KR101362442B1 - Method for preparing ladle filler and device used therein - Google Patents

Abstract

The present invention relates to a method for manufacturing a filler for a steel ladle and a filler manufacturing apparatus used therein, by the method of manufacturing the filler can be uniformly coated on the sand surface of the carbon-based material, it is possible to increase the thermal efficiency during manufacturing In addition, the working environment can be improved by suppressing ammonia gas by the decomposition of hexamine. As a result, the ladle filler produced by the manufacturing method of the present invention has no sintering or fusion, penetration of molten steel at the time of discharging molten steel, and shows high porosity.

Description

Manufacturing method of filler for steel ladle, and filler manufacturing apparatus used therein {METHOD FOR PREPARING LADLE FILLER AND DEVICE USED THEREIN}

The present invention is ammonia by the decomposition of hexamine with a high thermal efficiency of the filler filling in the molten steel discharge nozzle located in the lower portion of the ladle (ladle) that is a container containing molten iron (hereinafter referred to as 'molten steel') during the steel manufacturing process The present invention relates to a method for manufacturing a filler for a steel ladle, which can be manufactured without concern for generation of gas, and a filler manufacturing apparatus used therein.

When tapping the molten steel in the ladle, when the molten steel temperature was relatively lower than the present time, it was opened and closed by a stopper method. However, as the molten steel temperature rose to about 1700 ° C, the stopper head was melted. Recently, the sliding nozzle method (sliding nozzle) has been used. In this sliding nozzle method, an empty space is created inside the nozzle. If the space is left as it is, the space is more heat dissipated than the inside of the ladle body with molten steel, so that the molten steel is solidified and the tapping is impossible.

Therefore, in order to prevent such a phenomenon, a filler is introduced into the nozzle space to prevent molten steel from entering the space. If the sliding nozzle is opened while the filler is overcoming the iron static pressure of the molten steel, the filler is pulled out and the molten steel is pushed out. In this case, when the filler is sintered or fused by molten steel temperature or iron static pressure, or the molten steel penetrates into the filler and solidifies, it is impossible to proceed to the subsequent process.

Accordingly, technology development such as selection of appropriate materials and particle size distribution control to prevent sintering, fusion, and penetration of molten steel for ladle fillers has been continuously made.

Currently, chromite sand or silica sand is mainly used as a material for filling materials, and specific conditions such as the mixing ratio and particle size distribution can be adjusted according to the purpose of use, but have been established to almost standardized levels. In addition, silica and zircon can also be used as filler sands.

The best way to prevent sintering and fusion and to prevent penetration of molten steel is to use carbon that is not easily sintered and has low wettability of molten steel. As a concrete example, refractory materials such as MgO-C and Al ₂ O ₃ -C have been put to practical use.

In general, in the case of the filler, since the particles are in the form of sand and cannot form a carbon refractory material, various methods of mixing or coating carbon with the filler have been proposed.

Specifically, Japanese Patent Application Laid-Open No. 1983-061946 discloses a method for producing carbon coated sand, and Japanese Patent Application Laid-Open No. 1986-169127 discloses a method of coating graphite on sand by hot curing. It is. In addition, Japanese Patent Laid-Open No. 1992-084664 discloses a filler for sliding nozzles in which 0.05 to 5.0% of carbon black is blended, and Japanese Laid-Open Patent No. 1994/71424 discloses a ladle filler in which 1 to 5% of graphite is mixed. It is. In addition, Japanese Patent Application Laid-Open No. 1998-58126 discloses a method of manufacturing a filler for a sliding nozzle by heating silica sand to 150 ° C. and then kneading by adding a novolak-type phenolic resin and carbon. 1998-052751 discloses a method for preparing a ladle filler by coating carbon black on silica sand or chromite. In addition, Korean Patent No. 0269036 discloses a method in which a methyl alcohol is combusted and removed after mixing a coating liquid prepared by mixing carbon, a binder, and methanol with sand.

