneading the inventive product and the conventional product according to the compounding ratios shown in Table 1, the products were press-molded into a serpentine shape using a conventional method and dried at 250°C for 24 hours to obtain a specimen. And so. Corrosion resistance was determined by rotary erosion of the above specimen at 1500°C for 5 hours using an eroding agent (70% blast furnace slag).
An erosion test was conducted using 30% pig iron, and the erosion dimensions were measured after the test.

As is clear from the above results, the corrosion resistance of the product of the present invention was improved by 22 to 27% compared to the conventional product.

Example 2 After mixing and kneading the products of the present invention and the conventional product according to the compounding ratios shown in Table 2, the products were press-formed into a serpentine shape using a conventional method and dried at 250°C for 24 hours to obtain a specimen. And so. Corrosion resistance was determined by rotary erosion of the above specimen at 1650°C for 5 hours using an eroding agent (70% converter slag).
, 30% steel) was used to conduct an erosion test, and the dimensions of the erosion damage after the test were measured.

As is clear from the above results, the corrosion resistance of the products of the present invention was improved by 18 to 27% compared to the conventional products.

Furthermore, when the present invention product NQI and the conventional product Na4 were used by pasting each half on the slag line part of a pig iron mixer car, and the m/ch erosion dimensions after use were compared, the conventional product NQ4 was 0.5 / ah, whereas the invention product &1 had a value of 0.
4■/ch, an improvement of about 20%.

347 (Effect of the invention) As explained above, in the product of the present invention, since there are many refractory oxide materials of 1 to 0.5 degrees, the gap between the aggregate and the matrix in the brick is reduced, and the oxidation of the carbonaceous material is reduced. At the same time, it becomes difficult for the slag to penetrate around the aggregate, and the ratio of contact between the aggregate and the matrix increases, making it difficult for the aggregate to flow into the slag.Also, there are few aggregates below 0.5 m+ that enter the slag. By reducing melting and oxidation of bricks, the durability of carbon-containing refractories is greatly increased, and their industrial value is great.

Claims (2)

[Claims] (1) 10 to 30% by weight of a blend consisting of 3 to 30% by weight of carbonaceous material and the remainder being a refractory oxide material
A carbon-containing refractory characterized in that the refractory oxide material has a particle size of 1 to 0.5 mm in weight%. (2) A composition consisting of 3 to 30% by weight of carbonaceous material, 0.1 to 20% by weight of one or more of carbide materials, nitride materials, metal materials, and glassy materials, and the balance being refractory material. In 100% by weight of the product, 10 to 30% by weight is 1 to 0.
A carbon-containing refractory, characterized in that it is the refractory oxide material having a particle size of 5 mm.