JPH05117019A - Basic refractory brick - Google Patents

Abstract

PURPOSE:To give excellent corrosion resistance together with high hot strength without spoiling spalling resistance. CONSTITUTION:The basic refractory brick is made from a refractory raw material composed of 50-90wt.% high purity magnesia (MgO) clinker and 10-50wt.% spinel (MgO.Al2O3) clinker. To this refractory raw material, ultrafine powder alumina having <=6mum average particle size and being easily sintered is added by 1-3 outer wt.%.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a basic refractory brick used in, for example, a cement rotary kiln.

[0002]

2. Description of the Related Art Magnesia-chromic refractory bricks or basic refractory bricks such as magnesia-spinel refractory bricks are mainly used as refractories constituting the refractory surface of a cement rotary kiln. Among these, magnesia-spinel refractory bricks include high-purity magnesia clinker and spinel (MgO.Al) having different thermal expansion coefficients.
₂ O ₃ ) Clinker is mixed to generate microcracks between the magnesia particles of the high-purity magnesia clinker and the spinel particles of the spinel clinker during natural cooling from the firing step to room temperature. ing. Since these microcracks have the function of dispersing or absorbing the thermal stress generated during the temperature rise and cooling of bricks, there will be further demand in the future as a constituent material for refractory surfaces under operating conditions such as the cement rotary kiln, which is subject to particularly high thermal stress. Is increasing.

[0003]

However, since the magnesia-spinel refractory brick produces a low melting point substance during operation of the refractory surface and has a low hot strength, the magnesia-chromic refractory brick is On the other hand, it is easily corroded by molten cement and is inferior in corrosion resistance, and further improvement in durability is required.

The present invention has been proposed in view of the above conventional circumstances, and an object thereof is to provide a basic refractory having excellent corrosion resistance and high hot strength without impairing spalling resistance. Is to

[0005]

In order to achieve the above object, the present invention adopts the following means. That is, 50-
90% by weight of high-purity magnesia clinker and 10-5
In a basic refractory brick blended with 0% by weight of spinel clinker as a refractory raw material, the refractory raw material is coated with ultrafine alumina powder having an average particle size of 6 μm or less and easily sinterable. Basic refractory brick added by 3 wt%.

[0006]

In the above-mentioned structure, by adding not the completely sintered product but the temporarily sintered ultrafine alumina powder, the brick structure can be made more dense without damaging the microcracks generated in the structure. Therefore, corrosion resistance and hot strength can be improved.

The amount of the ultrafine alumina added is preferably 1 to 3% by weight based on the raw material of the refractory material, and if it is less than 1% by weight, sufficient corrosion resistance cannot be imparted.
On the other hand, when the content is 3% by weight or more, the effect of improving the spalling resistance due to the microcracks decreases and the coefficient of thermal expansion of the brick itself increases, which is not preferable. Also, it is desirable that the average particle size of this ultrafine alumina be 6 μm or less,
If the particle size is larger than 6 μm, it will not be dispersed in the tissue,
The effect of improving the corrosion resistance due to the addition of the ultrafine alumina cannot be obtained.

As the magnesia clinker used in the present invention, a high-purity product having a magnesia component of 95% or more is used, and as the spinel clinker, a commercially available one can be used, and one having few impurities is preferable. In that case, the blending amount of the magnesia clinker and the spinel clinker is in the range of 10/90 to 50/50% by weight defined by the conventionally known magnesia-spinel refractory brick.

[0009]

EXAMPLES Hereinafter, one example of the present invention will be described in comparison with a comparative example having a conventional composition.

Table 1 shows the chemical composition of each refractory material used in the examples according to the present invention and the conventional comparative examples, and each of the raw materials shown in Table 1 is mixed in the proportion shown in the upper column of Table 2. After kneading, the kneaded product is molded by a friction press, and
After drying at 0 ° C. for 24 hours, it was baked at 1800 ° C. for 17 hours. The physical properties of the obtained brick are shown in the lower column of Table 2.

It can be confirmed that the hot strength and corrosion resistance of the examples according to the present invention are remarkably improved as compared with the comparative examples, and the spalling resistance is comparable to the comparative examples. Table 1
In the spalling resistance test described in 1., the procedure of heating at 1200 ° C. for 15 minutes, cooling in water for 5 minutes, and then allowing to cool at room temperature for 10 minutes is one cycle. The loss index is SiO ₂ = 20%,
React with cement slag having a composition of Al ₂ O ₃ = 16%, MgO = 2%, CaO = 56% at 1500 ° C. for 5 hours,
It was represented by a relative index with the erosion amount of the comparative example as 100.

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

As described above, according to the present invention, the hot strength and the corrosion resistance can be improved without impairing the excellent spalling resistance, and in particular, the fire resistance with a high thermal stress such as in the cement rotary kiln. It is possible to provide a basic refractory brick exhibiting excellent durability as a refractory brick suitable for a surface.

Continuation of the front page (72) Inventor Koichiro Urakami 2 at 1576, Higashi-oki, Nakahiro, Ako-shi 2 Kawasaki Furnace Co., Ltd.

Claims (1)

[Claims] 1. A basic refractory brick used as a raw material for refractory material by blending 50 to 90% by weight of high-purity magnesia (MgO) clinker and 10 to 50% by weight of spinel (MgO.Al ₂ O ₃ ) clinker. In the above, a basic refractory brick is obtained by adding 1 to 3 wt% of superfine alumina powder having an average particle diameter of 6 μm or less and easily sinterable to the above-mentioned refractory material.