JPH068224B2 - Cement-free amorphous refractory raw material and method for producing cement-free amorphous refractory using this raw material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a cement-free amorphous refractory material, and is applied to refractory materials such as cupola, induction furnace, rotary kiln, etc. in the field of steel, casting, etc. It

(Prior Art) Amorphous refractories using alumina cermet as a binder are widely used in industries such as steel, cement, castings and pulp.

The castable refractory is a mixture of silica-alumina aggregate and alumina cement, and is generally SiO ₂ -A.
1 ₂ O ₃ —CaO composition (Japanese Patent Laid-Open No. 53-84).
No. 012).

Recently, alumina cement contained in castable refractories is often used in a low amount due to the following various reasons.

This is to obtain a high strength construction body. When the cement content is low, the amount of kneading water at the time of construction can be reduced, and the refractory material constructed by the kneading performed at a low water content has high strength.

This is for shortening the drying time of the kneaded product. If the cement content is high, the amount of water in the kneaded product used increases, and it takes time for the kneaded product to dry and exhibit strength.

This is to increase the content of alumina in the refractory. Castable refractories have a higher service temperature as the content of Al ₂ O ₃ increases, so high-purity alumina containing more alumina than alumina semet should be used as the aggregate and the amount of alumina cement should be reduced. Can increase the alumina content in the entire refractory.

This is because cracks do not occur in the fired product. Alumina cement forms a low melting point compound at high temperatures and may cause cracks in the fired product.

Further, in low cement castable refractories, by adjusting the particle size of the ultrafine powder added to the aggregate of the refractory, or by adjusting the compounding ratio of the binder consisting of alumina cement, ultrafine powder, dispersant, etc. It is known that the refractory material is made into a dense refractory material by making it into a cement and reducing the water content.

(Problems to be Solved by the Invention) However, in the conventional low cement castable refractories, the main component CaO of cement is anorthite (C
Since a low melting point compound such as aO.Al ₂ O ₃ .2SiO ₂ ) is generated, there is a problem that the fire resistance is lowered at a use temperature exceeding 1500 ° C. and the corrosion resistance against molten slag is lowered. In order to improve the fire resistance and corrosion resistance, there is one using hydraulic alumina or the like as a curing agent or a coagulant in place of the alumina cement, but in this case also, the fire resistance and corrosion resistance are insufficient, Moreover, the workability such as fluidity and curability and the strength are insufficient.

The present invention has been made in order to solve this general problem, does not contain cement, and improves the corrosion resistance and chemical resistance to chemical erosion by molten metal, molten slag, etc. The purpose is to provide an amorphous refractory material.

(Means for Solving the Problem) Therefore, the cement-free amorphous refractory raw material according to the first aspect of the present invention comprises 60 wt% or more of a refractory material composed of aggregate, intermediate particles and fine powder, silica and alumina. 2-20w of one or more of magnesia or chromite
t% and the average particle size contained in this ultrafine powder is 3 to 15 μm.
It is characterized by adding 0.2 wt% or less of a dispersant to a refractory composition composed of 2 to 10 wt% of hydraulic alumina of m.

The method for producing a cement-free amorphous refractory according to the second aspect of the present invention is constructed by adding 3 to 6 wt% of water to the cement-free amorphous refractory raw material according to the first aspect. Characterize.

The refractory material is composed of aggregates, intermediate particles, and fine powders, and is a main component in the raw material ratio. For example, bauxite, chamotte, high-purity alumina, zircon, chromia, etc. are preferably used alone or in combination. . In particular, it is desirable to mainly use, for example, fused alumina or sintered alumina at a site where heat resistance, wear resistance and corrosion resistance are required.

No cement is included in the refractory composition. This is because, when a binder such as alumina cement is included, the amount of added water required during construction increases and the average porosity of the dried product after construction increases, etc., causing low fire resistance and low hot strength. Because.

