JPH0450178A - Ladle-lining carbon-containing amorphous refractories - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a monolithic refractory for lining a ladle with excellent durability, and particularly to a refractory suitable for pouring.

[Conventional technology]

Traditionally, monolithic refractories for ladle lining have been made of silica, rosite, chamotte, and high alumina.

Magnesia materials, lorite-zircon materials, etc. 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.As the molten steel temperature rises and the hot water resistance time is extended, the processing conditions for molten steel in the ladle have changed. The conditions are becoming more and more severe, and conventional materials are no longer able to meet the demands in terms of corrosion resistance, spalling resistance, volume stability, etc.

As a refractory that can be adapted to such harsh processing conditions,
Spinel-alumina monolithic refractories using spinel clinker and alumina clinker are disclosed in JP-A-60-60935, JP-A-64-87577, and the like.

This spinel-alumina monolithic refractory has the characteristics of spinel clinker, such as a small coefficient of thermal expansion,
Due to its high slag erosion resistance, it has excellent corrosion resistance, spalling resistance, and volume stability.
When applied to the lining of a ladle, it provides greater durability than conventional amorphous materials.

However, under recent operating conditions, spinel-alumina monolithic refractories, which are mainly composed of spinel and alumina raw materials, are not only prone to structural spalling due to slag infiltration, which has been seen in the past. However, this method has the disadvantage of increased slag infiltration and the so-called build-up phenomenon caused by this, which has resulted in the problem that stable operation of the ladle is hindered.

The build-up phenomenon referred to here often occurs when receiving aluminized steel using Aβ metal as a deoxidizing agent added to molten steel in a ladle lined with a spinel-alumina monolithic refractory. This is a phenomenon in which deoxidized products mainly consisting of .

If the product is not subjected to high-temperature stirring treatment, etc., the attached deoxidized product will not be removed and a build-up layer will grow, resulting in an operational 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 reducing corrosion resistance. .

[Means to solve the problem]

The monolithic refractory for ladle lining of the present invention is made of refractory aggregate 80-95 consisting of alumina linker and spinel clinker.
A mixture of 1 part by weight and 5 to 20 parts by weight of alumina cement
This problem was solved by blending 0.2 to 5 parts by weight of carbon raw material with respect to 0.00 parts by weight.

As the alumina linker used in the present invention, Aj!
20+ High purity and minimal impurities, for example,
Preferably, sintered alumina, fused alumina, or calcined alumina is used. In this respect, the natural alumina raw material contains a large amount of flux components, particularly 5102, which causes the formation of low-melting substances and inhibits the build-up suppressing effect of spinel-alumina amorphous large-sized products. Further, the spinel clinker should preferably have few impurities, and may be either sintered spinel or fused spinel, or a combination thereof.

Its composition is MgO・Aj! It is not limited to the theoretical composition of so*, and the MgO/ACOs weight ratio is from 0.5 to
It may be within the range of 0.05.

In the composition of the present invention, the ratio of alumina/spinel used is not particularly limited, but the corrosion resistance of the material,
It is determined from slag infiltration resistance, volume stability, etc., and the alumina/spinel weight ratio is preferably 33/67 to 85/15.

As the alumina cement used as the binder, commercially available high alumina cement or super high alumina cement, which has a low CaO content and good strength development properties, is suitable.

Various materials such as pitch powder, graphite, and coke can be used as carbon raw materials, but materials with low volatile content and no increase in construction moisture due to hydrophobicity, in other words, those with a structure,
It is best to choose one that does not deteriorate corrosion resistance. As such a material, a material containing 80% by weight or more of planar carbon and having self-sintering properties is particularly preferred. The particle size of the carbon raw material is not particularly limited, but from the viewpoint of uniform dispersion in the matrix, one particle size or less is preferable.

In addition, condensed alkali phosphate is used to improve workability.

Add dispersants such as sodium polycarboxylate, organic, inorganic, metal fibers, etc. to impart explosion resistance and suppress peeling, as well as alumina and spinel, either alone or in combination. You can also do that.

[Effect]

The present invention is based on the knowledge that it is effective to suppress the formation of a slag infiltrated layer that is integrated with deoxidized products in order to suppress the build-up phenomenon.

