Molten iron manufacturing equipment and molten iron manufacturing method

Abstract

Provided are a molten iron production facility and a molten iron production method capable of minimizing the amount of energy required for melting. 【Solution means】The molten iron production facility according to an embodiment of the present invention includes a reduction unit capable of producing reduced iron, a melting unit capable of melting the reduced iron, and a processing unit disposed so as to be able to receive the supply of reduced iron from the reduction unit and to be able to receive the supply of exhaust gas discharged from the melting unit, and configured to react the received reduced iron with the exhaust gas and supply the reacted reduced iron to the melting unit. The molten iron production facility further includes an exhaust gas supply line disposed so as to connect the melting unit and the processing unit. The reduction unit includes a reduction furnace having a reduction space capable of producing reduced iron by receiving the supply of a reducing gas. The melting unit includes an electric furnace connected to the exhaust gas supply line and having a melting space capable of melting the reduced iron supplied from the processing unit using electric heat. The processing unit includes a main body having a processing space, a reduced iron inlet provided in the main body so as to be able to pour the reduced iron into the processing space, and an exhaust gas inlet provided in the main body and connected to the exhaust gas supply line so as to be able to pour the exhaust gas into the processing space. The exhaust gas inlet is provided at a position lower than the reduced iron inlet.

Description

Technical Field

[0001] The present invention relates to molten iron production equipment and a method for producing molten iron. More specifically, the present invention relates to molten iron production equipment and a method for producing molten iron, which produce reduced iron and melt the produced reduced iron to produce molten iron.

Background Art

[0002] Generally, molten iron, that is, hot metal, is produced through a blast furnace process. The blast furnace process involves processing iron ore and coal into forms suitable for use and charging them into the blast furnace while blowing in hot air. Here, the hot air burns the coal, and the carbon monoxide gas generated at this time causes a reduction reaction that separates oxygen from the iron ore. Further, the heat of 1,500 °C or higher generated inside the blast furnace causes a melting reaction that melts the iron reduced by the iron ore or carbon monoxide gas, thereby producing hot metal. In such a blast furnace process, the reduction reaction and the melting reaction occur simultaneously inside the blast furnace by the coal and the carbon monoxide gas generated therefrom. However, in such a blast furnace process, there is a problem that a large amount of carbon dioxide, which causes environmental problems such as global warming, is generated by the reduction reaction between carbon monoxide gas and iron ore.

[0003] In order to solve such problems, research and development efforts have been made on hydrogen reduction ironmaking process technologies for producing molten iron using hydrogen gas instead of fossil fuels such as coal. Fossil fuels such as coal produce carbon dioxide when reacted with iron ore, but hydrogen gas reacts with iron ore to produce water or steam. Therefore, according to the hydrogen reduction ironmaking process, carbon emissions can be significantly reduced in the production of molten iron.

[0004] In such a hydrogen reduction ironmaking process, iron ore is reduced to produce reduced iron, and the produced reduced iron is melted to produce molten iron. However, since the reduced iron produced by the reaction of hydrogen gas and iron ore has a very high melting point, a large amount of energy is required to melt it, which is a problem. In addition, a large amount of exhaust gas is generated in the process of melting the reduced iron, and at present, there is an urgent need for a device that can recycle such a large amount of exhaust gas generated in this way.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention provides molten iron production equipment and a method for producing molten iron that can minimize the amount of energy used for melting.

Means for Solving the Problems

[0007] The molten iron production equipment according to an embodiment of the present invention includes a reduction unit capable of producing reduced iron, a melting unit capable of melting reduced iron, and a processing unit disposed so as to be able to receive the supply of reduced iron from the reduction unit and also to be able to receive the supply of exhaust gas discharged from the melting unit, and reacting the received reduced iron and exhaust gas to supply the reacted reduced iron to the melting unit.

[0008] The molten iron production equipment further includes an exhaust gas supply line disposed so as to connect the melting unit and the processing unit. The reduction unit includes a reduction furnace having a reduction space capable of producing reduced iron by receiving the supply of reduction gas. The melting unit may be connected to the exhaust gas supply line and include an electric furnace having a melting space capable of melting the reduced iron supplied from the processing unit using electric heat.

[0009] The processing unit includes a main body having a processing space, an inlet for reduced iron provided in the main body so as to allow the reduced iron to flow into the processing space, and an exhaust gas inlet provided in the main body and connected to the exhaust gas supply line so as to allow the exhaust gas to flow into the processing space. The exhaust gas inlet may be provided at a position lower than the inlet for reduced iron.

[0010] The processing unit may further include a heater disposed in the main body so as to be able to heat the processing space.

[0011] The processing unit may further include a collector connected to the main body so as to be able to collect the reduced iron flowing out of the main body, and a circulation line connecting the collector and the main body so as to be able to supply the reduced iron collected in the collector to the main body.

[0012] The processing unit may further include a supplementary gas supply unit connected to the main body so as to be able to supply a supplementary gas having at least some components identical to those of the exhaust gas to the processing space.

[0013] The molten iron production facility has a storage space capable of storing raw materials, a raw material supply unit disposed so as to be able to supply the raw materials stored in the storage space to the reduction space, and an exhaust gas branch line branched from the exhaust gas supply line and capable of supplying a part of the exhaust gas discharged from the electric furnace to the raw material supply unit.

[0014] The exhaust gas branch line may be connected to the raw material supply unit so as to be able to directly supply the exhaust gas to the storage space, or so as to be able to transfer the heat of the exhaust gas to the air supplied to the storage space.

[0015] The molten iron production facility includes a purge gas supply line connected to the reduction furnace so as to be able to supply a purge gas to the reduction space, and a purge gas branch line branched from the purge gas supply line and capable of supplying a part of the purge gas supplied to the reduction space to the processing space. It may further include.

[0016] On the other hand, the method for producing molten iron according to an embodiment of the present invention includes a process of producing reduced iron, a process of reacting the produced reduced iron with a treatment gas, a process of melting the reacted reduced iron to produce a melt, and a process of using at least a part of the exhaust gas generated in the process of producing the melt as a treatment gas for reacting with the reduced iron.

[0017] The process of producing the reduced iron may include a process of preheating the raw material using the exhaust gas and a process of reacting the preheated raw material with a reducing gas to reduce it.

[0018] The process of preheating the raw material may include a process of spraying the exhaust gas onto the raw material or a process of spraying the air heated by receiving the heat transfer of the exhaust gas onto the raw material.

[0019] The raw material may include powdered iron ore having a particle size exceeding 0 mm and not exceeding 8 mm.

[0020] The treatment gas includes a gas containing a carbon component, and the process of reacting with the treatment gas may include a process of carbonizing at least a part of the reduced iron.

[0021] In the process of reacting the reduced iron with the treatment gas, the produced reduced iron can be reacted with the treatment gas without separate heat treatment.

[0022] The process of reacting the reduced iron with the treatment gas may include a process of reacting the produced reduced iron with the treatment gas at a temperature of 600 to 800°C.

[0023] The method for producing molten iron may further include a process of collecting the reduced iron flowing out from the treatment space where the reduced iron reacts with the treatment gas and a process of supplying the collected reduced iron to the treatment space.