As the ultrafine powder, it is desirable to mainly use powder having a particle size of 0.3 to 6 μm. This powder fills the pores and capillaries in the refractory, thereby reducing the average pore diameter and making the refractory highly dense. The reason why the addition amount of the ultrafine powder is 2 wt% or more is that the effect is small when it is less than this value, and the amount of 20 wt% or less is that the fluidity at the time of construction is deteriorated and the filling property is deteriorated when the value exceeds this value. This is because

Hydraulic alumina contained in the ultrafine particles has an average particle size of 3 to 1
The ultrafine powder contains 2 to 10 wt%. Hydraulic alumina generates heat due to hydration during construction. Therefore, the content of hydraulic alumina is 2 wt.
% Or more is necessary to increase the curability at the time of construction, and 10 wt% or less is to improve the fluidity at the time of construction.

As the dispersant, it is desirable to use a metal chelate compound, an alkali metal carbonate or the like. This dispersant promotes the dispersing effect of the base refractory composition and improves the workability such as fluidity and curability. If the amount of the dispersant exceeds 0.2 wt%, it will be difficult to cure during drying after construction, so the amount will be within a certain range.

When using the cement-free amorphous refractory raw material,
On the other hand, it is desirable to add water in the range of 3 to 6 wt%. This is because when the amount of water added is 3 wt% or more, fluidity is secured, and when it is 6 wt% or less, it solidifies and secures strength during drying after construction.

(Example) Hereinafter, the Example of this invention is described.

84 wt% refractory material consisting of aggregate, intermediate particles and fine powder,
A mixed powder of 16% by weight of ultrafine powder was used.

The refractory material is mainly composed of alumina and silica, and as a result of chemical analysis, Al ₂ O ₃ : 64 wt%, SiO ₂ : 31 wt
%, TiO ₂ : 2 wt%, Na ² O, etc .: 3 wt%.

The ultrafine powder contains alumina and silica at 24 wt% and 75 w, respectively.
It contained 5% and 7 wt% of other minor components.

Then, hydraulic alumina was contained in 16 wt% of ultrafine powder in a predetermined wt% shown in Table 1.

A refractory composition composed of these powders was added with a predetermined% of a dispersant composed of a carbo-chelate soda salt, and 4 wt% of water was added to the total amount thereof, and the construction was carried out.

In this case, as shown in Table 1, the contents of hydraulic alumina and dispersant were changed, and the workability and corrosion resistance were tested for various Examples 1-7 and Comparative Examples 1-5.
The results are shown in Table 1.

In Table 1, the wt% of hydraulic alumina indicates the weight ratio to the total amount of the refractory material consisting of aggregate, intermediate particles and fine powder and ultrafine powder, and the same applies to the dispersant. First
In the table, ⊚ indicates a particularly good one, ○ indicates a good one, Δ indicates a normal one, and x indicates a poor one.

As a result of the test, in Examples 1 to 7, the flowability and curability of the refractory raw material were good, and the corrosion resistance after drying was also relatively good.

On the other hand, Comparative Examples 1 to 3 could not be applied due to excessive or excessive hydraulic alumina, and Comparative Examples 4 and 5 could not be applied due to excessive or insufficient dispersant. Therefore, in any of Comparative Examples 1 to 5, the corrosion resistance could not be evaluated.

(Effects of the Invention) As described above, according to the cement-free amorphous refractory raw material of the present invention, it is possible to prevent the formation of a low melting point compound by not containing cement and to appropriately combine hydraulic alumina and a dispersant. Thereby, there is an effect that hot properties such as corrosion resistance, fire resistance and high temperature strength can be improved, and workability such as fluidity and hardening property can be surely enhanced.

Claims (2)

[Claims] 1. A refractory material 60 composed of aggregate, intermediate particles and fine powder.
2% to 20% by weight of ultrafine powder composed of one or more kinds of silica, alumina, magnesia or chromite, and 2 to 10% by weight of hydraulic alumina having an average particle size of 3 to 15 μm contained in the ultrafine powder. A cement-free amorphous refractory raw material, characterized in that a dispersant of 0.2 wt% or less is added to a refractory composition consisting of. 2. A method for producing a cement-free amorphous refractory, which is constructed by adding 3 to 6 wt% of water to the cement-free amorphous refractory raw material according to claim 1.