JPH01203276A - Castable refractories - Google Patents

Abstract

PURPOSE:To provide the title refractories which are easy to apply, have volumetric stability at the time of use and are capable of widening the application range to various applications by compounding metallurgical slag powder, etc., which contain an alkali metal component, B component and F component respectively at prescribed ratios and are modified to a specific basicity as a binder with refractory aggregate. CONSTITUTION:The metallurgical slag which contains the alkali metal component at 0.05-3wt.% as Li2O, K2O or Na2O, the B component at 0.1-5wt.% as B2O3, and the F component at 0-10wt.% as F and is modified to 1.5-5 basicity and the refractory superfine powder are prepd. as the binder. Silica flower, superfine alumina powder, etc., are used as the above-mentioned refractory superfine powder. The desired castable refractories are obtd. by compounding the above-mentioned binder with the refractory aggregate such as sintered alumina. The applied body obtd. by using said refractories is prepd. in a short period of time without requiring a special consideration for a drying treatment and heating treatment which are the pretreatment at the time of using the castable refractories applied body.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to the application of modified slag cement to castable refractories.

[Prior Art] For example, castable refractories contain 70 to 90% by weight of refractory aggregate (for example, fused alumina, sintered alumina, bauxite, andalusite, mullite, chamotte, yanite, silica, spinel, magnesia, etc.). It contains 10 to 30% by weight of alumina cement. This castable refractory is poured into various furnaces, applied by spraying and troweling, dried, heated, and put into practical use.

In addition, in recent years, ultrafine powder (e.g. silica flour,
Some products contain 2.5 to 4.0% by weight of ultrafine alumina powder, clay, etc., and are further mixed with a deflocculant.
However, this low-cement castable has high filling properties, low porosity, and low air permeability, and therefore explodes due to water vapor during heat treatment before use. Addition of metallic aluminum (
JP-A-54-3B2O) and addition of fiber raw materials (JP-A-61-44772).

[Problem to be solved by the invention] Castable refractories, unlike refractory bricks, are a single piece, are easy to construct, have volumetric stability during use, and are excellent refractories, and as the range of applications expands. Can be done. However, castables using alumina cement are hardened using the hydraulic properties of alumina cement during construction (6-10 hydrate). It is necessary to remove adhering water and crystallized water from alumina cement. However, when the crystallization water of alumina cement is evaporated, the strength deteriorates at 500 to 1000°C, resulting in volumetric instability, which may cause cracks or peeling. In particular, lower porosity (lower air permeability)
In low-cement castables, the vapor pressure inside the castables increases and there is a risk of explosive destruction.

As a measure to prevent this explosion, it has become common to add metal aluminum and heat it from the inside as described above, but this is extremely dangerous as the aluminum and water react to generate hydrogen gas. Another method is to add fiber raw materials to increase air permeability and make it easier for water vapor generated inside to escape, but this method has the disadvantages of increasing porosity, lowering corrosion resistance, and being expensive.

Therefore, the object of the present invention is to prevent conventional castable refractories from cracking, peeling, or even causing explosion failure if the work is not done carefully over a long period of time after construction, curing, and heating at operating temperatures. It's about solving shortcomings.

[Means for Solving the Problems] As a result of intensive research to solve the problems caused by drying and rapid heating after construction, which are the drawbacks of conventional castable refractories using alumina cement, the present inventors have developed an alternative to alumina cement. Modified steel slag cement (patent application 1986-312)
It has been discovered that a good castable refractory can be obtained by using the method (Japanese Patent Publication No. 481), and the present invention has been completed.

That is, in the present invention, the alkali metal component is 0.05 to 3% by weight as R2O (in the formula, R represents Li, K or Na).
, the boron component is added to B2O. As a binder, metallurgical slag powder and refractory ultrafine powder modified to have a basicity of 1.5 to 5 containing 0.1 to 5% by weight of F and 0 to 10% of fluorine component as F are used as a binder. To provide a castable refractory characterized by being blended with a refractory aggregate as a castable refractory.

[Function] The castable refractory of the present invention uses a binder mainly composed of modified metallurgical slag powder, which will be detailed below, instead of alumina cement, which is a binder for conventional castable refractories. .

This modified metallurgical slag powder has an alkali metal component of 0.05 to 3% by weight as R2O (in the formula, R represents Li, K or Na) and a boron component of 0.05% by weight as B2O.
1 to 5% by weight and 0 to 10% by weight with fluorine component as F
The metallurgical slag powder has a basicity (CaO/S io 2 weight ratio) of 1.5 to 5.