In the method of coating carbon in a conventional filler sand, in the case of the thermosetting method disclosed in Japanese Patent Laid-Open No. 1986-169127 or Japanese Patent Laid-Open No. 1998-058126, a temperature required for coating a phenol resin, that is, 100 to 110 ° C The coating process can be sufficiently performed by heating the sand at a degree, but the sand is heated to 150 ° C. or higher in consideration of the temperature drop when the heated sand is moved to the mixer. In addition, since the heating coating mainly uses a heating device in the form of a rotary furnace, a lot of heat loss. In general, in the case of a rotary furnace, the heated object exists only in the lower portion of the rotary furnace, and the upper end of the heated object exists as an empty space. By the way, the flame ejected from the heating burner heats the empty space and heats the heated object by this heat. Therefore, in some respects, the heating method is the same as that of the heating of the heated object, and the heating method is the same as that of the air heating in the empty space. As a result, in the rotary furnace heating method, the thermal efficiency is inevitably lowered, and there is a problem in that the carbon coating becomes uneven when there is a temperature deviation when the sand heated to about 150 ° C. is cooled.

In addition, Japanese Patent Laid-Open No. 2010-190544 discloses a sand heating device. However, when the sand heating apparatus is used, the sand heating time is long because the sand comes down in a bulk form and the productivity is low.

In addition, although Japanese Patent Laid-Open Publication No. 2001-321886 discloses a sand heating device, the sand heating device has a complicated heating pipe, which may interfere with sand flow, and fine sand blocks the hot air blowing holes in the pipe. There is a problem throwing away.

On the other hand, Japanese Patent Laid-Open No. 2009-208081 and Japanese Patent Laid-Open No. 1999-285779 disclose a sand heating apparatus using a fluidization furnace. However, in general, since the blowing electricity is very much required to blow the fluidizing hot air, it is a method that has little economic feasibility to fluidize the sand particles through the fluidizing furnace except in the case of fine powder.

The present invention has a high thermal efficiency, there is no fear of the generation of ammonia gas by the decomposition of hexamine, there is no sintering or fusion of molten steel, no penetration of molten steel during the discharge of molten steel, the filler for steel ladle can produce a filler having a high porosity To provide a method of manufacturing and the filler for the steel ladle produced thereby.

The present invention also provides an apparatus for producing a filler for a steel ladle useful for the production of the filler.

According to one embodiment of the invention, the step of heating while dropping the sand (sand) in the vertical heating furnace; Surface-treating the sand by spraying a surface treatment composition including a carbon-based material and a resol-type phenolic resin on the sand which is heated and dropped; And it provides a manufacturing method for a steel ladle comprising the step of mixing the surface-treated sand in a mixer.

The sand may be selected from the group consisting of silica sand, chromite sand, zircon sand, alumina, mullite ceramics, and mixtures thereof. .

The sand may be one having a particle size of 0.1mm to 1.3mm.

The heating process for the sand may be performed at 100 to 150 ° C.

The carbonaceous material may be selected from the group consisting of graphite, carbon black, ketjen black, acetylene black, carbon nanotubes, fullerene, activated carbon, vulcan black and mixtures thereof.

The carbonaceous material may have a particle size of 30 nm to 100 μm.

The surface treatment composition may include a carbon-based material and a resol-based phenol resin in a weight ratio of 10: 1 to 1: 1.

The surface treatment composition may be prepared by mixing a dispersion prepared by dispersing a carbon-based material in water and a solution prepared by dissolving a resol type phenol resin in a polyhydric alcohol.

The surface treatment composition further includes an additive selected from the group consisting of polyvinyl alcohol, sodium carboxymethyl cellulose, silica sol-based adhesives mixed with 2 to 5 wt% of potassium hydroxide in silica sol, sodium silicate, silica silicate, and mixtures thereof. can do.

The surface treatment process for the sand may be carried out at a temperature of 100 to 150 ℃.

The mixing process for the surface-treated sand may include a first mixing process and a second mixing process.

Filler for a steel ladle according to another embodiment of the present invention is manufactured by the above manufacturing method.

The filler may include a core including sand, and a surface treatment layer surrounding the core and including a carbonaceous material and a resol type phenol resin.

The filler may include a carbon-based material and a resol-based phenol resin in a weight ratio of 10: 1 to 1: 1.

According to still another embodiment of the present invention, a sand supply unit to which sand is introduced, which is located below the sand supply unit, heat treatment for sand dropped from the sand supply unit and surface treatment for sand that is heated and dropped continuously Provided is a vertical heating furnace to be carried out, and is located in the lower portion of the vertical heating furnace, and provides a manufacturing device for the filling material for steel ladle comprising a mixing unit is carried out a mixing process for the surface-treated sand dropped from the vertical heating furnace. do.

