JPH10279370A - Monolithic refractory material for blast furnace main trough - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a monolithic refractory material having a highly corrosion resistance used at a point where the flow velocity of molten iron is high by incorporating a graphite material, metal Al and metal Mg or Al-Mg alloy at respective specific wt.% into this material. SOLUTION: This monolithic refractory material contains 3 to 20 wt.% graphite material, 0.5 to 10 wt.% metal Al and metal Mg or Al/Mg alloy and 80 to 95 wt.% aggregate, such as Al2 O3 , ZrO2 and siliceous stone. Further, various kinds of assistants including a hardener, such as silica sol, an antioxidant, such as B4 C, a dispersant, such as sodium tripolyphosphate, and a curing retarder, such as oxalic acid, the further added at need to this refractory material. The metal Al and metal Mg or Al/Mg alloy are used after Al/Mg are compounded at a molar ratio of 1.8 to 4.0 therewith and are subjected to a treatment for preventing a hydration reaction by a coating treatment with a phenolic resin, etc. The metal Al and metal Mg form Al2 O3 and MgO, which crystallize the fine reactive spinel of a three-dimensional network form in the matrix at the time of heating. The aggregate particles and graphite particles are coated and bonded by the sintered network of the reactive spinel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an amorphous refractory material mainly used for a metal line of a blast furnace main gutter,
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alumina-spinel-graphite amorphous refractory material having excellent corrosion resistance, particularly useful in a region where the flow velocity of hot metal is large in a main gutter and excellent in corrosion resistance.

[0002]

2. Description of the Related Art In recent years, in a blast furnace, from the viewpoint of reducing the cost of producing pig iron, it has been aimed to reduce the basic unit of refractory materials by tapping for a long time. In particular, there is a strong demand for an improvement in a gutter material forming a gutter for transferring hot metal from a blast furnace to a transport vessel. Above all, in the main gutter (tapping gutter) for flowing hot metal and molten slag at the same time, corrosion resistance to both slag and metal must be taken into consideration, and it is the material that requires the most improvement.

Conventionally, a high SiC refractory has been used in the vicinity of the slag-air interface (slag line), while Al ₂ O ₃ − has been used in the vicinity of the slag-metal interface (metal line). SiC refractory, Al ₂ O ₃ -spinel-
SiC refractories are used. Others that have been developed solely for the purpose of improving corrosion resistance include those disclosed in
There are graphite-containing amorphous refractory materials as disclosed in JP-A-8-183666 and JP-A-8-183667.

[0004] Typical examples of graphite-containing amorphous refractory materials include:
Al_TwoO_Three-Graphite, Al_TwoO_Three -Spinel-graphite based
These materials include graphite.
Matrix in addition to improved corrosion resistance
Al_TwoO_ThreeAnd spinel (Al_TwoO _Three−MgO solid solution)
It can be said that it affects the corrosion resistance of the entire refractory. Especially
And spinel is Al_TwoO_ThreeCorrosion resistance to slag than
It is well known, but very expensive.
Therefore, spinel can be used as a material for blast furnace main gutters.
Medium size (30μm) or more
Coarse grains are used. From this, the conventional
The matrix of some amorphous refractories is Al_TwoO _ThreeFine powder sintering
Corundum (α-Al_TwoO_Three) And graphite
It is usually formed. It is a coarse spinel
Even if it is_TwoO_Three-Graphite based refractory
This is because the same or higher corrosion resistance can be obtained as compared with.

[0005]

As an irregular refractory material used in a blast furnace main gutter, particularly in a metal line, it is a simple method to disperse fine spinel in a matrix by using fine spinel powder. . However, as described above, spinel fine powder is extremely expensive, and there is no merit in using it industrially.

Accordingly, an object of the present invention is to provide an amorphous refractory material for a blast furnace main gutter having good corrosion resistance, containing a reactive spinel and graphite. Another object of the present invention is to provide an amorphous refractory material having excellent corrosion resistance which is useful in a metal line in a blast furnace main gutter, particularly at a location where the flow rate of hot metal is large.

