KR0136158B1 - Thermal insulation material for ladle - Google Patents

Abstract

The present invention relates to a ladle thermal insulation insulating material that is put on the slag in order to reduce the temperature drop of the silicon deoxidized steel contained in the ladle, the heat absorbing power, as well as the alumina absorption capacity of the silicon deoxidized steel slag and corrosion resistance to magnesia refractory It is an object of the present invention to provide an excellent ladle insulation insulating material for silicon deoxidation steel.

The present invention provides a ladle insulation insulating material that is injected in order to reduce the temperature drop of the silicon deoxidation steel contained in the ladle made of magnesia refractory material of the slag contact portion,

By weight% CaO: 35-45%, MgO: 5-10%, Al ₂ O ₃ : 5-10%, SiO ₂ : 15-25%, Carbon: 5-10%, remaining binders and other unavoidably contained and the silicon deoxidation STEEL ladle insulation insulation, characterized in that 3.0 the base - is made as a component, and the basicity (CaO / SiO ₂₎ of 1.4.

Description

Ladle insulation insulation for silicon deoxidation steel

The present invention relates to a ladle insulation insulating material for silicon deoxidation steel is put into the slag in order to reduce the temperature drop of the silicon deoxidation steel contained in the ladle.

In general, in the refining process of converter center, silicon deoxidized steel is manufactured by controlling the oxygen concentration in steel by adding ferroalloy such as silicon (Fe-Si) immediately after tapping. It is a wire rod. These steels require torsion and fatigue resistance during processing, so clean molten steel must be made. Therefore, such molten steel goes through various processes, and thus the phenomenon of dropping the molten steel temperature is inevitable. In particular, the molten steel after the outside refining stays in the ladle for more than 1 hour until the completion of continuous casting, so the temperature drop of the molten steel is severe. Therefore, the temperature drop of the molten steel is generally reduced by injecting a heat insulating material in the upper part of the slag layer immediately after the end of the furnace refining.

As is well known, the basic condition of the insulation must be solid, and the heat insulation layer should be formed for a long time to reduce heat dissipation as much as possible. In addition, the thermal insulation material should not inhibit the slag inherent properties, that is, the ability to absorb inclusions and erosion resistance to the refractory, even if reacted with the slag.

Conventionally used insulators for silicon deoxidation steel is Al ₂ O ₃ and SiO ₂ as the main components, as shown in Table 1 below, and consists of CaO and Fe ₂ O ₃ in addition.

The insulating material has a melting point of 1,400 ° C. or more, and the insulating material itself forms a relatively solid heat insulating layer, but has a disadvantage in that it loses its characteristic properties by reacting with the slag directly below the insulating material. That is, the representative slag composition of the silicon deoxidized steel is shown in Table 2, which is excellent in the ability to absorb alumina, which is a non-combustible inclusion. When the conventional heat insulating material as shown in Table 1 is in contact with such slag, the physical properties of the slag are changed by these chemical reactions. That is, not only the melting point is lowered, but the alumina absorbing ability is lowered.

In addition, the ladle refractories of the slag contact portion is made of magnesia, there is a problem that the refractory erosion is aggravated when the slag and the thermal insulation material chemical reaction as described above than when the slag alone. In addition, aluminum dross is used as a raw material of Al ₂ O _{3 in} the conventional heat insulating material to secure heat generation. Aluminum dross is a by-product when smelting aluminum (Al), and exists as a phase of aluminum and alumina, as well as aluminum nitride (AlN), and such dross contains a large amount of white lead at high temperatures. Occurs. Therefore, the conventional thermal insulation material has a problem that not only bad workability, but also pollute the environment because a large amount of white smoke is generated immediately after the input to the upper slag.

Accordingly, the present inventors have conducted research and experiments to solve the above-mentioned conventional problems, and based on the results, the present invention proposes the present invention. It is an object of the present invention to provide a ladle insulation thermal insulation for silicon deoxidation steel excellent corrosion resistance to vaginal refractory.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.

The present invention provides a ladle insulation insulating material which is injected to reduce the temperature drop for the silicon deoxidized steel contained in the ladle made of magnesia refractory material of the slag contact portion,

By weight% CaO: 35-45%, MgO: 5-10%, Al ₂ O ₃ : 5-10%, SiO ₂ : 15-25%, Carbon: 5-10%, remaining binders and other unavoidably contained The present invention relates to a ladle insulation insulating material for silicon deoxidized steel, which is composed of components and has a basicity (Cao / SiO ₂ ) of 1.4-3.0.

Hereinafter, the present invention will be described in more detail.

