KR20090072475A - Repairing materials composition - Google Patents

Abstract

A basic repairing material composition is provided to eliminate the impurities included in hot metal while maintaining proper properties of a repairing material by adding carbonate aggregate containing CaO to the repairing material. A basic repairing material composition is composed of 20-80wt% of carbonate aggregate, 4-12wt% of additive and basic refractories. The carbonate aggregate represents the aggregate including CaO. The additives are one or two materials selected from the group consisting of silica nanopowder and phosphonic acid binder. The basic refractories contain one or more materials selected from the group consisting of magnesia clinker, dolomite clinker and magnesia chrome clinker.

Description

Basic repairing material composition

The present invention relates to a basic repair material composition, and more particularly, to replace the refractory aggregate in the repair material composition used for partial protection of the steelmaking equipment or the internal casting of the continuous casting machine that occurs during the steelmaking industry to replace some carbonate aggregates. The present invention relates to a basic repair material composition which also improves cleanliness and is also advantageous for high-grade steel production.

In general, various steelmaking furnaces, such as converters, are used to repair damaged parts to prolong the life of the furnace when partially damaged parts occur during operation. There are hot repair methods and cold repair methods for repairing damaged parts, and the spraying method and the feeding method are applied. Conventional repair materials used for such repair work was made by adding an additive to the magnesia clinker or dolomite clinker which is a basic refractory aggregate. However, the conventional repair materials only had a function of protecting the internal refractories, and could not be expected to improve the cleanliness of molten steel.

In recent years, as the demand for high-grade steel with high cleanliness increases, efforts to manufacture high-purity steel with reduced inclusions and oxygen in steel have been increasing. There are many methods for manufacturing high clean steel, such as a method of increasing cleanliness by refining additives in a converter, a method of increasing cleanliness through steps such as AOD (Argon Oxygen Decarburization) and VOD (Vacuum Oxygen Decar-burization). The method of is used. As a part of such a method, a method of adding a CaCO ₃ -based additive to remove impurities has been applied. As the CaCO ₃ -based additive is added, CaO collects impurities in molten steel to improve cleanliness of the molten steel. However, CaCO ₃ additives used in such a method has a short lifespan compared to the magnesia material used in the prior art as a repairing material, and thus played a role as a repairing material.

The present invention has been made to solve the above problems, by providing a basic repair material composition that can improve the cleanliness of the molten steel at the same time as a suitable repair material by replacing a portion of the refractory aggregate in the repair material composition with carbonate aggregate. There is a purpose.

The basic repair material composition according to the present invention for achieving the above object is characterized in that the carbonate aggregate 20 to 80% by weight, the additive 4 to 12% by weight and the balance is made of a basic refractory aggregate.

At this time, the carbonate aggregate is characterized in that the aggregate containing CaO as a main component, in particular the carbonate aggregate is preferably dolomite.

In addition, the additive is characterized in that one or two or more kinds of ultrafine silica powder, phosphate-based binder and powder-based binder are selectively used.

And, the basic refractory aggregate is characterized in that it comprises one or two or more selected from the group consisting of magnesia clinker, dolomite clinker and magnesia chromium clinker, in particular, the basic refractory aggregate is preferably magnesia clinker.

And, the carbonate aggregate and the basic refractory aggregate is 5mm or less in particle size, the additive is characterized in that the water-soluble powder.

According to the present invention, as the carbonate aggregate containing CaO is added to the composition of the repairing material, it is possible to obtain an effect of increasing the cleanliness of the steel by removing impurities in the molten steel while maintaining proper properties of the repairing material.

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

First, the basic repairing material according to the present invention is not limited to a specific steelmaking process, and can be used in all processes in which contact with molten steel occurs. For example, converters, ladles, RH equipment, AOD equipment, VOD equipment, It can be applied at any stage where repair materials such as tundish are used.

The basic repair material composition according to the present invention consists of carbonate aggregates, additives and basic refractory aggregates.

