JPH02283656A - Carbon-containing refractory - Google Patents

Abstract

PURPOSE:To improve oxidation resistance, spalling resistance and corrosion resistance of the title refractory by adding a specific Fe-Si alloy to a refractory aggregate consisting of graphite and refractory raw material. CONSTITUTION:100 pts.wt. refractory aggregate consisting of 3-20 pts.wt. graphite (e.g. petroleum coke) and 97-80 pts.wt. refractory raw material (e.g. magnesia) is blended with 1-6 pts.wt. Fe-Si alloy having <=0.125mm granule size and containing 15-45wt.% Fe.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an AbOz C refractory which is designed to prevent carbon-containing refractories from being damaged by acid] and at the same time has improved durable poling properties and corrosion resistance.

[Prior art] Conventionally, high alumina, AlzO, -SiC has been used as a lining material for hot metal pretreatment furnaces such as hot metal ladles and hot metal mixing cars for transporting hot metal.
Carbon-containing refractories such as -C, Al2O, -spinel-〇, and Mg0-C are used.

In addition, intermediate repairs of furnaces are being carried out by hot spraying, and the service life of furnace lining materials has been significantly extended. Good results have been achieved as a material that suppresses intrusion and improves slag intrusion resistance.

However, the structure of the above-mentioned carbon-containing refractories deteriorates due to carbon oxidation, resulting in a significant decrease in strength. There was a problem in that it was insufficient to meet the requirements for durability as a furnace lining material that was subjected to physical shock.

To improve this, oxidation resistance has been improved by adding metal silicon or metal aluminum, or by increasing the molding pressure and making it denser.

For example, a refractory material has been proposed in which silicon and aluminum are added in a weight ratio of 3 to 10:10 to 3 to a refractory aggregate/compound containing 30% or less of carbon to the refractory aggregate. (Special Publication No. 6059184).

In addition, 10 to 30% of aluminum powder and 20 to 5% of bonded clay are added to the coarse grain member of silicon carbide or/and high alumina raw material.
0%, metal silicon or/and ferrosilicon 10~
A fire-resistant stamp material has been proposed, which is made by adding and kneading a fine powder member consisting of 50% and 20% of graphite or/and carbonaceous material and an organic binder (Japanese Patent Application Laid-Open No. 52-9
Publication No. 011).

Furthermore, M6043-87%, graphite 8-42% in weight ratio
A casting immersion nozzle composition comprising 3 to 12% of a silicon component consisting of SiC, SiOz, SL or Fe-3i has also been proposed (Japanese Patent Publication No. 5510340).

In addition, a refractory for blast furnaces has been proposed in which the refractory material is made by blending β-alumina-silicon carbide-graphite in a predetermined range and further contains 2 to 10% metallic silicon, and the particles are bonded with silicon carbide or carbon. (Japanese Patent Application Laid-Open No. 52-76313
Publication No.).

Furthermore, a stamp for tap taps is made by adding 5 to 50% by weight of ferrosilicon (Fe Si2) to silicon carbide, carbon, and fireclay-based raw materials, and kneading this with a binder such as valve waste liquid, molasses, and resin. The material is also known (Special Publication No. 50-2
Publication No. 4970).

[Problems to be Solved by the Invention] However, none of the above methods fundamentally improves the above-mentioned defects of unfired carbon bonded bricks.

In other words, conventional carbon-containing refractories are made by reacting graphite and silicon to form silicon carbide bonds and carbon bonds between particles, but the conditions for reacting Si and graphite to produce SiC are temperature and reaction time. is necessary.

However, in many cases, contact with slag occurs before silicon carbide is fully formed, and stress fracture occurs inside the refractory, so there are many points that are contrary to expectations.

Therefore, an object of the present invention is to provide a carbon-containing refractory that can accelerate the production rate of silicon carbide and increase its strength.

[Means for Solving the Problems] The present invention is directed to the production of SiC from the reaction of SiflL group and graphite.
We found that using a Fe-Si alloy accelerates the reaction with graphite and increases the amount of SiC produced.
The present invention has now been completed.

That is, the present invention uses 3 to 20 parts by weight of graphite and 80 to 80 parts by weight of refractory raw material.
1 to 6 parts by weight for 100 parts by weight of refractory aggregate consisting of 97 parts by weight
The present invention relates to a carbon-containing refractory comprising an Fe-3i alloy containing 15 to 45% by weight of Fe.