[0024] The process of manufacturing the reduced iron includes a process of supplying a purge gas to a reduction space for manufacturing the reduced iron, and the process of reacting the reduced iron with a processing gas may include a process of supplying a part of the purge gas supplied to the reduction space to the processing space.

[0025] In the process of using the processing gas, the exhaust gas and a supplementary gas having at least some components identical to those of the exhaust gas can be used as the processing gas.

[0026] The exhaust gas contains carbon monoxide gas, and the supplementary gas may contain at least one of natural gas and biomass gas.

Advantages of the Invention

[0027] According to the present invention, the exhaust gas generated during the process is reacted with the reduced iron to lower the melting point of the reduced iron, and the amount of energy required for melting the reduced iron can be minimized.

[0028] In addition, by directly reacting the reduced iron produced at a high temperature with the high-temperature exhaust gas, the equipment and resources required for the reaction can be minimized.

[0029] Moreover, by using the sensible heat of the exhaust gas having a high temperature for preheating the raw material and producing hydrogen gas, energy can be efficiently recovered.

Brief Description of the Drawings

[0030]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0031] Hereinafter, the present invention will be described in more detail based on the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and can be embodied in various different forms. The embodiments of the present invention are provided only to make the disclosure of the present invention complete and to fully inform those with ordinary knowledge of the scope of the invention. For the purpose of detailed description of the present invention, the drawings may be shown exaggerated, and in the drawings, the same reference numerals indicate the same components.

[0032] FIG. 1 is a diagram schematically showing the molten iron production equipment of the present invention, FIG. 2 is a diagram exemplarily showing a reduction furnace for producing reduced iron and an electric furnace for melting the reduced iron, and FIG. 3 is a diagram exemplarily showing the structure of the processing section according to an embodiment of the present invention. Further, FIG. 4 is a diagram showing the conditions under which reduced iron reacts with exhaust gas, and FIG. 5 is a diagram showing how raw materials are preheated using exhaust gas in the raw material supply section. In the drawings, the arrows indicated by dotted lines show the flow of raw materials and reduced iron, and the arrows indicated by solid lines show the flow of by-products and gas.

[0033] As shown in FIGS. 1 to 5, the molten iron manufacturing facility of the present invention includes a reduction unit 500 capable of manufacturing reduced iron, a melting unit 700 capable of melting reduced iron, and a processing unit 600 disposed so as to be able to receive the supply of reduced iron from the reduction unit 500 and also to be able to receive the supply of exhaust gas discharged from the melting unit 700, and capable of reacting the received reduced iron with the exhaust gas and supplying the reacted reduced iron to the melting unit 700. Further, the molten iron manufacturing facility of the present invention may further include a raw material supply unit 100 disposed so as to be able to supply raw materials to the reduction unit 500 and a reducing gas supply unit 200 disposed so as to be able to supply reducing gas to the reduction unit 500.

[0034] The raw material supply unit 100 is disposed so as to be able to supply raw materials to the reduction unit 500. Here, the raw materials may include iron ore, and the iron ore may include fine powder iron ore having a particle size exceeding 0 mm and not exceeding 8 mm, that is, powdered iron ore. The raw material supply unit 100 may include a storage device 110 having a storage space capable of storing raw materials. The raw materials may be stored in the storage space of the storage device 110 for a long time, or may be temporarily stored before supplying the raw materials to the reduction unit 500. Such a storage device 110 may include, for example, a hopper.

[0035] In the storage space of the storage device 110, the raw materials can be preheated, and the raw materials preheated in the storage space can be supplied to the reduction unit 500. At this time, the storage device 110 can receive a part of the exhaust gas discharged from the melting unit 700 to preheat the raw materials. For this purpose, the molten iron manufacturing facility of the present invention may further include an exhaust gas branch line EDL branched from the exhaust gas supply line EL and capable of supplying a part of the exhaust gas discharged from the melting unit 700 to the storage device 110. The content of preheating the raw materials using the exhaust gas supplied through the exhaust gas branch line EDL will be described later in connection with FIG. 5.

[0036] The reducing gas supply unit 200 is arranged to store a reducing gas and supply the reducing gas to the reduction unit 500. Here, the reducing gas may contain hydrogen gas, and the hydrogen gas may be contained in the overall reducing gas at a ratio of 80 to 100%. The hydrogen gas stored in the reducing gas supply unit 200 can be produced by electrolyzing water, but the present invention is not limited thereto, and it can be produced by various methods such as decomposing ammonia gas or causing a chemical reaction of natural gas to produce hydrogen gas. For example, ammonia gas can be decomposed into hydrogen gas and nitrogen gas at a high temperature, and the decomposed hydrogen gas can be used as a reducing gas, and the nitrogen gas can be used as a purge gas described later.

[0037] The reducing gas supply unit 200 can supply a reducing gas to the reduction unit 500 via reducing gas supply lines RL1 and RL2 that connect the reducing gas supply unit 200 and the reduction unit 500 to each other. At this time, the amount of the reducing gas supplied from the reducing gas supply unit 200 to the reduction unit 500 may be twice or more the amount required to reduce all of the raw materials supplied to the reduction unit 500. In order to improve the reaction efficiency between the raw material and the reducing gas, the amount of the reducing gas can be controlled, for example, within a range of twice or more and three times or less the amount required to reduce all of the raw materials supplied to the reduction unit 500.

[0038] A heating unit 300 for heating the reducing gas supplied from the reducing gas supply unit 200 to the reduction unit 500 may be disposed in the reducing gas supply lines RL1 and RL2. In the reduction unit 500, a raw material containing iron ore reacts with a reducing gas containing hydrogen gas to reduce the iron ore. Since such a reaction between iron ore and hydrogen gas is a strong endothermic reaction, the hydrogen gas supplied to the reduction unit 500 can improve the reaction efficiency when heated and supplied at a temperature of 800 °C or higher, more preferably 850 °C or higher. For this reason, the heating unit 300 is connected to the reducing gas supply unit 200 by the first reducing gas supply line RL1 and to the reduction unit 500 by the second reducing gas supply line RL2, and heats the low-temperature hydrogen gas supplied through the first reducing gas supply line RL1 to a temperature of 800 to 1200 °C and supplies it to the reduction unit 500 through the second reducing gas supply line RL2. Since various structures for directly or indirectly heating the reducing gas can be applied to the heating unit 300, a detailed description thereof will be omitted.

[0039] The molten iron production facility of the present invention may further include a purge gas supply unit 400 disposed so as to store the purge gas and supply the purge gas to the reduction unit 500. The reduction unit 500 has a reduction space capable of producing reduced iron, and the reduction space needs to be purged for maintenance between processes. Also, it may be necessary to supply the purge gas during the process. For example, when pulverized iron ore is used as the raw material, the purge gas can be supplied to increase the fluidity of the pulverized iron ore in order to prevent the pulverized iron ore from adhering to the reduction space. For this reason, the purge gas supply unit 400 can supply the purge gas to the reduction space through a purge gas supply line PL connecting the purge gas supply unit 400 and the reduction unit 500 to each other, and an inert gas such as nitrogen can be used as the purge gas.

