JPH06157131A - Calcined magnesia/dolomite brick - Google Patents

Abstract

PURPOSE:To drastically improve a structural spalling property, a joint erosion property and wear resistance by improving the slag permeation resistance of calcined magnesia/dolomite brick which has not been solved by the conventional technology. CONSTITUTION:Fine chrome oxide powder with <=10mum size of 0.3-5.0wt.%. is added to 100wt.% refactroy material consisting essentially of magnesia and dolomite. Thereby the obtained calcined magnesia.dolomite brick decreases by 17% in the slag penetration thickness even in the actual use, 37% reduction of the erosion rate is recognized and there is great, improvement effect in the slag penetration resistance. Also there is great effects in the structural spalling resistance and corrosion resistance, etc.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to fired magnesia dolomite bricks.

[0002]

2. Description of the Related Art Fired magnesia dolomite bricks are mainly used in AOD furnaces, molten steel pots, VOD pots and the like. In general, the features of magnesia dolomite brick are as follows.

It is highly corrosive to high basicity slag. Relatively good for spalling. Low hot strength and weak against wear. Digest. It is a low price.

When it is actually used, most of it is caused by chemical reaction with low to medium basicity slag, structural spalling, or joint erosion phenomenon. Most of these factors are caused by the penetration of slag, and suppression of this slag penetration has been a major issue. On the other hand, although measures such as densification of CaO-dispersed bricks in the matrix part were taken, the present situation is that there are no magnesia dolomite bricks that are sufficiently satisfied due to digestion problems and spalling problems. .

[0005]

SUMMARY OF THE INVENTION The present invention aims to improve slag penetration resistance, which has not been solved by the prior art, and thereby greatly improve structural spalling property, joint erosion resistance and wear property. Is.

[0006]

Means for Solving the Problems In the present invention, MgO, Ca
A method of intentionally adding components other than O to improve the matrix portion was adopted. As a result of various studies on additives C
It has been found that the r ₂ O ₃ component is effective. The Cr ₂ O ₃ component was added as fine powder of 10 μm or less. The reason for this is that it is added in a small amount to disperse more, and is added to the matrix part to bring out the effect of preventing binding or slag penetration.

Regarding the amount of addition, it was found as a result of various compounding tests that it was effective in the range of 0.3 to 5.0% by weight. (Table 1) This is because when added in an amount of more than 5.0% by weight, CaO.CrO _{3 which} is a low melting point mineral is excessively generated, which causes a problem due to softening in the production of bricks. Because it's small.

[0008]

[Table 1]

[0009]

When Cr ₂ O ₃ is mixed in the melt, it raises the viscosity of the melt. Therefore, especially in the case of low basicity slag with a large amount of SiO ₂ component in the slag, Cr ₂ O ₃ in the refractory is The effect of increasing the viscosity of the melt generated by the slag that has penetrated into the slag and preventing the progress of erosion is great. Further, in the high basicity slag, a CaO component in the slag and a high melting point compound are formed under a low oxygen partial pressure. As a result, penetration of slag from low basicity to high basicity can be sufficiently suppressed, and high corrosion resistance can be obtained. C
When the r ₂ O ₃ component is added as a fine powder to the matrix part,
In addition to the above effects, it also led to densification and increase in strength, and since CaO was stabilized as CaO.CrO _{3 on} the surface of the dolomite clinker, it also showed a tendency to be improved in digestion resistance.

[0010]

[Examples] Table 1 shows the composition and refractory properties of Examples and Comparative Examples of the present invention. In each case, a phenolic resin was added as a binder, and a brick was manufactured by kneading, molding and firing. Inventive product NO. Nos. 3, 4, and 5 are conventional products, and NO.
Compared with Nos. 1, 2, and 6, the slag penetration resistance was excellent, and due to this, a great effect was exerted on the structural spalling resistance and corrosion resistance.

Example No. 1 according to the present invention. 4 bricks 5
As a result of using it as a liner for 0VOD ladle, the results are shown in Table 2.

[0012]

[Table 2]

The conventional product has a small residual thickness, and the slag permeates the entire surface to the non-operating surface. Further, the operating surface of the product of the present invention was smoother than that of the conventional product and there was no tendency to spall.

[0014]

The fired magnesia dolomite brick obtained by adding 0.3 to 5.0% by weight of chromium oxide fine powder to the refractory material containing magnesia and dolomite as the main components has a slag permeation thickness reduced by 17% even in actual use. As a result 3
A 7% reduction in the erosion rate was observed, and a large improvement effect on the slag penetration resistance could be obtained. In addition, it has a great effect on structural spalling resistance and corrosion resistance.

Claims (1)

[Claims] Refractory material 100 based on magnesia and dolomite 100
0.3% of chromium oxide fine powder of 10 μm or less with respect to weight%
Burned magnesia dolomite brick made by adding 5.0% by weight.