JPH06263527A - Alumina refractory - Google Patents

Abstract

PURPOSE:To prevent occurrence of thermal spalling of refractory consisting essentially of an alumina material and structural spalling caused by slag permeation and to suppress damage to refractory such as crack resulting from it. CONSTITUTION:Alumina refractory comprises 0.1-20wt.% calculated as ZnO of zinc oxide and the rest of a refractory material consisting essentially of alumina.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refractory material mainly composed of an alumina material, which is used for various molten metal containers such as a hot metal ladle, a mixing pig, a steel ladle and a tundish.

[0002]

2. Description of the Related Art In recent years, refractory linings of molten metal containers such as ladles are mainly refractory mainly composed of rock from alumina mainly refractory from the viewpoint of slag corrosion resistance as operating temperature rises. The material is changing. Further, magnesia carbon brick has also been used from the viewpoint of the corrosion resistance of the molten metal container at high temperatures.

[0003]

However, when a magnesia carbon brick is used in a molten metal container, the magnesia carbon brick has a high thermal conductivity, so that the temperature of molten steel or hot metal tends to decrease. In the melting of low carbon steel, alumina-based refractory materials are often used because of concern about carbon penetration. Alumina refractory with Cr ₂ O ₃ added is also considered.
_{The addition of the 2} O ₃ component has a small effect of preventing the penetration of low-viscosity slag, and the chromium component is also problematic from the environmental aspect. Therefore, there is a demand for a refractory having improved corrosion resistance and sponging resistance among alumina refractories.

[0004]

DISCLOSURE OF THE INVENTION As a result of studying the improvement of corrosion resistance and spalling resistance of alumina-based refractory materials, the present inventors have found that zinc oxide is a solid solution in alumina and has a special low melting point. The inventors arrived at the present invention by paying attention to the fact that no compound is produced. That is, the present invention is an alumina refractory material containing zinc oxide as ZnO in an amount of 0.1 to 20% by weight, and the balance being a refractory material mainly containing alumina. Further, the refractory material of the present invention has a feature that it can be used in any form such as a fired or non-fired fixed shape refractory material or an amorphous refractory material.

Alumina-based refractory materials used in the present invention are alumina-based, alumina-silica-based, magnesia.
Various clinker of alumina spinel type can be used alone or in combination. In these refractory materials, Al ₂ O ₃ is preferably 50% by weight or more from the viewpoint of slag corrosion resistance. In addition to these, it is possible to use various commonly used refractory materials in combination.

The zinc oxide which is a feature of the present invention is
ZnO, Zn ₂ O, ZnO _{2 and the} like are known, and any form of zinc oxide can be used in the present invention.
Zinc oxide containing nO as a main component is generally used. The amount of ZnO is 0.1 to 20% by weight in the refractory, preferably 1
~ 10% by weight. When the amount of zinc oxide is less than 0.1% by weight, the effect of spooling resistance is not sufficiently exerted, and when it exceeds 20% by weight, refractory causes oversintering during use to cause spooling. Corrosion resistance is also reduced, which is not preferable. In the present invention, as the zinc oxide, zinc hydroxide, zinc carbonate, zinc nitrate, zinc sulfate, zinc chloride, zinc acetate, zinc oxalate, or the like, which changes into zinc oxide during firing or use, can also be used.

The method for producing an alumina refractory material of the present invention comprises:
When used as a standard refractory, a refractory material mainly containing alumina, zinc oxide, and other raw materials are weighed, a binder is added, and the mixture is kneaded and press-molded according to a conventional method. This can be used as it is or after being heat-treated at a temperature of 1000 ° C. or lower to be used as a non-fired brick, or can be used as a fired brick fired at a temperature of higher than 1000 ° C. As the binder, any of organic binders such as phenol resin and inorganic binders such as soda silicate, phosphate and bittern can be used.

The amorphous refractory material is mainly used as a casting material, but in the usual manner, a refractory material, a zinc oxide, a binder, a dispersant, a plasticizer, a curing modifier, etc. are appropriately selected. , Mixed with water and other solvents. As the binder, alumina cement, sodium silicate, phosphate or the like can be used.

[0009]

[Function] Alumina refractory has higher corrosion resistance as the content of Al ₂ O ₃ gradually increases, such as alumina-silica, high-alumina and pure alumina. However, even if it is not as high as magnesia refractory, it gradually becomes slag. Becomes easier to permeate and the anti-spooling resistance is reduced. Especially CaO / S
When iO ₂ becomes a low basicity slag of 1.5 or less, the slag easily penetrates deep into the refractory and easily causes structural sporing. Above all, when the slag has a low basicity and an Al ₂ O ₃ content of more than 20%, the viscosity of the slag remarkably decreases, so that the slag penetrates deeply into the refractory material, CaO-Al ₂ O ₃ , Ca
O-Al ₂ O ₃ -SiO ₂ and CaO-SiO ₂ compounds are formed, and the corrosion resistance is lowered and the structure is sputtered by secondary sintering.
It causes a ring.

