JP3126003B2 - Sprayed refractory - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an amorphous refractory used for lining various kilns in the steelmaking industry.

[0002]

2. Description of the Related Art Conventionally, spray repair has been mainly performed to repair locally damaged portions of linings of various kilns in the steelmaking industry sector. However, adhesion of sprayed refractories to linings of kilns has been performed. In consideration of the properties, basic spray refractories such as magnesia-dolomite, magnesia and dolomite using a binder such as phosphate and sodium silicate have been used. However, these sprayed refractories have insufficient hot strength, causing the sprayed refractories to fall off after spraying repair, the slag resistance of the sprayed refractories to be inferior, and the spray repaired parts to be melted down. there were. Although a basic spray refractory using alumina cement as a binder is used, the adhesive strength between the spray refractory and the lining of the kiln wall was low, and the spray refractory was easily peeled off from the lining, resulting in poor durability. On the other hand, an alumina-spinel sprayed refractory using alumina cement as a binder has poor workability and has not been used as a sprayed refractory.

[0003]

The conventional spray refractories are:
Since the above-mentioned binder was used, there was a defect that the adhesive strength with the lining of the kiln wall was insufficient, the slag resistance was poor, the durability was poor, and the workability was poor. . On the other hand, it has been found that by finding the optimum binder and curing agent, a sprayed refractory having excellent durability and high adhesive strength can be obtained.

[0004]

Means for Solving the Problems The present inventors have earnestly studied to obtain the optimum binder and curing agent, and have obtained the following findings. During the alumina-spinel castable table test, if a silica sol is mixed with the alumina-spinel castable base material to which a very small amount of magnesia ultrafine powder is added, it hardens within a few minutes and is used as a normal castable. I discovered that I could not do it. That is, SiO ₂ spheres (diameter mμ order) in silica sol in a metastable state, suspended in water, surrounded by its electric double layer,
Is a substance in which the electric double layer is destroyed by Mg ⁺² ions generated by the partial dissolution of magnesia ultra-fine powder in water, SiO ₂ globules begin to associate with water, and finally form a hydrogel (solid) state It is estimated to be. That is, a sol-gel reaction is caused by the silica sol and the magnesia ultrafine powder, and the refractory base material is hardened using this reaction.

[0005] The present inventors utilize this mechanism,
By using an alumina clinker and a spinel clinker as base materials and adding magnesia ultrafine powder and silica sol, a spray refractory which does not use a binder and a curing agent as in the prior art can be invented.

That is, the present invention provides an alumina clinker of 6
0 to 90 wt% and 10 to 40 wt% of spinel clinker
In% compounded preform, relative to the magnesia ultrafine said preform
The 0.05 to 1.0% and SiO ₂ in outer percentage Te 15
Silica sol containing about 25 wt% to the base material
It is a sprayed refractory characterized in that it is added in an amount of 6 to 8% by weight.

[0007]

The alumina clinker used in the present invention is a commercially available alumina clinker having an alumina content of 90% by weight or more.
Use As the spinel clinker used in the present invention, a commercially available high-purity spinel having a magnesia content of 20 to 30% by weight is used. The particle size and composition of the alumina clinker and the spinel clinker are as follows.
30 to 50 wt% of coarse particles of 3 mm and 3
0-40wt%, and fine powder of 0.074mm or less
30 wt% is blended. When the silica sol is less than 6%, the curing of the sprayed refractory is delayed, and when it exceeds 8%, the curing is accelerated too much. When the magnesia ultrafine powder is less than 0.05%, the solidification reaction of the silica sol is delayed, and when it exceeds 1.0%, excessive magnesia ultrafine powder remains in the silica sol solidification reaction. Next, the production and spraying method of the sprayed refractory of the present invention will be described. First, an alumina clinker and a spinel clinker and magnesia ultrafine powder were mixed with an Erich mixer.
The powder mixture mixed by the above is pneumatically fed to the spray nozzle of the spray gun, while the silica sol solution is pumped up and sent to the spray nozzle, and the sprayed refractory mixed in the spray nozzle is sprayed on the workpiece. .

[0008]

EXAMPLES Table 1 shows the composition of the raw materials, the workability of each sample, and the curing time of the samples of Examples and Comparative Examples of the sprayed refractory of the present invention. Each sample shown in Table 1 was weighed by 2 kg at a time, and after kneading for 3 minutes with a universal mixer, the workability and curing time of the sample were measured. From this table, it can be seen that the hardening time is drastically shortened only when ultra-fine magnesia powder is added to the raw material composition, and can be used as a sprayed refractory.

[0009]

[Table 1]

[0010]

EFFECTS OF THE INVENTION Magnesia ultrafine powder and silica sol solution are used as a curing agent for a base material of alumina-spinel amorphous refractory which could not be used as a sprayed refractory because of poor workability and long curing time. By adding C, it became possible to use it as a sprayed refractory. As a result of using this sprayed refractory in a molten steel ladle, the life of the molten steel ladle was extended, and the basic unit and unit cost of the refractory were reduced.

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C04B 35/66

Claims (1)

(57) [Claims] 1. A base material containing 60 to 90% by weight of alumina clinker and 10 to 40% by weight of spinel clinker, and ultrafine magnesia powder is applied to the base material in an amount of 0.1%.
A silica sol containing 0.5 to 1.0 wt% and 15 to 25 wt% of SiO ₂ is externally applied to the base material by ₆ to 8 wt%.
% Sprayed refractory characterized by adding