The mixing unit is a first mixing unit in which the first mixing process is performed on the surface-treated sand dropped from the vertical heating furnace, and a mixture located in the lower portion of the first mixing unit, and the first mixed in the first mixing unit And a second mixing unit in which the secondary mixing process is performed.

Other details of the embodiments of the present invention are included in the following detailed description.

According to the method of manufacturing the filler for steel ladle, it is possible to uniformly coat carbon-based materials such as graphite (graphite) on the surface of the sand, increase the thermal efficiency during manufacture, and generate ammonia gas by decomposition of the curing agent such as hexamine. There is no concern to improve the working environment. As a result, the filler for the ladle produced by the method of manufacturing the filler for the steel ladle, there is no sintering or fusion, penetration of molten steel at the time of discharging molten steel, and exhibits high porosity.

1 is a schematic diagram schematically showing an apparatus for manufacturing a filler for a steel ladle according to an embodiment of the present invention.
2 is a microscopic picture of a filler for a steel ladle prepared according to the embodiment.
3 is a microscopic picture of a filler for a steel ladle prepared according to a comparative example.

Hereinafter, embodiments of the present invention will be described in detail. However, this is presented as an example, by which the present invention is not limited and the present invention is defined only by the scope of the claims to be described later.

Before taking the molten steel, the interior of the nozzle of the ladle is filled with the filling material and then the molten steel is finished. After the completion of the molten steel, the molten steel is discharged through the nozzle to proceed with the subsequent process. At this time, when sintering or fusion occurs in the filler or molten steel penetrates and solidifies, molten steel is not discharged, which causes a big problem in the process.

On the other hand, in the present invention, when manufacturing the filler for steel ladle using the thermosetting method, the horizontal rotary furnace commonly used in the sand heating device is replaced with a vertical heating furnace, and resol type phenol resin is used instead of the novolac phenol resin. Therefore, the filler for the steel ladle coated with graphite uniformly on the sand surface can be manufactured with high thermal efficiency without fear of contamination of the working environment, and the prepared filler can be sintered or fused at the time of discharging molten steel, and the penetration of molten steel The present invention was completed by finding out that a high porosity can be obtained.

That is, the method of manufacturing a filler for a ladle according to an embodiment of the present invention, the step of heating while dropping sand in the vertical heating furnace; Surface-treating the sand by spraying a surface treatment composition including a carbon-based material and a resol-type phenolic resin on the sand which is heated and dropped; And mixing the surface treated sand in a mixer.

Each step will be described below.

First, sand is introduced into a filler manufacturing apparatus equipped with a vertical heating furnace as a core material for preparing a filler for steel ladle, and heated while dropping sand in the vertical heating furnace.

The sand is selected from the group consisting of silica sand, chromite sand, zircon sand, alumina, mulite ceramics, and mixtures thereof. Can be used.

The sand preferably has a particle size of 0.1 mm to 1.3 mm in terms of porosity.

The heating process for the sand is preferably carried out at 100 to 150 ℃ in consideration of the temperature drop of the sand, more preferably 100 to 120 ℃.

Next, the sand is surface-treated by spraying the surface treatment composition containing a carbonaceous substance and a resol-type phenol resin with respect to the sand which heats and falls.

The surface treatment composition may be prepared by mixing a dispersion prepared by dispersing a carbon-based material in water and a solution prepared by dissolving a resol type phenol resin in a polyhydric alcohol.

In this case, the carbon-based material may be selected from the group consisting of graphite, carbon black, ketjen black, acetylene black, carbon nanotube, fullerene, activated carbon, vulcan black and mixtures thereof.

The carbon-based material preferably has a particle size of 30 nm to 100 μm in terms of coating efficiency, and more preferably, has a particle size of 30 nm to 50 μm.

In the present invention, a resol type phenolic resin is used as an adhesive for surface treatment on sand.

In the case of using a conventional noblock type phenolic resin, hexamine must be used as a curing agent, and thus there is a problem of ammonia generation due to pyrolysis of hexamine and contaminating working environment. However, the resol type phenolic resin does not need to use a curing agent, so there is no concern about generating ammonia gas and it is possible to improve the working environment in manufacturing the filler for steel ladle.

In addition, in the present invention, since the spray coating of the carbon-based material and the resol-type phenol resin in order to increase the thermal efficiency in the production of the filler, it is preferable to use a resol-type phenol resin in the liquid form.