[0040] The reduction unit 500 can produce reduced iron by reducing the raw material. That is, the reduction unit 500 receives the supply of iron ore as the raw material from the raw material supply unit 100 and the supply of the reducing gas from the reducing gas supply unit 200, and can produce reduced iron by reacting the iron ore with the reducing gas. Such a reduction unit 500 may include a reduction furnace having a reduction space capable of producing reduced iron using the reducing gas. Such a reduction furnace may include fluidized bed reduction furnaces 510, 520, 530, 540 that produce reduced iron while flowing the raw material. The fluidized bed reduction furnaces 510, 520, 530, 540 may be provided individually, but in order to effectively reduce low-grade iron ore or powdered iron ore with a low iron content, as shown in FIG. 2, a plurality of fluidized bed reduction furnaces 510, 520, 530, 540 may be connected to each other to produce reduced iron while sequentially moving the raw material. At this time, there is no limit to the number of fluidized bed reduction furnaces 510, 520, 530, 540, but in order to sufficiently reduce the raw material, the reduction unit 500 may be composed of four reduction furnaces including the first fluidized bed reduction furnace 510, the second fluidized bed reduction furnace 520, the third fluidized bed reduction furnace 530, and the fourth fluidized bed reduction furnace 540, as shown in FIG. 2. At this time, the raw material supply unit 100 can supply the raw material to the first fluidized bed reduction furnace 510, and the reducing gas supply unit 200 can supply the reducing gas to the fourth fluidized bed reduction furnace 540. The raw material supplied to the first fluidized bed reduction furnace 510 can be produced as reduced iron by being reduced while moving through the second fluidized bed reduction furnace 520, the third fluidized bed reduction furnace 530, and the fourth fluidized bed reduction furnace 540 in this order.

[0041] The reduced iron produced in the reduction unit 500 is supplied to the processing unit 800 described later. As shown in FIG. 2, the reduced iron produced through the first fluidized reduction furnace 510, the second fluidized reduction furnace 520, the third fluidized reduction furnace 530, and the fourth fluidized reduction furnace 540 is discharged from the fourth fluidized reduction furnace 540 and supplied to the processing unit 800. Here, as described above, preheated raw materials and a reducing gas at 800°C or higher are supplied to the reduction space to produce reduced iron. Therefore, the reduced iron produced in the reduction unit 500 is discharged in a high-temperature state of, for example, 600 to 800°C even considering heat loss. In this way, the reduced iron discharged in a high-temperature state can be directly supplied to the processing unit 800 without passing through a separate heat treatment device. In the processing unit 800, by directly reacting the reduced iron produced in a high-temperature state with high-temperature exhaust gas, the equipment and resources involved in the reaction can be minimized as much as possible, which will be described later in association with the processing unit 800.

[0042] On the other hand, a large amount of by-products are discharged from the reduction unit 500 in addition to the reduced iron. The by-products discharged from the reduction unit 500 may contain steam. As described above, in the reduction unit 500, iron ore reacts with hydrogen gas to produce reduced iron. At this time, the oxygen component of the iron ore reacts with the hydrogen component of the hydrogen gas, and a large amount of water vapor is generated in the reduction space. The generated water vapor is discharged from the reduction unit 500 as a by-product. In addition, the by-products discharged from the reduction unit 500 may contain hydrogen gas and nitrogen gas. As described above, the reducing gas is supplied in a range of 2 times or more and 3 times or less the amount required to completely reduce the raw materials supplied to the reduction unit 500. Therefore, the remaining hydrogen gas that does not react with the raw materials is discharged from the reduction unit 500 as a by-product. In addition, as described above, purge gas, for example, nitrogen gas, can be supplied to the reduction unit 500 for various reasons. In this way, the nitrogen gas supplied for purging is discharged from the reduction unit 500 as a by-product. The by-products move along the flow of the reducing gas in the reduction unit 500 and are discharged from the first fluidized reduction furnace 510. The discharged by-products can be supplied to the extraction unit 600 via the by-product supply line BL connected to the reduction unit 500.

[0043] That is, the molten iron production facility according to the embodiment of the present invention may be arranged so as to receive the supply of by-products discharged from the reduction unit 500, and may further include an extraction unit 600 capable of extracting hydrogen gas from the by-products.

[0044] The extraction unit 600 extracts hydrogen gas from the by-products discharged from the reduction unit 500. As described above, the by-products discharged from the reduction unit 500 contain water vapor, hydrogen gas, and nitrogen gas. The extraction unit 600 is connected to the reduction unit 500 via the by-product supply line BL, and can extract hydrogen gas from the by-products supplied via the by-product supply line BL. Such an extraction unit 600 can extract hydrogen gas from the by-products by the pressure swing adsorption (PSA; Pressure Swing Absorption) method. That is, the pressure swing adsorption method extracts gas using the adsorption selectivity of each component with respect to the adsorbent. The extraction unit 600 can use a carbon molecular sieve capable of adsorbing hydrogen components as the adsorbent in order to extract hydrogen gas from the by-products containing various gases in addition to hydrogen gas. At this time, the hydrogen components adsorbed on the adsorbent can be desorbed and extracted as hydrogen gas. The extraction unit 600 can thus extract hydrogen gas from the by-products by repeatedly performing the adsorption and desorption of hydrogen components.

[0045] Residue discharged without being adsorbed by the extraction unit 600 may contain water vapor and nitrogen gas. Here, the residue containing water vapor and nitrogen gas can be supplied to the reduction unit 500 as purge gas. Water vapor is a reaction product generated by the reaction of iron ore, which is a raw material, and hydrogen gas in the reducing gas, and since its reactivity with iron ore and the reducing gas is low, it can be supplied to the reduction unit 500 as purge gas. Also, when water vapor is supplied to the reduction unit 500 as purge gas, the heat of the water vapor can be utilized for the reduction reaction, and the energy required for the reduction reaction can be saved. In order to supply the residue to the reduction unit 500 as purge gas, a residue discharge line (not shown) may be connected to the extraction unit 600, and the residue discharge line may be connected to the purge gas supply line PL or directly connected to the reduction unit 500 to supply the residue to the reduction unit 500 through a path different from the purge gas. Needless to say, this is also possible.

[0046] The hydrogen gas extracted in the extraction unit 600 can be used for various purposes. For example, the reduction unit 500 can reduce a raw material, that is, iron ore, using the extracted hydrogen gas. Although hydrogen gas is used in a large amount more than twice the amount required to reduce all of the raw material supplied to the reduction unit 500 and is a very expensive gas, for cost reduction through resource recycling, the hydrogen gas extracted in the extraction unit 600 can be reused as a reducing gas for reducing iron ore. For this purpose, a hydrogen gas supply line HL is connected to the extraction unit 600, and the hydrogen gas supply line HL is connected to the first reducing gas supply line RL1, and the extraction unit 600 can supply hydrogen gas to the first reducing gas supply line RL1, and the extracted hydrogen gas can be supplied to the reduction unit 500 along the hydrogen gas supply line HL, the first reducing gas supply line RL1, and the second reducing gas supply line RL2 and used for the reduction of iron ore.