[0007]

Means for Solving the Problems While examining the above problems, the inventors noticed that spinel is a solid solution of Al ₂ O ₃ and MgO, and these are all oxides of a low melting point metal. Metal Al, metal
We studied what happens when Mg or its alloy is added. As a result, the obtained refractory, when heated and dried after application, the metal Al and metal Mg are melted or vaporized and uniformly dispersed in the matrix, and oxidized in the air atmosphere, so that fine Al ₂ O ₃ , MgO was found to be dispersed. And in the case of this refractory, fine Al ₂ O
_3. It was also found that MgO reacted with each other and crystallized fine spinel. Further, the crystallized reaction spinel forms a fine sintered network dispersed in a three-dimensional network in a refractory matrix, and binds while covering other aggregates and graphite, thereby forming a sintered network. It has been found that the corrosion resistance of graphite-containing amorphous refractories is further improved.

The present invention has been developed based on such findings. That is, the present invention provides a graphite material of 3 to 20.
It is an amorphous refractory material for a blast furnace main gutter, characterized by containing 0.5% to 10% by weight of metal Al and metal Mg in total or 0.5 to 10% by weight of Al-Mg alloy.

In the present invention, the metal Al and the metal Mg
Is contained in a molar ratio of Al and Mg of Al / Mg = 1.8
It is preferred to mix at a ratio of .about.4.0. Further, in the present invention, the metal Al, metal Mg and Al-Mg alloy are coated on their surfaces by wet and dry methods, respectively, of phenolic resin, epoxy resin, urethane resin, melamine resin and acrylic resin. It is also preferable to use a material which has been subjected to a chemical conversion treatment with chromate, vanadium, molybdenum, a phosphoric acid derivative, an organic acid or the like to prevent hydration. Further, in the present invention, it is preferable that a three-dimensional network-like reaction spinel is crystallized in the refractory matrix after heating and drying. Further, in the present invention, the reaction spinel is preferably a fine powder having a particle size of 5 μm or less.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the amorphous refractory material according to the present invention, various graphites are blended together with aggregates described later. The compounding amount of this graphite is irregular refractory material (aggregate: 80 ~
97 wt%) in the range of 3 to 20 wt%. The reason is that if the blending amount of the graphite is less than 3 wt%, the inherent effects of graphite such as high thermal conductivity and slag resistance cannot be sufficiently obtained, while the blending amount of the graphite exceeds 20 wt%. This is because the oxidation resistance becomes a problem and the fluidity is reduced, so that a dense molded refractory material cannot be obtained.
The preferred range of the graphite content is 5 to 15% by weight.

However, the graphite-containing amorphous refractory material generally does not have such a high mechanical strength in the operating temperature range of the gutter (high temperature range in contact with hot metal and slag). This is because graphite itself does not have sintering properties, and graphite inhibits formation of ceramic bonds generated by sintering of fine powder material. For this reason, simply adding graphite does not provide sufficient strength to cover from room temperature to high temperature. Also,
Graphite also has a disadvantage that it is easily oxidized in a high-temperature air atmosphere.

In order to overcome these weak points of graphite, the present invention uses a fine reaction spinel. The reason for using this fine reaction spinel is that, when the refractory is heated and dried, especially in the temperature range of the gutter material, a fine three-dimensional network-like reaction spinel is crystallized in a matrix, and a sintered network of this fine reaction spinel is used. -By
This is because by coating the aggregate particles, fine powder, and graphite particles and serving to hold them together, the strength of the refractory, and thus the corrosion resistance, can be enhanced. That is, the feature of the present invention resides in that a fine reaction spinel sintered network is formed in the refractory matrix.

That is, in the present invention, in order to enhance the corrosion resistance of a matrix of an amorphous refractory material, fine reaction spinels are uniformly dispersed in the matrix and a sintered network is formed by using them. . Therefore, in the present invention, the metal Al and the metal Mg are melted or vaporized by mixing the low melting point metal Al and the metal Mg into the refractory raw material at the stage of raising the temperature of the amorphous refractory material in the atmosphere. And uniformly dispersed in the amorphous refractory material and oxidized to Al
₂ O ₃ and MgO were present in the refractory matrix of the amorphous refractory material. Then, these Al ₂ O
_3. MgO further reacts with each other to crystallize fine reaction spinel.

