KR101071319B1 - Method for manufacturing refractories of a taphole sleeve - Google Patents

Abstract

The present invention comprises the steps of (a) hydrophilizing the surface of the metal powder and the surface of the graphite powder; (b) mixing and dispersing the graphite powder and the metal powder together with an oxide raw material in an aqueous solution to form a mixture; (c) adding an organic monomer, a crosslinking agent and an initiator to the mixture to produce a shaped body; And (d) discloses a method for producing a refractory of the tap sleeve characterized in that the molded body is irradiated with a microwave of 2.5 kHz and heat-treated at a temperature of 1000 ℃ to 1200 ℃. Refractory manufacturing method of the outlet sleeve as described above can produce a refractory to reduce damage due to heat and wear, it is possible to implement a stable operation.

Hydrophilization, molded body, microwave, heat treatment

Description

METHODS FOR MANUFACTURING REFRACTORIES OF A TAPHOLE SLEEVE}

The present invention relates to a method for producing a refractory material of a tap sleeve, and more particularly, to a method for producing a refractory material for a tap sleeve that can improve strength.

Converter is used in steelmaking process of steel process. The converter is charged with molten iron, scrap metal and raw materials from the blast furnace. Oxygen is injected into the converter to remove impurities in the molten iron, and necessary components are added to produce molten steel of a desired component and an appropriate temperature. Molten steel produced through the converter is discharged through the converter outlet.

In general, a refractory is attached to the inside of the converter. Refractories protect the converter from hot molten steel. Among these refractory materials, the refractory material of the outlet sleeve is most damaged. The refractory material of such a hatch sleeve generally uses MgO-C fluorine products.

In the past, the sleeve refractory for the outlet was joined using mortar in a split structure, but such a joint had a problem of being rapidly eroded. Because of this, the outlet sleeve refractory is generally produced in one piece using cold isostatic press (CIP) molding. In CIP molding, the raw material is put into a rubber mold and sealed. These rubber molds are inserted in water or in oil and pressurized in the same direction. This produces a uniform and compact shaped body, i.e., the tap sleeve refractory.

However, this molding method is excellent in strength, but is not a continuous molding process, the equipment itself is expensive. Because of this, a significant cost is required to produce the refractory.

In addition, the outlet sleeve refractory is generally used in a non-preheated state. For this reason, in the early stage of use, rapid gas release occurs due to decomposition of the binder, and molten steel is splashed or unstablely discharged. In addition, sufficient high-temperature strength is not developed, and rapid damage of the outlet sleeve refractory is advanced by molten steel. Due to this phenomenon, there is a disadvantage that the stability of the operation is lowered.

The present invention is to provide a refractory manufacturing method of the tap sleeve that can reduce the damage caused by the heat and wear of the tap refractory due to the tapping operation of the molten steel at low cost.

In addition, the present invention is to provide a refractory manufacturing method of the tap sleeve that can implement a stable tapping operation.

The present invention comprises the steps of (a) hydrophilizing the surface of the metal powder and the surface of the graphite powder; (b) mixing and dispersing the graphite powder and the metal powder together with an oxide raw material in an aqueous solution to form a mixture; (c) adding an organic monomer, a crosslinking agent and an initiator to the mixture to produce a shaped body; And (d) discloses a method for producing a refractory of the tap sleeve characterized in that the molded body is irradiated with a microwave of 2.5 kHz and heat-treated at a temperature of 1000 ℃ to 1200 ℃.

In addition, the oxide raw material comprises magnesia, dolomite or spinel containing MgO, and the metal powder discloses a refractory manufacturing method of the tap sleeve, characterized in that it comprises Al, Al-Mg or Mg-B.

In addition, the organic monomer may include acrylamide or methacrylamide, the crosslinking agent may include polyethylene glycol dimethacrylate (PEGDMA) or methylenebisacrylamide (MBAM), and the initiator may include ammonium persulfate. Disclosed is a method for producing a refractory material of a tap-hole sleeve characterized by the above-mentioned.

In addition, the microwave discloses a method for producing a refractory material for a steel tap sleeve characterized in that the molded body is irradiated with an output of 500W to 1000W.

In the method for producing a refractory material of a tap sleeve of the present invention, hydrophilized metal powder and graphite powder are mixed and dispersed together with an oxide raw material in an aqueous solution to form a mixture, and heat treatment is performed after addition of an organic monomer, a crosslinking agent and an initiator is made.

In particular, heat treatment is carried out at a temperature of 1000 ℃ to 1200 ℃ by microwave irradiation. This heat treatment can be combined with the addition of organic monomers, crosslinkers and initiators to improve the heat resistance and wear strength of the refractory from the shaped body.