[Function] The carbon-containing refractory of the present invention is characterized by the addition of an Fe-Si alloy to the refractory raw material and graphite. As a result, although the details of the bonding form have not yet been fully clarified, the fine powder part of the refractory, which is thought to be oxygen-poor, reacts with Fe-3i alloy and graphite due to heating, resulting in Fe-C formation.
The system produces Fe and C. In addition, Si-C-based β-3i
It is thought that the refractory raw material and graphite etc. form a strong bond by producing C and lowering the porosity. Furthermore, graphite Fe-3i alloy is more active and produces a larger amount of SiC than Si metal.

First, regarding the reactivity of graphite and Fe-3i, F
Fe-Si alloy powder with an e content of 22.5% by weight and a Si content of 77.5% by weight with a particle size of 0.149+am or less and C
Graphite powder with a particle size of 0.1471 or less with an O content of 98.5% is
C-Fe-S blended at an i:C molar ratio of 1:1 and molded
i sample, also containing Si 99.5% heavy electric charge and particle size 0.14
Using Si metal of 9+a+a or less, graphite powder is Si:
Table 1 shows the amount of SiC produced after heating a molded C-9t sample in a reducing atmosphere of breeze packing.

East - 1, 1, 1, 11 SiC generation amount reduction competition is 1d, U competition is waiting.
Si sample 1.2 6.6 7.
3C-Si sample 1.0 1.3
3.7 Note: C-3i sample 1000℃/3 hours S
The amount of iC produced is shown as 1.0.

As is clear from Table 1, the Fe-Si alloy is S
It is more active and has excellent reactivity than i-metal, and produces a larger amount of SiC. Note that even if the holding time is changed at a constant temperature, the amount of SiC produced is similarly larger in the Fe-8i alloy.

As the Fe-3i alloy powder exhibiting such characteristics, it is preferable to use a Fe-3i alloy powder containing 15 to 45% by weight of Fe. The amount of Fe in Fe-3i alloy powder is 45
If it exceeds % by weight, the amount of Fe=C produced increases, and although the oxidation resistance of graphite is good, the corrosion resistance decreases, which is not preferable.

Regarding the quality of the Fe-3i alloy powder used in the present invention, those generally commercially available for use as deoxidizing agents for steel manufacturing can be used, and the particle size of the alloy powder is 0 from the viewpoint of reactivity and uniform dispersibility. It is preferable to use one with a diameter of .125 mm or less.

The blending ratio of the Fe-3i alloy powder is 1 to 6 parts by weight per 100 parts by weight of the refractory raw material and graphite refractory aggregate, and if the blending amount is less than 1 part by weight, the addition effect will be small. Moreover, if it exceeds 6 parts by weight, although oxidation resistance is achieved, hot strength decreases and durability decreases, which is undesirable.

In addition, B, C, AN, A(-8i, Al
- One or more types of Mg can be added as appropriate, but the amount blended is less than 6 parts by weight per 100 parts by weight of the refractory aggregate.

As the refractory raw material used in the present invention, oxides such as magnesia, spinel, alumina, silica, zircon, and zirconia, and non-oxides such as silicon carbide, silicon nitride, and boron nitride can be used. Although it is not limited and varies depending on the purpose of use of the carbon-containing refractory of the present invention, those mainly composed of magnesia, spinel, and alumina are preferable.

To explain the case where the carbon-containing refractory of the present invention is used for a hot metal pretreatment furnace, it is possible to use Al2O as the refractory raw material if the amount of Al2O contained in the raw material itself is 50% by weight or more, for example. Bauxa, Ito, Sintered Alumina,
These are fused alumina, sintered mullite, fused mullite, and sintered spinel, and these can be used alone or in combination of two or more. The blending amount of these refractory raw materials is preferably 60 to 85 parts by weight. If the amount of the above-mentioned refractory raw material is less than 60 parts by weight, the corrosion resistance will decrease;
Exceeding the weight part is not preferable because the durable polling property is reduced.

Further, SiC can be used as another refractory raw material, but it is preferable to use SiC with a purity of 80% by weight or more, and more preferably a purity of 90% by weight or more. The blending amount of SiC is preferably 5 to 20 parts by weight.

