JP2003254673A - METHOD OF MANUFACTURING ALUMINA CASTABLE USING COATED MgO-C BRICK - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem of hydration and thermal decomposition which are induced by infiltration of moisture in the air inside a constant MgO-C brick which is a reinforcement material of an alumina castable refractory product used for melting metal so as to generate methane gas and vapor, to cause cracks, and to inhibit durability. <P>SOLUTION: A manufacturing method is developed for preventing moisture from infiltrating into the inside by applying and coating waterproof coating and glaze on a constant MgO-C brick, which is a reinforcement. Thus, this invention gives effects for preventing cracks of the constant MgO-C bricks and elongating a life of the refractory by applying waterproof coating. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention applies a coating treatment of a typical MgO-C brick as a reinforcing material used for melting a metal, to thereby produce a refractory material by the generated methane gas or steam pressure in a refractory material. The present invention relates to a manufacturing method for the purpose of extending the life of a refractory by suppressing cracks and tissue collapse of the refractory.

[0002]

2. Description of the Related Art In recent years, as the mass production of steel has become higher grade, vacuum refining method mainly for degassing and decarbonization, especially RH degassing method,
The DH degassing method is generally adopted and many apparatuses using alumina castable are used.

An example of a conventional product using alumina castables is a lance pipe as a means for blowing a carrier gas or an inert gas to adjust the product quality during melting of metal. There are various types of lance pipes in consideration of the purpose of use, conditions of use, etc., and endless research has been conducted on durability. Therefore, a conventional manufacturing method will be described by taking a lance pipe as an example.

As shown in the block diagram of FIG. 2, when the lance pipe 10 is manufactured, the alumina castable 3 is made of alumina or alumina-magnesia by taking measures against corrosion resistance against molten metal, spalling resistance and high densification. A wide variety of products have been developed depending on the application, such as a system, an alumina-carbon system, and an alumina-chromium system.

However, even with these alumina castables 3, wear due to molten steel flow, spalling due to thermal cycling,
There are many problems such as damage and loss due to joint intrusion of slag,
The appropriate life extension measures for the lance pipe 10 have not yet been reached.

Therefore, referring to FIG. 2, by arranging the standard MgO-C bricks 4 on the lance pipe 10, the melting loss due to slag-in is solved, the deformation of the iron core 1 supporting the lance pipe 10 is suppressed, and A method has been devised that seeks an effect as a measure to suppress omissions. However, the effect is still insufficient and alumina castable 3 and standard MgO-C brick 4
Due to the difference in thermal conductivity and thermal expansion coefficient between the two materials, the joints between the two materials expanded and the damage was increased. As a countermeasure against this, an uneven array and a reinforcing stud 2 are being added to cope with this.

In another method, it has been considered to cast it into the alumina castable 3 as a reinforcing ring of a standard MgO-C brick 4. In this method, a reinforcing ring of a standard MgO-C brick 4 is inserted and fixed between the iron core 1 and the reinforcing stud 2 in the process of manufacturing the lance pipe 10,
In this method, the castable alumina 3 is poured into a molding mold for molding.

By embedding the iron core 1 with the same idea as the reinforcement, the influence from the external environment such as slag is protected, and the alumina castable 3 and the standard MgO-C brick 4 are used.
Slag-in measures have been taken by eliminating the joints to be bonded with, and life-saving measures have been taken due to the reinforcing effect.

[0009]

However, the hydration reaction of aluminum carbide newly produced from the carbon-containing refractory during the production by this method becomes a serious problem. Explaining the problem with reference to FIG. 3, the standard MgO-C brick 4a, which is a carbon-containing refractory, is added with Al metal in order to improve oxidation resistance and hot strength. This added Al
The metal reacts with carbon at about 700 ° C or higher during heating and Al ₄
Generate C ₃ (not shown).