The heat insulating material composition of the present invention is characterized by adding superior metallurgical properties (alumina absorption ability and refractory resistance to refractory) while having a heat insulating power equal to or higher than that of the conventional heat insulating material. As can be seen from Table 2, the ladle slag of the silicon deoxidized steel has a basicity (CaO / SiO ₂ ) of 1.0-1.3 and is present in the liquid phase at 1,400 ° C. or higher. As described above, since the thermal insulation material should exist in the solid phase for as long as possible, the basicity of the thermal insulation material should be 1.3 or more. However, when the basicity is 3.0 or more, the thermal insulation itself exists in the solid phase, but solidifies the liquid slag directly under the thermal insulation, thereby inhibiting metallurgical characteristics such as aluminum absorption ability. Therefore, in the present invention, it is preferable that the basicity of the thermal insulation is 1.4-3.0.

On the other hand, both MgO and Al ₂ O ₃ of the silicon deoxidized steel slag are in the range of 5-10% by weight, which is the metallurgical best composition for the silicon deoxidized steel. That is, it is a slag excellent in the absorption of alumina inclusions in steel with little corrosion of magnesia series refractory materials. Therefore, MgO and Al ₂ O ₃ is essential in order for the insulation to not inhibit the properties of the slag, the amount of addition is preferably in the range of 5-10% by weight, the same level of slag.

In addition, carbon and Al should be added to reduce the temperature drop caused by the heat content of the insulation. Conventional heat insulating material mainly used expensive Al, but inexpensive carbons are preferable in economical and workability. The more carbon is added, the better the thermal insulation properties, but the amount of MgO and Al ₂ O ₃ is limited. Therefore, in the present invention, carbon is added in order to reduce the temperature drop at a level higher than the conventional thermal insulation power, and the amount of the addition is preferably selected to 5-10% by weight, which can maintain the thermal insulation power at a level higher than the conventional thermal insulation power. Do.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

This example was conducted to derive a composition that satisfies the essential condition that the thermal insulation material should exist in the solid phase for a long time.

That is, the components other than CaO and SiO ₂ were made constant, the basicity was changed to form a heat insulating material, and the melting point results of the composition with the changed basicity are shown in Table 3 below.

In general, fluxes including thermal insulation materials contain various components in addition to CaO, MgO, Al ₂ O ₃ , SiO ₂ , unless the pure reagent is used, and the content varies depending on the raw material selection. In the present embodiment, the total content of CaO, MgO, Al ₂ O ₃ , SiO ₂ and carbons was 80% by weight in consideration of maximum practicality, and the content thereof was changed as shown in Table 3 below. In addition, as a result of the preliminary test, components other than the five components had no significant effect on the melting point.

As shown in Table 3, Comparative Material 1 has a composition similar to that of silicon deoxidized steel, and has a lower melting point than that of Inventive Material (1-3). On the other hand, Comparative Material 2, although having a higher melting point than the invention material, solidifies liquid slag, thereby inhibiting the metallurgical characteristics of the slag.

Example 2

Based on the results of Example 1, to obtain the appropriate range of MgO, Al ₂ O ₃ , and carbons to evaluate the alumina absorption capacity, magnesia erosion resistance, and insulation for the compositions shown in Table 4, the results Is shown in Table 4 below.

Since there has not yet been established a method for quantitatively evaluating such evaluations, the present study carried out a relative evaluation of each composition. That is, good means that there is no problem in metallurgy and operation, and generally means that there is no problem in practical use because it has characteristics that are higher than those of conventional materials. In the present embodiment, MgO, Al ₂ O _3, because it contains 5 to 10% by weight, the slag component, as described above was the lower limit of these components is 5% by weight. Further, the upper limit was 10% by weight when the amount of carbon flow is good or more in order to ensure Thermal Insulation, given the limits on MgO, Al ₂ O ₃ amount.

In addition, the preliminary tests showed that the components other than the five components had no significant effect on the alumina absorption capacity, the magnesia corrosion resistance, and the thermal insulation.

As shown in Table 4, the erosion resistance is good as the MgO content increases, while the alumina absorption capacity is better the lower the AlO content. On the other hand, it can be seen that the thermal insulation effect equivalent to the conventional material can be obtained in the range of 5-10 weight% of carbon addition amount. That is, the characteristics of the conventional material is only a heat insulating power, but in the case of the present invention, it can be seen that in addition to the heat insulating power, metallurgical characteristics, that is, magnesia corrosion resistance and high alumina absorption ability.

Claims (1)

In the ladle insulation insulation material which is injected to reduce the temperature drop of the silicon deoxidation steel contained in the ladle made of magnesia refractory material, the refractory material of the slag contact portion is CaO: 35-45%, MgO: 5-10%, Al ₂ O ₃ : 5-10%, SiO ₂ : 15-25%, Carbon: 5-10%, remaining binders and other inevitable components, and basicity (CaO / SiO ₂ ) is 1.4-3.0 Ladle insulation insulating material for silicon deoxidation steel.