JPH07267745A - Refractory for flowed-in forming - Google Patents

Abstract

PURPOSE:To improve flowability and fillability at the time of flowed-in forming as the lining of a molten metal vessel and to improve durability and corrosion resistance as the lining. CONSTITUTION:In refractories for flowed-in forming based on refractory aggregate such as alumina, spinel or bauxite, spherical refractory aggregate having sphericity of >=0.75 is allowed to account for 10-50wt.% of the total amt. and spherical pitch having sphericity of >=0.75 is incorporated by 1-5wt.%. The pref. diameter of the spherical refractory aggregate is in the range of 0.5-5mm and that of the spherical pitch is in the range of 0.5-2mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a cast molding refractory used for lining molten metal containers such as blast furnace tap gutters, ladles, and tundish. The present invention relates to a cast molding refractory material which is suitable for applications such as being complicated or requiring a wide construction surface and having a smooth surface, and having excellent fluidity and filling properties and excellent corrosion resistance to molten metal and slag.

[0002]

2. Description of the Related Art Casting refractories used for lining molten metal containers are usually prepared by mixing a peptizer and a water reducing agent with refractory materials such as alumina, spinel, bauxite, silicon carbide, alumina cement, and refractory clay. ing. After kneading with a mixer at the construction site, put it in a predetermined mold and apply a vibrator to prevent the formation of unfilled parts with cavities and voids inside the molded product, and to improve the filling degree. I am raising. In recent years, it has been proposed to reduce the amount of alumina cement added and use ultrafine powder of alumina, silica, and silicon carbide to improve the strength after curing and improve the corrosion resistance to molten metal and slag.

[0003]

However, in some cases, the vibrating is insufficient, the thickness of the refractory material is thin, or the portion having a complicated shape still has an unfilled portion. For filling in a portion having a complicated shape, means for vibrating the frame itself to promote fluidity and filling property is required. If the vibrator is not properly applied, the refractory may leak out of the predetermined mold. In addition, when the construction surface is wide and a smooth surface is required, it is extremely difficult to obtain smoothness because the surface has irregularities even when applied with a vibrator. Further, there is a problem that the vibrating work requires a full-time worker and this work involves heavy labor.

On the other hand, if the amount of added water of the refractory material is increased, the fluidity is improved, but the increased amount of the added water decreases the filling property of the construction body and causes the deterioration of the durability performance of the refractory material. It is also known that the use of deflocculants such as phosphates and carboxylates, and the addition of ultrafine powder materials such as alumina and silica improve the flowability of refractories, but it reduces or eliminates the need for vibration. It is the current situation that the effect to the effect is not obtained.

In order to solve these various problems, the flowability and the filling property of the cast molding refractory after the hydro-kneading are good, and even if the vibration is reduced even in a narrow space, or even if the vibration is omitted, the structure of the construction body can be reduced. Without forming an unfilled part inside,
It is preferable that refractory can be constructed. Hereinafter, in the present invention, the property of good flowability and filling property is referred to as self-flowing property without depending on the physical external force such as the vibration of the cast refractory by the vibrator. An object of the present invention is to provide a cast refractory material having good self-flowing property.

[0006]

Therefore, according to the present invention, a cast refractory material mainly composed of a refractory aggregate such as alumina, spinel, bauxite, etc. is a spherical refractory aggregate having a sphericity of 0.75 or more. It was made to occupy 10 to 50% by weight of the whole, and 1 to 5% by weight of a spherical pitch having a sphericity of 0.75 or more was contained. The spherical refractory aggregate preferably has a particle size of 0.5 to 5 mm, and the spherical pitch preferably has a particle size of 0.5 to 2 mm.

[0007]

The spherical refractory aggregate is one or more selected from alumina, spinel and bauxite. All of them are excellent in corrosion resistance to molten metal and slag, and are used as aggregates of ordinary cast refractory materials. Spherical refractory aggregates have a particle sphericity of 1
It is preferably about 0.75. The sphericity is the diameter D at a position 90 degrees from the position with respect to the longest diameter D1.
The ratio is 2. The content ratio of the spherical refractory aggregate (refers to those having a sphericity of 0.75 or more) is preferably 10 to 50% by weight. When it is 10% by weight or less, the effect is poor in fluidity and filling property. If it is 50% by weight or more, the corrosion resistance to the molten metal decreases. This is because a particle having a smooth surface is inferior in physical bonding between particles as compared with an irregular and random particle. Therefore, in order to improve the corrosion resistance, the size of the spherical refractory aggregate to be contained is preferably an intermediate grain, and specifically, the spherical refractory aggregate having a particle size of 0.5 to 5 mm is most suitable. There is. As coarse particles and fine powder, it is rather preferable to use irregular and random particles having a strong physical bond.

