JP3475256B2 - Basic refractories - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tuyere of an AOD furnace and its surroundings, a ladle lining for refining,
H lining, magnesia-chrome brick which shows strong resistance to erosion when used in places with severe erosion such as tuyere for copper refining, around tuyere, and basin of sludge melting furnace About. [0002] Magnesia-chromic bricks are chemically stable to basic slag, have high hot strength, and are excellent in corrosion resistance and spalling resistance. For this reason, magnesia-chrome bricks are used for refining ladle, RH, non-ferrous melting furnace,
It is used as a lining material in non-ferrous refining furnaces and kilns for melting various molten materials. However, recently, in order to improve the quality and efficiency of products, chemical damage to magnesia-chromic bricks has been caused by prolonging the processing time, raising the processing temperature, and increasing the stirring force due to the increase in the amount of inert gas blown and the speed of blowing. Volume and physical damage are increasing. [0004] For this reason, there has been a demand for bricks having higher resistance to chemical damage and physical damage than conventional magnesia-chromic bricks, and various attempts have been made. The proposed method is to increase the amount of chromia in magnesia-chromic brick, and to reduce the generation of low-melting-point substances, it has less impurities (SiO ₂ , Al ₂ O ₃ , Fe ₂ O ₃ ) This is a method using raw materials. [0005] Conventional magnesia-chromic bricks have been made by combining magnesia clinker, electrofused magcro, chromite ore, and the like. Recently, these have been replaced by Chromia (C
r ₂ O ₃ ) with high content and low impurities (SiO ₂ , Al ₂ O ₃ , Fe ₂ O ₃ etc.) Magnesia-chrome brick with high corrosion resistance is used. It is known that among these methods, the method using electrofused picrochromite has the highest corrosion resistance. [0006] The blending of electrofused picrochromite raw material with magnesia-chromic brick greatly improves the corrosion resistance. However, a large number of slag,
Invasion of karami etc. was observed. The invasion of slag, karami, etc. has caused the destruction of the brick tissue, and it was thought that if this could be reduced, the service life would be further improved. SUMMARY OF THE INVENTION An object of the present invention is to provide a magnesia-chromic brick which has reduced intrusion of slag, lumps and the like and further increased corrosion resistance. SUMMARY OF THE INVENTION The present invention provides a chromium carbide (Cr ₃
It was found that by using electrofused picrochromite containing C ₂ , Cr ₇ C ₃ , and Cr ₂₃ C ₆ ), a dense and low-permeability brick can be obtained, and the infiltration of slag can be remarkably suppressed. [0008] As the electrofused picrochromite of the present invention, those satisfying Table 1 are used. [Table 1] [0010] [Table 2] [0011] The fired magnesia-chromium brick containing at least 10 wt% of electrofused picrochromite containing chromium carbide in an amount of 0.3 to 0.7 wt% in terms of C is a conventional magnesia-chromium containing electrofused picrochromite. 1700 ° C due to the effect of chromium carbide contained in electrofused picrochromite compared to brick
Thus, a dense brick structure is formed during firing. For this reason, the brick according to the present invention is dense and has a small air permeability, and has an effect of suppressing the penetration of the melt. [0012] If the carbon content in the electrochromic picrochromite containing chromium carbide exceeds 0.7 wt%, the brick structure after firing does not become dense, and the carbon in the electrochromic picrochromite containing chromium carbide does not. If the amount is less than 0.3% by weight, the effect of chromium carbide is not obtained, and the effect of suppressing the permeation of the melt is not exhibited. [0013] In addition, chromium carbide is 0.3 to 0.7 wt% in terms of carbon content.
Even when the contained electrofused picrochromite is used, if the added amount is less than 10% by weight, no remarkable effect is exerted on the permeation suppression effect and the improvement of corrosion resistance. [0014] Table 3 shows the physical properties of the conventional magnesia-chromic brick and the product of the present invention, the erosion index and the slag penetration index in the erosion test. The erosion index and slag permeation index of electrofused picrochromite containing no chromium carbide
The amount of erosion and the amount of slag permeated in Comparative Example 1 used at 0 wt% were indicated relative to each other as an index of 100. The smaller the index, the better the erosion and penetration. [Table 3] Note 1) The erosion index The erosion amount was compared by a rotational erosion test method. Table 4 shows erosion materials
Was used. Test temperature is 1700 ℃ ~ 1750 ℃
For 12 hours. After the test, the amount of erosion was measured and indicated by an index. [Table 4] Note 2) Slag permeation index The slag permeation amount was obtained by cutting the sample after the rotary erosion test and measuring the thickness of the altered layer. The thickness was indicated by an index. [0017] The magnesia-chromic calcined brick of the present invention containing electrochromic picrochromite containing chromium carbide is a denser and more breathable brick containing electrochromic picrochromite containing no chromium carbide. Has a small value, the penetration of slag is small, and it has an effect of excellent corrosion resistance.

Claims (1)

(57) [Claims] [Claim 1] Chromium carbide (Cr ₃ C ₂ , Cr ₇ C ₃ , C
Fused to 0.3~0.7wt containing r ₂₃ C ₆₎ at C content
The pixels potter's wheel mite blended least 10 wt%, the balance being magnesia clinker, fused pixels runner chromite, fused Magukuro, chromium ore, is composed of chromium oxide and a portion thereof,
And magnesia-chrome brick fired at 1700 ° C. or higher.