KR20110078508A - Filling material for molten steel tap hole and manufacturing method thereof - Google Patents

Abstract

PURPOSE: A filler for ejecting ingot steel and a manufacturing method thereof are provided to increase quality and productivity since high mobility and sintering resistance are satisfied and the rate of a hole becomes high in refining and casting processes. CONSTITUTION: A filler for ejecting ingot steel(2a) comprises a core material, a coating layer and an adhesive layer. The core material comprises fireproof composition. The coating layer is formed on the surface of the core material and contains a carbon-based material. The adhesive layer is installed between the core material and the coating layer.

Description

Filling material for molten steel discharge and its manufacturing method {FILLING MATERIAL FOR MOLTEN STEEL TAP HOLE AND MANUFACTURING METHOD THEREOF}

The present invention relates to a filler used in the filling of the molten steel outlet in the furnace, ladle, tundish, etc. in the steel manufacturing process, and a manufacturing method thereof.

1 to 10 mm particle diameter for the purpose of temporary closing and opening at the exit of the electric furnace for melting steel scrap during the steel manufacturing process to produce molten steel, the nozzle at the bottom of the ladle, and the nozzle at the bottom of the tundish. Fills refractory materials such as granular olivine, magnesia, chrome ore, silica sand and dolomite.

Up to now, the above refractory materials have been used by simply adjusting the particle size in an integrated steel mill starting from a blast furnace, an electric steel mill using iron scrap, or a molten steel outlet. As a result, the refractory material is easily sintered or melted when the refractory material is in contact with hot molten steel of 1500 ° C. or more, so that molten steel is not properly discharged, that is, a poor pore state is continuously generated. In fact, if the hole is in poor condition during operation in a facility such as an electric furnace, ladle, tundish, forced opening work such as blowing oxygen or drilling with a drill is required. However, such open hole defects and forced open work have a high risk of occurrence of safety problems, and there is a problem such that productivity is lowered due to deterioration of steel quality.

It is an object of the present invention to provide a molten steel discharge filler and a method for manufacturing the same, which can increase the steel quality and productivity by increasing the porosity at the time of tapping from an electric furnace, ladle or tundish.

The present invention, the core material comprising a refractory composition; A coating layer formed on the surface of the core material and including a carbon-based coating material; And it provides a molten steel discharge filler comprising an adhesive layer interposed between the core material and the coating layer.

The present invention also provides a method of manufacturing a filler for molten steel discharge, comprising coating a carbon-based coating material on the surface of a core material including a refractory composition using an adhesive.

The filler according to the present invention has high fluidity and sintering resistance in itself, thereby increasing the porosity in the refining and casting process in the electric furnace, ladle, tundish, etc. during the steel manufacturing process, to improve the steel quality and productivity Can be increased. In addition, the filler according to the present invention can improve the safety in operation because there is no scattering of dust when filling the molten steel outlet.

Hereinafter, the present invention will be described in detail.

Molten steel filling material according to the present invention, the core material comprising a refractory composition; A coating layer formed on the surface of the core material and including a carbon-based coating material; And an adhesive layer interposed between the core material and the coating layer.

In this case, the molten steel includes molten steel and molten pig iron, the carbon-based material means a material containing a carbon component or made from a carbon-based compound, carbon black, graphite, Ketjen black, acetylene black, carbon nanotubes , Fullerene, activated carbon, Vulcan and the like.

Hereinafter, each component will be described in detail.

(Core material)

The core material includes a fire resistant composition.

The refractory composition can be used without particular limitation as long as it is used as a filler for conventional molten steel discharge.

Specifically, olivine, magnesia, or silica sand is mentioned, These can be used individually by 1 type or in mixture of 2 or more types.

The refractory composition may further include additives such as dolomite, magnesia-based carbonaceous waste refractory. At this time, the additive may be included in 10 to 90% by weight based on the total weight of the core material.

The core material preferably has a particle diameter of 1 to 10 mm, and more preferably, has a particle diameter of 2 to 8 mm so as to exhibit good fluidity upon injection into the molten steel outlet.

