JPH05842A - Refractory for molten iron vessel - Google Patents

Abstract

PURPOSE:To enhance volume stability by blending sintered SiO2 or silica and aluminous raw material, an aluminous raw material and carbon or the mixed material of carbon and SiC at the specified weight ratio. CONSTITUTION:10-70wt.% (hereinafter shown in %) SiO2 such as agal-matolite or silica and aluminous raw material sintered at 1000-1100 deg.C, 10-87% aluminous raw material such as sintered Al2O3 and 3-30% carbon material such as graphite or the mixture of carbon material and SiC are blended. Furthermore, a binder such as phenol resin, metallic powder such as Al and glass powder are added to this blended raw material. These are mixed and molded, and thereafter, heat-treated at 200-600 deg.C to obtain refractory for a molten iron vessel excellent in volume stability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refractory for a hot metal container such as a hot metal car and a hot metal pot, which can carry out hot metal pretreatment such as desiliconization, dephosphorization and desulfurization as well as hot metal transportation. is there.

[0002]

2. Description of the Related Art Conventionally, low-stone or chamotte refractory has been used as a refractory for hot metal containers such as a hot metal car, a hot metal ladle, etc. , Hot metal ladle, etc. not only serve as a transport container between the blast furnace and converter, but also serve as a refining container for pre-treatment of hot metal such as desiliconization, dephosphorization, and desulfurization. Alumina, silicon carbide, and carbonaceous refractories have been used because the conventional slag and other refractory materials such as low-grade stones have been greatly worn.

Although this alumina / silicon carbide / carbonaceous refractory has a high corrosion resistance, it has a small residual expansion coefficient, so that it causes a joint opening during use, infiltration of a base metal, and a preceding melting damage of the joint and its result. There is a defect that peeling wear occurs because cracks occur in the resulting kamaboko-shaped convex portion due to repeated heating and cooling. Further, in a hot metal container using a refractory of this system, the thermal stress generated in the refractory is large, so that cracking of the cell is also observed.

As a means for compensating for this drawback, Japanese Patent Laid-Open No. 2-2
Japanese Patent No. 2167 discloses a lozenge / alumina / silicon carbide / carbonaceous refractory in which a raw stone having high thermal expansion and high residual expansiveness is used for alumina / silicon carbide / carbonaceous refractory.

[0005]

However, this roe stone / alumina / silicon carbide / carbonaceous refractory material causes the preceding erosion of the brick which comes into contact with the joints of the conventional alumina / silicon carbide / carbonaceous refractory material, and the result thereof. It was possible to prevent peeling and wear of the resulting kamaboko-shaped protrusions, but 1000-
When it is used in a hot metal container due to its large thermal expansion at 1200 ° C, the bricks on the back side are pushed up and moved too much, which causes a problem that the building bricks become loose. Moreover, the large thermal expansion and residual expansion at 1000-1200 ℃ of loach also adversely affected the volume stability of the brick.

The present invention has been made in order to solve the above-mentioned conventional problems. By using a brick used by firing at 1000 to 1100 ° C., the required characteristics of the raw stone raw material are impaired. It is an object of the present invention to provide a refractory for a hot metal container which is excellent in volume stability by reducing large volume expansion due to mineral change occurring around this temperature.

[0007]

As a result of various studies, the inventors of the present invention have solved the above-mentioned inconvenience in the refractory for a hot metal container, and as a result of various studies to eliminate the volume stability of the brick and the looseness of the brick of the hot metal container, as a result, the rock stone The present invention has been completed by finding that the problem can be solved by using a raw material of calcined lozenge for the raw stone of alumina, silicon carbide, and carbonaceous refractory. That is, the present invention, as a hot metal container, is a calcined silica or silica-alumina raw material 10
.About.70% by weight, 10 to 87% by weight of an alumina raw material, a carbon material or a refractory material containing a carbon material and 3 to 30% by weight of silicon carbide is used.

The silica or silica-alumina raw material used in the present invention is lozenge, silica stone, porcelain stone, etc., alone or in a mixture, and among them, lozenge is most suitable. This is fired at 1000 to 1100 ° C. When this firing temperature is low, the expansion at around 1200 ° C is too large and the volume stability, which is a feature of this invention, is poor. Is too small to prevent joint opening. The amount used is 10 to 70% by weight. If it is less than 10% by weight, the joint opening cannot be prevented, and conversely, if it exceeds 70% by weight, the corrosion resistance is extremely deteriorated, which is not preferable. Further, in order to keep the corrosion resistance as much as possible, it is desirable to use the raw material while avoiding the fine powder portion.

