JP3157310B2 - Refractory - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refractory used for lining a container for holding or refining molten metal, molten slag, and the like.

[0002]

2. Description of the Related Art In steel production in recent years, refining contents have become extremely strict with respect to refractory linings in accordance with stricter quality of steel products. This problem is becoming particularly apparent with regard to refractories used in facilities in the secondary refining process that have the greatest effect on product quality (hereinafter, refractory for secondary refining). Conventionally, magcro brick has been widely used as a refractory for secondary refining. Magnesium bricks make use of chromium ore to improve their weakness and easy slag infiltration while making use of the corrosion resistance, which is the strength of magnesia, which is the main component, to provide durability.

[0003] However, even if a highly durable magcro brick is used for secondary refining, due to recent changes in operating conditions,
Lack of durability is becoming a problem. In particular, slag infiltration cannot be completely suppressed by the addition of chromium ore,
As a result, deterioration of the structure, structural spalling, and the like occur, and wear of the refractory proceeds. In order to solve this problem, more effective measures for preventing slag infiltration are required.

[0004]

However, slag easily infiltrates the refractory made of magnesia alone, and is liable to be worn. Therefore, in order to obtain an excellent refractory in which the properties of magnesia are maximized, it is necessary to suppress slag infiltration. An object of the present invention is to provide a new refractory that effectively suppresses slag infiltration.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above objects, the present invention provides a method for preparing calcium zirconate (CaO.Zr).
O ₂ ) 0.1 to 5 % by weight, and a refractory characterized by adding a small amount of an additive to a material composed of magnesia, and calcium zirconate (CaO.Zr).
O ₂ ) 0.1 to 5 % by weight, and the remainder consisting of magnesia includes spinel, chromite, mullite, and alumina.
Disclosed is a refractory characterized by adding 0.1 to 30% by weight of a kind or two or more kinds in total and a small amount of an additive.

The present invention further achieves the above object by providing
Calcium zirconate (CaO · ZrO ₂₎ 0.1~
5 % by weight and a balance of magnesia to which a small amount of an additive is added to form a refractory fired at 1500 to 1900 ° C., and calcium zirconate (CaO 2)
・ ZrO ₂ ) 0.1 to 5 % by weight, with the balance being composed of magnesia, spinel, chromite, mullite, aluminum
One or two or more of the above are added to a total of 0.1 to 30% by weight, and a small amount of an additive is formed.
Provide refractories fired at 〜1900 ° C.

[0007]

When calcium zirconate and magnesia are blended to form a refractory, the infiltrated slag is made highly viscous by the ZrO ₂ component in the calcium zirconate, and the intrusion of the slag is suppressed. In addition, since calcium zirconate also has an effect of accelerating sintering of magnesia, the refractory itself is sintered and densified, thereby suppressing slag infiltration.

[0008] The addition amount of calcium zirconate is 0.
If it is less than 1%, the effect of suppressing slag infiltration cannot be sufficiently obtained,
Further, since impair the corrosion resistance is 5 percent, preferably set to 0.1 to 5%. In the case of a refractory made of calcium zirconate and magnesia, magnesia may be added in an amount of 70 to 99.9% in order to secure sufficient corrosion resistance.

A refractory material other than calcium zirconate and magnesia may be blended for the purpose of improving corrosion resistance or thermal shock resistance. Examples of refractory materials that can be blended include spinel, chromite, mullite, and alumina, and one or more of these can be blended. However, if the amount exceeds 30%, the corrosion resistance or thermal shock resistance may be impaired. If the amount is less than 0.1%, the effect of improving the corrosion resistance or the thermal shock resistance cannot be obtained.

The refractory according to the present invention is obtained by mixing calcium zirconate with magnesia or other refractory materials, further adding a binder, and as it is as an amorphous refractory.
Alternatively, it can be molded to form a fixed refractory, or further heat-treated to form a fired refractory.

The method for producing a refractory according to the present invention will be described below. Regarding the quality of the calcium zirconate used, the ZrO ₂ component is 90 to 50%, and the particle size is 0.5 to 0.5%.
mm or less may be used. Magnesia clinker is about 90% or more MgO component, natural sintered product,
Either a synthetic sintered product or a synthetic fused product may be used. The particle size can be appropriately adjusted to about 5 mm or less. Regarding other refractory materials, those having a chemical composition and a particle size within the range usually used for refractories may be used.

As the additive for the fixed refractory, a binder or the like usually used for a basic refractory may be used.

[0013] As an additive for forming an amorphous refractory, various cements, phosphates, glasses, coagulants, various resins, polysaccharides, water glass and the like having a function as a binder may be used. As other additives, substances for improving workability and workability, such as silica flour, deflocculant and wetting agent, may be added.

For molding, a friction press, an oil press, a CIP or the like can be used in the same manner as ordinary refractories.

[0015] The firing temperature for making a fired refractory is 150
It is desirable that the temperature be 0 to 1900 ° C or higher. This is 15
If the temperature is lower than 00 ° C., sintering does not proceed sufficiently, and the quality of the product is not stable. On the other hand, if the firing temperature is higher than 1900 ° C., energy costs and facility construction costs are high.