[0047] The melting unit 700 can receive the supply of the reduced iron reacted in the processing unit 800 described later and melt it in various ways. For example, the melting unit 700 can receive the supply of the reacted reduced iron in the form of fine powder or agglomerated state from the processing unit 800 and heat and melt it. Further, in addition to the reacted reduced iron, the melting unit 700 can also receive the supply of iron scraps etc. and melt the reacted reduced iron and iron scraps together. Such a melting unit 700 may include electric furnaces 710, 720 having a melting space capable of melting the reacted reduced iron using electric heat. Such electric furnaces 710, 720 may include an electric furnace body 710 having a melting space and electrode rods 720 at least a part of which is arranged in the melting space so as to be able to generate electric heat. When the reacted reduced iron is charged into the melting space of the electric furnaces 710, 720, electric power is applied to the electrode rods 720 to melt the reacted reduced iron.

[0048] In the melting unit 700, in order to adjust the carbon content of the melt produced by melting the reacted reduced iron, a carbonaceous additive having a carbon component is charged. Further, the carbonaceous additive can be charged in order to generate a large amount of slag (mineral slag) during the melting of the melt. In this case, the electrode rods 720 can be in a state of being immersed in the slag and receive the application of electric power to generate resistance heat, and the reacted reduced iron can be more easily melted by the generated resistance heat. On the other hand, at least a part of the raw material that has not been reduced, that is, partially reduced reduced iron or iron ore, can be supplied to the melting unit 700. Thus, at least a part of the raw material that has not been reduced has an oxygen component, and in the melting space, the oxygen component reacts with the carbon component of the carbonaceous additive or the carbon component of the reacted reduced iron described later. For this reason, from the melting unit 700, exhaust gas containing carbon monoxide gas, that is, exhaust gas having a high concentration of carbon monoxide (CO-rich), is discharged during the melting after receiving the supply of the reacted reduced iron from the processing unit 800. Thus, the exhaust gas discharged from the melting unit 700 is discharged at a high temperature of about 1,200 °C or higher.

[0049] When the reduced iron produced in the reduction unit 500 is charged into the melting unit 700 without any separate treatment, a large amount of energy is required to melt the reduced iron in the melting unit 700. That is, the reduced iron produced in the reduction unit 500 without any separate treatment will have the component of metallic iron (Fe), that is, pure iron, and such pure iron has a melting point of about 1,538°C. Moreover, the reduced iron contains a large amount of gangue in addition to such pure iron component, and the reduced iron cannot be melted unless it is heated to a temperature above the melting point of pure iron. Moreover, when the reduced iron produced in the reduction unit 500 is charged into the melting unit 700 without any separate treatment, a large amount of carburizer is required to adjust the carbon content of the melt.

[0050] On the other hand, when the reduced iron is carbonized, the component of pure iron will change to the cementite (Fe3C) phase, which has a melting point of about 1,200°C or lower. Thus, when melting the reduced iron in which at least a part of the components has been changed to the cementite (Fe3C) phase, the amount of energy used for melting the reduced iron can be minimized as much as possible. Moreover, when melting the carbonized reduced iron, that is, iron carbide, the melt has a part of carbon component. Therefore, when melting iron carbide, the amount of carburizer charged to adjust the carbon content of the melt can be minimized as much as possible.

[0051] Therefore, the present invention is provided with a treatment unit 800 that can react the reduced iron supplied from the reduction unit 500 with the exhaust gas having a high concentration of carbon monoxide (CO-rich) discharged from the melting unit 700 and supply the reacted iron carbide to the melting unit 700. For this purpose, the molten iron production facility of the present invention may further include an exhaust gas supply line EL disposed so as to connect the melting unit 700 and the treatment unit 800.

[0052] At this time, as shown in FIG. 3, the processing unit 800 includes a main body 810 having a processing space, a reduced iron inlet 812 provided in the main body 810 so that reduced iron can be poured into the processing space, and an exhaust gas inlet 816 provided in the main body 810 and connected to an exhaust gas supply line EL so that exhaust gas can be poured into the processing space.

[0053] The main body 810 has a processing space capable of accommodating the reduced iron supplied from the reduction unit 500. In order to pour the reduced iron into the processing space, a reduced iron inlet 812 is provided in the main body 810, and a reduced iron supply pipe FL is connected to the reduced iron inlet 812 so that the reduced iron produced and conveyed in the reduction unit 500 can flow into the processing space through the reduced iron supply pipe FL. Further, the exhaust gas discharged from the melting unit 700 can flow into the processing space of the main body 810. For this purpose, an exhaust gas inlet 816 can be formed in the main body 810, and the exhaust gas inlet 816 can be connected to the exhaust gas supply line EL. In FIG. 3, the processing unit 800 is shown as being composed of a single main body 810, but it goes without saying that the processing unit 800 can also carbonize the reduced iron while connecting a plurality of main bodies 810 to each other and sequentially moving the reduced iron.

[0054] Here, the exhaust gas inlet 816 may be provided at a position lower than the reduced iron inlet 812. For example, as shown in FIG. 3, the exhaust gas inlet 816 may be provided on the lower surface of the main body 810, and the reduced iron inlet 812 may be provided on the side surface of the main body 810. In this way, by providing the exhaust gas inlet 816 at a position lower than the reduced iron inlet 812, the reduced iron supplied from the reduced iron inlet 812 can be reacted with the exhaust gas while flowing in the main body 810. On the other hand, the processing unit 800 may further include a dispersion plate 817 provided in the main body 810 and formed with a number of nozzles (not shown) for uniformly dispersing the exhaust gas supplied from the exhaust gas inlet 816 into the processing space.

[0055] At this time, the reduced iron produced in the reduction unit 500 is discharged, for example, in a high-temperature state of 600 to 800 °C, and the discharged reduced iron is directly supplied to the processing unit 800 without passing through a separate heat treatment device. Further, since high-temperature exhaust gas of about 1,200 °C or higher is supplied to the processing space, even considering the heat loss of the reduced iron during the conveyance process, the processing space can maintain a temperature of 600 to 800 °C. For this reason, a separate heating means for heating the processing space may not be provided in the processing unit 800. However, since there is a possibility that the initial driving of the equipment or the need to further increase the temperature of the processing space may occur, the processing unit 800 may further include a heater 820 disposed in the main body 810 so as to be able to heat the processing space. At this time, the heater 820 can selectively operate to heat the processing space when it is necessary to heat the processing space. Such a heater 820 is disposed, for example, on the side surface of the main body 810 and can supply oxygen gas, and the supplied oxygen gas can react with the exhaust gas in the processing space to increase the temperature of the processing space. At this time, the amount of oxygen gas supplied from the heater 820 may be controlled so as to maintain the processing space within a temperature range of 600 to 800 °C.

[0056] The processing unit 800 reacts the reduced iron supplied from the reduction unit 500 with the exhaust gas to carbonize it. As shown in a Bauer-Glaessner diagram showing the conditions under which the reduced iron shown in FIG. 4 reacts with the exhaust gas, the reduced iron can react and carbonize as in the following reaction formula when the temperature of the processing space is maintained at 600 to 800 °C and the partial pressures of carbon monoxide and carbon dioxide in the processing space satisfy specific conditions.