Carbon raw materials have the property of not being easily wetted by slag, have the function of suppressing slag infiltration and the so-called build-up phenomenon, and have a low volatile content, so there is no deterioration of the structure.
Furthermore, since it forms a strong carbon bond and has strong oxidation resistance, it has a strong effect of suppressing slag infiltration and can eliminate the build-up phenomenon. Further, by blending a carbon raw material containing 80% by weight or more of planar carbon and having self-sintering properties, the build-up suppressing effect can be enhanced without deteriorating corrosion resistance. however,
If the amount added is less than 0.2 parts by weight, the effect of suppressing slag infiltration will not be very noticeable, and if it exceeds 5 parts by weight, structural deterioration will occur due to an increase in added water.

In addition, during operation of alumina cement, the CaO component in the alumina cement reacts with the A j7203 component in the matrix, producing a compound called Ca0.6A14.03, which gives the material appropriate expandability, and bonding. In order to provide sufficient strength as an agent, it is necessary to use 5 parts by weight or more. On the other hand, if it exceeds 20 parts by weight, CaOAl2O5
MgOSiC,.

CaO-AAzO3-3io2 system or Ca0AR2
This is not preferable because the amount of 03-based low melting products produced increases.

〔Example〕

Table 1 shows the chemical composition of the raw materials used in the examples of the present invention.

Table 2 shows the characteristic values of the carbon raw materials used in the examples of the present invention.

A predetermined amount of water was added to the compositions shown in Table 1 and Table 3, and the mixture was kneaded and cast, and cured at 20° C. for 24 hours to obtain a cured sample. This cured sample was kept at 110° C. for 24 hours, and then fired at 15° C. for 3 hours, and its quality was then measured.

The corrosion resistance evaluation test was carried out using a high-frequency induction furnace lined with aluminum killed steel 1 converter slag and metal aluminum as an eroding agent.
Four cycles of 1 hour were repeated at 0°C, and the amount of erosion, slag infiltration, and build-up tendency were investigated. The results are summarized in Table 3. In the same table, the erosion index and slag infiltration index are 10
It is expressed as an index set to 0, and the smaller the value, the smaller the amount of erosion and slag infiltration.

From the same table, it can be seen that although conventional samples No. 7 and No. 7 without carbon additives exhibit build-up phenomenon, samples Nα1 to Nα6, which are examples of the present invention, show build-up without causing a significant decrease in corrosion resistance. This problem has been resolved and good results have been obtained. In particular, the effects of the present invention are remarkable when carbon raw materials with high areal carbon content and self-sintering properties are used.

Comparative samples No. 8, which contain a small amount of carbon raw material, have an insufficient build-up suppressing effect, and conversely, sample Nα9, which contains a large amount of carbon raw material, has a large decrease in corrosion resistance, which is not preferable.

Alumina cement) Sample Nα with l less than the range of the present invention
10, the strength development is insufficient and the amount of expansion is insufficient.

Further, Samples No. 11, in which the amount of alumina cement is larger than the range of the present invention, are unsuitable because they tend to oversinter and deteriorate corrosion resistance due to the increase in the amount of low-melting substances due to the large amount of CaO.

(Hereinafter, this page margin) [Effects of the Invention] The monolithic refractories of the present invention can provide the following effects.

(1) The build-up phenomenon, which was a drawback of ladles lined with spinel-alumina monolithic refractories, has been eliminated, allowing stable operation of the ladle.

(2) By restricting the use of carbon raw materials, it is possible to improve slag infiltration resistance without reducing corrosion resistance.

(3) As a result, peeling during operation is reduced and high durability is achieved.Representative of the patent applicant: Kurosaki Ceramics Co., Ltd. (and one other person)
Masu Kobori

Claims (2)

[Claims] 1. 80-95 parts by weight of fireproof aggregate consisting of alumina clinker and spinel clinker, 5-20 parts by weight of alumina cement
A carbon-containing ladle lining monolithic refractory obtained by adding 0.2 to 5 parts by weight of a carbon raw material to 100 parts by weight of a mixture consisting of parts by weight. 2. A carbon-containing ladle lining monolithic refractory, wherein the carbon raw material according to claim 1 has a surface area carbon of 80% by weight or more and has self-sintering properties.