This Al ₄ C ₃ reacts with water vapor in the air when the refractory material is cooled to room temperature to form a hydrated form of MgO.
-C Generate in brick. In FIG. 3, α indicates the intrusion direction of water. Further, upon reheating, the compound aluminum hydroxide decomposes to generate water vapor 8. Specifically, it is expressed by the following formulas 1 and 2.

[0011]

[Chemical 1] (S) represents a solid state and (g) represents a gas state.

[Chemical 2] (S) represents a solid state and (g) represents a gas state.

In the typical MgO-C brick 4a, the gasified methane gas 7 and water vapor 8 expand with this reaction, causing cracks 9 in the typical MgO-C brick 4a and causing the typical MgO to break.
-C brick leads to the collapse of 4a.

Further, it is considered that moisture in the air is likely to penetrate into the typical MgO-C brick 4 in the non-firing process in the drying treatment at about 300 ° C. or less, and water also penetrates during castable casting work. Therefore, it is considered that the hydration reaction of Al ₄ C ₃ and the thermal decomposition of the compound easily occur. The water penetration direction in this case is represented by a direction β.

Therefore, it is desired to develop a method in which moisture cannot easily penetrate into the standard MgO-C bricks and further improve the durability.

[0015]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and its gist is to provide an alumina castable refractory product used for melting a metal. , Reinforcement standard MgO-C
The brick is coated with water-resistant paint or glaze on the surface, embedded in a mold for refractory products, and cast with alumina castable to prevent moisture from entering the standard MgO-C brick. And a method for producing an alumina castable using a coated MgO-C brick, which is characterized by preventing the generation of methane gas or water vapor generated by a hydration reaction or thermal decomposition to maintain durability. Further, the present invention relates to a method for producing an alumina castable using a coated MgO-C brick, which is produced by using a non-fired fixed-form MgO-C brick obtained by performing a drying treatment at about 250 ° C. Manufactured using heat-reduced and standardized MgO-C bricks obtained by heat treatment at about 1400 ° C. or lower. M subjected to the coating, characterized
The present invention relates to a method for producing castable alumina using gO-C bricks.

[0016]

The present invention will be described in detail with reference to the drawings of the embodiments.

(Example) FIG. 2 of a block diagram shows a general manufacturing process of an example lance pipe. Generally, a lance pipe is a powder injection lance that injects a treatment agent for the purpose of de-Si, de-P, de-S, etc. into molten steel and hot metal together with a carrier gas, and a gas blow lance that injects an inert gas for temperature control of molten steel and uniform components. and so on.

FIG. 1 shows a longitudinal section of a lance pipe 10 according to an embodiment of the present invention, which is used as a reference embedding position for the coated MgO-C brick 4 of the present invention.
The product length and thickness of gO-C brick 4 are for reference and are not determined in this figure. The lance pipe 10 is manufactured according to the performance by pouring the alumina castable 3 whose shape and raw material are adjusted to each purpose into a casting mold, and therefore, a general manufacturing method will be described in this figure.

In FIG. 1, the slag surface 6 of the lance pipe
The vicinity is usually made with a diameter of about 400 mm, and the iron core 1 is used as a reinforcing material over about 7,000 mm of the total length, and V-shaped reinforcing studs 2 are arranged in each main part for casting and fixing the alumina castable 3. It FIG. 1 shows a cross section of the lance pipe near the slag molten metal surface 6.

As shown in FIG. 2, in a separate step, a standard MgO-
C brick 4 is a hollow pipe (usually about 340 to 380 mm x φ
220 to 270 mm) and dried at about 250 ° C. to produce unfired standard MgO—C brick 4. Here, the steps of the coating treatment 5 of the present invention will be described.

This coating treatment 5 is a standard MgO-
C to brick 4 in air or to alumina castable 3
Block the entry of moisture into the standard MgO-C brick 4
Al _FourC₃To prevent the hydration reaction of and its thermal decomposition
It is conceivable to apply a water resistant paint with the above. Water resistant coating
Dye or brush on the surface of standard MgO-C brick 4
Applying water to the surface will prevent water from entering from the outside.
A coating process 5 can be performed to prevent this.