[0057] [Reaction formula] TIFF2025525175000002.tif9128

[0058] That is, when reduced iron and exhaust gas in a high-temperature state are supplied to the processing space and the processing space is maintained at a temperature of 600 to 800°C, the reduced iron is carbonized by reacting as in the above reaction formula when the partial pressure Pco of carbon monoxide has a value of about 90% or more with respect to the value Pco+Pco2 obtained by adding the partial pressure Pco of carbon monoxide and the partial pressure Pco2 of carbon dioxide. Here, as described above, the melting part 700 may include electric furnaces 710 and 720 capable of melting reduced iron, that is, an electric smelting furnace (ESF: Electric Smelting Furnace) or a submerged arc furnace (SAF: Submerged Arc Furnace) that is immersed in the slag formed in the electric furnace body 710 and can melt reduced iron by slag resistance heat. Such electric furnaces 710 and 720 have a closed structure and have almost no inflow of oxygen or air. Therefore, the content of carbon dioxide in the exhaust gas is very low, and the oxygen component of the unreduced raw material and the carbon component of the carbon additive react to have a high concentration of carbon monoxide. That is, the exhaust gas discharged from such electric furnaces 710 and 720 has a value of about 90% or more with respect to the value Pco+Pco2 obtained by adding the partial pressure Pco of carbon monoxide and the partial pressure Pco2 of carbon dioxide, and can effectively carbonize reduced iron under the temperature condition of 600 to 800°C.

[0059] On the other hand, the molten iron production facility according to the embodiment of the present invention may further include a supplementary gas supply unit 900 arranged so as to be able to supply a supplementary gas having at least some components the same as those of the exhaust gas to the processing space of the processing unit 800. The supplementary gas supply unit 900 can supply a supplementary gas having at least some components the same as those of the exhaust gas, that is, a carbon-containing gas, to the processing unit 800, and the supplementary gas supply unit 900 can supply the carbon-containing gas to the processing unit 800 via a supplementary gas supply line SL. Here, the supplementary gas supply line SL can be connected to the exhaust gas supply line EL to supply the supplementary gas together with the exhaust gas, or can supply the supplementary gas to the processing unit 800 through a path different from the exhaust gas supply line EL. The supplementary gas may include at least one of natural gas having a carbon component and biomass gas obtained by gasifying biomass.

[0060] Further, the molten iron manufacturing facility according to the embodiment of the present invention may further include a purge gas branch line PDL branched from the purge gas supply line PL and capable of supplying a part of the purge gas supplied to the reduction space to the treatment space. The treatment space needs to be purged for maintenance, and purge gas can be supplied to prevent fine reduced iron from adhering to the treatment space during the process. Therefore, the purge gas branch line PDL can be branched from the purge gas supply line PL and supply purge gas to the treatment space.

[0061] Thus, the reduced iron reacted in the treatment unit 800, that is, iron carbide, is supplied to the melting unit 700. Here, the reaction between the reduced iron and the exhaust gas according to the above-described reaction formula corresponds to an exothermic reaction. Therefore, the iron carbide supplied from the treatment unit 800 to the melting unit 700 is discharged in a state at substantially the same temperature as the treatment space, for example, a high temperature state of 600 to 800°C, even considering heat loss. In this way, the iron carbide discharged in the high temperature state can be directly supplied to the melting unit 700 in the high temperature state without passing through a separate cooling device, and the amount of energy required for melting the reduced iron can be minimized.

[0062] On the one hand, most of the reduced iron supplied to the processing space is supplied to the melting part 700 after reacting in the processing space. However, the fine reduced iron cannot fully react with the exhaust gas and may flow due to the exhaust gas and flow out of the processing space together with the exhaust gas. Therefore, the processing unit 800 may further include a collector 840 connected to the main body 810 so as to be able to collect the reduced iron flowing out from the main body 810, and a circulation line CL connecting the collector 840 and the main body 810 so as to be able to supply the reduced iron collected in the collector 840 to the main body 810. At this time, the collector 840 may be disposed so as to be connected to the upper part of the main body 810 and connected to the discharge pipe XL through which the exhaust gas is discharged. The fine reduced iron collected in the collector 840 can also be resupplied to the processing space of the main body 810 through the circulation line CL. At this time, the circulation line CL may be directly connected to the processing space, but it can also be connected to the above-described reduced iron supply pipe FL to resupply the fine reduced iron collected in the collector 840 to the processing space of the main body 810.

[0063] As described above, the exhaust gas discharged from the melting part 700 can be supplied to the processing unit 800 and used to carbonize the reduced iron. However, as described above, the exhaust gas discharged from the melting part 700 is discharged in a high-temperature state of about 1,200 °C or higher. Therefore, the present invention can also preheat the raw material by utilizing the thermal energy of the exhaust gas.

[0064] As shown in FIG. 5, the raw material supply unit 100 may include a storage tank 110, and the storage tank 110 has a storage space capable of storing raw materials. In the storage space of the storage tank 110, the raw materials can be preheated, and the raw materials preheated in the storage space can be supplied to the reduction unit 500. For this purpose, the raw material supply unit 100 may further include a preheating gas supply device 120 arranged so as to be able to supply preheating gas to the storage space of the storage tank 110. At this time, as shown in FIG. 5(a), the preheating gas supply device 120 is connected to the exhaust gas branch line EDL and can directly supply high-temperature exhaust gas E having a temperature of about 1,200° C. or higher to the storage space to preheat the raw materials. Further, as shown in FIG. 5(b), the preheating gas supply device 120 may be arranged so as to heat the external air A supplied to the storage space with the heat of the exhaust gas having a temperature of 1,200° C. or higher and supply the heated air to the storage space to preheat the raw materials. For this purpose, the preheating gas supply device 120 may be arranged so as to intersect the exhaust gas branch line EDL, that is, may be arranged above the exhaust gas branch line EDL, whereby the sensible heat of the exhaust gas passing through the exhaust gas branch line EDL can reach the external air A.

[0065] The molten iron production facility according to the embodiment of the present invention can produce reduced iron by moving reduced iron and exhaust gas along the above-described respective pipes and reacting them. The movement of the reduced iron and the exhaust gas can be controlled using valves (not shown) arranged in the pipes, and it goes without saying that such valves can be arranged at various positions to control the flow rate and flow velocity of the reduced iron and the gas moving along each pipe.

[0066] Hereinafter, a method for producing molten iron according to an embodiment of the present invention will be described. The method for producing molten iron according to the embodiment of the present invention may be a method for producing molten iron using the above-described molten iron production facility. For this reason, since the content described above regarding the molten iron production facility is applicable as it is, the description of overlapping content will be omitted.

[0067] FIG. 6 is a diagram schematically showing a method for producing molten iron according to an embodiment of the present invention.

[0068] As shown in FIG. 6, the method for producing molten iron according to the present invention includes a process (S100) of producing reduced iron, a process (S200) of reacting the produced reduced iron with a processing gas, a process (S300) of melting the reacted reduced iron to produce a melt, and a process (S400) of using at least a part of the exhaust gas generated in the process of producing the melt as a processing gas for reacting with the reduced iron. Here, each process can be continuously performed to produce molten iron, and it goes without saying that it may not correspond to a chronological relationship in which another process is performed after any one process is performed and completed.

