JP2000351674A - Monolithic refractory material for blast furnace runner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a refractory material capable of reducing the local damages of blast furnace runners made thereof by incorporating a refractory material containing a large amount of silicon carbide with a specified amount of MgO-Al2 O3-based spinel ultrafine powder with a specific particle size. SOLUTION: This refractory material suitable for blast furnace runners is obtained by including >=65 wt.% of silicon carbide and 0.5-5 wt.% of MgO-Al2 O3-based spinel ultrafine powder with a particle size of <=20 μm. Incorporation of small amounts of the MgO-Al2O3-based spinel ultrafine powder promotes the initial oxidation of the silicon carbide in the form of ultrafine powder to form SiO2, which takes the form of a thin protective film coating the refractory material and thereby suppress further oxidation of the silicon carbide along with reducing the refractory material's damages; furthermore, the SiO2 thus produced promotes sintering and densifying the refractory texture, therefore enabling this refractory material to be improved in resistance to melted pig iron and slag.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an amorphous refractory for a blast furnace gutter, and more particularly to an amorphous refractory for a blast furnace gutter suitable for use in a metal line portion of a blast furnace gutter.

[0002]

2. Description of the Related Art As an irregular refractory for a blast furnace gutter,
Alumina / silicon carbide / carbonaceous cast materials excellent in corrosion resistance and spalling resistance are widely used. It is known that the slag line part and the hot metal contact part (metal line part) in the blast furnace gutter have different damage mechanisms, and the blast furnace gutter mainly uses a zone drying structure in which the material of the metal line part and the material of the slag line part are different. It has become. As the amorphous refractory for the slag line portion, a high silicon carbide material having a high resistance to slag is applied, and some improvements have been proposed.

For example, JP-A-3-164479 discloses that the SiC content is 70 wt% or more and the porosity is 10%.
Hereinafter, the filling bulk specific gravity is 1.25 or more for coarse grains and 1.6 for medium grains.
Using 0 or more silicon carbide aggregates, silicon carbide 70 to 95% by weight, carbonaceous material 1 to 7% by weight, alumina fine powder 3 to
Disclosed is a pouring refractory for a blast furnace tapping gutter characterized by adding a dispersant and a binder to a composition containing 20% by weight and 0.5 to 5% by weight of silica ultrafine powder. Japanese Patent Application Laid-Open No. 4-77368 discloses that a silicon carbide-based material is 20 to 90% by weight, a carbonaceous material is 1 to 10% by weight, metallic aluminum is 0.1 to 1.5% by weight, and metal silicon is 0 to 90% by weight. A blast furnace containing 0.3 to 12.0% by weight of boron carbide with respect to the total content of the silicon carbide-based material and the carbonaceous material. An amorphous refractory for gutter material or the like is disclosed. Further, Japanese Patent Application Laid-Open No. 5-58752 discloses a high silicon carbide pouring gutter having a total silicon carbide content of 80 to 98 wt%, wherein molybdenum carbide is contained in an amount of 1 to 1 wt.
A high silicon carbide pouring gutter material characterized by containing 0 wt% is disclosed. Also, Japanese Patent Application Laid-Open No. 5-70249
Japanese Unexamined Patent Publication (Kokai) No. 7-175, discloses an amorphous refractory for a blast furnace tapping gutter, which contains 70% by weight or more of silicon carbide and 1 to 25% by weight of ultrafine silicon carbide powder having a particle size of 1 μm or less and 40% by weight or more. Is disclosed. Further, JP-A-5-70
No. 250 discloses that a base material containing 70 to 90% by weight of silicon carbide contains 1 to 3% by weight of metal silicon powder, 0.5 to 3.0% by weight of boron carbide powder, and 1 to 3 of high melting point pitch powder.
There is disclosed a pouring gutter material for tapping gutters characterized by adding wt%. Also, Japanese Patent Application Laid-Open No. 9-27854
No. 0 discloses a compound containing 2 to 92% by weight of silicon carbide and 2 to 7% by weight of a carbon material, or 2 to 7% by weight of a carbon material, and a mixture of cobalt oxide, a cobalt salt, and metal cobalt powder. There is disclosed a corrosion-resistant and oxidation-resistant amorphous refractory characterized in that at least one of them is added in an amount of 0.01 to 0.5% by weight in terms of metallic cobalt. All of the materials described in these publications are characterized by high resistance to slag.