(Coating layer)

The coating layer is formed on the surface of the core material and serves to suppress oxidation and sintering of the core material, and includes a carbon-based coating material.

Specifically, carbon black, graphite, Ketjen black, acetylene black, carbon nanotube, fullerene, activated carbon, vulcan, etc. can be mentioned, It can be used individually by 1 type or in mixture of 2 or more types.

The coating material is preferably having a particle diameter of less than 10 microns (μm) because it can further improve the coating effect and the sintering inhibiting ability. Normally, carbon black is extremely fine particles of 1 µm or less, but graphite is preferably pulverized and used after reducing the particle size to several micron units.

If the coating amount of the coating material is too high when coating the coating material on the core material, the fluidity as a filler is lowered, the economical efficiency due to a large amount of coating, the carbon component is dissolved in the molten steel, there is a fear that the quality of the molten steel deteriorates. On the other hand, if the coating amount of the coating material is too low, the coating amount is too small to uniform coating on the granular core material in the manufacturing process, there is a fear that the sintering inhibiting effect is lowered. Accordingly, the coating amount of the coating material on the core material is preferably 0.01 to 1.2% by weight, more preferably 0.3 to 0.5% by weight based on 100% by weight of the core material.

(Adhesive layer)

The adhesive layer serves to adhere the coating material to the core material.

As an adhesive agent which forms an adhesive bond layer, Organic adhesives, such as a phenol, polyvinyl alcohol (PVA), carboxymethylcellulose (CMC); Or inorganic adhesives, such as a silica-sol adhesive which mixed 2-5 weight% of silica sol and potassium hydroxide (KOH) which is a hardening | curing agent, sodium silicate, and a silicate silica, can be used.

When using sodium silicate or silicate as an adhesive, it is preferable to use sodium silicate or silicate as a dilute solution prepared by adding sodium silicate or silicate to a solvent such as water to a concentration of 20 to 40% by weight, preferably 30% by weight. .

The adhesive is preferably included in 2 to 6% by weight, preferably 4% by weight relative to 100% by weight of the core material.

Molten steel filler having a configuration as described above may be prepared by a manufacturing method comprising the step of coating a carbon-based coating material on the surface of the core material including a refractory composition using an adhesive.

The core material, coating material and adhesive are as described above.

However, the coating method for the core material may be performed using a conventional coating method, and specifically, may be performed by a method such as impregnation, coating, spraying, or the like.

After coating of the coating material to the core material, it is preferred to dry at a temperature of 100 to 400 ℃, preferably 200 to 250 ℃. If the temperature at the time of drying is too high, the coating material is easily oxidized and lost, and economical efficiency is low. On the other hand, if the temperature at the time of drying is too low, the drying efficiency is low, so it is preferable to carry out the drying process within the above temperature range.

The filler prepared by the manufacturing method as described above may be used as a filler for filling the molten steel outlet formed inside the nozzle for discharging the molten steel in an electric furnace, ladle, tundish and the like.

1 is a cross-sectional view of an electric furnace in which the filler according to the present invention is installed, FIG. 2 is a cross-sectional view of a tundish in which the filler according to the present invention is installed, and FIG. 3 is a cross-sectional view of the ladle in which the filler according to the present invention is installed.

1 to 3, the filler according to the present invention is filled in the molten steel outlet (1a, 1b, 1c) in the refining and casting process in the electric furnace, tundish, ladle, etc. during the steel manufacturing process, when the molten steel discharged The sliding gates 3a, 3b and 3c are opened to discharge the molten steels 2a, 2b and 2c.

Filler according to an embodiment of the present invention has a high flowability in itself with sintering resistance to suppress the sintering of the oxide (refractory). As a result, when the sliding gate of the metal housing provided under the molten steel discharge nozzle at the time of tapping is opened, the filler blocking the inside of the nozzle is not sintered, so that it immediately flows down to facilitate the discharge of the molten steel. As such, the filler according to the present invention exhibits high porosity, thereby increasing steel quality and productivity.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the scope of the present invention is not limited to the following examples.

