BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to a device for manufacturing molten iron, and a method for manufacturing molten iron using the same. More particularly, the present invention relates to a device for manufacturing molten iron in a FINEX process for maintaining an inside of a fluidized bed reduction furnace used for reduction of powdered iron ore in the FINEX process at a temperature that is appropriate for the reduction of powdered iron ore, and a method for manufacturing molten iron using the same.
(b) Description of the Related Art
Steel used in modern industries such as for vehicles, shipbuilding, home appliances, or construction is generally manufactured in an order of an iron making process, a steel making process, a continuous casting process, and a rolling process. Pig iron is manufactured by using a blast furnace method in the iron making process. The blast furnace method represents a method for inputting coke manufactured with iron ore having undergone a sintering process and bituminous coal as base materials into a blast furnace and supplying oxygen thereto, thereby manufacturing pig iron.
However, according to the blast furnace method, subsidiary installations such as a coke manufacturing installation for manufacturing bituminous coal to

be coke and a sintering installation for sintering iron ore have to be provided. Further, environment-contaminating materials are generated by the subsidiary installations, so a cleansing installation for cleansing the environment contaminating materials has to be provided together with the subsidiary installations according to the blast furnace method. Additional costs caused by supplying the subsidiary installation and the cleansing installation are applied to a steel production cost, so the production cost of steel is high according to the blast furnace method. Therefore, the blast furnace method is replaced with a fusion and reduction method in the current steel industry. The fusion and reduction method is also referred to as a FINEX method.
The blast furnace method uses iron ore in a lump (or lump iron ore) form having undergone a sintering process or natural lump iron ore, while the FINEX process uses iron ore in a powder form (powdered iron ore). In addition, the blast furnace method uses coke generated by processing bituminous coal, and the FINEX process uses coal for a general use. The FINEX method does not need a coke manufacturing installation, an iron ore sintering installation, and a cleansing installation, and uses powdered iron ore that is less expensive than lump iron ore and coal for a general use that is less expensive than bituminous coal, so it has the merit of reducing the steel production cost. Also, the FINEX method has a very eco-friendly merit compared to the blast furnace method.
In the FINEX process, a fluidized bed reduction furnace for reducing powdered iron ore and a melter-gasifier for manufacturing pig iron by fusing the reduced powdered iron ore and the coal for a general use are used. To reduce powdered iron ore, a combustible gas and oxygen are supplied into the fluidized

bed reduction furnace. The combustible gas passes through a dispersing plate formed on a lower portion of the fluidized bed reduction furnace, is uniformly input into the fluidized bed reduction furnace, and fluidizes powdered iron ore.
Oxygen is input to the fluidized bed reduction furnace through a bed burner mounted on a side of the fluidized bed reduction furnace to react with the combustible gas and control an internal temperature of the fluidized bed reduction furnace to be appropriate for the reduction of powdered iron ore. However, when the combustible gas in the fluidized bed reduction furnace is combusted with oxygen, carbon dioxide and aqueous vapor are formed. As shown in FIG. 1, when a ratio of carbon dioxide and aqueous vapor in the combustible gas increases, the reduction force on the powdered iron ore is weakened.
To solve this problem, the use amount of the coal for a general use functioning as a reducing agent is increased, which however deteriorates a work efficiency of the FINEX process and substantially increases the production cost.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.
SUMMARY OF THE INVENTION
The present invention has been made in an effort to provide a device for manufacturing molten iron of a FINEX process for supplying heat to a fluidized bed in a fluidized bed reduction furnace without a loss of reduced gas, and a method for manufacturing molten iron by using the same.