In addition, when the refractory manufactured according to the present invention is installed in the converter outlet sleeve, the refractory is damaged due to the molten steel due to the improved heat resistance and wear strength, it is possible to implement smooth tapping operation.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, if it is determined that the detailed description of the related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

1 is a flow chart showing a method for producing a refractory of the tap sleeve according to a preferred embodiment of the present invention.

First, the step of hydrophilizing the surface of the metal powder and the surface of the graphite powder is made (S101).

In step S101, the metal powder includes Al, Al-Mg, or Mg-B, and is surface treated to have hydrophilicity. For example, when the metal powder is Al, such metal powder is heat-treated for 0.3 hours to 0.5 hours at a temperature of 550 ° C. to 620 ° C. under an oxygen partial pressure of 5 × 10 ⁻² to 2 × 10 ⁻¹ atm. For this reason, the oxide layer is minutely formed on the surface of the metal powder. That is, Al which is a metal powder becomes hydrophilic. In addition, the graphite powder is also surface treated with H ₂ O _{2 or the} like to become hydrophilic.

Subsequently, a step of generating a mixture is performed (S102). In step S102, the surface hydrophilized metal powder and graphite powder is mixed and dispersed in an aqueous solution together with the oxide raw material.

In step S102, the oxide raw material preferably comprises magnesia, dolomite or spinel containing MgO and is included in the mixture.

In addition, the mixture preferably comprises 85% by weight of oxide raw material and 15% by weight of graphite powder, and the metal powder extrapolates 2% by weight.

Subsequently, a step of forming a molded body is performed (S103). At this time, the organic monomer, the crosslinking agent and the initiator are added to the mixture produced through step S102.

As the organic monomer and the crosslinking agent are added to the mixture in step S103, a polymerization reaction occurs between the organic monomer and the crosslinking agent. The organic monomer added at this time is preferably 10% by weight, containing acrylamide or methacrylamide, the crosslinking agent is preferably 5% by weight, polyethylene glycol dimethacrylate (PEGDMA) or methylenebisacrylamide ( MBAM).

When the polymerization reaction between the organic monomers and the crosslinking agent occurs, an initiator is added to the mixture. The initiator added at this time preferably comprises 0.5% by weight of ammonium persulfate by extrapolation. Such initiators trigger polymerization reactions between organic monomers and crosslinkers. As a result, 99% or more of the organic monomers are polymerized within 10 minutes, and the mixture is formed into a shaped body.

On the other hand, it is preferable that the molded body is formed in the state in which the mixture in which the organic monomer, the crosslinking agent, and the initiator were added is put into the molding mold. The molding mold is manufactured according to the shape of the desired outlet sleeve, and a mixture is added to the molding mold to produce a molded body. Such step S103 is generally referred to as gel casting (gel casting) molding.

Subsequently, a step in which the molded body is heat treated is performed (S104). In step S104, the molded body is discharged from the molding mold and irradiated with microwaves of 2.5 kHz and heat-treated at a temperature of 1000 ℃ to 1200 ℃. At this time, the irradiated microwave preferably has an output of 500W to 1000W.

When microwaves are irradiated to the molded body, the molded body has an internal heat generation caused by carbon or carbon silicon, and the temperature rises. This results in decomposition of the aqueous solution contained in the mixture in the molded body and decomposition of organic binders such as organic monomers, crosslinking agents and initiators, and solid phase bonding by metal powder is achieved.

In particular, solid phase bonding by the metal powder can improve the heat resistance and wear strength of the refractory. For example, when the metal powder is Al, solid phase bonding is continued as follows. Al, which is a metal powder, is formed into fine alumina by reacting with carbon particles such as graphite powder present in the surroundings. The alumina reacts with the MgO particles present in the surroundings to form a solid phase bond with the spinel particles. In addition, the Al metal powder may react with the carbon present in the surroundings to form Al ₄ C ₃ to form a solid phase bond.

In order for the decomposition of such an organic binder and the solid phase bond by a metal powder to be expressed smoothly, the temperature of heat processing is 1000 degreeC-1200 degreeC.

Experimental Example

In order to confirm the strength against heat and abrasion of the refractory body of the tap sleeve manufactured according to the present invention, the same experiment was performed to measure the thermal shock resistance and wear damage resistance of the refractory prepared according to the present invention. The experiment is as follows.

Specimens used in this experiment were manufactured to a constant size.