Examples 1 to 7, and Comparative Examples 1 to 3

To the ingredients and contents shown in Table 1 below, the filler was prepared by surface coating of olivine alone or by mixing carbon black and graphite.

In detail, the dispersion prepared by dispersing carbon black and graphite in an adhesive was impregnated with olivine having a predetermined particle size, and then dried at a rotary dryer at 250 ° C. to complete surface coating.

TABLE 1

division Example (% by weight) Comparative example (% by weight) One 2 3 4 5 6 7 One 2 3 Core material peridot 100 100 100 100 100 100 100 100 100 100 Particle diameter
(mm) 1 to 10 2 to 4 2 to 4 2 to 6 3 to 8 4 to 8 3 to 9 1 to 10 2 to 6 3 to 8 Coating material Carbon
black 0.01 0.02 0.01 0.20 0.60 0.03 1.20 - - - black smoke - 0.03 0.02 0.10 0.60 0.20 - - - - glue Silica Sol System * ¹ - 4 - - - 3 - - - - Phenolic Resin 3 - - - - - 4 - - - PVA * ² - - 2 - - - - - - - CMC * ³ - - - 5 - - - - - - Dilute silicate solution * ⁴ - - - - 4 - - - - - * Adhesive with 3 wt% KOH added to ¹ silica sol
* ² PVA: Polyvinyl Alcohol
* ³ CMC: Carboxymethylcellulose
* ⁴ A solution containing 30 wt% of silicate silica in water
* The content of the coating material and the adhesive in the above table is weight percent based on 100 weight percent of the core material.

Test Example  One: Opening rate  evaluation

The fillers of Examples 1 to 7, and Comparative Examples 1 to 3 prepared above were added to the molten steel outlet at a time of 80 kg each, and then the porosity when the gate of the nozzle was opened was measured. The results are shown in Table 2.

TABLE 2

division Example Comparative example One 2 3 4 5 6 7 One 2 3 Opening rate
(%) 81 89 95 99 90 92 89 52 61 62

As shown in Table 2, the fillers of Comparative Examples 1 to 3, which are conventional olivine-based fillers without any coating, exhibited a porosity of up to 62%, whereas the fillers according to Examples 1 to 7 contained 0.01 weight of carbon black. The filler of Example 4 coated with carbon black and graphite at a total of 0.3% by weight in total, including the filler of Example 1 coated with% by 81%, showed a porosity of up to 99%. It showed a significantly improved porosity compared to the filler of 1 to 3.

Example  8 to 13, and Comparative example  4 to 7

A filler was prepared in the same manner as in Example 1 except for using the ingredients and contents shown in Table 3 below.

[Table 3]

division Example (% by weight) Comparative example (% by weight) 8 9 10 11 12 13 4 5 6 7 Core material Magnesia * ¹ - - - 40 40 10 100 - - - Dolomite * ² - 70 - - - - - 100 - - Waste Refractory * ³ - - 50 - 20 - - - 100 - Silica sand * ⁴ 100 - - - - - - - - 100 Olivine * ⁵ - 30 50 60 40 90 - - - - Coating material Carbon black 0.1 0.5 0.05 0.1 0.6 0.04 - - - - black smoke 0.1 0.7 0.05 0.1 - 0.04 - - - - glue Silica Sol Type * ⁶ 4 3 - - - - - - - - Phenolic Resin - - 2 - - - - - - - PVA * ⁷ - - - - - 4 - - - - CMC * ⁸ - - - - 4 - - - - - Dilute hook silicate solution * ⁹ - - - 5 - - - - - - * ¹ magnesia: particle size 1-10 mm
* ² dolomite: particle size 3-8 mm
* ³ waste refractories: including MgO and magnesia, particle size: 2-6 mm
* ⁴ silica sand: particle size: 1-3 mm
* ⁵ olivine: particle size: 2-6 mm
* ³ Silica Sol with 3% by weight of KOH
* ⁷ PVA: Polyvinyl Alcohol
* ⁸ CMC: Carboxymethylcellulose
* ⁹ A solution containing 30% of silicate in water
* The content of the coating material and the adhesive in the above table is weight percent based on 100 weight percent of the core material.