An exemplary embodiment of the present invention provides a device for manufacturing molten iron including: a fluidized bed reduction furnace for providing reduced iron; a melter-gasifier for charging the reduced iron and inputting oxygen to manufacture molten iron; and a plasma torch for inputting plasma gas into the fluidized bed reduction furnace.
The plasma torch may form a flame by use of the plasma gas and may supply heat into the fluidized bed reduction furnace.
The plasma gas may be one of hydrogen, nitrogen, helium, and argon
gas.
0 An average temperature of a fluidized bed provided inside the fluidized
bed reduction furnace may be 500℃ to 1000 ℃.
The device may further include a power supply installed outside the fluidized bed reduction furnace, and connected to the plasma torch.
The power supply may supply energy of 1 to 100 MWh to the plasma 5 torch.
The fluidized bed reduction furnace may include a dispersing plate
through which reduced gas passes, and the plasma torch may be provided on
the dispersing plate and may be provided on an external wall of the fluidized bed
reduction furnace.
0 A plurality of plasma torches may be provided on the external wall of the
fluidized bed reduction furnace.
The device may further include a reduced gas supply pipe for supplying reduced gas discharged by the melter-gasifier to the fluidized bed reduction furnace.

According to the exemplary embodiment of the present invention, the plasma torch for supplying heat into the fluidized bed reduction furnace is installed to raise the temperature of the fluidized bed in the fluidized bed reduction furnace.
Further, the dispersing plate may be prevented from being damaged by installing the plasma torch at an appropriate location.
In addition, plasma gas is used to raise the temperature of the fluidized bed and no reduced gas is used, thereby increasing the reduction rate of powdered iron ore and increasing the work efficiency of the FINEX process.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a phase equilibrium diagram of CO, CO2, H2, H2O, Fe, FeO, Fe3O4, and Fe2O3.
FIG. 2 shows a configuration of a device for manufacturing molten iron according to an exemplary embodiment of the present invention.
FIG. 3 shows a fluidized bed reduction furnace according to an exemplary embodiment of the present invention.
FIG. 4 shows a top plan view of a fluidized bed reduction furnace according to an exemplary embodiment of the present invention.
FIG. 5 shows a flowchart of a method for manufacturing molten iron according to an exemplary embodiment of the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers, and/or sections, they are not limited thereto. These terms are only used to

distinguish one element, component, region, layer, or section from another
element, component, region, layer, or section. Thus, a first element,
component, region, layer, or section discussed below could be termed a second element, component, region, layer, or section without departing from the teachings of the present invention.
The technical terms used herein are to simply mention a particular exemplary embodiment and are not meant to limit the present invention. An expression used in the singular encompasses the expression of the plural, unless it has a clearly different meaning in the context. In the specification, it is to be understood that the terms such as "including", "having", etc., are intended to indicate the existence of specific features, regions, numbers, stages, operations, elements, components, or combinations thereof disclosed in the specification, and are not intended to preclude the possibility that one or more other specific features, regions, numbers, operations, elements, components, or combinations thereof may exist or may be added.
Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meanings as those generally understood by those with ordinary knowledge in the field of art to which the present invention belongs. Such terms as those defined in a generally used dictionary are to be interpreted to have the meanings equal to the contextual meanings in the relevant field of art, and are not to be interpreted to have idealized or excessively formal meanings unless clearly defined in the present application.
The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of

the invention are shown. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.
FIG. 2 shows a device for manufacturing molten iron according to an exemplary embodiment of the present invention. The device for manufacturing molten iron of FIG. 2 exemplifies the present invention, and the present invention is not limited thereto. Therefore, the device for manufacturing molten iron is modifiable in various ways.
The device for manufacturing molten iron 100 includes a fluidized bed reduction furnace 20 and a melter-gasifier 10. The device for manufacturing molten iron 100 may include other devices as needed.
The fluidized bed reduction furnace 20 transforms iron ore and a supplementary material into reduced iron by reducing and firing the same. The iron ore charged into the fluidized bed reduction furnace 20 is formed in advance, passes through the fluidized bed reduction furnace 20, and is manufactured to be reduced iron. The iron ore and the supplementary material charged into the fluidized bed reduction furnace 20 form a fluidized bed 1 inside the fluidized bed reduction furnace 20. The fluidized bed reduction furnace 20 is a packed bed type of reduction furnace, and it receives reduced gas from the melter-gasifier 10 and forms a packed bed inside the same.
The melter-gasifier 10 includes the coal packed bed inside the same, and it charges reduced iron and inputs oxygen into the same to thus manufacture molten iron. The reduced gas discharged by the melter-gasifier 10 is supplied to the fluidized bed reduction furnace 20 through a reduced gas supply pipe 40,

