JP4073059B2 - Fired magnesia-chromic brick - Google Patents

Description

【０００９】
【発明の効果】
実施例の本発明品を表１のＮｏ６の平均粒径１５μｍ以下のＺｒＯ₂を、３重量％添加した焼成マグクロ質れんがを６０tonＡＯＤ炉の羽口周辺及びスラグラインに一般品（基本配合）と張り分けテストした。実炉使用結果溶損量は一般品溶損量２．１０ｍｍ／ｃｈに対し本発明品は１．８２ｍｍ／ｃｈと約１３％少なく大きな効果が認められた。[0001]
BACKGROUND OF THE INVENTION
The present invention mainly relates to a fired magnesia-chromic brick (hereinafter referred to as magchromatic brick) lined in an AOD furnace.
[0002]
[Prior art]
The AOD furnace for refining stainless steel in the out-of-furnace refining furnace is a refining furnace whose main purpose is decarburization with strong stirring by oxygen blowing and Ar gas blowing. The operating temperature is up to 1750 ° C, slag basicity (CaO / SiO ₂ ) varies in the range of about 1.0 to 2.5. Therefore, magchromic bricks having high corrosion resistance and high hot strength as lining materials for AOD furnaces, especially semi-ribboned magchromic bricks based on a dense electrofused magcroclinker, exhibit the best durability. Other examples include magnesia-dolomite and direct bond-type magchrom bricks, which show a significantly low durability due to low hot strength and changes in slag components. In the AOD furnace, there is a tendency for high-temperature, strong stirring refining for a longer time for further improvement of durability or refining of special stainless steel, and there is a need to increase hot strength as a brick property. .
[0003]
For this method, the most effective method is to raise the firing temperature, but generally the temperature rise / fall in the tunnel kiln leads to short life of the tunnel kiln, resulting in variations in quality and the ability of the tunnel kiln itself to be limited. For example, the firing temperature cannot be easily increased, and the firing is usually performed at about 1800 ° C. Accordingly, various improvements in the temperature range have been made. One is to reduce the natural chromium ore that produces pores. In other words, it is to increase the usage ratio of electrofused magcro clinker to make a dense body. However, although this method can reduce the porosity, the heat resistant sparkling property is lowered and the overall effect is small. The other methods are similarly less effective and cannot cope with the severe operation of the future. Therefore, there is a need for a technique for strengthening the bonding by sintering while maintaining an appropriate porosity at a firing temperature of about 1800 ° C.
[0004]
[Problems to be solved by the invention]
It was an object to improve the wear resistance, that is, the hot strength, of semi-ribboned type bricks mainly used in AOD furnaces.
[0005]
[Means for Solving the Problems]
As a result of examining various additives based on a semi-ribboned type mainly composed of an electrofused magcro clinker, the ZrO ₂ component tended to increase in strength most. This is because the CaO component in the matrix and CaO.ZrO ₂ are formed. The ZrO ₂ component has the possibility of easily forming CaO · ZrO ₂ with the CaO component in the slag, and the CaO component has a tendency to collapse the structure of the macular brick and stabilizes the CaO. It was considered necessary.
[0006]
Therefore, an active product in the ultrafine powder region was also examined to obtain a general fine powder. (Table 1)
The hot bending strength increased with the addition amount. However, the amount of each peak added differs depending on the firing conditions and the reaction with other components in the brick. The smaller the particle size, the more effective the addition. This is because the activity is higher and CaO · ZrO ₂ is formed and stabilized, and the penetration of CaO into the brick is suppressed. Excessive addition forms other components in the brick, SiO ₂ and a low melting point compound, and softens. On the other hand, the corrosion resistance important in the use conditions of the AOD furnace was evaluated by the high frequency induction furnace lining method. The addition of ZrO ₂ component reacts with the CaO component in the slag to form CaO · ZrO ₂ , which increases in correlation with the added amount. However, it is considered that the reactivity with SiO ₂ is suppressed because the smaller the particle diameter of the additive is, the stronger the bond is formed.
In view of the above, the added particle size of the ZrO ₂ component is smaller, and a smaller amount is desirable. However, considering the lowering of the corrosion resistance, the upper limit of each is ZrO _{2 with} the average particle size of 15 μm or less in Table 1 No5 to No8. The fine powder was set to 1 to 7 % by weight. Also, if less than 1% by weight, the effect is small, so it was out of range. In addition, since the amount of natural chromium ore containing the flux composition inevitably increases when the amount of the electrofused magcrocliner in the semi-ribbon type brick for AOD furnace is less than 60% by weight, there is no effect of the ZrO ₂ component. Out of range.
[0007]
【Example】
In the present invention, baked mug brick was produced at a blending ratio shown in Table 1. In the same manner as in the general product (basic composition) of Table 1 and the comparative product, 2% by weight of an aqueous binder was added, mixed, molded with a friction press or a hydraulic press, and fired at 1800 ° C. with a tunnel kiln. Table 1 shows the material property values and the quality test measurement results.
[0008]
[Table 1]

[0009]
【The invention's effect】
Inventive products of the examples were baked mug bricks added with 3% by weight of No. 6 of ZrO ₂ having an average particle size of 15 μm or less in Table 1 with a general product (basic composition) around the tuyere and slag line of a 60 ton AOD furnace. Tested separately. As a result of using the actual furnace, the amount of erosion caused by the present furnace was 1.82 mm / ch, which was about 13% less than that of the general product erosion amount 2.10 mm / ch.

Claims (1)

Fused magnesia - chrome clinker - a Semiribondo type magnesia containing 60 wt% or more - with constituting chromium brick, Oite to the Semiribondo type sintered magnesia chrome brick, the average particle size 15μm or less of ZrO ₂ fine as the raw material A calcined magnesia-chromic brick obtained by adding 1 to 7% by weight.