[0069] The process (S100) of producing reduced iron is performed by supplying a raw material and a reducing gas to a reduction unit 500. That is, the process (S100) of producing reduced iron may include a process of supplying a raw material to the reduction unit 500, a process of supplying a reducing gas to the reduction unit 500, and a process of reducing the raw material by reacting it with the reducing gas.

[0070] The process of supplying the raw material is performed by a raw material supply unit 100 arranged to supply the raw material to the reduction unit 500 supplying the raw material to the reduction unit 500. Here, the raw material may include iron ore, and the iron ore may include fine iron ore having a particle size exceeding 0 mm and not exceeding 8 mm, that is, powdered iron ore. On the other hand, the process of supplying the raw material may include a process of preheating the raw material. The present invention can suppress as much as possible the energy required for reduction by supplying and reducing the preheated raw material, that is, iron ore.

[0071] The process of supplying the reducing gas is carried out by the reducing gas supply unit 200 supplying the reducing gas to the reduction unit 500. Here, the reducing gas may contain hydrogen gas, and the hydrogen gas may be contained in the total reducing gas at a ratio of 80 to 100%. The process of supplying the reducing gas is carried out by the reducing gas supply unit 200 supplying the reducing gas to the reduction unit 500 via the reducing gas supply lines RL1 and RL2 that connect the reducing gas supply unit 200 and the reduction unit 500 to each other. At this time, the amount of the reducing gas supplied to the reduction unit 500 in the process of supplying the reducing gas can be controlled within a range of not less than 2 times and not more than 3 times the required amount for reducing all the raw materials supplied to the reduction unit 500.

[0072] In the process of supplying the reducing gas, the reducing gas can be heated to a temperature of 800 to 1200 °C and then supplied to the reduction unit 500. When hydrogen gas is used as the reducing gas, the iron ore supplied to the reduction unit 500 reacts with the hydrogen gas to produce reduced iron. Since such a reaction between the iron ore and the hydrogen gas is a strong endothermic reaction, the hydrogen gas supplied to the reduction unit 500 can be heated to a temperature of 800 °C or higher, more preferably 850 °C or higher. When the reducing gas heated in this way is supplied, the reaction efficiency can be improved.

[0073] Also, the process (S100) of manufacturing reduced iron may further include a process of supplying a purge gas to the reduction unit 500. Here, the process of supplying the purge gas can be carried out by the purge gas supply unit 400 arranged to be able to supply the purge gas to the reduction unit 500 supplying the purge gas to the reduction space via the purge gas supply line PL. At this time, as the purge gas, an inert gas such as nitrogen can be used.

[0074] In the process of reacting and reducing the raw material with the reducing gas, the reduction unit 500 receives the supply of the raw material from the raw material supply unit 100 and the supply of the reducing gas from the reducing gas supply unit 200, and can react and reduce the iron ore with the reducing gas. Such a reduction unit 500 may include a reduction furnace having a reduction space capable of producing reduced iron using the reducing gas. The reduction furnace may be provided as a single unit. However, as described above, in order to effectively reduce low-grade iron ore or powdered iron ore with a low iron content, a plurality of reduction furnaces can be connected to each other to produce reduced iron while sequentially moving the raw material.

[0075] On the other hand, in the process of reacting and reducing the raw material with the reducing gas, a large amount of by-products are generated in addition to the reduced iron. The by-products generated and discharged in the reduction unit 500 may include water vapor generated by the reaction of iron ore and hydrogen gas, and may also include hydrogen gas that could not react with the raw material and nitrogen gas supplied to the purge gas. In addition to these, dust generated in the reduction unit 500 can be included in the by-products and discharged. The by-products can move along the flow of the reducing gas in the reduction unit 500 and be discharged from the reduction furnace.

[0076] Thus, the by-products discharged from the reduction furnace can be used in the production of hydrogen gas. That is, the method for producing molten iron of the present invention may further include a process of collecting the by-products generated in the process of producing reduced iron and a process of extracting hydrogen gas from the collected by-products. As described above, the by-products discharged from the reduction unit 500 include water vapor, hydrogen gas, nitrogen gas, and dust. An extraction unit 600 is disposed in the reduction unit 500 so as to be able to receive the supply of the by-products discharged from the reduction unit 500. Here, the dust may be removed before the by-products are supplied to the extraction unit 600 or from within the extraction unit 600. The extraction unit 600 can extract hydrogen gas from the by-products received through the by-product supply line BL by means of pressure swing adsorption.

[0077] In the process of extracting hydrogen gas, the extracted hydrogen gas can be used for various purposes. However, the reduction unit 500 uses hydrogen gas to reduce the raw material, i.e., iron ore, and the hydrogen gas is used in a large amount more than twice the amount required to reduce all the raw materials supplied to the reduction unit 500. Since it is a very expensive gas, for cost reduction through resource recycling, the hydrogen gas extracted in the extraction unit 600 can be reused as a reducing gas for reducing iron ore. For this reason, the method for producing molten iron according to the present invention can be used for reducing iron ore by supplying it as a reducing gas during the process (S100) of producing reduced iron with the extracted hydrogen gas. On the other hand, the residue discharged without being able to extract hydrogen gas in the process of extracting hydrogen gas can be supplied to the reduction unit 500 as a purge gas. The water vapor in the residue is a reaction product generated by the reaction of the raw material iron ore and the hydrogen gas in the reducing gas, and since its reactivity with the iron ore and the reducing gas is low, it can be supplied to the reduction unit 500 as a purge gas. Also, when water vapor is supplied to the reduction unit 500 as a purge gas, the heat of the water vapor can be utilized in the reduction reaction, and the energy required for the reduction reaction can be saved.

[0078] In the process (S200) of reacting with the treatment gas, the reduced iron produced in the reduction unit 500 is reacted with the treatment gas. Here, the treatment gas includes a gas containing a carbon component, and the process (S200) of reacting with the treatment gas may include a process of carbonizing at least a part of the reduced iron produced in the reduction unit 500.

[0079] That is, as described above, when the reduced iron produced in the reduction unit 500 is melted without any separate treatment, since the reduced iron has a very high melting point, a large amount of energy is required for melting. However, in contrast, when the reduced iron is carbonized, the melting point can be lowered by several hundred degrees Celsius or more. Therefore, in the method for producing molten iron of the present invention, by reacting the reduced iron with a treatment gas and supplying the reacted reduced iron, that is, iron carbide, to the melting unit 700 for melting, the amount of energy used for melting can be suppressed as much as possible. At this time, the treatment gas may include a gas containing a carbon component.

[0080] Here, in the process (S200) of reacting with the treatment gas, the reduced iron can be reacted with the treatment gas without any separate heat treatment. That is, the reduced iron produced in the reduction unit 500 is discharged, for example, in a high-temperature state of 600 to 800°C, and the discharged reduced iron is directly supplied to the treatment unit 800 without passing through a separate heat treatment device. Further, since the exhaust gas at a high temperature of about 1,200°C or higher is supplied to the treatment space, even considering the heat loss of the reduced iron in the transportation process, the treatment space can be maintained at a temperature of 600 to 800°C. Therefore, in the process (S200) of reacting with the treatment gas, the produced reduced iron can be reacted with the treatment gas at a temperature of 600 to 800°C. When there is a need for an initial stage of the process or further temperature increase, the treatment space can be selectively heated via the heater 820.