It should be noted that it is generated in the mechanism described above.
Since Al ₂ O ₃ and MgO are melted and dispersed or dispersed via a gas phase, they are formed as fine particles. Therefore, the spinels produced by their reaction and crystallization also form extremely fine grains. The particle diameter of the reaction spinel obtained by the inventor in the experiment is 5 μm or less, and it is preferable to use a fine powder of 1-2 μm.

Moreover, since these reaction spinels are formed by solidification from a molten state or a gas phase, they are formed so as to cover aggregate particles and graphite particles. Occurs. In addition, since a fine reaction spinel is sintered and dispersed in a sintering network, that is, a three-dimensional network, the sintering aid is effective.

Here, the addition of the metal Al and the metal Mg to the refractory raw material can be carried out in the form of an Al-Mg alloy in addition to the simultaneous addition of each of Al and Mg as a single metal. However, if the total amount of Al and Mg is less than 0.5 wt%, the effect of improving corrosion resistance by the fine spinel particles is not sufficient.
Further, when fine spinel particles exceeding 10% by weight are generated, fine cracks are remarkably generated in the matrix due to the effect of volume expansion in spinel generation, resulting in a reduction in strength and a reduction in corrosion resistance due to the reduction. Therefore, Al,
The amount of Mg or Al-Mg alloy added to the raw material is desirably 0.5 to 10% by weight in terms of the total weight of Al and Mg.

Since the above-mentioned reaction spinel required in the present invention is a solid solution of Al ₂ O ₃ and MgO, the ratio of Al and Mg to be mixed with the refractory raw material does not need to be constant. However, the molar ratio of Al ₂ O ₃ / MgO of spinel which can generally improve corrosion resistance sufficiently as a refractory is in the range of 0.9 to 2.0, so that the ratio of Al / Mg to be blended is 1.8 to 4 in molar ratio. .
It is desirable to add in the range of 0.

Further, the amorphous refractory material according to the present invention comprises:
Since the mixture is kneaded with water, molded and dried, it is preferable to perform a treatment for preventing a hydration reaction of each metal when adding Al, Mg, and Al-Mg alloy. For this reason, as a surface treatment method of Al, Mg, Al-Mg alloy, a method of coating phenol resin, epoxy resin, urethane resin, melamine resin, acrylic resin by wet or dry method, and a method of chromate, vanadium , Molybdenum, a phosphoric acid derivative, an organic acid, etc.

The irregular refractory material according to the present invention comprises:
In addition to the graphite, metal Al, metal Mg and their alloys described above, as a matter of course, as the aggregate constituting the skeleton component of the amorphous refractory, one selected from basic, neutral, and acidic ones or It is preferable to use two or more kinds. For example, it contains about 80 to 95% by weight of alumina, zirconia, zircon, silica, pyroxene, silicon carbide, chamotte, and the like. The particle size of these aggregates is preferably adjusted separately for coarse particles, medium particles, fine particles, and fine particles so as to obtain a densely packed structure.

Further, various auxiliary agents are used in the amorphous refractory material according to the present invention, if necessary. As the curing agent (binder), alumina cement, silica sol, alumina sol, or the like generally used for refractories is used. As the antioxidant, B ₄ C, SiC, Si, Al or the like is used. Dispersing agents include inorganic salts such as sodium tripolyphosphate, sodium hexametaphosphate, sodium ultrapolyphosphate, sodium acid hexametaphosphate, sodium borate, sodium carbonate, sodium citrate, tartrate, sodium polyacrylate, sodium sulfonate and One or two or more selected from sodium naphthalene sulfonate are used. Oxalic acid, citric acid, gluconic acid, boric acid and the like are used as a curing retarder.

The irregular refractory material according to the present invention comprises:
Known fibers, metal powders and the like may be further added in addition to the above-mentioned blends as long as the effects of the present invention are not impaired.