In the alumina refractory material of the present invention, the added zinc oxide is added during use or firing during production.
As a solid solution as xAl ₂ O ₃ · (1-x) ZnO in alumina, which shows a moderate sintering effect, and does not form a compound with a specific low melting point with alumina, it greatly reduces the fire resistance of refractory materials. There is no.

During the use of the refractory material of the present invention, the slag penetrates into the refractory material, and at that time, zinc oxide free or dissolved in magnesia melts into the slag to increase the viscosity, Prevents slag from penetrating into refractories. Furthermore, slag components CaO, MgO, SiO ₂ , A
Ca ₂ ZnSi ₂ O by reacting with l ₂ O ₃ and Fe oxide
₇ , Zn ₂ SiO ₄ , Zn ₂ Al ₄ Si ₅ O ₁₈ , Mg ₂ Si
O ₄ and (Mg, Fe) ₂ SiO ₄ and other compounds are deposited and taken in, and at the same time the slag component is taken in, the pores are blocked, the refractory is densified, and it helps prevent the penetration of slag, and sponging resistance of the refractory. Contributes to the improvement of sex.

Further, the zinc oxide of the present invention has a coefficient of thermal expansion of 7x10 ^-6 / ° C, which is 8x10 ^-6 / ° C of alumina.
It is even smaller than magnesia's 14x10 ^-6 / ° C, and it is also effective in terms of heat-resistant spooling.

[0013]

[Examples] Trials were made using materials and binders having the compositions shown in Table 1. The formulations in Table 1 are all expressed in parts by weight. The molding method "P" in Table 1 is kneading and press molding according to a conventional method, and "V" is vibration casting using a rod-shaped vibrator after adding water to the material. . Similarly, "dry" in the firing column of Table 1 is 70
It is dried at ~ 150 ℃ for 24 hours, and "heat" is at 300 ℃.
Heat treated for 15 hours, "Bake 1" was fired at 1400 ° C for 20 hours, and "Bake 2" was fired at 1550 ° C for 20 hours. The physical properties of the sample thus manufactured are also shown in Table 1.

The slag test also serves as a structural spalling test. A rotary slag test furnace is used, and an oxygen-propane burner is used at 1600 to 1650 ° C. for a total of 3.5 hours. One hour after the set temperature is reached, The operation of turning off the burner and performing forced air cooling with a fan for 30 minutes was performed three times. The results are shown in Table 1. Incidentally, the slag composition is Al ₂ O ₃ 25%, SiO ₂ 22
%, Fe ₂ O ₃ 12%, CaO 33%, MnO ₂ 3%, Mg
O 5.2% and C / S 1.5 were used. In the results of Table 1, "none" indicates that almost no cracks were observed on the cut surface of the sample after the test, "large" indicates that the sample was separated by a large crack, and "medium" indicates medium. It is the crack of.

In addition, the heat spooling test was performed in air at 10
The sample is heated at each temperature in increments of 100 ° C. between 00 and 1500 ° C. for 10 minutes, immediately taken out, and naturally air-cooled to represent the temperature at which cracks occur.

[0016]

[Table 1]

As can be seen from the results of the slag test in Table 1, samples containing the zinc oxide of the present invention (Examples 1 to 1)
Compared to those containing no zinc oxide (Comparative Examples 1, 3 to 6), 6) had a very shallow penetration depth of slag, and almost no cracks were observed due to structural spooling. The result was that there was little melting loss. However, if the amount of zinc oxide is too large (Comparative Example 2), penetration of slag can be prevented to some extent, but the amount of erosion is increased.

Furthermore, the temperature at which cracks occur in the sample of the present invention, as seen in the thermal spooling test, is alumina brick (Comparative Example 1), alumina-spinel brick (Comparative Example 3) or alumina-mullite brick. (Comparative example 5)
It is 200 to 300 ° C. higher than that of No. 1, and it can be seen that the refractory material of the present invention is also excellent in heat-resistant spooling property.

[0019]

According to the present invention, zinc oxide is added to the alumina-based material to prevent the penetration of slag into the refractory material, as is clear from the results of the examples, and to provide structural spooling. It is possible to minimize damage to the refractory due to. Also, it has excellent heat-resistant spooling and slag corrosion resistance.

Claims (1)

[Claims] 1. An alumina refractory material containing zinc oxide in an amount of 0.1 to 20% by weight as ZnO, and the balance being a refractory material mainly containing alumina.