Such modified slag powder is produced by adding alkali metals and boron components to the slag components during the production of alloys such as stainless steel and ferrochrome, or by adding alkali metals and boron components to the slag components, or by adding alkali metals and boron components to conventional slag. It is remelted and modified, and after cooling, it is made into a powder.

In the present invention, B2O. A crystalline powder of steelmaking slag or ferroalloy slag containing 0.3 to 10% by weight of Bffi and 3 to 10% by weight of F is suitable.

The particle size of such modified slag powder is not particularly limited, but in many cases it is 1,500 to 8,000 cm in plain specific surface area.
7 g, preferably in the range of 2000 to 6000 cI12/lF.

Such modified slag powder has excellent hydraulic properties with a small amount of water,
Furthermore, unlike ordinary cements such as alumina cement and Portland cement, there is no strength deterioration even when the hardened product is heated, and it has excellent heat resistance, making it ideal as a binder for castable refractories.

Therefore, in the present invention, this is hereinafter defined as modified slag cement.

As mentioned above, modified slag cement has the characteristic properties of being hydraulic and heat resistant, unlike conventional cement, but in the present invention, a refractory fine powder is used as an auxiliary agent. Since the physical properties such as strength of the castable refractory can be improved by the above method, the present invention is characterized in that the binder is blended with such fine powder.

Refractory ultrafine powders include activated silica, alumina ultrafine powder,
Ultra-fine powder refers to clay, etc., and ultra-fine powder is a relative term to the particle size of refractory aggregate, and refers to a finer powder than the finest part of the refractory aggregate, but in many cases, it is finer than the average particle size of modified slag cement. It also has a fine particle size distribution.

Among these, activated silica is particularly suitable.

Here, activated silica refers to a silica raw material that causes a neutralization reaction, so-called hozolan reaction, with basic components such as calcium in modified slag powder in the presence of water. Examples include flower, humid silica, silica sol, activated clay, etc.
In particular, ultrafine silica powder such as ferrosilicon dust and fumed silica is suitable.

The composition of these two components varies depending on the physical properties of the binder and the type of refractory aggregate, but in most cases, the refractory ultrafine powder is in the range of 5 to 50 parts by weight per 100 parts by weight of modified slag cement. Preferably it is in the range of 7 to 30 parts by weight.

The amount of binder added to the refractory aggregate is 1 to 30% by weight, and when added to low cement castable refractories, it is preferably 1 to 10% by weight.The reason for this is that the modified slag cement has 2 Ca Since O-3i is mainly composed of O2, it cannot be added in large amounts to alumina-based castable refractories.
In addition, since it is used as a nokuingu, 30% by weight is considered to be the upper limit from the viewpoint of fire resistance. On the other hand, if the amount of addition/blending is less than 1% by weight, the effect of addition cannot be obtained.

Examples of refractory aggregates include fused alumina, sintered alumina,
Bauxite, andalusite, mullite, chamotte, kyanite, silica, spinel, magnesia, aluminide, silicon carbide, etc. can be used.

Further, as the refractory ultrafine powder, silica flour, alumina ultrafine powder, clay, etc. can be used.

The addition and blending amount of the refractory ultrafine powder is 1 to 7% by weight.

In addition, when using the castable refractory according to the present invention, in addition to the above-mentioned components, conventional components such as a deflocculant such as a phosphate salt can be appropriately added and blended.

The castable refractories of the present invention having the above-mentioned composition can be made to have the same properties as conventional castable refractories by adding and kneading 5 to 40 parts by weight, preferably 6 to 25 parts by weight, of water per 100 parts by weight of the binder. A constructed body can be obtained using the construction method. The obtained construction body does not deteriorate in strength during heating, does not exhibit abnormal expansion or contraction, and is extremely stable in terms of volume.

Therefore, it is suitable for furnaces and structures that use thermal cycles with significant temperature changes between heating and cooling, and is also suitable for use as castables for rocket launch pads, etc., for example.

[Examples] The castable refractories of the present invention will be further explained below with reference to Examples.

Example 1: Castable refractories (products of the present invention and conventional products) having the composition shown in Table 1 below are poured into a formwork, and a 230×114
A construction body having a shape of 65 mm was obtained.

The product of the present invention had the same fluidity as the conventional product and could be cured in the same manner.

The various properties of the obtained construction body are also listed in Table 1.

1st - 11th Bag - (Blended double weight %) In Table 1, the composition of the modified slag cement is as shown below, and the silica flour is ferrosilicon dust manufactured by Yakushima Electric Co., Ltd.