In the case of using a conventionally novolak phenolic resin having a relatively large particle size, when a large particle resin is added to a heated sand, the noblock resin having a smaller amount of input than the sand is softened locally. However, it is difficult to uniformly spread the surface softened phenolic resin throughout the sand. In contrast, in the present invention, by spray coating the liquid resol type phenolic resin, uniform coating is possible by spray particles having a larger surface area than the sand surface area.

The surface treatment composition includes a carbon-based material and a resol-based phenol resin in a weight ratio of 10: 1 to 1: 1, and preferably in a weight ratio of 5: 1 to 1: 1. When included in the content ratio is preferable because it can be a uniform coating that does not adhere to each other between particles.

The surface treatment composition may further include an additive selected from the group consisting of polyvinyl alcohol, sodium carboxymethyl cellulose, silica sol-based adhesives containing 2 to 5 wt% of potassium hydroxide in silica sol, sodium silicate, silica silicate, and mixtures thereof. It may be included, the additive is preferably used to adjust the content according to the purpose of use.

The surface treatment step for the sand is preferably carried out at a temperature of 100 to 150 ℃, more preferably at a temperature of 100 to 120 ℃. If the temperature during the surface treatment is less than 100 ℃, uniform surface treatment of the resol-type phenol resin to the sand is difficult.

The surface treated sand is then mixed in a mixer.

The mixing process is to form a surface treatment layer with a uniform thickness with respect to the sand surface, the mixing process may be carried out divided once to several times. Preferably, the mixing step is a secondary mixing step in which the carbon coating liquid-coated sand and the less-coated sand are mixed, that is, a first mixing process in which the spreading process is performed, and a homogeneous mixing and solvent volatilization, such as alcohol, are performed in a state where the carbon coating liquid is expanded. It is divided, and more preferably, may be divided into a first mixing process of mixing at 35 to 45 rpm and a second mixing process of mixing at 35 to 45 rpm. By dividing the mixing process in two steps as described above, the mixing time can be reduced, the efficiency can also be increased, and the surface treatment layer having a more uniform thickness for the sand can be formed.

By the above-mentioned manufacturing method, carbon-based materials such as graphite can be uniformly coated on the sand surface, and thermal efficiency during manufacturing can be improved, and there is no fear of generating ammonia gas due to decomposition of hardener such as hexamine. Can be improved. As a result, the ladle filler produced by the manufacturing method of the present invention has no sintering or fusion, penetration of molten steel at the time of discharging molten steel, and shows high porosity.

Accordingly, according to another embodiment of the present invention provides a filler prepared by the manufacturing method.

Specifically, the filler is a core including a sand; And a surface treatment layer surrounding the core and comprising a carbonaceous material, a resol type phenol resin, and optionally an additive.

The type and content of the sand, carbon-based material, resol type phenol resin and additives are the same as described above.

The filler may exhibit an excellent filler effect by including the carbon-based material and the resol-based phenol resin in a weight ratio of 10: 1 to 1: 1, preferably 5: 1 to 1: 1.

In addition, the surface treatment layer is formed uniformly with respect to the core material as shown in Figure 2 with respect to the core material.

The present invention provides a manufacturing apparatus useful in the manufacture of the filler according to another embodiment.

1 is a schematic diagram schematically showing an apparatus for manufacturing a filler for a steel ladle equipped with a vertical heating furnace according to an embodiment of the present invention. 1 is only an example of the present invention and the present invention is not limited thereto.

Referring to Figure 1, the manufacturing apparatus is located in the sand supply unit 1, the sand supply unit to which the sand is injected, the heat treatment for the sand dropped from the sand supply unit and the sand to be heated and dropped It includes a vertical heating furnace (2), the surface treatment is continuously performed, the mixing unit is located in the lower portion of the vertical heating furnace, the mixing process is performed for the surface-treated sand dropped from the vertical heating furnace. At this time, the mixing section is also located in the first mixing section 3, the first mixing section, the first mixing section is performed on the surface-treated sand dropped from the vertical heating furnace, 1 in the first mixing section It may include a second mixing unit 4 is performed a secondary mixing process for the secondary mixed mixture.