[0004] On the other hand, damage to the metal line is mainly caused by local erosion found slightly below the boundary between the slag and the hot metal, and the cause is caused by the slag film containing FeO generated from the slag and the hot metal. It is said that. Silicon carbide is easily oxidized by FeO contained in the slag film, and silicon carbide wets well with molten metal and is chemically unstable, and particularly easily dissolves in molten iron. For example, it is considered to be unfavorable as a main raw material for irregular refractories for blast furnace gutter metal lines. Therefore, despite the fact that silicon carbide-based materials have high thermal conductivity and low thermal expansion and are extremely excellent in spalling resistance, application to blast furnace gutter metal line sections is difficult, and the solution is also difficult. Not proposed.

[0005] Therefore, the hot metal part of the blast furnace gutter (metal line)
Part), the silicon carbide content of the refractory lined
The amount of silicon carbide is limited to 10 to 25% by weight.
It has become common. In addition, it has an irregular shape for metal lines.
In order to improve the durability of fire, for example, Japanese Patent Application Laid-Open
Japanese Patent No. 206532 discloses an electrofusing and calcining method in which the particle size is adjusted.
Or sintered alumina, electrofused or sintered spinel, charcoal
Refractory aggregate and aluminum containing silicon carbide and amorphous carbon
Amorphous refractory containing nacement and traces of peptizer
A silicon carbide content of 5 to 12% by weight.
And 50% or less of the fine particles having a particle size of 75 μm or more and 1 mm or less.
And the average particle size is 0.3 mm or less,
In addition, 50% or less of the electrofused or sintered spinel has a particle size of 1
Irregular refractories characterized by fine grains of not more than mm
And, in Japanese Patent Application Laid-Open No. Hei 5-339065,
Silicon carbide 5 to 25%, carbon 1 to 5%, average particle size 5 μm or less
Lower alumina fine powder 5-15%, alumina cement 0.
5-7%, balance MgO-Al _TwoO_ThreeSystem spinel as main material
A blast furnace gutter pouring material comprising a mixed composition is disclosed.
You.

In order to reduce the complexity of the zone drying, for example, Japanese Patent Application Laid-Open No. 4-369571 discloses that the total content of silicon carbide and magnesia-alumina spinel is 80% by weight to 90% by weight. An amorphous refractory for a blast furnace tapping gutter of silicon carbide-magnesia-alumina spinel, which is within the range and contains silicon carbide in an amount of 40% by weight or more, is disclosed.

However, when spinel is added to an amorphous refractory containing silicon carbide, a reaction between the spinel and silicon carbide occurs, and as a result, the oxidation of silicon carbide is greatly promoted, so that cracks are likely to occur during use. , Hindering improvement in durability. Therefore, when spinel is added to an amorphous refractory containing silicon carbide, the reaction between spinel and silicon carbide is reduced by minimizing the amount of silicon carbide added or increasing the particle diameter of the added spinel. It needed to be suppressed.

Accordingly, an object of the present invention is to provide an irregular-shaped refractory for a blast furnace gutter capable of minimizing local damage of a hot metal contact portion (metal line portion) of the blast furnace gutter.

[0009]

Means for Solving the Problems The present invention intensively studied to solve the above problems, a refractory containing a large amount of silicon carbide, when adding MgO-Al ₂ O ₃ spinel to, by specifying the particle diameter and addition amount of MgO-Al ₂ O ₃ spinel addition, the aforementioned MgO-Al ₂
It has been found that the oxidation of silicon carbide by the reaction between an O ₃ -based spinel and silicon carbide can be used for improving the durability of amorphous refractories.