Spherical pitch (having a sphericity of 0.75 or more) is a carbon material that is difficult to wet with molten metal, and therefore is used for enhancing penetration resistance to various molten metals. Here again, it was found that the use of spherical pitch is effective for free flowing. Spherical pitch is a technique in which liquid pitch that has been melted by heating is made into droplets from a container with an orifice tube and dropped into water to make it spherical, or liquid pitch that is melted by heating is sprayed from a steam pressure cooker through a nozzle to make it spherical. Those manufactured by the method can be used. A spherical pitch having a particle size of 0.5 to 2 mm is used in an amount of 1 to 5% by weight.

When the construction body receives heat, the pitch softens from about 100 ° C., and when it exceeds 200 ° C., the volatile components in the pitch scatter, and the residual fixed carbon components and voids corresponding to the volatile components remain therein. . Therefore, if the spherical pitch is 2 mm or more, the voids in the construction body become large and the structure is not uniform, which is not preferable. On the other hand, if it is 0.5 mm or less, not only does it not contribute to the improvement of the free-flowing property which is the object of the present invention, but conversely, the water repellent characteristic of the material is exhibited, the viscosity of the kneaded product increases, and the fluidity is impaired.

When the content of the spherical pitch is 5% by weight or more,
As described in the restrictions on the adopted particle size, there are many voids in the construction body, the structure becomes non-uniform, and the packing density decreases. On the other hand, if it is less than 1% by weight, the carbon material is poor in the enhancement of penetration resistance and poor in corrosion resistance.

The refractory material group such as spherical alumina, spinel, bauxite, etc. to be adopted and the spherical pitch are divided into the particle size and the compounding amount which are respectively defined by the pitch as mentioned above. In addition to having the property of being softened by receiving heat, the specific gravity of alumina, spinel, bauxite, etc. is remarkably different from the specific gravity of pitch. That is, alumina, which is a general raw material usually used for refractories, has a specific gravity of 4.0, spinel has a specific gravity of 3.6, bauxite has a specific gravity of 1.3, while bauxite has a specific gravity of 1.3.
The former (alumina etc.) and the latter (pitch) have a difference in specific gravity of about 3 times.

In addition to these materials, it is effective to contain silicon carbide in an amount of about 10 to 35% by weight as an aggregate and a fine powder for the purpose of improving the thermal shock resistance and corrosion resistance of refractory materials.

Further, ultrafine alumina powder, ultrafine silica powder,
The refractory for casting according to the present invention is constituted by adding refractory clay, alumina cement, and deflocculants such as phosphates and carboxylates.

[0014]

EXAMPLES Examples of the present invention will be described below. Table 1 is an example in which spherical alumina aggregate is adopted. Here, spherical alumina aggregate having a sphericity of 0.93 and a spherical pitch having a sphericity of 0.88 are used.

Example 1 in Table 1 is an example in which the spherical alumina aggregate is 20% by weight, Example 2 is 30% by weight, and Example 3 is 40% by weight. Further, Example 4 is Example 3 In comparison with Comparative Example 1, the spherical pitch is increased. Comparative Example 1 is an example in which a conventional alumina aggregate and a fine powder pitch are adopted, which requires a larger amount of added water than Examples 1 to 4, and is also inferior in free flowing. as a result,
Also in terms of physical properties and corrosion resistance, the examples are better. Comparative Example 2 is a case where the amount of the spherical alumina aggregate is small, and the free flowing property is at the same level as that of Comparative Example 1.
It is understood to be much worse than. Comparative Example 3
Shows an example in which the total amount of the aggregate portion is spherical alumina aggregate, and in comparison with Example 3, the free flowing property is improved, but the physical property is deteriorated. This is because although the ball bearing effect was exhibited by increasing the amount of spherical alumina aggregate used and the free-flowing property was improved, the bonding force between particles was reduced and the physical properties were reduced, further leading to lower corrosion resistance. It is believed that

In comparison with Example 2, Comparative Example 4 has a smaller spherical pitch amount, and although Comparative Example 4 is superior in free flowing property to Comparative Example 1 which does not employ spherical alumina aggregate, Inferior to 2. Incidentally, in Comparative Example 4, the strength is improved and the porosity is lowered, but this is because the sintering progresses and the strength is increased due to the decrease in the pitch amount which is a carbon material, and at the same time, the pitch volatile content decreases. It is thought that this caused the porosity to decrease. Furthermore, the fact that the corrosion resistance is greatly reduced supports the fact that the amount of carbon was reduced and the carbon was easily penetrated.

