JPS6354521B2 - - Google Patents

Description

[Detailed description of the invention]

BACKGROUND OF THE INVENTION It is widely practiced to inject gas through porous refractories for purposes such as refining molten metal.
Such porous refractories are generally molded from raw materials with relatively few fine particles by adjusting the particle size, or by interposing an organic substance and blowing it into the refractory using the dissipation pores. However, the former has disadvantages such as variations in pore diameter within the refractory, resulting in localized intrusion of molten metal or the creation of areas into which gas cannot be blown. Also, the latter one is, for example, JP-A-Sho.
As described in Japanese Patent Nos. 47 to 42531, it is difficult to mold the material so that the pores are specified at predetermined positions. In addition, the surface of porous refractories that comes into contact with molten metal needs to be porous, but it is preferable that the surface that comes into contact with supporting bricks etc. be dense in order to prevent gas leakage and to improve erosion resistance. In the past, the outer circumferential surface of the porous refractory was manufactured separately from a dense refractory and fitted into it. The present invention improves the inconvenient molding method for porous refractories and provides a method for easily manufacturing refractories for the intended purpose. The central part is made relatively porous or made porous by incorporating fibers. Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional view of a porous refractory for gas injection obtained by the method of the present invention, in which a mold corresponding to the refractory portion is prepared, and coarse-grained, medium-grained,
Water and/or a binder are added to a refractory raw material prepared using fine particles with an appropriate particle size, and the mold is rotated. As a result, a centrifugal force acts on the refractory raw material, and a relatively large number of coarse particles gather in the outer peripheral portion 1, making it dense. On the other hand, the central part 2 has a relatively large number of fine particles, so it is more porous than the outer peripheral part. Therefore, by attaching the gas introduction pipe 3 in the direction of the rotation axis as shown in FIG. 1, the injected gas is blown into the molten metal only through the central portion. Since the outer peripheral part 1 is dense, it naturally has high corrosion resistance, and the central part 2 is also protected from corrosion by molten metal by the gas blown into it, so this porous refractory is simply formed using centrifugal force. This means that a product with extremely high corrosion resistance can be obtained. In the figure, numeral 4 is an iron skin. In addition, when organic and/or inorganic fibers are blended into the refractory raw material in the present invention, since the fibrous material has a lower specific gravity than ordinary refractory raw materials, it gathers in the center in rotational molding using centrifugal force, and the fibers are concentrated in the center. The direction is also often aligned in the direction of the rotation axis. Therefore,
By firing this, pores become concentrated in the direction of travel of the injected gas,
The gas blowing effect is even better. During rotational molding, it is preferable that the refractory raw material and fibers are appropriately mixed, so in this case, by applying vibration to the mold during rotational molding, a porous refractory for gas injection with higher strength can be produced. Obtainable. Example 1 Sintered alumina 8-14# 10% Same as above 14-60# 30% Same as above 60-325# 15% Same as above 325#-15% Sintered mullite 7-35# 20% Fireclay 0.5mm or less 10 % Fishing line 0.5mm 1.5% (external ratio) Water was added to this mixture and poured into a mold. This mold was rotated at 700 to 900 revolutions per minute. The physical properties of this fired body were as shown in the table. Example 2 Seawater magnesia 2.38 to 1 mm 50% Same as above 1 mm to 325# 30% Same as above 325# to 20% Nylon fiber 0.2 mm 1.0% (external ratio) Pipe waste liquid was added to this mixture and cast into a mold. This mold was rotated at 700 to 900 revolutions per minute. The physical properties of this fired body were as shown in the table.

[Table] When a comparison test was conducted with a conventional product using a 50 ton ladle containing molten steel, the conventional product had 4 to 5 heats/piece, whereas the product of Example 1 had 10 to 12 heats/piece, and Example 2 Regarding the conventional product, it was 12 to 16 heats/piece compared to 6 to 9 heats/piece.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the porous refractory for gas injection according to the present invention. 1...Outer periphery, 2...Central part, 3...Gas introduction pipe, 4...Iron shell.

Claims (1)

[Scope of Claims] 1. A method for producing a porous refractory for gas injection, which comprises molding a mixture of a refractory raw material, water and/or a binder in a rotating mold, and firing the molded product. 2. The method for producing a porous refractory for gas injection according to claim 1, which comprises blending organic and/or inorganic fibers. 3 Claims 1 and 2, characterized in that molding is performed by applying vibration to a rotating mold.
A method for producing a porous refractory for gas blowing as described in 2.