[0010] That is, the present invention relates to a method for producing Mg having a particle size of 20 μm or less.
O-Al ₂ O ₃ spinel micronized 0.5 to 5 wt%, and according to the silicon carbide in the blast furnace trough for monolithic refractories characterized by containing more than 65 wt%.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The refractory for blast furnace gutters of the present invention is a refractory containing a large amount of silicon carbide, which is made of MgO-Al.
By adding a small amount of ₂ O ₃ -based spinel ultrafine powder, the initial oxidation of silicon carbide in the fine powder portion is promoted and SiO ₂ is generated, but the SiO ₂ becomes a thin protective film covering the refractory material, Can suppress the oxidation of the refractory and reduce the damage to the refractory. In addition, the generated SiO
No. ₂ promotes sintering of the refractory structure and densifies the structure, thereby improving resistance to hot metal and slag. Furthermore, since the MgO-Al ₂ O ₃ -based spinel has the ability to form a solid solution of FeO in the slag, the MgO-Al ₂ O ₃ -based spinel ultrafine powder added to the material contains FeO to silicon carbide. Erosion can be reduced. In the examples of the above-mentioned Japanese Patent Application Laid-Open No. Hei 4-375571, MgO-A
l ₂ O ₃ system but spinel be used as aggregate disclosed, the aggregate, which refers coarse normal particle size 10Mm～75myuemu, medium grain, fine, micronized, MgO- Al
There is no example in which ₂ O ₃ spinel is used in combination with silicon carbide as ultrafine powder.

[0012] The addition amount of the following MgO-Al ₂ O ₃ spinel ultrafine particle size 20μm for use in the blast furnace trough for monolithic refractories of the present invention is 0.5 to 5 wt%, preferably 1 to 3% by weight. Here, the addition amount of MgO-Al ₂ O ₃ spinel ultrafine powder is less than 0.5 wt%, the promotion of an initial oxidation of the silicon carbide is not sufficient, a thin covering refractory S
The formation of the iO ₂ protective film is not sufficient, and the damage is increased, which is not preferable. Further, the addition amount of MgO-Al ₂ O ₃ spinel ultrafine powder exceeds 5 wt%, SiO ₂ and MgO-Al ₂ O ₃ spinel ultrafine produced by the initial oxidation of the silicon carbide is reacted, low melting point Since the substance is easily generated, the damage is increased, which is not preferable. In addition, MgO-Al ₂
It is desirable that the particle size of the ultrafine O ₃ -based spinel powder is 20 μm or less. When the particle size exceeds 20 μm, the promotion of the initial oxidation of silicon carbide is not sufficient, and the amount of SiO ₂ covering the refractory is reduced, and the refractory is damaged more.

The compounding amount of silicon carbide in the irregular refractory for blast furnace gutters of the present invention is at least 65% by weight, preferably at least 70% by weight. If the amount of silicon carbide is less than 65% by weight, the amount of the SiO ₂ film covering the refractory is not sufficient, and the damage is increased, which is not preferable. Further, the content of silicon carbide fine powder having a particle size of 75 μm or less is preferably 10 to 20% by weight of the silicon carbide used. Particle size 7
If the content of the silicon carbide fine powder of 5 μm or less is less than 10% by weight, it is not possible to sufficiently secure the generation amount of the SiO ₂ film covering the refractory and the residual amount of the silicon carbide fine powder after the initial oxidation. Is undesirably large. On the other hand, when the content of the silicon carbide fine powder having a particle size of 75 μm or less exceeds 20% by weight, the fluidity as an amorphous refractory is unfavorably deteriorated.

In the refractory for blast furnace gutters of the present invention, Mg
In addition to the O-Al ₂ O ₃ -based spinel ultrafine powder and silicon carbide,
Alumina can be used. The addition and blending amount of alumina is in the range of 8 to 34% by weight. Here, if the amount of alumina is less than 8% by weight, it is not preferable because the effect of adding alumina is difficult to be exhibited, and if it exceeds 34% by weight, other components including a binder cannot be added. Not preferred. Alumina has a particle size of 75μ.
m and / or fine powder having a particle size of 75 μm or less.