[0016]

【Example】

Example 1 A refractory was prototyped using calcium zirconate and magnesia, and its characteristics were investigated. Calcium zirconate powder and magnesia clinker were mixed, a small amount of a binder was added, and the mixture was molded. The mixture was fired at a maximum temperature of 1650 ° C. to produce a refractory, which was evaluated by an erosion test. The erosion test was performed by a lining method using an induction furnace. The conditions are as follows: temperature is 1650 ° C, slag composition is CaO
/ SiO ₂ = 3.3, Al ₂ O ₃ = 30%, MgO = 10
%Met. After the experiment, the amount of erosion and the depth of slag infiltration were measured, and the erosion index of the maximum eroded portion of the refractory consisting of magnesia alone was taken as 100 to obtain the erosion index. The slag infiltration thickness from the eroded surface after erosion was represented by an index with the amount of erosion at the maximum eroded portion being 100, and this was defined as the slag infiltration index.

FIG. 1 shows the relationship between the amount of added calcium zirconate and the slag infiltration index and the erosion index. When calcium zirconate is added in an amount of 0.1% or more, the slag infiltration index is greatly reduced, indicating that excellent slag penetration is obtained. Regarding the erosion, when the calcium zirconate is added in the range of 0.1 to 5 %, the erosion index is smaller than that when no calcium zirconate is added. On the other hand, when calcium zirconate is added in more than 5 %, the erosion index becomes larger than that when no calcium zirconate is added. That is, it can be seen that excellent slag infiltration resistance and corrosion resistance can be obtained by adding 0.1 to 5 % of calcium zirconate.

Example 2 Raw materials were mixed in the composition shown in Table 1, a small amount of a binder was added, molded, and fired to produce a refractory, which was evaluated by an erosion test. The erosion test was performed by a lining method using an induction furnace. The condition is that the temperature is 1650
° C, slag composition: CaO / SiO ₂ = 3.3, Al ₂ O ₃
= 30% and MgO = 10%. After the experiment, the amount of erosion and the depth of slag infiltration were measured and indexed with the amount of erosion of the refractory consisting of magnesia alone as 100. The smaller this value is, the higher the corrosion resistance or slag resistance is. As a comparative example, the characteristics of a refractory made of magnesia alone are also shown in Table 1.

[0019]

[Table 1]

As a result of the test, the slag infiltration of the refractory according to the present invention is less than one-third of that of the comparative magnesia brick F , and a remarkable effect of slag infiltration is recognized. The erosion is also improved by 10 to 25%.

The brick B of Example 1 was divided into quarters of the slag line of a 150-ton smelting ladle. As a result, the erosion rate was about 15% smaller than that of the conventional product (magcro direct bond brick). As a result of investigation of the used product, the conventional product was found to have a deteriorated layer formed by infiltration of slag to a depth of 60 mm from the working surface, and a large parallel crack was generated between the deteriorated layer and the non-changed layer on the working surface. On the other hand, in the case of C according to the present invention, the altered layer was about 20 mm, and there was almost no crack.

Example 3 Raw materials were mixed according to the composition shown in Table 2, a small amount of a binder and water were added and kneaded, and the mixture was cast into a mold, dried and dried to produce a refractory. It was evaluated by a test. The erosion test was performed by a lining method using an induction furnace. As conditions, the temperature is 1650 ° C and the slag composition is C
aO / SiO ₂ = 3.3, Al ₂ O ₃ = 30%, MgO =
10%. After the experiment, the amount of erosion and the depth of slag infiltration were measured.
It was indexed as The smaller this value is, the higher the corrosion resistance or slag infiltration resistance is. As a comparative example, the characteristics of a refractory made of magnesia alone are also shown in Table 2.

[0023]

[Table 2]

As a result of the test, the slag infiltration of the refractory according to the present invention is not more than one third of the magnesia brick K as a comparative product, and a remarkable effect of slag infiltration is recognized. The erosion is also improved by 10 to 25%.

[0025]

The refractory of the present invention has excellent properties such as slag infiltration hardly occurring and high corrosion resistance. Applying this refractory to kilns will greatly contribute to improving productivity and reducing production costs.

[Brief description of the drawings]

FIG. 1 shows the relationship between the amount of calcium zirconate added (%) and the slag infiltration index and the erosion index.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Nobuhiko Kaji 1-1 Higashihama-cho, Yawatanishi-ku, Kitakyushu-shi, Fukuoka (72) Inventor Takeyuki Tamaki 1-1 Kurosaki, Higashihama-cho, Yawatanishi-ku, Kitakyushu-shi, Fukuoka (56) References JP-A-63-162566 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 35/00-35/22

Claims (4)

(57) [Claims] Claims: 1. A calcium zirconate (CaO.Zr)
O ₂ ) A refractory comprising 0.1 to 5 % by weight, and a balance of magnesia, to which a small amount of an additive is added. 2. Calcium zirconate (CaO.Zr)
O ₂ ) 0.1 to 5 % by weight, and the remainder consisting of magnesia includes spinel, chromite, mullite, and alumina.
A refractory, characterized in that a total of 0.1 to 30% by weight of a kind or two or more kinds and a small amount of an additive are added. 3. Calcium zirconate (CaO.Zr)
O ₂ ) A material obtained by adding a small amount of an additive to a material composed of 0.1 to 5 % by weight and a balance of magnesia, and formed into a material of 1500
Refractories fired at ~ 1900 ° C. 4. Calcium zirconate (CaO.Zr)
O ₂ ) 0.1 to 5 % by weight, and the remainder consisting of magnesia includes spinel, chromite, mullite, and alumina.
One or two or more kinds are added in a total amount of 0.1 to 30% by weight, and a small amount of an additive is formed.
Refractory fired at 0 ° C.