[0022]

【Example】

Example 1 This example reports the results of an evaluation test when the amorphous refractory material of the present invention was used in a blast furnace main gutter metal line. That is, the amorphous refractory materials used in this test were alumina: 45 parts by weight, medium-grain (30 μm or more) spinel: 43 parts by weight, artificial graphite: 10 parts by weight, the remainder being cement,
Based on an amorphous refractory material for blast furnace main gutter metal line consisting of dispersing agent and hardening retarder, changing the addition amount of metal Al, metal Mg or Al-Mg alloy, average grain size 1-2
The composition was adjusted so that the μm reaction spinel was dispersed and crystallized in the matrix. The fine powder portion was made of alumina and graphite, and the graphite used was artificial graphite having an average particle size of 25 μm. The Al-Mg alloy, the metal Al, and the metal Mg were all phenolic resins wet-coated to prevent hydration.

FIG. 1 shows the results of corrosion resistance evaluation when an amorphous refractory material having different addition amounts of metal Al, metal Mg, and an Al—Mg alloy was applied to a high-frequency furnace. FIG. 2 shows the strength evaluation results at that time. FIG. 3 shows the results of the oxidation resistance evaluation.

As shown in FIG. 1, the erosion index decreases when the addition amount of the metal Al, Mg, or Al-Mg alloy is 0.3% or more. The erosion index exceeded 100, resulting in insufficient corrosion resistance. Also, as shown in FIG. 2, the bending strength shows an effect from 0.5% of these additives, but begins to decrease from 5%, and
At 10% or more, the strength was insufficient. Further, as shown in FIG. 3, the effect of the oxidation resistance was exhibited when the addition amount was 0.5% or more. From the above results, Al
It was confirmed that the addition amount of 0.5% or more and 10% or less is preferable in both cases of adding the -Mg alloy or the metal Al and the metal Mg at the same time. In addition, X
The line analysis confirmed that all of the Al-Mg alloys and the case where metal Al and metal Mg were added at the same time all produced a reaction spinel.

Example 2 A comparative evaluation was performed in the case where the amount of graphite was changed while the amount of the Al-Mg alloy was fixed at 3% based on the same refractory material as in Example 1. The graphite used for the implementation of this example had an average particle size of 25
There are two types: artificial graphite of μm and earthy graphite with an average particle size of 40 μm. FIG. 4 shows the results. As can be seen from the figure, when the graphite content is less than 3% and 20% or more, the corrosion resistance is insufficient in any case, and the graphite content is 3% or more and 20% or more.
The following results were shown to be preferable.

[0026]

As described above, according to the present invention, it is possible to provide a highly corrosion resistant amorphous refractory material useful as a refractory for a blast furnace main gutter metal line. Cost can be reduced.

[Brief description of the drawings]

FIG. 1 is an evaluation diagram of corrosion resistance of Example 1.

FIG. 2 is an evaluation diagram of bending strength of Example 1.

FIG. 3 is an oxidation resistance evaluation chart of Example 1.

FIG. 4 is a graph showing the relationship between the graphite content and the erosion index in Example 2.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Masato Kumagai 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Inside the Technical Research Institute of Kawasaki Steel (72) Inventor Masato Takagi 1-1-1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Kawasaki Inside the Technical Research Institute of Iron and Steel Corporation (72) Takashi Haraoka 1st Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Inside the Technical Research Center of Kawasaki Steel Corporation (72) Inventor Shinzo Kosaka 1576 Higashi-oki -2 Kawasaki Furnace Materials Co., Ltd.

Claims (3)

[Claims] 1. A graphite material of 3 to 20 wt%, a metal Al and a metal Mg of 0.5 to 10 wt% in total or an Al-Mg alloy of 0.5 to 10 wt%.
An amorphous refractory material for blast furnace main gutters, characterized by containing 10wt%. 2. The refractory material according to claim 1, wherein, when the metal Al and the metal Mg are contained, Al and Mg are mixed in a molar ratio of Al / Mg = 1.8 to 4.0. . 3. The irregular refractory material according to claim 1, wherein the metal Al, the metal Mg, and the Al—Mg alloy are used whose surfaces are each subjected to a hydration prevention treatment.