JPH02141480A - Castable refractory - Google Patents

Abstract

PURPOSE:To effectively inhibit the penetration of slag and to improve spalling and corrosion resistances by blending a specified refractory material with a binder. CONSTITUTION:100 pts.wt. refractory material consisting of 10-70wt.% spinel clinker (a) of <=3mm diameter consisting of 10-90wt.% Al2O3 and 90-10wt.% MgO, 20-80wt.% alumina clinker (b) of >=97% purity and <=5mm diameter and 5-15wt.% superfine powder component (c) consisting of 1 pt.wt. superfine alumina powder of <=1mum average particle size and 0.5-1.5 pts.wt. superfine silica powder of <=1mum average particle size is blended with 5-7 pts.wt. binder consisting of 1 pt.wt. alumina sol having 10-30% concn. of solid matter and 0.5-1.5 pts.wt. silica sol having 10-40% concn. of solid matter.

Description

DETAILED DESCRIPTION OF THE INVENTION In this specification, "%" and "parts" mean "% by weight" and "parts by weight," respectively.

BACKGROUND OF THE INVENTION In recent years, molten steel containers such as ladles and tundishes have been made into irregular shapes in order to save labor and energy. In the case of ladles, zircon-silica-based castable refractories are widely used as pouring materials, and alumina-based castable refractories are also used in some cases. However, with advances in steelmaking technology, advanced treatments such as vacuum degassing have come to be performed, and operating conditions are becoming more severe, such as increasing molten steel temperature and lengthening residence time. Under such severe conditions, zircon-silica-based castable refractories suffer from severe melting loss, and known alumina-based castable refractories suffer from metal adhesion.

On the other hand, there is a demand for higher quality steel, especially 5i
Since there is a need to prevent the contamination of 02, there is a need for basic castable refractories. In order to meet this demand, castable refractories based on magnesia have been attempted, but they have not been put into practical use because of their poor heat and structural spalling resistance.

Spinel castable refractories have also been proposed. For example, JP-A No. 60-60985 discloses a castable refractory containing spinel clinker as a main component and alumina cement as a binder;
Publication No. 23004 discloses a castable refractory using high alumina cement as a binder. However, these castable refractories lack denseness due to a large amount of added water, and are presumed to have poor corrosion resistance due to an increase in CaO due to the large amount of alumina cement used.

JP-A-60-60986 discloses a castable refractory in which at least one of vaporizable silica, amine silicate, and water-soluble aluminum phosphate is blended as a binder with an aggregate consisting of magnesia clinker, alumina clinker, and spinel clinker. are doing. This castable refractory has a small hot linear expansion and is excellent in heat spalling resistance, and is far superior in corrosion resistance compared to zircon castable refractories, and is also excellent in cleaning steel. However, this castable refractory cannot prevent the penetration of slag, and has the drawback of being susceptible to structural spalling.

Means for Solving the Problems In view of the problems of the prior art as described above, the inventor of the present invention has conducted various studies in order to make the most of the characteristics of spinel castable refractories. By combining this refractory material with a binder of a specific composition, we succeeded in obtaining a castable refractory that can suppress slag penetration.

That is, the present invention provides the following castable refractories: "A spinel castable refractory containing (a) 10 to 70% spinel clinker, (b) 20 to 80% alumina clinker, and (c) 1 part of ultrafine alumina powder and 0.5 to 1 part of ultrafine silica powder.
(d) 1 part of alumina sol and 0.0 parts of silica sol to 100 parts of a refractory material consisting of 5 to 15% of ultrafine powder components; 5-1.5
The spinel clinker used in the present invention is a castable refractory characterized by blending 5 to 7 parts of a binder component consisting of Aρ203
A wide composition range of 10 to 90% Mg and 90 to 10% Mg can be used.

Further, the manufacturing method thereof is not particularly limited, and both sintered spinel and fused spinel can be used. The amount of spinel clinker in the refractory material is 10-70
%. If the amount is less than 10%, the excellent effects based on the characteristics of spinel will not be fully exhibited.
The disadvantages of alumina castable are magnified. On the other hand, 7
If it exceeds 0%, a decrease in corrosion resistance and a decrease in the effect of preventing slag penetration are observed. The particle size of the spinel clinker is not particularly limited, but is usually about 3 mm or less. Particularly, from the viewpoint of suppressing slag penetration, it is preferable to use particles having a particle diameter of 74 μm or less that can form a matrix portion and account for 10% or more of the weight of the refractory material.

Both sintered alumina and fused alumina can be used as the alumina clinker. The purity of the alumina clinker is preferably 97% or more. The amount of alumina clinker in the refractory material is between 20 and 80
%. If the amount is less than 20%, melting loss and slag penetration will increase. On the other hand, 80%
If it exceeds this, a decrease in the slag penetration prevention effect is observed. The particle size of the alumina clinker is also not particularly limited, but is usually about 5 mm or less.

