JPH0483765A - Unfixed refractory - Google Patents

Abstract

PURPOSE:To obtain the title refractory having excellent spalling resistance and slag impregnation resistance and capable of preventing build up phenomenon by using a specific clinker as a refractory aggregate. CONSTITUTION:The aimed amorphous refractory constituted by using a clinker containing 1-<10wt.% CaO and consisting substantially of corundum and CaO-Al2O3 based compound as a refractory aggregate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a monolithic refractory with excellent durability and suitable as a cast refractory.

[Conventional technology]

Hitherto, as monolithic refractories for pouring into ladle linings, silica, loite, chamotte, high alumina, magnesia, loite-zircon, and the like have been used.

In recent years, improvements in vacuum degassing, continuous casting, and ladle refining technology have led to the refining of high-grade steels, and processing conditions have become increasingly harsh due to increases in molten steel temperature and longer hot-water times. Therefore, conventional materials are no longer adequate in terms of corrosion resistance, spalling resistance, volume stability, etc.

For this reason, Japanese Patent Laid-Open No. 60-60985 discloses a spinel-alumina monolithic refractory that uses spinel clinker and alumina clinker from the viewpoint of materials as a refractory that can be adapted to such severe processing conditions.

It is disclosed in Japanese Patent Application Laid-Open No. 64-87577.

This spinel-alumina monolithic refractory has excellent corrosion resistance, spalling resistance, and volume stability due to the spinel clinker's small coefficient of thermal expansion and high slag erosion resistance, making it highly durable. It made it possible to have sex.

However, with the recent diversification of operating conditions, spinel-alumina monolithic refractories, which are mainly composed of spinel and alumina raw materials, are experiencing structural spalling due to slag infiltration, which has been seen in the past. In addition, depending on the operating conditions, there has been a problem in that slag infiltration increases and a so-called build-up phenomenon occurs due to this, which hinders stable operation of the ladle.

The build-up phenomenon referred to here is a phenomenon that often occurs when receiving aluminium-killed steel using metal A1 as a deoxidizing agent added to molten steel in a ladle lined with spinel-alumina monolithic refractories. This is a phenomenon in which deoxidized products, mainly consisting of If the molten steel is not subjected to high-temperature stirring treatment, etc., the adhered deoxidation products will not be removed, and a build-up layer will grow, resulting in an industrial problem of insufficient ladle capacity.

[Problem to be solved by the invention]

The present invention eliminates the drawbacks of conventional spinel-alumina monolithic refractories, and provides a ladle-lined monolithic refractory that eliminates the build-up phenomenon without significantly reducing corrosion resistance. It is.

[Means to solve the problem]

The characteristics of the monolithic refractory of the present invention are that it contains 1% by weight or more and less than 10% by weight of CaO, and contains substantially frundum and CaO.
The reason is that a clinker consisting of -Ai+203 type compound is blended as a refractory aggregate.

Examples of alumina materials that can be used as refractory aggregates with the above clinker include electro-fused or sintered alumina.

Sintered or calcined products of activated alumina, electrofused or synthetic mullite, and bauxites are used as magnesia materials, such as seawater maghon aclinker. Electrofused magnesia clinker,
Magnesite ore and its sintered or electrofused products can be used, and as the spinel material, electrofused or sintered spinel clinker can be used.

Moreover, the above-mentioned monolithic refractory is constituted by containing auxiliary raw materials such as a binder, finely powdered silica, clay, and carbon raw materials in addition to the above-mentioned refractory aggregate.

As the binder, colloidal silica, vaporizable silica, amorphous silica such as gel silica, hydraulic cement such as alumina cement and Portland cement, and inorganic binders such as aluminum phosphate and orthophosphoric acid can be used.

Furthermore, the present invention uses dispersants such as alkali condensed phosphates and sodium polycarboxylate for work adjustment within a range that does not impede the effects of the present invention, and organic, inorganic, metal, etc. for imparting explosion resistance and suppressing peeling. It is also possible to add fibers, alumina coarse particles, and spinel coarse particles singly or in combination.

[Effect]

The present invention was completed based on the knowledge that it is effective to suppress the build-up phenomenon by suppressing the formation of a slag infiltration layer that is integrated with the deoxidized product.

Clinker, which is essentially composed of corundum and CaO-A I2Os-based compounds, has a higher CaO content than conventional alumina cement, so the amount of erosion caused by slag is greater, but on the other hand, slag infiltration is reduced, resulting in so-called It has the function of suppressing build-up phenomenon.

The above clinker has a content of (AA203+CaO) of 9
It contains 5% by weight or more and consists of corundum and CaOARz○3 type compounds as the main constituent mineral phases.

Minerals other than those listed above 1, for example β-A120. , mullite,
Although it may contain periclase, etc., the amount thereof is small and does not impede the effects of the present invention, and there is no problem as a clinker consisting essentially of the above-mentioned main constituent mineral phase.

In addition, CaO-Δf,03 type compound is CaO・6Aj
! 200. CaO'ALO3,12CaO-7A! ,
03. Ca 0 ・2 Al2O2 or CaO and A1. A non-stoichiometric compound consisting of o3 (hereinafter (A1゜Ca
)O)) etc.

FIG. 1 shows a three-component phase equilibrium diagram of CaO, AA203, and AA5102. , the larger the amount of CaO, the more CaO・Af20
312cao ・7 Generation of low melting point components such as AA and 03, or SiO which is an infiltrated component from ladle slag
Due to the reaction with 2, a rapid decrease in the eutectic point temperature is observed. Therefore, when a composition with a high CaO content is applied, erosion due to slag increases, the material exhibits a property of being easily eroded, and the formation of a slag infiltration layer is reduced and leveled.

However, when the CaO content in the fine powder region is increased, the difference in corrosion resistance between the aggregate and the fine powder region becomes significantly large, resulting in a significant decrease in corrosion resistance, resulting in a so-called matrix-first erosion form.

The present invention utilizes substantially corundum and C with high CaO content.
By using clinker made of aOARz○3 type compound as a refractory aggregate, the above-mentioned drawbacks can be suppressed, and the erosion loss can be balanced between the aggregate and the fine powder region, and the erosion loss can proceed appropriately to prevent the slag infiltration layer. This makes it possible to suppress the formation.

If the CaO content in the clinker, which consists essentially of corundum and CaO-ACCL-based compounds, is less than 1% by weight, the material containing this clinker will not be able to achieve adequate melting loss, and will not be effective in suppressing the formation of a slag infiltrated layer. poor.

On the other hand, if the CaO content is 10% by weight or more, unreacted CaO remains in the clinker and a digestion phenomenon occurs, making it unusable. Alternatively, the amount of low melting substances in the clinker becomes excessive, impairing the heat resistance of the clinker itself, and significantly reducing the corrosion resistance of the material.

〔Example〕

Hereinafter, the effects of the present invention will be specifically explained using Examples.

Table 1 shows the physical properties of the clinker consisting essentially of corundum and CaOAfaCL compounds used as the refractory aggregate in the monolithic refractory of the present invention, and the physical properties of conventional commercially available alumina cement and spinel clinker. show.

Table 2 shows the effects when alumina cement is used as a binder for the monolithic refractory of the present invention.

After adding a predetermined amount of water to the monolithic refractories listed in the same table and kneading them, the refractories were molded into a size of 40 mm x 40 mm x 160 mm. After curing for 24 hours at 20℃,
After drying at 110°C for 24 hours, the quality was measured after baking at 1500°C for 3 hours. Furthermore, the corrosion resistance and build-up suppressing effect were tested as follows.

A high-frequency induction furnace is lined with aluminum killed steel, converter slag, and metal aluminum as corrosive agents at 1650℃.

The amount of erosion loss and the amount of slag infiltration were measured by repeating 4 cycles with 1 hour as one cycle, and the amount of erosion loss and the amount of slag infiltration were expressed as an index with Comparative Example 2 as 100.

The smaller the value, the smaller the amount of erosion and slag infiltration. Furthermore, regarding the buildup suppressing effect, the cut surface of the above corrosion resistance evaluation sample was observed to determine the presence or absence of a buildup layer in the steel bath section.

From the same table, Examples 1 to 7 in which clinker consisting essentially of corundum and CaOAf203-based compounds were used as the refractory aggregate suppressed the formation of a slag infiltrated layer without showing significant deterioration in corrosion resistance, and the build-up phenomenon It can be seen that the expression of

In addition, Comparative Example 4.5 in the same table describes the effect of increasing the amount of alumina cement II and adding carbonate in fine powder to increase the CaO content in the refractory. It is unsuitable because there are concerns that corrosion resistance will deteriorate due to an increase in low-melting substances in the area, and spalling resistance will deteriorate due to improper sintering. Furthermore, with regard to carbonates, corrosion resistance significantly deteriorated, clearly demonstrating the superiority of the product of the present invention.

Table 3 shows the effects when amorphous silica is used as a binder for the amorphous refractory of the present invention.

Furthermore, Table 4 shows the effects when colloidal silica is used as a binder for the monolithic refractory of the present invention.

From these Table 3.4, it can be seen that the products of the present invention are significantly superior in the build-up suppressing effect compared to the conventional products.

Table 5 shows an example in which Example 2, which is an example of the present invention, was put to practical use.

As shown in the table, it was possible to suppress the build-up phenomenon, prevent a decrease in the capacity of the t1 ladle, and significantly increase the amount of steel received compared to Comparative Example 2. Furthermore, since the deterioration in corrosion resistance was slight, the ladle life did not decrease and stable operation was possible.

Table 5 [Effects of the Invention] The monolithic refractories of the present invention can provide the following effects.

[1] Since it contains clinker consisting essentially of corundum and CaO-AfzCL-based compounds as a refractory aggregate, it has the ability to alleviate thermal stress as a refractory structure due to its softening effect, and has excellent resistance. Spalling property is obtained.

(2) Substantially corundum and Ca OA flx Os
By using a clinker consisting of a system compound,
It is possible to improve slag infiltration resistance without reducing corrosion resistance, and it is possible to reduce peeling during operation.

[3] When the monolithic refractory of the present invention is used for lining a ladle, it is possible to eliminate the build-up phenomenon that was a drawback of ladles lined with alumina or spinel-alumina monolithic refractories. , stable operation of the ladle is possible.

[Brief explanation of drawings]

Figure 1 shows CaO and Aj! It is a figure which shows the phase equilibrium phase diagram of a 3-component system of z03 and 5103.

Claims (1)

[Claims] A monolithic refractory made of a clinker containing 1.1% by weight or more and less than 10% by weight of CaO and consisting essentially of corundum and a CaO-Al_2O_3-based compound as a refractory aggregate.