Carbonate aggregates use aggregates containing CaO and MgO as the main component, because the impurities in the molten steel are removed as CaO and MgO traps and floats non-metallic inclusions in the molten steel, such as alumina (Al ₂ O ₃ ). This is because the cleanliness of molten steel can be improved.

Carbonate aggregates use natural and artificially synthesized carbonates capable of supplying hot activated CaO and MgO, in particular CaO. As such carbonate aggregates, dolomite is used which maintains fine calcium oxide and magnesium oxide forms that are hotly activated at a temperature of 1000 ° C. or higher during a temperature increase period and have high reactivity. Dolomite forms a low specific gravity compound through the reaction with inclusions present in the molten steel when it comes into contact with molten steel to float it upwards, and serves to stretch the non-extensible inclusions into stretchable inclusions. However, carbonate aggregates, such as dolomite, have disadvantages in terms of their contents, which show lower specific gravity and lower strength due to hot decomposition. Therefore, carbonate aggregates are used in combination with basic refractory aggregates that can increase strength and improve erosion. .

The basic refractory aggregate can be used by selecting one or two or more selected from the group consisting of magnesia clinker, dolomite clinker and magnesia chromium clinker as necessary.

Magnesia clinker is a lump made by baking magnesite or magnesium hydroxide at 1500 ° C or higher, and has magnesium oxide as a main component and has good resistance to basic slag. Magnesia clinker includes sintered magnesia clinker sintered at high temperature and electrolytic molten magnesia clinker. In the present invention, either sintered magnesia clinker or molten magnesia clinker may be used. . The magnesia clinker can be replaced with an amount of magnesia chromium clinker as needed.

Dolomite clinker is composed of calcium oxide as a main ingredient in addition to magnesium oxide, and has strong corrosion resistance against slag and excellent penetration inhibitory effect. In addition, it is effective for maintaining mesophilic strength by fast firing capacity. However, since it is extinguishable and tends to differentiate well when reacted with moisture, a content of more than a certain component is not preferable. In addition, since calcium oxide is used as a component, a complex structure is formed with magnesium oxide, and thus reactivity and activity are poor, and the dolomite clinker alone lowers the refining effect.

The additive is a conventional additive suitable for hot repair or cold repair. For example, ultrafine silica powder used as a binder, phosphoric acid binder for reducing moisture and fluidity, powder binder for imparting hot strength, etc. This is used. However, in consideration of being applied in the form of a spray, the additive is preferably in the form of a water-soluble powder. When the total compounding amount of the additive is added less than 4% by weight, poor adhesion occurs during construction, and when it exceeds 12% by weight, there is a problem that the solvent content is lowered.

In addition, basic refractory aggregates used to obtain high corrosion resistance to molten steel or slag and carbonate aggregates used to improve the cleanliness of molten steel should be mixed at an appropriate blending ratio to maintain proper performance of each element. Aggregate is added 20 to 80% by weight, the additive is added 4 to 12% by weight as described above, the remainder is preferably made of a basic refractory aggregate.

In this case, the carbonate aggregate and the basic refractory aggregate are preferably 5 mm or less in diameter in consideration of being applied in a spray form.

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

Examples 1 to 4 and Comparative Examples 1 to 4 were combined as shown in Table 1 below, water was added thereto, kneaded and then placed in a mold, and then heated to 300 ° C. to prepare a specimen, at 110 ° C. for 24 hours, After maintaining for 3 hours at 1000 ℃ and 1500 ℃ in an electric furnace was measured the compressive strength at room temperature.

On the other hand, in order to evaluate the proper construction quality and the elevated temperature, the test was carried out by constructing directly in the model tundish, and after 24 hours of drying, a test was performed at 1000 ° C. using a burner.

Examples 1 to 4 are examples according to the present invention, and Comparative Example 1 is a comparative example in which carbonate aggregates are added alone, and in Comparative Example 2, only limestone is added as a composition conventionally used for refining. It is a comparative example, Comparative Example 3 is a comparative example in which only limestone in carbonate is added, and Comparative Example 4 is a comparative example in which only magnesia clinker is added as a composition conventionally used for repair.