As the ultrafine alumina powder used in combination with the ultrafine silica powder in the present invention, calcined alumina with an average particle size of 1 μm or less is suitable. If the average particle diameter of the ultrafine alumina powder exceeds 1 μm, the fluidity will be insufficient and the reactivity with the ultrafine silica powder will also decrease. Ultrafine silica powder is a by-product of manufacturing ferrosilicon, silicone, etc. with an average particle size of 1 μm or less.
Silica flour" is preferred. However, silica flour may contain relatively many impurities such as Fe203, C5Na20, SO3 roots, and these impurities are
Because it reduces the fire resistance and fluidity of castable,
It is preferable to use one having a 5i02 content of 95% or more. When the average particle diameter of the ultrafine silica powder exceeds 1 μm, the fluidity tends to be insufficient and the reactivity with the ultrafine alumina powder tends to decrease. The blending ratio of ultrafine alumina powder and ultrafine silica powder is 1 part of the former to 0.5 to 1 part of the latter.
Approximately 5 copies. When the blending ratio of both ultrafine powders is within this range, the penetration of slag into the refractory is most effectively suppressed, and an appropriate residual expansion property is exhibited after firing at around 1500°C. That is, when the fired product was mineralogically analyzed, mullite was detected as the main component, and it is assumed that this was produced by a reaction between ultrafine alumina powder and ultrafine silica powder. It is considered that due to the formation of this mullite, the castable, which should originally exhibit residual shrinkage upon firing, now exhibits residual expandability.

When ultrafine alumina powder is present in excess, slag penetration increases, while when ultrafine silica powder is present in excess, corrosion resistance tends to decrease and residual shrinkage tends to increase. The amount of ultrafine powder components of ultrafine alumina powder and ultrafine silica powder in the refractory material is 5 to 15%. If the amount is less than 5%, sufficient fluidity cannot be imparted to the castable refractory, while if it exceeds 15%, shrinkage due to sintering becomes large.

In the present invention, alumina sol and silica sol are used in combination as the binder component of the above-mentioned fireproof material. There are no particular restrictions on the alumina sol and silica sol, and commercially available products can be used as they are. The solid content concentration of such alumina sol is usually about 10 to 30%, and the solid content concentration of silica sol is usually about 10 to 40%. The mixing ratio of alumina sol and silica sol (as solid content) is approximately 1 part of the former and 0.5 to 1.5 parts of the latter. The reason for specifying the blending ratio in this way is almost the same as the reason for specifying the blending ratio of ultrafine alumina powder and ultrafine silica powder in the ultrafine powder component.

The blending amount of the binder component per 100 parts of the fireproof material is:
The amount should be about 4 to 8 parts. If the amount of binder is less than 4 parts per 100 parts of refractory material, sufficient fluidity for pouring will not be obtained, whereas if it exceeds 8 parts, water floating, fine powder floating, etc. will occur after construction. , and a dense construction body cannot be obtained.

In addition, in the present invention, in order to accelerate hardening, alumina cement l-, silicates of alkali metals and alkaline earth metals, phosphates, etc. may be used within a range not exceeding 2% of the weight of the refractory material. I can do it. If the usage exceeds 2%,
It should be avoided as it reduces heat resistance.

Effects of the Invention According to the present invention, it is possible to obtain a castable refractory that effectively suppresses slag penetration and has excellent structural spalling resistance and corrosion resistance.

Moreover, since the castable refractory of the present invention has a low 5i02 content, it can also contribute to improving the quality of steel by suppressing the inclusion of SiO2.

EXAMPLES Examples and comparative examples are shown below to further clarify the features of the present invention.

Examples 1 to 3 and Comparative Examples 1 to 2 Castable refractories were obtained by blending raw materials in the proportions shown in Table 1.

Using the castable thus obtained, 40 fights
A sample was prepared by pouring it into a mold of 40 mm x 160 mm, and after firing at 1500°C for 3 hours, the characteristics of the fired body were measured. The results are shown in Table 2.

In addition, in the results shown in Table 2, the slag test and the heat-resistant spalling test were conducted as follows.

Slag test: Using a mixture of ordinary steel and converter slag = 1:1, a test was conducted at 1650° C. for 5 hours by a rotary method. Zircon castable refractory (Zircon 65
%) is set as 100, and is expressed as a relative value.

Heat resistance spalling property: Heating at 1350℃ for 15 minutes.
The results shown in Table 2, in which the 15-minute air cooling cycle was repeated and the number of cycles until peeling occurred, revealed the following facts.

The product of the present invention shows a positive linear change rate after firing at 1500°C, in other words, shows residual expansibility. On the other hand, the comparative example product has a negative linear change rate, in other words, it shows residual shrinkage.

The air permeability of the product of the present invention is lower than that of the comparative example product.

In the slag test, the corrosion loss ratio of the product of the present invention was lower than that of the comparative example product, and was less than half of that of the zircon castable refractory. Also, in terms of slag penetration rate,
The product of the present invention has a resistance comparable to that of zircon castable refractories, and is significantly lower than that of comparative example products.

Regarding heat spalling resistance, the product of the present invention has not yet experienced flaking after 20 cycles, whereas the comparative product has experienced flaking after 12 to 14 cycles.

Therefore, the castable refractory according to the present invention exhibits high durability as a pouring material for a ladle, etc., which is significantly superior to that of a zircon refractory.

(that's all)

Claims (1)

[Scope of Claims] 1. Spinel castable refractory containing (a) 10 to 70% spinel clinker, (b) 20 to 80% alumina clinker, and (c) 1 part of ultrafine alumina powder and 0.5 to 0.5 ultrafine silica powder. 1.
(d) 4 to 8 parts of a binder component consisting of 1 part of alumina sol and 0.5 to 1.5 parts of silica sol are blended into 100 parts of a refractory material consisting of 5 to 15% of an ultrafine powder component constituted by 5 parts of A castable refractory characterized by: