JPH085718B2 - Silicon Carbide for Blast Furnace Wall-Method for Manufacturing Carbonaceous Brick - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a silicon carbide-carbonaceous brick used as a brick for a furnace wall of a blast furnace for iron making.

[Conventional technology]

The conditions required for blast furnace wall bricks are the resistance to abrasion by various raw materials to be charged, like the bricks for blast furnace wall, and the resistance to other working conditions due to the structure of the furnace. It is excellent in poling, alkali resistance, CO gas resistance, oxidation resistance, and thermal conductivity.

Conventionally, chamotte brick, high alumina brick, and corundum brick have been used as the brick for the furnace wall of the blast furnace, but the above conditions are not sufficiently satisfied.

In order to improve the wear resistance and spalling resistance of these oxide refractories, Si oxide is used instead of such oxide refractories.
A method for producing a refractory material having a matrix made of sialon containing each phase of -Al-ON system is disclosed in Japanese Patent Publication No. 60-6305.

On the other hand, for the morning glory of blast furnaces, hot water tanks, furnace bottoms, and side walls, alkali bricks, CO gas resistance, and oxidation resistance are used to improve the short life of carbon bricks mainly due to dissolution into the molten metal and corrosion such as oxidation. A silicon carbide refractory having excellent thermal conductivity is disclosed in, for example, Japanese Patent Publication No. 60-47224. And, as this silicon carbide-based brick, a silicon carbide brick of β-SiC bond, a silicon carbide brick of silicon nitride bond and a carbon-silicon carbide brick obtained by adding a small amount of SiC to carbon brick tend to be often used, and the From the standpoint of spalling property, it has spalling resistance equal to or higher than that of oxide refractories used for conventional furnace walls.

[Problems to be solved by the invention]

The present invention replaces the above-mentioned conventional oxide refractory brick as a brick for a side wall of a blast furnace, and has excellent carbonization properties such as alkali resistance, CO gas resistance, oxidation resistance, and thermal conductivity in terms of the blast furnace operating environment. This is to solve the problems in applying silicon-based bricks.

That is, the silicon carbide-based brick has spalling resistance equal to or higher than that of the conventional alumina or the alumina-silica-based brick as described above, but still sufficiently satisfies the required properties. It does not have proper characteristics, and silicon carbide-based bricks have a problem in oxidation resistance due to the tendency of carbon to oxidize.

From this point, as described in JP-B-60-47224, a carbon-silicon carbide refractory having sialon compound, alumina, silicon nitride, silicon carbide, etc. formed in the structure is used for the side wall. It could be applied to bricks,
In the case of the refractory described in the publication, Al reacts with SiO in the refractory clay because the refractory clay is added to the composition, and A
It becomes l ₂ O ₃ , which prevents the formation of AlN and reduces corrosion resistance and oxidation resistance, which is a problem. Further, in the case of the one described in the same publication, the formation of silicon nitride is observed, but the formation of this silicon nitride hinders the densification of the molded brick and is not suitable as a brick for a furnace wall of a blast furnace.

The object of the present invention is to solve the problems in applying a silicon carbide-based brick in place of the conventional oxide-based refractory brick to obtain a brick for a blast furnace wall having long-term durability to obtain the blast furnace itself. Achieving longer life.

[Means for solving problems]

The present invention improves the spalling resistance by adding scaly graphite to silicon carbide powder, improves the oxidation resistance by blending Si, and further molds using a high residual carbon resin binder as a binder, and 1200 ° C. Baking in the above non-oxidizing atmosphere, to improve the bondability of the structure, to obtain a brick that satisfies the above required characteristics as a furnace wall brick of a blast furnace,
This is a solution to the above problem.

If the blending amount of flake graphite is less than 10% by weight, the effect of improving spalling resistance is insufficient, and 30% by weight.
If it exceeds, the oxidation resistance is greatly reduced, and the wear resistance is also reduced, so that it cannot be used for the furnace wall of the blast furnace.

As the flake graphite, the larger the scale is, the more the spalling resistance is improved. In addition to scale-like graphite, earth-like graphite, artificial graphite, electrode powder, calcined anthracite, coke coke,
Pitch coke can also be used in combination with flake graphite if it is selected in consideration of oxidation resistance and alkali resistance.

Further, in the present invention, the powder of metallic silicon is blended with the carbon powder in the silicon carbide powder, and β-SiC is formed during firing in a non-oxidizing atmosphere to obtain the oxidation resistance and wear resistance of the brick itself. Improve. Its compounding amount is 4.8 as Si
If less than 10% by weight, the effect of the composition is insufficient for the furnace wall of the blast furnace, and if added in excess of 10% by weight, the amount of β-SiC produced becomes too large,
Since the spalling resistance and alkali resistance are reduced, it cannot fully function as a blast furnace wall.

Further, it is possible to replace a part of the starting material silicon carbide powder with silicon nitride powder up to 50% by weight for the purpose of spalling resistance.