passes through the fluidized bed reduction furnace 20, is used for reducing and firing the iron ore and the supplementary material, and is then discharged to the outside.
Respective constituent elements configuring the device for
manufacturing molten iron 100 according to an exemplary embodiment of the present invention will now be described in detail.
The device for manufacturing molten iron 100 temporarily stores powdered iron-containing ore with a particle size that is less than 8 mm and at room temperature and supplementary materials in a hopper, removes moisture in a drier, and mixes to manufacture an iron-containing mix. The manufactured iron-containing mix is charged into the fluidized bed reduction furnace 20. The device for manufacturing molten iron 100 includes an equalizing and relief system between the drier and the fluidized bed reduction furnace 20 so that the iron-containing mix at room temperature may be charged, at normal pressure, into the fluidized bed reduction furnace 20 that is maintained at a pressure of 1.5 to 3.
The powdered iron-containing ore and the supplementary material supplied to the fluidized bed reduction furnace 20 contact a reduced gas at a high temperature to form a bubbling fluidized bed, which increases the temperature to be equal to or greater than 80 ℃, and is changed to the reduced iron at a high temperature, which is reduced by 80 % and is fired by equal to or greater than 30 %.
Although not shown in FIG. 2, a high temperature solidifying device may be further included so as to prevent a drift loss that is generated when the

reduced iron discharged by the fluidized bed reduction furnace 20 is charged into the melter-gasifier 10.
Lump coal or a coal briquette including powdered coal is supplied to the melter-gasifier 10 to form a coal packed bed. The lump coal or coal briquette input to the melter-gasifier 10 is gasified by a thermal decomposition reaction on an upper portion of the coal packed bed and a combustion reaction caused by the oxygen on a lower portion. The high-temperature reduced gas generated by the melter-gasifier 10 according to a gasifying reaction passes through the reduced gas supply pipe 40, is supplied to the fluidized bed reduction furnace 20, and is used as a reducing agent and a fluidizing gas.
An empty space in a dome form is formed on an upper portion of the packed bed of the melter-gasifier 10. By reducing a gas velocity by this, a large amount of fine particles included in the charged reduced iron and fine particles generated according to a steep rise of temperature of the coal charged into the melter-gasifier 10 are prevented from being discharged out of the furnace. Further, variations of pressure in the melter-gasifier 10 caused by irregular variations of the generated amount of gas caused by direct use of coal are absorbed. In the packed bed, coal drops to a lower portion to be devolatilized and is gasified, and it is combusted by the oxygen blown through a tuyere provided on the lower portion of the furnace. The combustion gas in this instance rises on the packed bed, is changed to high-temperature reduced gas, and is discharged outside of the melter-gasifier 10, and part of it passes through a dust collector, its dust is removed, and it is cooled so that the pressure applied to the melter-gasifier 10 may be maintained at the range of 3.0 to 3.5.

A cyclone collects flue gas generated by the melter-gasifier 10, supplies dust to the melter-gasifier 10, and supplies gas to the fluidized bed reduction furnace 20 through the reduced gas supply pipe 40. The reduced iron drops together with coal in the packed bed, is finally reduced and fused by reduced gas and combustion heat generated by coal gasification and combustion, and is discharged to the outside.
The reduced gas discharged by the melter-gasifier 10 passes through the fluidized bed reduction furnace 20 and its temperature gradually lowers, so the device for manufacturing molten iron according to the present exemplary embodiment may additionally include a plasma torch 30 for raising the temperature.
FIG. 3 shows a fluidized bed reduction furnace and a plasma torch according to an exemplary embodiment of the present invention. Referring to FIG. 3, to prevent the temperature-raised reduced gas from damaging a dispersing plate 21 provided on a lower portion of the fluidized bed reduction furnace 20 or clogging the dispersing plate 21 according to an exemplary embodiment of the present invention, plasma gas 2 is input to an area to which reduced gas of the fluidized bed reduction furnace 20 is provided, and it is then combusted.
For this purpose, according to the present invention, as shown in FIG. 3, the plasma torch 30 is provided on an external wall of the fluidized bed reduction furnace 20, and is disposed on an upper portion of the dispersing plate 21 to thus supply the plasma gas 2 into the fluidized bed reduction furnace 20.
FIG. 4 shows a top plan view of a fluidized bed reduction furnace and a