If the blending amount of SiC is less than 5 parts by weight, the antioxidant effect of graphite is reduced, so there is no addition effect, and if it exceeds 20 parts by weight, the corrosion resistance is lowered, which is not preferable.

Next, the case where the carbon-containing refractory of the present invention is used for sliding nozzle play 1 to brick will be described. As the refractory raw material, sintered alumina, fused alumina, mullite, etc. can be used. The purity of these refractory raw materials is preferably as high as possible, and the purity as alumina or mullite is preferably 98% or more.

As the graphite used in the present invention, natural graphite such as earthy graphite and scaly graphite, or artificial graphite such as electrode scrap, petroleum coke, and carbon black can be arbitrarily used, but it is preferable to use petroleum coke with few impurities. The blending ratio of the graphite is preferably 5 to 20 parts by weight based on 100 parts by weight of the refractory aggregate made of the refractory raw material and graphite.

If the amount of graphite is less than 5 parts by weight, the property that graphite is difficult to wet with slag and the improvement in spall resistance cannot be sufficiently exhibited. On the other hand, if it exceeds 20 parts by weight, sufficient strength cannot be expected and it is difficult to obtain a dense structure.

The carbon-containing refractory of the present invention is produced by adjusting the particle size-adjusted refractory raw materials, graphite, and Fe-Si alloy in a predetermined mixing ratio, adding a binder such as tar, pitch, phenolic resin, or furan resin, and then processing by a conventional method. An unfired product can be obtained by kneading, molding, and drying at about 200°C. Also, 90
It can be fired in a reducing atmosphere at about 0 to 1500°C and used as fired refractories.

[Examples] Next, the carbon-containing refractories of the present invention will be specifically explained with reference to Examples.

Example 1 A compound having the proportions shown in parts by weight in Table 2 was kneaded with 4 parts by weight of a resol type phenolic resin, and 1000 k
It was molded into a regular shape of 230xl 14x65wn using a molding pressure of W/a@' and dried at 200°C for 5 hours.

The properties of the obtained unfired carbon-containing refractory are also listed in Table 2. As is clear from Table 2, the products of the present invention are superior in bending strength and elastic modulus to the products made by Hisame.

Next, inventive product 3 and comparative product 1 were lined in a 200-ton hot metal pretreatment furnace, and when the hot metal was mainly desulfurized and dephosphorized, S
Compared to Comparative Product 1 containing i-metal, the loss was 100, whereas Product 3 of the present invention had a loss of 85, making it possible to reduce the loss in an actual furnace.

Example 2 A compound having the compounding ratio shown in the heavy wall portion in Table 3 was kneaded with 4 parts by weight of resol type phenolic resin, and the mixture was kneaded to 1000 k
It was molded into a regular shape of 230x114x65a+m with a molding pressure of y/cm2, and then dried at 200°C for 5 hours.

The properties of the obtained unfired carbon-containing refractory are also listed in Table 3. As is clear from Table 3, the products of the present invention are superior to the comparative products in terms of bending strength and elastic modulus.

[Effects of the Invention] By adding an Fe-Si alloy to the refractory raw material and graphite, the bending strength and elastic modulus of the carbon-containing refractory increases due to SiC generation, and the oxidation resistance and corrosion resistance are improved.

Claims (3)

[Claims] 1. 1 to 6 parts by weight of F per 100 parts by weight of refractory aggregate consisting of 3 to 20 parts by weight of graphite and 80 to 97 parts by weight of refractory raw materials.
A carbon-containing refractory comprising an Fe-Si alloy containing 15 to 45% by weight of e. 2. Contains an Fe-Si alloy containing 1 to 6 parts by weight of Fe in an amount of 15 to 45% by weight based on 100 parts by weight of refractory aggregate consisting of 3 to 20 parts by weight of graphite, 60 to 85 parts by weight of alumina, and 5 to 20 parts by weight of SiC. A carbon-containing refractory for hot metal pretreatment furnaces. 3. An Fe-Si alloy containing 1 to 6 parts by weight of Fe in an amount of 15 to 45 parts by weight per 100 parts by weight of a refractory aggregate consisting of 3 to 20 parts by weight of graphite, 75 to 90 parts by weight of alumina, and 5 to 15 parts by weight of mullite. A carbon-containing refractory for sliding nozzle plates.