In the production of the brick of the present invention, as a resin binder for molding, resins such as tar, pitch, phenolic resin, pitch-modified phenolic resin, epoxy resin, etc., which retain a large amount of carbon during firing are used to prevent increase in porosity and strength. Used for the purpose of preventing deterioration. However, from the viewpoint of workability and cost, phenolic resins and pitch-modified phenolic resins are generally suitable.

In the production method of the present invention, the firing of the molded body of the refractory compound is performed at 1200 ° C. or higher in a non-oxidizing atmosphere such as N ₂ stream, Ar stream, or carbon powder. In this firing process, Si in the compound is combined with carbon to form an appropriate amount of β-SiC dispersedly in the structure, and the residual carbon from the binder tightens the substrate to maintain the compactness, and the blast furnace wall As a working brick, a brick having excellent spalling resistance, abrasion resistance, oxidation resistance, and alkali resistance can be obtained.

〔Example〕

The compounds shown in Table 1 were kneaded, molded into a shape of 500 × 200 × 80 mm by a friction press, and fired at 1250 ° C. in a non-oxidizing atmosphere consisting of carbon powder.

If the addition amount of the scaly graphite powder from Comparative Examples 1 and 2 is less than 10% by weight, there is a problem with spalling resistance and alkali resistance, particularly spalling resistance, and from Comparative Examples 3 and 4, scaly graphite powder. It can be seen that if the addition amount of Al exceeds 30% by weight, problems occur in oxidation resistance and wear resistance.

According to Examples 1 to 3, the addition amount of flake graphite is 10 to 30% by weight.
The above-mentioned drawbacks have been resolved by keeping it within the range.

From Example 4 and Comparative Example 5, when the Si content is less than 4.8% by weight, the alkali resistance and the oxidation resistance are significantly lowered. From Example 5 and Comparative Example 6, it can be seen that when Si exceeds 10% by weight, the spalling resistance is significantly deteriorated. Therefore, Si is 4.8
It can be seen that it must be in the range of ~ 10% by weight.

When Examples 7 and 8 are compared with Example 2, the physical properties are slightly deteriorated, but Si ₃ N ₄ can also be used.

It can be seen from Examples 9, 10 and 11 that carbon powders other than the flake graphite powder can be used in combination although the physical properties are slightly lowered as compared with Example 2.

The composition shown in Example 2 in Table 1 was kneaded and molded under the same conditions as described above, and baked in a non-oxidizing atmosphere at 1000 ° C, 1150 ° C, 1250 ° C, 1350 ° C.

 The quality obtained is shown in Table 2.

From the results in Table 2, Si + is required unless the firing temperature is 1200 ° C or higher.
The reaction of C-β-SiC formation is not sufficient, and the alkali resistance is greatly reduced.

As described above, the present invention has found that the lack of spalling resistance of conventional silicon carbide bricks and the lack of oxidation resistance of carbon-silicon carbide bricks are solved by adding an appropriate amount of carbon powder. In that case, the firing temperature in a non-oxidizing atmosphere must be 1200 ° C. or higher from the viewpoint of improving alkali resistance.

[Advantages of the Invention] According to the present invention, it is possible to practically suitably use a silicon carbide-based brick having excellent wear resistance and alkali resistance in place of the oxide-based brick that has been used for a blast furnace. , The life of the blast furnace itself has been extended.

Continuation of front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location C04B 35/591 C04B 35/58 102 L 102 W (72) Inventor Hiroshi Kano 1 Higashihama-cho, Hachiman Nishi-ku, Kitakyushu, Fukuoka No. 1 within Kurosaki Ceramics Co., Ltd. (72) Inventor Nobuhiko Kaji 1-1, Higashihama-cho, Hachimansai-ku, Kitakyushu, Fukuoka Prefecture (56) Within Kurosaki Ceramics Co., Ltd. (56) Reference JP-A-58-36978 (JP, A) Sho 62-119162 (JP, A)

Claims (2)

[Claims] 1. Flake graphite in an amount of 10 to 30% by weight and metallic silicon
Contains 4.8 to 10 wt% as Si, the balance is kneaded and molded a mixture containing silicon carbide powder and a high residual carbon resin binder,
A method for producing a silicon carbide-carbonaceous brick for a blast furnace wall, which comprises firing in a non-oxidizing atmosphere at 1200 ° C or higher to have a bulk specific gravity of 2.3 or higher and an apparent porosity of 10 to 19%. 2. 10 to 30% by weight of flake graphite and metallic silicon
4.8 to 10 wt% as Si, the balance is kneading and molding a mixture containing silicon carbide powder, silicon nitride powder and a high residual carbon resin binder, fired in a non-oxidizing atmosphere of 1200 ℃ or more, a specific gravity of 2.3. A method for producing a silicon carbide-carbonaceous brick for a blast furnace wall, which has an apparent porosity of 10 to 19% as described above.