plasma torch according to an exemplary embodiment of the present invention. Referring to FIG. 4, a plurality of plasma torches 30 may be provided along an external circumference of the fluidized bed reduction furnace 20, and the number of plasma torches 30 is variable.
In the present exemplary embodiment, the plasma torch 30 may use plasma gas 2 to form a flame 3 and supply heat into the fluidized bed reduction furnace 20, and hence, the fluidized bed 1 in the fluidized bed reduction furnace 20 absorbs heat. An average temperature of the fluid bed 1 may be maintained at 500℃ to 1000 ℃.
In the present exemplary embodiment, the plasma gas 2 may be
hydrogen, nitrogen, helium, or argon gas. Accordingly, the device for
manufacturing molten iron 100 according to the present exemplary embodiment may supply heat to the fluidized bed 1 in the fluidized bed reduction furnace 20 without using the reduced gas supplied into the fluidized bed reduction furnace 20 from the melter-gasifier 10.
Further, it is not combusted by using oxygen, so carbon dioxide and aqueous vapor are not generated in the fluidized bed reduction furnace 20, and the reduction rate of powdered iron ore may be increased. As a result, as the powdered iron ore manufactured at a high reduction rate is used by the melter-gasifier 10, the work efficiency of the FINEX process is increased and the pig iron production cost may be decreased.
A length of the flame 3 using plasma gas 2 is generally less than a length of a diffusing flame formed by the bed burner used in the fluidized bed reduction furnace 20, so a contact area with the fluidized bed 1 is reduced, and the amount

of the fused material generated in the fluidized bed reduction furnace 20 may be reduced by the high-temperature flame.
In the present exemplary embodiment, the plasma torch 30 may receive electric power from a power supply 31 installed outside the fluidized bed reduction furnace 20. The power supply 31 may provide energy of 1 to 100 MWh to the plasma torch 30.
The power supply 31 may include a controller for controlling an energy supply amount so that the temperature of the fluidized bed 1 may be maintained at 500℃ to 1000 ℃. As described, the device for manufacturing molten iron
100 according to present exemplary embodiment includes an independent power supply 31, so it may independently control the heat supplied into the fluidized bed reduction furnace 20 regardless of the working conditions of the fluidized bed reduction furnace.
A method for manufacturing molten iron by use of the above-described device will now be described.
FIG. 5 shows a flowchart of a method for manufacturing molten iron according to an exemplary embodiment of the present invention. Referring to FIG. 5, the device for manufacturing molten iron 100 according to an exemplary embodiment of the present invention allows an iron-containing mix generated by mixing a powdered iron-containing ore and a supplementary material to pass through the fluidized bed reduction furnace 20, reduces them, fires them, and thereby changes them into reduced iron (S100). The powdered iron-containing ore and the supplementary material contact the high-temperature reduced gas flow to form a bubbling fluidized bed, and they are changed to high-temperature