Test Example  2: Opening rate  evaluation

The fillers of Examples 8 to 13 and Comparative Examples 4 to 7 prepared above were added to the molten steel outlet at a rate of 80 kg each, and then the porosity was evaluated. The results are shown in Table 4.

[Table 4]

division Example Comparative example 8 9 10 11 12 13 4 5 6 7 Opening rate
(%) 81 89 95 99 95 92 51 56 49 55

As shown in Table 4, the fillers of Comparative Examples 4 to 7, which are conventional fillers without any coating, exhibited a porosity of up to 56%, while coating carbon black alone or a mixture of carbon black and graphite. Fillers of Examples 8 to 13 shows a porosity of at least 81% to a maximum of 99%, it can be seen that the porosity is significantly improved compared to the fillers of Comparative Examples 1 to 4.

In addition, the coating on the magnesia having a particle size of 1 to 10 mm, or the core material containing the magnesia as a main component, was performed in a 1: 1 weight ratio by mixing a mixture of carbon black and graphite in a total weight of 0.2 wt%. When coated, it showed the highest porosity of 99%.

In addition, in the case of silica sand conventionally used as a filler for molten steel discharge, the silica sand of Example 8 coated with a mixture of carbon black and graphite exhibited a porosity of 81%, which is significantly improved compared to the silica sand of Comparative Example 7 without any coating. The porosity is shown.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of the invention.

1 is a cross-sectional view of an electric furnace in which a filler according to the present invention is installed.

Figure 2 is a cross-sectional view of the tundish is installed filler in accordance with the present invention.

3 is a cross-sectional view of the ladle in which the filler according to the present invention is installed.

Description of the main parts of the drawing

1a, 1b, 1c: molten steel outlet filled with filler

2a, 2b, 2c: molten steel

3a, 3b, 3c: sliding gates for molten steel discharge

Claims (11)

A core material comprising a fire resistant composition; A coating layer formed on the surface of the core material and including a carbon-based coating material; And Adhesive layer interposed between the core material and the coating layer Filling material for molten steel discharge comprising a. The method of claim 1, The refractory composition is a filler selected from the group consisting of olivine, magnesia, silica and mixtures thereof. The method of claim 2, The refractory composition further comprises an additive selected from the group consisting of dolomite, magnesia-based carbonaceous inner compound and mixtures thereof. The method of claim 1, The core material is a filler having a particle diameter of 1 to 10 mm. The method of claim 1, The carbon-based coating material is selected from the group consisting of carbon black, graphite, Ketjen black, acetylene black carbon nanotube, fullerene, activated carbon, vulcan and mixtures thereof. The method of claim 1, The coating material is a filler coated on the core material in an amount of 0.01 to 1.2% by weight. The method of claim 1, The adhesive layer is a filler comprising a adhesive selected from the group consisting of phenol, polyvinyl alcohol, carboxymethyl cellulose, silica sol 2 to 5% by weight of potassium hydroxide in silica sol, sodium silicate, and silica silicate. A method of manufacturing a filler for discharging molten steel comprising coating a carbon-based coating material on a surface of a core material including a refractory composition using an adhesive. The method of claim 8, The refractory composition is a method of producing a filler selected from the group consisting of olivine, magnesia, silica and mixtures thereof. The method of claim 8, The carbon-based coating material is carbon black, graphite, Ketjen black, acetylene black carbon nanotubes, fullerene, activated carbon, vulcan and a method for producing a filler selected from the group consisting of a mixture thereof. The method of claim 8, The adhesive is a phenol, polyvinyl alcohol, carboxymethyl cellulose, a silica sol-based adhesive mixture of potassium hydroxide 2 to 5% by weight of silica sol, a method of producing a filler comprising an adhesive selected from the group consisting of sodium silicate and silica silicate.

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