[0081] The reduced iron can be carbonized by reacting as in the above reaction formula when the partial pressure of carbon monoxide and the partial pressure of carbon dioxide in the treatment space satisfy specific conditions when the treatment space is maintained at a temperature of 600 to 800°C. That is, when the reduced iron and the exhaust gas in a high-temperature state are supplied to the treatment space and the treatment space is maintained at a temperature of 600 to 800°C, the reduced iron reacts and is carbonized as in the above reaction formula when the partial pressure Pco of carbon monoxide has a value of about 90% or more with respect to the value Pco + Pco2 obtained by adding the partial pressure Pco of carbon monoxide and the partial pressure Pco2 of carbon dioxide.

[0082] Here, in order to react reduced iron with a processing gas to carbonize it, the molten iron production method of the present invention may include a process (S400) of using at least a part of the exhaust gas generated during the production of the melt as a processing gas for reacting with the reduced iron. That is, in the process (S400) of using as the processing gas, at least a part of the exhaust gas generated in the process (S300) of producing the melt is used as a processing gas for reacting with the reduced iron in the process (S200) of reacting the produced reduced iron with the processing gas. As described above, the melting section 700 may include electric furnaces 710 and 720 having a melting space capable of melting reduced iron using electric heat. In such a melting section 700, in order to adjust the carbon content of the melt produced by melting the reduced iron, a carbonaceous additive having a carbon component is introduced. On the other hand, the melting section 700 can be supplied with at least a part of the raw material that has not been reduced, that is, partially reduced reduced iron or iron ore. In this way, at least a part of the raw material that has not been reduced has an oxygen component, and in the melting space, the oxygen component reacts with the carbon component of the carbonaceous additive. For this reason, from the melting section 700, exhaust gas containing carbon monoxide gas, that is, exhaust gas having a high concentration of carbon monoxide (CO-rich), is discharged during the melting of the reduced iron. In this way, the exhaust gas discharged from the melting section 700 is discharged at a high temperature of about 1,200 °C or higher.

[0083] At this time, the melting section 700 may include electric furnaces 710 and 720 capable of melting reduced iron, that is, an ESF (Electric Smelting Furnace) or SAF (Submerged Arc Furnace) capable of melting reduced iron by slag resistance heat by being immersed in the slag formed in the electric furnace body 710. Such electric furnaces 710 and 720 have a very low carbon dioxide content in the exhaust gas, and the oxygen component of the unreduced raw material reacts with the carbon component of the carbonaceous additive to have a high concentration of carbon monoxide. Therefore, the exhaust gas discharged from the electric furnaces 710 and 720 has a value of about 90% or more with respect to the value Pco + Pco2 obtained by adding the partial pressure Pco of carbon monoxide and the partial pressure Pco2 of carbon dioxide, and can effectively carbonize the reduced iron under the temperature condition of 600 to 800 °C.

[0084] On the other hand, in the process of reacting with the processing gas (S200), a supplementary gas in which at least some components are the same as those of the exhaust gas can be used as the processing gas together with the exhaust gas. As described above, the supplementary gas supply unit 900 can supply a supplementary gas in which at least some components are the same as those of the exhaust gas, that is, a carbon-containing gas, to the processing unit 800, and the supplementary gas supply unit 900 can supply the carbon-containing gas to the processing unit 800 via the supplementary gas supply line SL. Here, the supplementary gas supply line SL is connected to the exhaust gas supply line EL and can supply the supplementary gas together with the exhaust gas, and the supplementary gas may contain at least one of natural gas having a carbon component and biomass gas obtained by gasifying biomass.

[0085] At this time, most of the reduced iron supplied to the processing space in the process of reacting with the processing gas (S200) reacts with the exhaust gas and is supplied to the melting part 700, but the fine reduced iron cannot fully react with the exhaust gas and may flow due to the exhaust gas and flow out of the processing space together with the exhaust gas to the outside.

[0086] Therefore, the method for producing molten iron according to the present invention may further include a process of collecting the reduced iron flowing out from the processing space where the reduced iron reacts with the processing gas and a process of supplying the collected reduced iron to the processing space.

[0087] Here, the process of collecting the flowing-out reduced iron is performed via a collector 840 connected to the main body 810 so as to collect the reduced iron flowing out from the main body 810, and the collector 840 may be disposed so as to be connected to the upper part of the main body 810 and connected to the discharge pipe XL through which the exhaust gas is discharged. Further, in the process of supplying the collected reduced iron to the processing space, the fine reduced iron collected in the collector 840 is re-supplied to the processing space of the main body 810 via the circulation line CL. At this time, the circulation line CL may be directly connected to the processing space, but may also be connected to the above-described reduced iron supply pipe FL to re-supply the fine reduced iron collected in the collector 840 to the processing space of the main body 810.

[0088] The process (S300) of manufacturing the melt is carried out by the melting unit 700 receiving the reduced iron, i.e., iron carbide, reacted from the processing unit 800 and melting the received iron carbide. That is, the melting unit 700 can receive the supply of fine powder or agglomerated iron carbide from the processing unit 800 and heat and melt it. Also, the process (S300) of manufacturing the melt can be carried out by the melting unit 700 receiving the supply of iron carbide from the processing unit 800 and melting the received iron carbide using electric heating. At this time, the melting unit 700 may be provided with an electric furnace having a melting space capable of melting iron carbide using electric heating. Such an electric furnace may include an electric furnace body having a melting space and electrode rods at least a part of which is disposed in the melting space to generate electric heat. The melting unit 700 can apply electric power to the electrode rods to melt the iron carbide when reduced iron is charged into the melting space.

[0089] Here, the process (S300) of manufacturing the melt may include the process of charging a carbonizing agent into the melting unit 700, i.e., the melting space of the electric furnace. In the melting unit 700, a carbonizing agent having a carbon component is charged to adjust the carbon content of the melt produced by melting the reduced iron. Also, the carbonizing agent can be charged to generate a large amount of slag during the melting of the melt. The electrode rods 720 can be immersed in such slag to generate resistance heat, and the generated resistance heat can make it easier to melt the iron carbide. At this time, since the iron carbide supplied from the processing unit 800 already contains a large amount of carbon component, the usage amount of the carbonizing agent can be minimized in the process (S300) of manufacturing the melt.

[0090] On the one hand, as described above, from the melting unit 700, exhaust gas containing carbon monoxide gas, that is, exhaust gas having a high concentration of carbon monoxide (CO-rich) and a temperature of about 1,200 °C or higher is discharged during the melting of reduced iron. Therefore, in the process of preheating the above-described raw material, the exhaust gas discharged from the melting unit 700 in this way, that is, the exhaust gas discharged in the process of producing the melt described below, can be used to preheat the raw material. Since the exhaust gas discharged from the melting unit 700 is discharged in a high-temperature state of about 1,200 °C or higher, the heat energy of the exhaust gas can be utilized to preheat the raw material.