In addition, the typical MgO-C brick 4 is about 140
Apply water-resistant paint to the surface of standard MgO-C bricks 4 by dipping or brushing the product in the process of reduction baking at 0 ° C or less, and further perform coating treatment to prevent water from entering the surface. Can be done.

Furthermore, the type of coating is not limited to water-resistant paint, and a coating treatment for preventing water intrusion is possible even if a glaze is applied to the surface and baked for a certain period of time.

As shown in FIG. 1, a standard MgO-C brick 4 coated with a coating treatment 5 was inserted into a lance pipe molding mold, installed at a predetermined position, and then an alumina castable 3 was flowed thereinto to form a standard MgO-C brick 4. To be buried. After that, the castable 3 is dried and the quality is checked to complete the product of the lance pipe.

Although the lance pipe, which is an alumina castable product using a typical MgO-C brick, has been described above as an example, all alumina castable products using a typical MgO-C brick are also coated. A typical MgO-C brick can be used.

[0026]

EFFECTS OF THE INVENTION By applying a water resistant coating to a typical MgO-C brick according to the present invention, the hydration reaction of Al ₄ C ₃ contained in the typical MgO-C brick and the thermal decomposition of its compound are prevented. , A standard Mg by preventing cracks
This increases the durability of the OC brick and extends the life of the lance pipe.

The present invention can be said to be an excellent method for reinforcing alumina castables in which a life prolonging effect can be expected by easily coating a standard MgO-C brick without using a complicated device.

[Brief description of drawings]

FIG. 1 is a reference cross-sectional view in which a coated refractory brick is embedded in an intermediate portion of a lance pipe according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a manufacturing process of a lance pipe in which a coated refractory brick is embedded in an intermediate portion of the lance pipe according to the embodiment of the present invention.

FIG. 3 is a reference cross-sectional view in which a normal refractory brick is embedded in the middle portion of a conventional lance pipe.

[Explanation of symbols]

1 iron core 1a iron core 2 Reinforcement stud 2a Reinforcement stud 3 Alumina castable 3a Alumina castable 4 Standard MgO-C brick 4a Standard MgO-C brick 5 coating treatment 6 slag surface 7 Methane gas 8 water vapor 9 cracks 10 Lance pipe 10a Lance pipe α direction β direction

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shinichi Goto             3-1 Ohatacho, Tajimi City, Gifu Prefecture Tokyo Ceramic Industry Co., Ltd.             Inside the company (72) Inventor Hiroyasu Tomimatsu             3-1 Ohatacho, Tajimi City, Gifu Prefecture Tokyo Ceramic Industry Co., Ltd.             Inside the company (72) Inventor Takafumi Imaeda             3-1 Ohatacho, Tajimi City, Gifu Prefecture Tokyo Ceramic Industry Co., Ltd.             Inside the company F-term (reference) 4K051 EA02 FA08 GA01 GA05 LC00

Claims (3)

[Claims] 1. A standard Mg reinforcing material in an alumina castable refractory product used to melt metals.
O-C bricks are coated with a water-resistant paint or glaze on the surface of the bricks, then embedded in a mold for refractory products and cast into alumina castables to remove moisture from the standard MgO-C bricks. To stop the intrusion,
A method for producing alumina castables using a coated MgO-C brick, which is characterized by preventing the generation of methane gas or water vapor generated by hydration or thermal decomposition and extending the life. 2. The coated Mg according to claim 1, which is produced by using a non-fired standard MgO-C brick obtained by drying at about 250 ° C.
A method for producing alumina castables using OC bricks. 3. The coated MgO-C brick as claimed in claim 1, which is manufactured by using a reduced-sized typical MgO-C brick obtained by heat treatment at about 1400 ° C. or lower. Alumina castable manufacturing method.