JPH08188475A - High-alumina refractory - Google Patents

Abstract

PURPOSE: To reduce the cost of high-alumina refractory by recovering the less- contaminated part from a used high-alumina refractory article, crushing and sieving the recovered refractory and compounding with a powdery refractory component to form a monolithic refractory. CONSTITUTION: A porous plug having a truncated conical form and made of a high-alumina porous material is used in a steel-making process and taken out when the length of the plug is shortened to an unusable level. The tip 13 of the used truncated conical porous plug 1 is lost by melting and the adjoining part 12 is infiltrated with molten steel. A chisel is applied to the boundary between the infiltrated part 12 and the non-infiltrated part 11 and struck with a hammer to apply an impact force to the plug and the broken steel-infiltrated part 12 is removed to recover the non-contaminated high-alumina refractory. The recovered high-alumina refractory is crushed and the particle size is adjusted to obtain aggregate having a prescribed particle diameter. A monolithic refractory is produced by compounding the aggregate with refractory components such as alumina powder and mullite raw material and stirring the mixture.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to high alumina refractories used mainly in the field of steelmaking.

[0002]

2. Description of the Related Art Generally, a refractory having an Al ₂ O ₃ content of 55% (by weight) or more is called a high alumina refractory and is widely used in various fields of steelmaking. The amount of Al ₂ O ₃ varies depending on the required fire resistance, but the lining of the ladle is 85% or more, and the furnace porous plug for blowing inert gas is 87%.
The above high alumina contents are adopted.

Since alumina for refractory must have high purity, it is usually made of pulverized fused alumina. Although this material is expensive, currently used high-alumina refractory materials have no way to be reused as refractory materials.

[0004]

SUMMARY OF THE INVENTION The present invention was made with the intention of recycling used high-alumina refractory materials and reusing them as refractory materials. It is impure from such used refractory materials. Based on the discovery that high-purity raw materials can be obtained at low cost,
The purpose is to suppress the generation of industrial waste, to effectively use resources, and to reduce the cost of steelmaking.

[0005]

The high-alumina refractory material of the present invention is a powder-type refractory material obtained by recovering a portion of a used high-alumina refractory material with less pollution and crushing it to adjust the particle size. It is a high-alumina refractory that is blended with a material component to form an amorphous refractory, or is crushed and blended with a refractory component to form a fired or non-fired brick.

Among the high alumina refractories used,
The most convenient one is a used porous plug used for blowing an inert gas for stirring from the bottom of the furnace for steelmaking. This removes the molten steel infiltration part of the surface and uses the remainder.

It is also possible to use an lining brick of a molten steel ladle, and the remaining portion can be used by removing the portion which appears inside and is deteriorated by contact with molten steel or slag.

Further, the refractory used for the ceiling of the electric furnace and the tundish for continuous casting can also be used as a raw material as a used high-alumina refractory.

[0009]

[Function] When the inventors intended to recycle used high-alumina refractory materials, they found that the used porous plugs or used ladle bricks could be altered by the infiltration of molten steel or the reaction with slag. The rest of the removed material is of surprisingly good quality, and is not only competitive with new refractory raw materials, but also has a history of being sufficiently heated over a long period of time, so that no further thermal change will occur. It turned out to be an advantage. The problem is how to recover the good quality part with less labor and cost, but it turns out that this can also be unexpectedly convenient.

As is well known, a porous plug has a structure in which a gas supply pipe is attached to the bottom of a frustoconical porous high-alumina refractory and the periphery is surrounded by a dense high-alumina sleeve. are doing. With use, the top is melted and gradually shortened. When the porous plug (1) is taken out after shortening to a length that cannot be used, as shown in FIG. 1, there is a portion (12) infiltrated with molten steel over a certain thickness at the top of the porous plug (1). This portion can be easily cracked and removed from the uninfiltrated portion (11) by applying an impact. The code (1
3) shows the part lost by melting.

Similarly, as shown in FIG. 2, in the used ladle lining brick (2), the slag reaction portion (22) becomes an unaltered portion (21) after the melting damage portion (23) is left. It is in a row. Since there is a difference in expansion coefficient between the two, cracks are often formed almost along the boundary surface in the cold state. Therefore, it is possible to separate even with a comparatively small impact, and it is possible to recover the high alumina refractory material with a small amount of contamination in the contaminated portion.

By crushing or crushing the recovered high-alumina refractory material, and forming an amorphous refractory material by blending other refractory components, or by blending with other refractory components and molding (and optionally firing) Brick formation can be readily carried out according to techniques established in refractory manufacture using virgin raw materials.

[0013]

Example: 87% of Al ₂ O ₃ (% by weight, the same applies hereinafter), S
A porous plug using a high alumina porous body containing 8% of iO ₂ and 2% of CaO as main components was used for steelmaking. Porous plug part is frustoconical with bottom diameter of 150
mm, the diameter of the top is 100 mm, and the height is 250 mm. This was used for melting 3 times and then taken out.
It was reduced to 50-160 mm. Top thickness 10-20
Molten steel was infiltrated in the range of mm. By applying a chisel to the boundary with the uninfiltrated portion and hitting it with a hammer, the molten steel infiltrated portion was easily cracked and removed, and the unaltered high alumina refractory could be recovered.

The refractory material collected is crushed to obtain an average particle size of 1.0.
mm aggregate. This aggregate is 30% (weight), grain size 20
30% alumina powder of 0 mesh or less and 40% mullite raw material were blended and sufficiently stirred to obtain a high alumina castable refractory material.

When this castable refractory was used as a refractory for lining a tundish for continuous casting of steel, it exhibited the same durability as castables conventionally used.

[0016]

EFFECT OF THE INVENTION By recovering and reusing the high-alumina refractory material from the used high-alumina refractory material according to the present invention, a high-quality refractory material can be obtained at a low recovery cost and a virgin raw material is used. If you do, you can get the same results. As a result, it is possible to meet the demand for resource saving and cost reduction in the steelmaking industry.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a used porous plug.

FIG. 2 is a cross-sectional view showing an example of used refractory bricks.

[Explanation of symbols]

1 Used porous plug 11 Uninfiltrated part 12 Molten steel infiltrated part 13 Meltable part 2 Used refractory brick 21 Unaltered part 22 Altered part 23 Meltable part

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B22D 41/02 A C04B 35/00 35/101

Claims (4)

[Claims] 1. A non-constant refractory product is prepared by collecting a portion of a used high-alumina refractory product which is less contaminated and crushing it to adjust its particle size to a powder refractory component. Alternatively, a high-alumina refractory that is crushed and blended with a refractory component to form a fired or unfired brick. 2. The high-alumina refractory product according to claim 1, wherein the used high-alumina refractory product is a used porous plug which is used after removing the surface infiltrated with molten steel or slag. 3. The high-alumina refractory product according to claim 1, wherein the used high-alumina refractory product is a recovered brick of a molten steel ladle, and the altered portion is removed before use. 4. The high alumina refractory product according to claim 1, wherein the used high alumina refractory product is a used refractory product for an electric furnace ceiling or a tundish.