[0091] To describe this in more detail, the process of preheating the raw material may include a process of directly spraying a part of the exhaust gas discharged from the melting unit 700 onto the raw material. In the process of supplying the raw material, the raw material stored in the storage space of the storage vessel 110 is supplied to the reduction unit 500. Such a storage vessel 110 may be provided with a preheating gas supply device 120 arranged so as to be able to supply preheating gas to the storage space of the storage vessel 110. At this time, in the process of preheating the raw material, the raw material can be preheated by spraying high-temperature exhaust gas having a temperature of about 1,200 °C or higher from the preheating gas supply device 120 onto the raw material stored in the storage space. Further, the preheating gas supply device 120 can also preheat the raw material by spraying heated external air onto the raw material stored in the storage space. At this time, in the process of preheating the raw material, the preheating gas supply device 120 can also heat the external air with the heat of the exhaust gas having a temperature of 1,200 °C or higher and supply the heated air to the storage space to preheat the raw material.

[0092] Thus, according to the present invention, the exhaust gas generated during the process can be reacted with the reduced iron to lower the melting point of the reduced iron, and the amount of energy used for melting the reduced iron can be minimized as much as possible.

[0093] In addition, by directly reacting the reduced iron produced in a high-temperature state with the high-temperature exhaust gas, the equipment and resources required for the reaction can be minimized as much as possible.

[0094] Moreover, by using the sensible heat of the exhaust gas having a high temperature for preheating the raw material and producing hydrogen gas, energy can be efficiently recovered.

[0095] As described above, the preferred embodiments of the present invention have been described and illustrated using specific terms. However, these terms are merely for clearly explaining the present invention, and it is obvious that various changes and modifications can be made to the embodiments of the present invention and the described terms without departing from the technical idea and scope of the claims. These modified embodiments should not be individually understood as departing from the idea and scope of the present invention, but should be said to belong within the scope of the claims of the present invention.

Explanation of Reference Numerals

[0096] 100 Raw material supply section 110 Reservoir 120 Preheated gas supply device 200 Reducing gas supply section 400 Purge gas supply section 500 Reduction section 510, 520, 530, 540 Fluidized reduction furnace 600 Treatment section 700 Melting section 710, 720 Electric furnace 800 Treatment section 810 Main body 812 Reduced iron inlet 816 Exhaust gas inlet 817 Dispersion plate 820 Heater 840 Collector 900 Make-up gas supply section

Claims

1. A reduction section capable of producing reduced iron, A melting section capable of melting the reduced iron, A treatment section disposed so as to be capable of receiving the supply of reduced iron from the reduction section and also capable of receiving the supply of exhaust gas discharged from the melting section, and reacting the received reduced iron with the exhaust gas to supply the reacted reduced iron to the melting section, A molten iron production facility characterized by comprising these components.

2. Further comprising an exhaust gas supply line disposed so as to connect the melting section and the treatment section, The reduction section includes a reduction furnace having a reduction space capable of producing reduced iron by receiving the supply of reduction gas, The melting section is connected to the exhaust gas supply line and includes an electric furnace having a melting space capable of melting the reduced iron supplied from the treatment section using electric heat. The molten iron production facility according to Claim 1.

3. The treatment section, A main body having a treatment space, A reduced iron inlet provided in the main body so as to be capable of pouring reduced iron into the treatment space, An exhaust gas inlet provided in the main body and connected to the exhaust gas supply line so as to be capable of pouring exhaust gas into the treatment space, Comprises, The molten iron production facility according to Claim 2, characterized in that the exhaust gas inlet is provided at a position lower than the reduced iron inlet.

4. The treatment section, Further comprising a heater disposed in the main body so as to be capable of heating the treatment space. The molten iron production facility according to Claim 3.

5. The treatment section, A collector connected to the main body so as to be capable of collecting the reduced iron flowing out of the main body, A circulation line connecting the collector and the main body so as to be capable of supplying the reduced iron collected in the collector to the main body, Further comprising these components. The molten iron production facility according to Claim 3.

6. The treatment section, Further comprising a supplementary gas supply section connected to the main body so as to be capable of supplying a supplementary gas having at least some components identical to those of the exhaust gas to the treatment space. The molten iron production facility according to Claim 3.

7. A raw material supply section having a storage space capable of storing raw materials and disposed so as to be capable of supplying the raw materials stored in the storage space to the reduction space, An exhaust gas branch line branched from the exhaust gas supply line and capable of supplying a part of the exhaust gas discharged from the electric furnace to the raw material supply section, Further comprising these components. The molten iron production facility according to Claim 2.

8. The molten iron manufacturing facility according to claim 7, wherein the exhaust gas branch line is connected to the raw material supply unit so as to directly supply exhaust gas to the storage space or to transfer the heat of the exhaust gas to the air supplied to the storage space.

9. A purge gas supply line connected to the reduction furnace so as to supply purge gas to the reduction space; A purge gas branch line branched from the purge gas supply line and capable of supplying a part of the purge gas supplied to the reduction space to the treatment space; The molten iron manufacturing facility according to claim 3, further comprising the same.

10. A process of manufacturing reduced iron; A process of reacting the produced reduced iron with a treatment gas; A process of melting the reacted reduced iron to produce a melt; A process of using at least a part of the exhaust gas generated in the process of producing the melt as a treatment gas for reacting with the reduced iron; A method for manufacturing molten iron, comprising the same.

11. The process of manufacturing the reduced iron is A process of preheating the raw material using the exhaust gas; A process of reducing the preheated raw material by reacting it with a reducing gas; The method for manufacturing molten iron according to claim 10, comprising the same.

12. The process of preheating the raw material is The method for manufacturing molten iron according to claim 11, comprising a process of spraying the exhaust gas onto the raw material or spraying the air heated by receiving the heat transfer of the exhaust gas onto the raw material.

13. The raw material includes pulverized iron ore having a particle size exceeding 0 mm and not exceeding 8 mm, according to the method for manufacturing molten iron according to claim 11.

14. The treatment gas includes a gas containing a carbon component, The process of reacting with the treatment gas is The method for manufacturing molten iron according to claim 10, comprising a process of carbonizing at least a part of the reduced iron.

15. In the process of reacting the reduced iron with the treatment gas, The method for manufacturing molten iron according to claim 10, wherein the produced reduced iron is reacted with the treatment gas without separate heat treatment.

16. The process of reacting the reduced iron with the treatment gas is The method for manufacturing molten iron according to claim 10, comprising a process of reacting the produced reduced iron with the treatment gas at a temperature of 600 to 800°C.

17. A process of collecting the reduced iron flowing out from the treatment space where the reduced iron is reacted with the treatment gas; A process of supplying the collected reduced iron to the treatment space; The method for producing molten iron according to claim 10, further comprising

18. The process of producing the reduced iron includes a process of supplying a purge gas to the reduction space for producing the reduced iron, The process of reacting the reduced iron with a processing gas includes a process of supplying a part of the purge gas supplied to the reduction space to the processing space, and is characterized in that it is the method for producing molten iron according to claim 17.

19. In the process of using as the processing gas the method for producing molten iron according to claim 10, characterized in that the exhaust gas and a supplementary gas having at least some components identical to the exhaust gas are used as the processing gas.

20. The exhaust gas contains carbon monoxide gas, The method for producing molten iron according to claim 19, characterized in that the supplementary gas contains at least one of natural gas and biomass gas.

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