As the alumina-based raw material, fused alumina,
Sintered alumina, sillimanite, bauxite, etc., and the Al ₂ O ₃ content in the raw material is preferably 50% by weight or more from the viewpoint of corrosion resistance, and particularly alumina raw materials such as fused alumina and sintered alumina are preferable. . The amount of the alumina-based raw material used is 10 to 87% by weight, and if it is less than 10% by weight, the corrosion resistance is poor, and if it exceeds 87% by weight, the spalling resistance is poor and neither is preferable.

The carbon material contributes to corrosion resistance and spalling resistance due to being hard to be wetted by slag, and silicon carbide suppresses oxidation of the carbon material to exert high corrosion resistance and high spalling resistance of the carbon material. There is an effect, and the amount used is 3 to the total amount of carbon material or carbon material and silicon carbide.
30% by weight. If this amount is less than 3% by weight, the effect of the carbon material will not be sufficiently exhibited, and if it exceeds 30% by weight, the strength and corrosion resistance will decrease.

In addition to the above raw materials, it is possible to add metal powder such as aluminum and magnesium, glass material, etc., whereby the oxidation resistance is further improved. According to a conventional method, a binder is added to these raw materials, and the raw materials are kneaded, molded, and then heat treated to be used as an unfired brick. A resin-based binder is preferable as the binder, and a phenol resin that is cured by heat treatment is preferable. Heat treatment after molding is 200 ~
It is performed in the range of 600 ° C. The unfired brick obtained as described above is used by lining a part or the whole of a hot metal wheel, a hot metal ladle or the like.

[0012]

[Function] By heating the SiO ₂ component present in the silica or silica-alumina raw material, high thermal expansion and high residual expansion due to transformation from α-quartz to β-quartz and cristobalite, and further broaching at high temperature This prevents the opening of the refractory joints, but this transformation
It starts at 00 ℃ and continues to around 1400 ℃. On the other hand, the pyrophyllite contained at the same time is heated to 1000-1100 ℃
To vitrify.

Silica or silica used in the present invention
The alumina raw material is a raw material obtained by firing at 1000 to 1100 ° C., and after firing, SiO ₂ is in the form of quartz and pyrophyllite is vitrified. Therefore, this firing raw material does not undergo a rapid expansion at around 1200 ° C., so that the volume stability of the brick is ensured. Further, since the pyrophyllite is vitrified, stress relaxation in the temperature range of 1300 ° C or higher becomes remarkable, and the thermal stress generated inside the refractory is reduced.

[0014]

[Examples] The composition shown in Table 1 was kneaded and molded by a friction press, and the molded product was heat-treated at 300 ° C for 10 hours to obtain an unfired brick. Table 1 also shows the physical properties of the brick after heat treatment, the values of the coefficient of thermal expansion at 1200 ° C. and 1400 ° C., the value of the residual linear expansion coefficient and the maximum generated thermal stress. The corrosion resistance was measured by a rotary slag test method at 1400 ° C. for 3 hours. Its slag composition is CaO: 46% by weight, Fe ₂ O ₃ : 42% by weight, C
aF _2: was used of 12% by weight. The results are from Comparative Example 1.
It was represented by a melt loss index of 100.

[0015]

[Table 1]

[0016] According to Table 1 above, by changing the raw raw stone of the brick for a hot metal container to a calcined raw stone fired at 1000 to 1100 ° C, the thermal expansion coefficient and the residual linear expansion coefficient can be reduced without significantly lowering the corrosion resistance. It became possible to secure the volume stability of the brick by lowering it (for example, Example 4 and Comparative Example 1). Moreover, since the degree of decrease in the coefficient of thermal expansion and the coefficient of residual linear expansion are not as great as those of alumina / silicon carbide / carbonaceous brick (Comparative Example 7), it was also possible to prevent joint opening at high temperature.
Further, it can be seen that the generated thermal stress is even lower than that in the case of raw rock stone, which also contributes to the prevention of seri cracking.

[0017]

As described above, according to the present invention, the thermal expansion coefficient, the residual linear expansion coefficient, and the generated thermal stress can be controlled appropriately by using the silica or the silica-alumina raw material that has been subjected to the firing treatment. It keeps the value of the refractory, secures volume stability of the refractory, prevents loosening of the building brick when it is used as a hot metal container, and has a special effect that it can be operated stably without joint opening, peeling wear and cracking.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hirokuni Takahashi 1799-1 Ibe, Bizen City, Okayama Prefecture (72) Inventor Hiroshi Yasui 32 Takeda, Okayama City, Okayama Prefecture

Claims (1)

Claims: 1. Calcined silica or silica.
Alumina raw material 10-70 wt%, Alumina raw material 10-87 wt%, carbon material or carbon material and silicon carbide 3-30 wt%
A refractory material for hot metal containers, characterized by being blended with.