In detail, when sand is supplied into the sand supply part 1 through the sand inlet 1a, the supplied sand falls to the vertical heating furnace 2 located below the sand supply part 1. Heat heated by a heating device 2a such as a burner mounted in the vertical furnace 2 rises from the bottom of the vertical furnace 2 and naturally preheats the sand charged into the vertical furnace 2. The preheated sand is gradually heated while falling and moving down the furnace.

When the sand reaches a temperature suitable for the surface treatment of the carbon-based material to 100 to 150 ℃ to spray the surface treatment composition to be coated on the sand surface.

Although the heating device 2a is illustrated as being located at the side of the heating furnace 2, the position is not particularly limited, and may be located at the center of the heating furnace.

Sand coated with a carbon-based material is collected in the first mixing portion 3 below the heating furnace and firstly mixed at 35 to 45 rpm, and then moved to the second mixing portion 4 located at the bottom of the first mixing portion. After the second mixing process at 35 to 45rpm is discharged through the outlet (5).

As described above, the manufacturing apparatus including the vertical heating furnace has high thermal efficiency because the air heated by the heating device directly heats the sand, and also has a low temperature variation, so that the surface treatment of the resol type phenolic resin to the sand is uniform. Is possible.

Since the filler prepared by the above-described manufacturing method and manufacturing apparatus includes a uniform resol type phenolic resin layer on the sand surface, there is no sintering or fusion, penetration of molten steel during discharge of molten steel, and high porosity. .

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

Example  : steel For ladle Filler  Produce

500 g of graphite powder having a particle size of 44 µm or less, 50 g of polyvinylalcohol (PVA), and 50 g of sodium carboxymethyl cellulose (CMC) were added to 1 L of water, followed by stirring to prepare a graphite dispersion. Separately, 500 g of the resol-type phenol resin was dissolved in 1 L of ethylene glycol as a polyhydric alcohol to prepare a phenol resin solution. The graphite dispersion solution and the resol-type phenol resin solution prepared above were put into a stirrer and stirred at 500 rpm for 5 minutes to prepare a surface treatment composition including graphite and a resol type phenolic resin.

100 kg of sand having a particle size of 0.1 mm to 1.3 mm was added to a heating device having a structure as shown in FIG. 1, and the injected sand was heated in a heating zone of 100 to 120 ° C. and then dropped onto a stirring plate at the bottom of the heating zone. The prepared surface treatment composition was sprayed. At this time, the surface treatment process for the sand surface was carried out while maintaining a temperature of 100 to 120 ℃. The surface treated sand was first mixed at 35 to 45 rpm on the lower stir plate, and then mixed at 35 to 45 rpm in the stirrer directly below to prepare a filler for steel ladle.

Comparative Example  : steel For ladle Filler  Produce

A graphite dispersion was prepared by adding 500 g of graphite powder having a particle size of 44 μm or less, 50 g of polyvinylalcohol (PVA), and 50 g of sodium carboxymethyl cellulose (Na-CMC) in 1 L of water, followed by stirring. Separately, 500 g of a particulate novolak-type phenol resin was prepared.

100 kg of sand having a particle size of 0.1 mm to 1.3 mm was added to a heating apparatus equipped with a horizontal heating rotary furnace, and the injected sand was heated in a rotary furnace at 150 ° C., and then the graphite dispersion liquid prepared in the above-described form and a particulate noblock type Phenol resin was added and mixed for 5 to 10 minutes. While the mixing was almost finished, the filling material for the steel ladle was prepared by spraying the hexaamine aqueous dispersion, which is a curing agent, to the extent that the adhered particles were disintegrated.

Test Example  : Property evaluation

1) fluidity evaluation

The fillers prepared in Examples and Comparative Examples were placed in the upper and lower opening cylinders for the fluidity test, respectively, and then the cylinders were lifted to measure the height (H) of the filler.

Experimental results The filler of Example 1 has a lower height (H) than the filler of the comparative example.

2) Anti-blocking Resistance

50 g of each of the fillers prepared in Examples and Comparative Examples was charged to an alumina crucible, put in a dry oven maintained at 100 ° C., 200 ° C. and 300 ° C., respectively, and maintained for 30 minutes, and then the degree of adhesion was compared.

As a result of the experiment, both the fillers prepared in Examples and Comparative Examples showed good blocking resistance without adhesion.