Firstly, the molten steel deposited on these specimens is 100 kg of steel melted using an induction furnace. Thermal shock resistance was evaluated by depositing the specimen in molten steel, cooling it in the atmosphere, and applying a constant impact. In addition, wear damage resistance was evaluated by rotating the specimen at 10 rpm for 1 hour while the specimen was deposited in molten steel, and then measuring the remaining thickness of the specimen.

Specimens for Experimental Example 1 and Experimental Example 2 were prepared according to the method for producing a refractory of the tap sleeve according to the present invention. Here, the oxide raw material is a magnesia powder having a purity of 99% and a particle size of 3 mm to 5 mm, 1 mm to 3, 1 mm or less and 0.075 mm mm or less, and a metal powder having an average diameter of 20 µm and a purity of 99%. Al powder was used, and graphite powder was used as natural flake graphite having a purity of 98% or less of 100mesh. In addition, the metal powder and the black surface powder were hydrophilized, especially the black surface powder was made by H ₂ O ₂ .

The oxide raw material, the metal powder, and the graphite powder were mixed and dispersed in an aqueous solution to add an organic monomer and a crosslinking agent, and additionally, an initiator was added. At this time, the organic monomer was used as the organic monomer acrylamide (manufactured by Junsei Chemical), the crosslinking agent was polyethylene glycol dimethacrylate (manufactured by Aldrich Chemcal, Mn = 536), the initiator was ammonium persulfate ( Manufactured by Shinyo Pure Chemical). For this reason, it hardened | cured in the molding mold and the molded object was formed.

This molded body was irradiated with heat with a microwave having a constant output in a microwave furnace. At this time, by varying the temperature, the specimen of Experimental Example 1 was heat-treated at 1000 ℃, the specimen of Experimental Example 2 was heat-treated at 1200 ℃.

In Comparative Examples 1 to 5, the specimens of Comparative Example 1 to Comparative Example 5 used the same magnesia as the specimens of the test examples, but there were examples in which spinel was applied instead of magnesia. In addition, the molding of the specimens were made through CIP or uniaxial molding, unlike the specimens of the experimental examples, heat treatment was performed at a temperature of 300 ℃ or 800 ℃ by applying hot air to the molded body in place of microwave heating.

Table 1 below shows the results of evaluating thermal shock resistance and abrasion damage resistance according to each specimen. Here, the thermal shock resistance and the abrasion damage resistance of the specimens were set to 100 as the measured value of the specimen of Comparative Example 1.

Manufacture conditions Test result Oxide raw material Molding method Heat treatment condition Heat resistant
Impact Wear and tear
Resistance Temperature (℃) Way Comparative example One Mg-C CIP 300 sirocco 100 100 2 Mg-C CIP 800 sirocco 90 90 3 Spinel-c CIP 300 sirocco 100 110 4 Spinel-c CIP 800 sirocco 90 90 5 Mg-C Uniaxial molding 300 sirocco 110 85 Experimental Example
One Mg-C Gel casting 1000 Microwave heating 150 140 2 Mg-C Gel casting 1200 Microwave heating 145 150

As shown in Table 1, the experimental examples were found to be excellent in both thermal shock resistance and wear damage resistance as compared with the comparative examples. Thus, the method for producing the tap refractories according to the present invention can provide improved heat resistance and wear strength as compared to the conventional method. In addition, the tap refractories can reduce the damage caused by the molten steel can implement a stable tapping operation.

While the present invention has been described in connection with certain exemplary embodiments, it will be understood by those skilled in the art that various changes may be made without departing from the scope of the present invention.

1 is a flow chart showing a method for producing a refractory of the tap sleeve according to a preferred embodiment of the present invention.

Claims (4)

(a) hydrophilizing the surface of the metal powder and the surface of the graphite powder; (b) mixing and dispersing the graphite powder and the metal powder together with an oxide raw material in an aqueous solution to form a mixture; (c) adding an organic monomer, a crosslinking agent and an initiator to the mixture to produce a shaped body; And (d) the molded article is refractory to a microwave of 2.5 kHz and heat-treated at a temperature of 1000 ℃ to 1200 ℃ comprising the step of manufacturing a refractory of the tap sleeve. The method of claim 1, The oxide raw material includes magnesia, dolomite or spinel containing MgO, and the metal powder includes Al, Al-Mg or Mg-B. The method of claim 1, The organic monomer may include acrylamide or methacrylamide, the crosslinking agent may include polyethylene glycol dimethacrylate (PEGDMA) or methylenebisacrylamide (MBAM), and the initiator may include ammonium persulfate. Refractory manufacturing method of a tap-hole sleeve made into. The method of claim 1, And the microwave is irradiated to the molded body at an output of 500W to 1000W.

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