[-9 wt% CaO46, l 5in, 16.8 AlzOs 14.6 Mg0 10.7 Fe, 0. 2.2 Cr2O2 2. IF 6.8B2O.
0.5 N ago 0 , 2 From Table 1, 5
After firing at 00°C and 800°C, a slight increase in porosity was observed in the products of the present invention, but it was found that there was little decrease in strength.

The hot linear expansion curves (0 to 1000°C) of both constructed bodies are shown in Figure 1.The constructed bodies of the present invention do not exhibit abnormal expansion or contraction like fired bricks, and do not exhibit abnormal expansion or contraction when heated or cooled. There was no green change. On the other hand, the conventional product contracted as the temperature rose, and further contracted when cooled.

Next, form a plate of 300 x 300 x 10 mm, and
After drying at 92°C, an experiment was conducted in which one side was heated with a flame of 1300°C or higher for 10 minutes, and then cooled. The plate using the conventional product had many cracks and its strength deteriorated, but the plate using the product of the present invention showed no change at all.

Furthermore, when a glaze was sprayed on a board using the product of the present invention by putting it in a flame, foaming occurred while the glaze was melting. From this, it was confirmed that steam was coming out from the plate, but
It was confirmed that rapid heating can also be tolerated.

Contribution 11 Using the castable refractories shown in Table 2 below (products of the present invention and conventional products), briquettes of 160 x 160 x 40++a were left, dried at 105°C, and then heated to 1000°C in advance and placed in a furnace. No change was observed in the briquettes using the product of the present invention, but the briquettes using the conventional product peeled off due to water vapor and several cracks were observed.

When the air permeability of the samples after drying was measured, a large difference was observed.The water vapor generated in the briquettes using the product of the present invention easily escapes to the outside, which is thought to be the reason why no tissue destruction occurs.

Daiichi No-Daichi (Blended double weight %) The composition of the modified slag cement used in this example is as follows.

Bo-ichibuichi Weight % CaO51.5 Mg0 7.5 S i 0218, 1 A1.0. 15.5 N a2O 0 , IBzOz
0.4 F 5.8 % iJL expenditure Castable refractories (products of the present invention and conventional products) having the compositions listed in Table 3 below are used as blasting material for pig gutters to maintain the inside of the furnace at various temperatures. The spraying was carried out, and the situation of explosion and peeling of the castable refractories after spraying was investigated.

As a result, the conventional product did not explode at furnace temperatures up to 300°C, but it did explode at higher furnace temperatures; the inventive product did not explode at furnace temperatures up to 500°C. The product of the present invention also had excellent properties as a hot spray material.

Table 3 (Composition: Weight %) 0 In the table, "outside" represents outside.

■The same modified slag cement as in Example 1 was used.

[Effect of the invention] The construction body obtained using the castable refractory of the present invention does not require special consideration for drying treatment and heat treatment, which are pre-treatments when using the castable refractory construction body, and can be carried out in a short period of time. be able to.

Furthermore, since the modified slag cement used in the castable refractories of the present invention is a secondary product using steelmaking slag, it is advantageous in terms of cost compared to conventional castable refractories using alumina cement or the like as a binder. .

[Brief explanation of the drawing]

Figure 1 shows the hot linear expansion curves (0 to 10
00℃). Patent applicant Nihon Kagaku Kogyo Co., Ltd.

Claims (5)

[Claims] 1. The alkali metal component is R_2O (in the formula, R is Li, K
basicity 1.05 to 3% by weight as Na), 0.1 to 5% by weight as B_2O_3 as a boron component, and 0 to 10% as F as a fluorine component.
1. A castable refractory, characterized in that a metallurgical slag powder modified to have a composition of 5 to 5 and a refractory ultrafine powder are blended with a refractory aggregate as a binder. 2. The castable refractory according to claim 1, wherein the modified metallurgical slag powder is a steelmaking slag powder such as stainless steel. 3. The castable refractory according to claim 1, wherein the ultrafine refractory powder is activated silica powder. 4. The binder has a plain specific surface area value of 1500 to 800.
The castable refractory according to claim 1, which has a composition of 5 to 50% by weight of ultrafine refractory powder per 100 parts by weight of modified metallurgical powder of 0 cm^2/g. 5. 70 to 99% by weight of refractory aggregate, 0.05 to 8% by weight of an alkali metal component as R_2O (in the formula, R represents Li, K or Na), and 0.1 to 5% by weight of a boron component as B_2O_3. and metallurgical slag powder (A) and refractory ultrafine powder (B) modified to have a basicity of 1.5 to 5 and containing 0 to 10% by weight of fluorine component F.
However, the castable refractory is characterized in that the binder (B) is present in a proportion of 1 to 30 parts by weight per 100 parts by weight of (A).