3) Sinterability

50 g of each of the fillers prepared in Examples and Comparative Examples was charged into an alumina crucible, set in a vacuum furnace, and maintained at 1500 ° C. for 30 minutes, and then the degree of sintering was compared.

As a result of the experiment, both the fillers of Examples and Comparative Examples were not sintered, but in the case of the fillers of Comparative Examples, some entanglement occurred.

4) Coating state

Carbon coating conditions of the steel fillers prepared in Examples and Comparative Examples were examined under a microscope. The results are shown in FIGS. 2 and 3, respectively.

2 is a microscopic picture of a filler for a steel ladle prepared according to the embodiment, Figure 3 is a microscopic picture of a filler for a steel ladle prepared according to a comparative example.

As shown in Figure 2, the filler prepared according to the embodiment is carbon is uniformly coated, in particular it can be seen that evenly coated at an angled corner. On the other hand, the filler prepared according to the comparative example as shown in Figure 3 can be seen that the coating state is uneven and the corner portion is not properly coated.

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 right.

1: Sand supply part 1a: Sand inlet
2: vertical furnace 2a: heating device
3: first mixing unit 4: second mixing unit
5: Outlet
10: apparatus for manufacturing filler for steel ladle

Claims (16)

Heating the sand while dropping it in the vertical furnace;
Surface-treating the sand by spraying a surface treatment composition including a carbon-based material and a resol-type phenolic resin on the sand which is heated and dropped; And
Mixing the surface treated sand in a mixer
Lt; / RTI >
The grain size of the sand is 0.1mm to 1.3mm,
Mixing the surface-treated sand in the mixer is a method of manufacturing a filler for steel ladle comprising a first mixing step and a second mixing step. The method of claim 1,
Said sand is selected from the group consisting of silica sand, chromite sand, zircon sand, alumina, mulite-based ceramics and mixtures thereof. delete The method of claim 1,
The heating process for the sand is a method of producing a filler for steel ladle is carried out at 100 to 150 ℃. The method of claim 1,
The carbon-based material is graphite, carbon black, Ketjen black, acetylene black, carbon nanotubes, fullerene, activated carbon, vulcan black and a method for producing a filler for steel ladle is selected from the group consisting of. The method of claim 1,
The carbon-based material is a manufacturing method of the filler for steel ladle having a particle size of 30nm to 100㎛. The method of claim 1,
The surface treatment composition is a method for producing a filler for steel ladle comprising a carbon-based material and a resol-based phenol resin in a weight ratio of 10: 1 to 1: 1. The method of claim 1,
The surface treatment composition is a method for producing a filler for a steel ladle is prepared by mixing a dispersion prepared by dispersing a carbon-based material in water and a solution prepared by dissolving a resol type phenol resin in a polyhydric alcohol. The method of claim 1,
The surface treatment composition further comprises an additive selected from the group consisting of polyvinyl alcohol, sodium carboxymethyl cellulose, silica sol-based adhesives mixed with 2 to 5% by weight of potassium hydroxide in silica sol, sodium silicate, silica silicate, and mixtures thereof. Method for producing a filler for steel ladle. The method of claim 1,
The surface treatment process for the sand is a method of producing a filler for steel ladle is carried out at a temperature of 100 to 150 ℃. delete The filler material for a steel ladle manufactured by the manufacturing method of any one of Claims 1, 2, and 4-10. The method of claim 12,
The filler comprises a core comprising a sand, and a surface treatment layer surrounding the core, comprising a carbon-based material and a resol type phenolic resin. The method of claim 12,
The filler is a steel ladle filler comprising a carbon-based material and a resol-based phenol resin in a weight ratio of 10: 1 to 1: 1. Sand supply unit into which sand is injected,
Located in the lower portion of the sand supply unit, the vertical heating furnace for continuously performing the heat treatment for the sand dropped from the sand supply unit and the surface treatment for the sand falling by heating, and
Located in the lower portion of the vertical furnace, the mixing unit is performed a mixing process for the surface-treated sand dropped from the vertical furnace
Lt; / RTI >
The grain size of the sand is 0.1mm to 1.3mm,
The mixing unit is a first mixing unit in which the first mixing process is performed on the surface-treated sand dropped from the vertical heating furnace, and a mixture located in the lower portion of the first mixing unit, and the first mixed in the first mixing unit Apparatus for manufacturing a filler for a steel ladle comprising a second mixing unit is a secondary mixing process for. delete

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