JPH06172020A - Magnesia component-containing refractory material - Google Patents

Abstract

PURPOSE:To produce a magnesia component-containing refractory material, useful as a lining of a vessel for steel manufacture or refining of a molten metal, capable of inhibiting generation of heat by a reaction between an added powdery metal and water in a binder and suitable for a high resistant refractory material. CONSTITUTION:This refractory material is obtained by blending a raw material composed of magnesia and chromia or magnesia and alumina, a powdery ferrochrome or aluminum having <=100mum particle diameter and a resin as a binder, e.g. a phenol resin, a furan resin or a silicone resin low in water content and containing about 60wt.% nonvolatile components and about 20wt.% fixed carbon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refractory material suitable as a lining material for steelmaking furnaces, refining vessels and the like.

[0002]

2. Description of the Related Art As a lining for a steelmaking container, it has been conventionally used as a base material mainly containing magnesia because of its durability and steel quality under severe conditions such as long-term contact with slag or molten steel flow at high temperature. Refractory materials are widely used.

However, in recent years, as seen in the secondary refining process, the durability of the lining refractory is extended by extending the treatment time and raising the treatment temperature in steel refining, and further by stirring the molten steel by gas blowing and refining the flux. Is declining.

As the refractory material for secondary refining, a refractory material having improved durability is magkuroren disclosed in JP-A-62-207757. This is to improve the corrosion resistance of magnesia, which is the main component of magnesia brick, while improving the slag infiltrating property, which is a disadvantage, by adding chromia such as chrome ore and metallic chromium powder to impart durability. There is.

However, even with the use of magro bricks, durability under recent severe operating conditions is becoming a problem. In particular, slag infiltration cannot be completely suppressed, and wear of refractories progresses due to deterioration of the structure and structural spalling.

In order to solve this problem, Japanese Patent Laid-Open No. 2-1
No. 41465, Japanese Patent Application Laid-Open No. 3-54160, Japanese Patent Application Laid-Open No. 3-228866, Japanese Patent Application No. 3-48191, etc., discloses a maguro refractory material containing a metal powder such as ferrochrome or aluminum. ing.

By molding this refractory material and firing it at a high temperature, it is possible to obtain a dense magcro brick having excellent slag infiltration resistance. This is because the compounded metal powder oxidizes during firing and reacts with the surrounding magnesia to generate a large amount of secondary spinels such as magnesiochromite, picromchromite, and common spinel, which expands in volume and fills the pores. This is to make it more compact.

However, such a metal powder sometimes reacts easily with water to form a hydrate. That is, when a binder, a so-called binder containing a large amount of water is used, hydration occurs during kneading and heat is generated, resulting in an extremely high compounding temperature. This accelerates the change in the composition of the composition with time, resulting in a decrease in the filling property, that is, a decrease in the bulk specific gravity of the base material, which impairs the effect of improving the densification and slag infiltration resistance by adding the metal powder to the magro brick. For this reason, using the bitter or molasses aqueous solution that is usually used as the binder of the magro mix may not be able to bring out the inherent properties of this refractory material.

[0009]

DISCLOSURE OF THE INVENTION An object of the present invention is to add a binder as a binder when a raw material mainly containing magnesia and chromia or magnesia and alumina is mixed with metal powder. It is intended to solve the problem of characteristic deterioration over time due to heat generation due to the reaction between the water content and the metal powder, and to enable stable supply of a refractory material containing a highly durable magnesia component.

[0010]

[Means for Solving the Problems] In order to achieve this object, a binder having a low water content was examined, and it was found that the use of a resin was effective. It is characterized in that a raw material containing at least one of chromia and alumina as a main component is mixed with a ferrochrome or aluminum powder having a particle diameter of 100 μm or less and a resin as a binder.

Ferrochrome or aluminum powder may be used as the metal powder in an amount of 1 to 40% by weight.

Further, the particle size of the metal powder needs to be 100 μm or less in order to secure a specific surface area, to stably cause oxidation and reaction from a lower temperature, and to secure dispersibility.

As the raw material containing unidirectional magnesia and chromia, or magnesia and alumina, any raw materials used for general magnesia-containing refractories can be used.
That is, if the magnesia has a purity of 95% or more, both a sintered product and an electromelted product can be used. Mug is M
The total content of gO and Cr ₂ O ₃ is 70% by weight or more, and both sintered products and electromelted products can be used. Chromium ore is C
It can be used as long as the total amount of r ₂ O ₃ and MgO is 40% by weight or more. The spinel has a total content of MgO and Al ₂ O ₃ of 90% by weight or more, and either a sintered product or an electromelted product can be used. Chromium oxide having a purity of 90% by weight or more and a particle size of 100 μm or less can be used. Further, the kneading, forming and firing steps may be carried out by methods similar to those used for producing conventional magro bricks.

The resin as the binder may be the one usually used for magnesia carbon brick or alumina carbon brick. That is, a non-volatile content of about 60% by weight and a fixed carbon content of about 20% by weight such as a phenol resin, a furan resin, or a silicone resin can be used.

The refractory material of the present invention can be applied to unfired refractory materials and amorphous refractory materials. That is, an unfired refractory can be obtained by omitting the firing step, and an amorphous refractory can be obtained by omitting the molding step. When these are actually used in various kilns, they utilize the heat that they generate to oxidize the metal powder and generate a large amount of secondary spinel through the reaction with magnesia, which leads to pore expansion and densification due to volume expansion. To be

[0016]

When the resin cures, it generates a maximum of about 20% of water due to the condensation reaction, but originally contains almost no water. Unlike the case of bitter or molasses aqueous solution containing 50 to 70% of water, even if a resin is used as a binder, heat generation due to hydration of metal powder does not occur during kneading. Therefore, it is possible to sufficiently bring out the densification and the improvement of the slag infiltration resistance by the addition of the metal powder without the drying due to the change of the composition with time.

[0017]

[Examples] Table 1 is a comparison of physical properties and corrosion resistance when phenol resin and bitter juice were used as binders of magro bricks containing various metal powders, in order to investigate the effect when the resin was used as a binder. Is.

[0018]

[Table 1] As the sample, various raw materials containing magnesia and chromia as main components were mixed with an appropriate amount of ferrochrome or aluminum powder, kneaded with phenol resin or bittern as a binder, molded, dried, and then baked at a maximum temperature of 1850 ° C. . The metal powders used each had a particle size of 74 μm or less, the ferrochrome had a chromium content of 70% by weight, and the aluminum powder had an aluminum content of 98% by weight.

As a method of evaluating the corrosion resistance, a lining erosion test using a high frequency induction furnace was adopted. The test method is as follows. The brick was cut into strips and lined inside the induction furnace to melt ordinary steel and hold it at 1700 ° C. After that, the slag synthesized by mixing the reagents was charged to erode the brick. The composition of the slag is 55:45 CaO and SiO ₂ . Four
After holding for a while, the slag and molten steel were discharged, and after cooling, the brick sample was collected. This sample was cut to measure the remaining thickness of the maximum wear portion, and the wear amount was calculated by subtracting it from the original size measured in advance, and the wear index was calculated with 100 when bitter juice was used as the binder. The smaller the wear index, the better the corrosion resistance.

Regarding the general physical properties, when a phenolic resin is used, since there is no change with time due to an increase in the compounding temperature, the bulk specific gravity of the base material is high, the porosity is low and the hot strength is high.
Corrosion resistance is also about 30% better than when bitter juice is used.

Example 1 of Table 1 and Comparative Example 6 of magro brick according to the present invention were used by being attached to the side wall of the lower tank of the RH furnace. As a result, in the residual thickness at the time of stopping the furnace, Example l is Comparative Example 6
It was about 25% more prominent than Further this Example l
Was completely used on the side wall of the lower tank of the RH furnace. as a result,
The number of treatments in the RH lower tank is improved by 25% compared to the conventional one,
Significant life extension was achieved.

[0022]

By using the brick according to the present invention as a lining material for a kiln for refining and holding molten metal,
It has become possible to greatly extend the life of various kilns.
Therefore, it can be concluded that the present invention has a great industrial effect and is extremely important.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kiyoshi Goto 20-1 Shintomi, Futtsu, Chiba Shin Nippon Steel Co., Ltd. Technology Development Division (72) Inventor Akio Ishii 20-1 Shintomi, Futtsu, Chiba Shin-Nihon Steel Engineering Co., Ltd.

Claims (1)

[Claims] 1. A particle size of 100 μm is added to a raw material containing magnesia and at least one of chromia and alumina as a main component.
A refractory material containing the following ferrochrome or aluminum powder and a magnesia component mixed with a resin as a binder.