In Example 4, the spherical pitch was increased more than in Example 2, and in Comparative Example 5, the amount was increased more than in Example 4. Comparative Example 5 is not preferable in terms of corrosion resistance because the amount of spherical pitch, which is a carbon material, is too large, the degree of improvement in free-flowing property is poor, and the porosity is large.

The spherical alumina is obtained by granulating the calcined alumina as a raw material to obtain a spherical body, which is dried and then calcined in a rotary kiln and classified. Al ₂ O ₃ 99% or more Was used, and each of the particles had a ball shape.

Table 2 is an example in which spherical spinel aggregate is used, and Table 3 is an example in which spherical bauxite aggregate is used. For the spherical spinel aggregate and bauxite aggregate, spinel and bauxite raw ore are finely pulverized by a ball mill. The product was granulated into a spherical body, dried and calcined, and then sieved in the range of 0.5 to 5 mm to adjust the particle size before use.

The spherical spinel aggregate used in the examples of Table 2 had a sphericity of 0.81. Example 1 in Table 2 is an example in which the spherical spinel aggregate is 30% by weight, and Example 2 is 50% by weight, which is improved in free-flowing property, physical property and corrosion resistance as compared with Comparative Example 1 in which the conventional aggregate is adopted. Therefore, the same effect as in Table 1 is recognized.

Table 3 is an example in which spherical bauxite aggregate was adopted, and the sphericity was 0.78. It can be seen that Examples 1 and 2 employing the spherical bauxite aggregate and spherical pitch also have improved self-flow properties, physical properties, and corrosion resistance as compared with Comparative Example 1.

[0022]

[Table 1]

[Table 2]

[Table 3] Free-flow test value Cast iron flow table with diameter 300 mm and φ100 × φ7
0xH60mm trapezoidal flow cone (JISR5201
The physical test method for cement) was used to fill the material mixed in the flow cone placed on the flow table with a predetermined amount of added water. After the filling is complete, remove the flow cone and
After standing for 2 seconds, the diameter of the material that flowed and spread under its own weight was measured. The larger the value, the better the free-flowing property.

Bending strength Compressive strength A predetermined amount of added water was added, and the material under kneading was 40 × 40 × 16.
Pour into a 0 mm mold, let it cure overnight in the room, and deframe it at 110 ° C.
Bending strength and compressive strength were measured with a hydraulic uniaxial compression tester (Amsler) by using a test sample that was dried for 24 hours and baked in a reducing atmosphere at 1450 ° C for 3 hours in an electric furnace. did.

A sample similar to the test sample for measuring the porosity and bulk specific gravity was prepared, and the weight in air was measured, and then the weight in water and the weight in water were measured and calculated by the vacuum hydrate method.

In a corrosion resistance high frequency induction furnace melting and erosion tester, FC20 cast iron 2 kg and blast furnace slag 100 gr 150 were used as test materials for lining materials.
The amount of erosion loss of each test material at the time of the dissolution and erosion test at 0 ° C to 1600 ° C was measured. Further, the evaluation was made by indexing the amount of erosion of the other test materials by proportional calculation with Comparative Example 1 being 100. A number larger than 100 is inferior in corrosion resistance, and a small number is inferior to good corrosion resistance. .

[0026]

The cast refractory material of the present invention has the following excellent properties. Compared to conventional cast molding refractories, it has excellent self-flow property even in the region where the amount of added water is small. As a result, physical properties as well as corrosion resistance to molten metal are improved, and the life of the refractory is extended. Further, by exhibiting the self-flowing property, it is possible to reduce or eliminate the need for a vibrator for filling, which leads to labor saving and labor saving in the construction work.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Kojima 1 Kimitsu, Kimitsu-shi, Chiba Shin-Nippon Steel Co., Ltd. Kimitsu Steel Co., Ltd. (72) Inventor Noriyuki Inoue 4-3-3 Misato, Toyota, Aichi 72) Inventor Hideaki Ohashi 1-24-2, Eiyo-cho, Toyota-shi, Aichi (72) Inventor Fumiaki Osawa 2-107-3, Aoki-cho, Toyota-shi, Aichi (72) Inventor Shinji Honike Toyota-shi, Aichi 3-13-7 Hirashiba-cho

Claims (3)

[Claims] 1. A cast refractory material mainly composed of refractory aggregates such as alumina, spinel, bauxite, etc., and spherical refractory aggregates having a sphericity of 0.75 or more are 1% of the total.
A cast refractory material comprising 0 to 50% by weight and 1 to 5% by weight of a spherical pitch having a sphericity of 0.75 or more. 2. The particle diameter of the spherical refractory aggregate is 0.5 to
The cast refractory material according to claim 1, wherein the refractory material is 5 mm. 3. The particle diameter of the spherical pitch is 0.5 to 2 mm.
The cast refractory material according to claim 1 or 2, wherein