The main chemical components of the raw materials used in Examples 1 to 4 and Comparative Examples 1 to 4 were magnesia clinker 90% by weight of magnesium oxide and 10% by weight of other impurities, and dolomite clinker 25% by weight of calcium oxide and magnesium oxide 70 It is 5% by weight and 5% by weight of other impurities, and applied to granules with a particle size of 0.3mm or more to reduce the quality deviation caused by differentiation.

Carbonate aggregate was used by heating the aggregate containing 95% by weight or more dolomite, dolomite was maintained by 35% by weight of calcium oxide and 15% by weight of magnesium oxide by heating.

division Example Comparative example One 2 3 4 One 2 3 4 Magnesia clinker 74.4 54.4 34.4 14.4 29.4 95.6 Dolomite Clinker 15 Carbonate aggregate (limestone) 50 94.4 Carbonate Aggregate (Dolomite) 20 40 60 80 93.3 Ultrafine Silica Powder 2 2 2 2 2 2 2 0 Discourse 0.4 0.4 0.4 0.4 0.4 0.4 0.2 0.2 Silica flower 3 3 4 4 4 3 3 4 Fiber 0.2 0.2 0.3 0.3 0.3 0.2 0.2 0.2 Required amount 21-22% Strength (kgf / cm ² ) 110 ℃ X 24hr 20 18 15 11 - 5 14 26 1500 ℃ X 3hr 107 89 65 44 - 62 - 138 Specimen state at room temperature cooling after elevated temperature (1000 ℃) Good Good Good Good part Good part Good Dry Overall good Elevated temperature Good Good Good Good Good Good part Good Erosion index 90 70 60 55 - 30 - 100

As can be seen in Table 1, in the case of Examples 1 to 4, the low temperature and high temperature strength were good, and when the temperature was lowered to room temperature after the temperature was raised, the characteristics were maintained for 3 hours or more, and the temperature was also good.

However, in the case of Comparative Example 1 in which excessive dolomite was added, the specimen was prematurely differentiated when cooled to room temperature after the temperature was raised or components during drying were unable to measure physical properties. In the case of Comparative Example 2, the refining properties of the composition used in the conventional refining could be expected, but the corrosion resistance index was lower than the Example. In the case of Comparative Example 3 is the case of adding excessive limestone, both the elevated temperature and the physical properties showed the part form. In the case of Comparative Example 4, the composition used in the past for good, exhibits a good compressive strength at both low temperature and high temperature, even when cooled to room temperature after elevated to 1000 ℃ exhibited good properties. In the case of Example 4, however, no carbonate aggregate is added, so a cleaning effect cannot be expected.

In addition, in Comparative Examples 1 to 4, even if the content of the carbonate aggregate for the production of clean steel was added in comparison with Comparative Example 2, the erosion index was high in the erosion index through the rotational erosion test to ensure erosion stability. Therefore, in the case of Comparative Examples 1 to 4 it is possible to secure the erosion stability and at the same time can remove the non-metal inclusions in the molten steel according to CaO contained in the dolomite.

Claims (7)

20 to 80% by weight of carbonate aggregate, 4 to 12% by weight of additive and the remainder of the basic repair material composition comprising a basic refractory aggregate. The method of claim 1, The carbonate aggregate is a basic repair material composition, characterized in that the aggregate containing CaO as a main component. The method of claim 2, The carbonate aggregate is a basic repair material composition, characterized in that the dolomite. The method of claim 1, The additive is a basic repair material composition characterized in that one or two or more of the ultrafine silica powder, phosphate-based binder and powder-based binder is selectively used. The method of claim 1, The basic refractory aggregate is a basic repair material composition comprising one or two or more selected from the group consisting of magnesia clinker, dolomite clinker and magnesia chromium clinker. The method of claim 5, The basic refractory aggregate is a basic repair material, characterized in that the magnesia clinker. The method of claim 1, The carbonate aggregate and the basic refractory aggregate has a particle diameter of 5mm or less, and the additive is a basic water repellent composition, characterized in that the water-soluble powder.