reduced iron of which the temperature rises to be greater than 80 ℃, and which
is reduced by 80 %, and which is fired by equal to or greater than 30 %.
The reduced iron is charged into the melter-gasifier 10, and the oxygen is input thereto to manufacture molten iron (S200). Lump coal or coal briquettes made of powdered coal is supplied to the melter-gasifier 10 to form a coal packed bed. The lump coal or the coal briquettes input to the melter-gasifier 10 is gasified by a thermal decomposition reaction on the upper portion of the coal packed bed and a combustion reaction by oxygen on the lower portion. The reduced iron drops together with coal in the coal packed bed, it is finally reduced and melted by reduced gas generated by coal gasification and combustion and heat of combustion, and it is discharged to the outside.
The high-temperature reduced gas generated by the melter-gasifier 10 according to a gasifying reaction is supplied to the fluidized bed reduction furnace 20 through the reduced gas supply pipe 40 (S300).
The temperature of the reduced gas generated by the melter-gasifier 10 is gradually lowered when it passes through the fluidized bed reduction furnace 20, so the method for manufacturing molten iron according to the present exemplary embodiment inputs plasma gas 2 to the area to which reduced gas is input and combusts the same in the stage S100 for changing the iron-containing mix into reduced iron.
The plasma gas 2 forms a flame to supply heat to the fluidized bed reduction furnace 20, so the fluidized bed 1 inside the fluidized bed reduction furnace 20 absorbs heat. The average temperature of the fluidized bed 1 may be maintained at 500℃ to 1000 ℃.

Accordingly, the method for manufacturing molten iron according to the present exemplary embodiment may supply heat to the fluidized bed 1 provided inside the fluidized bed reduction furnace 20 without using reduced gas supplied to the fluidized bed reduction furnace 20 from the melter-gasifier 10.
Further, it is not combusted by using oxygen, so the carbon dioxide and aqueous vapor are not generated in the fluidized bed reduction furnace 20 and the reduction rate of powdered iron ore may be increased. As a result, as the powdered iron ore manufactured at a high reduction rate is used by the melter-gasifier 10, the work efficiency of the FINEX process is increased and the pig iron production cost may be decreased.
The length of the flame 3 using plasma gas 2 is generally less than a length of a diffusing flame formed by the bed burner used in the fluidized bed reduction furnace 20, so a contact area with the fluidized bed 1 is reduced, and the amount of the fused material generated in the fluidized bed reduction furnace 20 may be reduced by the high-temperature flame.
While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

We claim:
1. A device for manufacturing molten iron comprising:
a fluidized bed reduction furnace for providing reduced iron;
a melter-gasifier for charging the reduced iron and inputting oxygen to manufacture molten iron; and
a plasma torch for inputting plasma gas into the fluidized bed reduction furnace.
2. The device of claim 1, wherein
the plasma torch forms a flame by use of the plasma gas and supplies heat into the fluidized bed reduction furnace.
3. The device of claim 2, wherein
the plasma gas is one of hydrogen, nitrogen, helium, and argon gas.
4. The device of claim 1, wherein
an average temperature of a fluidized bed provided inside the fluidized bed reduction furnace is 500℃ to 1000℃.
5. The device of claim 1, further comprising
a power supply installed outside the fluidized bed reduction furnace, and connected to the plasma torch.

6. The device of claim 5, wherein
the power supply supplies energy of 1 to 100 MWh to the plasma torch.
7. The device of claim 1, wherein
the fluidized bed reduction furnace includes a dispersing plate through which reduced gas passes, and
the plasma torch is provided on the dispersing plate, and is provided on an external wall of the fluidized bed reduction furnace.
8. The device of claim 7, wherein
a plurality of plasma torches are provided on the external wall of the fluidized bed reduction furnace.
9. The device of claim 1, further comprising
a reduced gas supply pipe for supplying reduced gas discharged by the melter-gasifier to the fluidized bed reduction furnace.
10. A method for manufacturing molten iron, comprising:
allowing an iron-containing mix generated by mixing and constructing powdered iron-containing ore and a supplementary material to pass through a fluidized bed reduction furnace, and performing reduction and firing to change the same to reduced iron;
charging the reduced iron into a melter-gasifier, and inputting oxygen to the melter-gasifier to manufacture molten iron; and

supplying reduced gas discharged by the melter-gasifier to the fluidized bed reduction furnace,
wherein the changing of the iron-containing mix to reduced iron includes inputting plasma gas to the area in which the reduced gas is input, and combusting the same.
11. The method of claim 10, wherein
the plasma gas is one of hydrogen, nitrogen, helium, and argon gas.
12. The method of claim 10, wherein
an average temperature of a fluidized bed inside the fluidized bed reduction furnace is 500℃ to 1000 ℃.