The refractory aggregates other than silicon carbide and alumina constituting the amorphous refractory for blast furnace gutters of the present invention can be any refractory raw materials usually used depending on the intended use, and are not limited. is not. For example, a mullite raw material, a rock, a silica fine powder, a pitch pellet and the like can be used. When these refractory raw materials are used, the blending amount is about 5% by weight or less.

Further, the amorphous refractory for blast furnace gutters of the present invention may use a cold-setting binder such as alumina cement or clay, or a thermosetting binder such as sodium silicate as a binder. The addition and blending amount of the binder is in the range of 0.1 to 5% by weight, preferably 0.5 to 3% by weight. Here, if the compounding amount of the binder is less than 0.1% by weight, it is not preferable because sufficient strength cannot be obtained, and if it exceeds 5% by weight, the corrosion resistance is unfavorably reduced.

If necessary, a dispersant used in a usual casting material can be used. As a dispersant, for example,
One or more selected from alkali metal phosphates, alkali metal carboxylate, sodium polycarboxylate, and the like, and substances having similar effects can be used.

[0018]

EXAMPLES Hereinafter, the amorphous refractory for blast furnace gutters of the present invention will be further described with reference to examples. Example The present invention product and the comparative product were prepared at the compounding ratios shown in Table 1 below, poured into a metal line portion of an actual blast furnace tapping gutter, constructed and operated. After the end of the operation, the damage thickness of the maximum erosion portion of the metal line portion was measured, and the damage thickness was divided by the amount of pig iron, and the damage amount per 1000 t was taken as the damage speed. Table 1 also shows the obtained results.

[0019]

[Table 1]

[0020]

When the irregular refractory for blast furnace gutter of the present invention is applied to a blast furnace gutter metal line, local damage of a hot metal contact portion is reduced, and the life of the blast furnace gutter can be greatly extended. In addition, silicon carbide is a raw material having high thermal conductivity and low thermal expansion properties, and refractories containing a large amount of silicon carbide have excellent spalling resistance. Cracks and peeling occurring on the substrate can be greatly suppressed. Furthermore, refractories with a high content of silicon carbide are:
Durability even when applied to blast furnace gutter slag line (melting resistance)
, The conventional two-layer construction is not required, and naturally, it is not necessary to change the lining shape of the gutter, so that the conventional construction equipment can be used as it is. In addition, the amorphous refractory for blast furnace gutters of the present invention is characterized in that silicon carbide is added to the hot metal part by 65%.
It is a refractory containing more than 10% by weight, and can be applied to hot metal gutters, inclined injection gutters and the like. Furthermore, the amorphous refractory for blast furnace gutters of the present invention can be used not only for casting but also for wet spraying using a pressure pump.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kiyotaka Enoki 2-2-1 Otemachi, Chiyoda-ku, Tokyo Shinagawa White Brick Co., Ltd. (72) Inventor Shinichi Yamaoka 2-2-2, Otemachi, Chiyoda-ku, Tokyo No.1 item Kawashira Brick Co., Ltd. F term (reference) 4G033 AA02 AA17 AA24 AB01 AB02 AB25 4K015 EC08

Claims (4)

[Claims] 1. An ultrafine MgO—Al ₂ O ₃ spinel powder having a particle size of 20 μm or less is 0.5 to 5% by weight, and silicon carbide is 6% by weight.
An amorphous refractory for blast furnace gutters, characterized in that it contains at least 5% by weight. 2. A method in which silicon carbide fine powder having a particle size of 75 μm or less is
The amorphous refractory for a blast furnace gutter according to claim 1, wherein the refractory is contained in an amount of from 20 to 20% by weight. 3. The refractory according to claim 1, wherein the refractory contains 8 to 34% by weight of alumina. 4. The irregular shaped refractory for a blast furnace gutter according to claim 1, which is used for a blast furnace gutter metal line portion.