Steelmaking method

Abstract

A steelmaking method according to an embodiment of the present invention includes the steps of charging first raw materials into a blast furnace to produce molten pig iron, charging second raw materials into an electric furnace to produce first molten steel, and charging the molten pig iron, the first molten steel, and iron scrap into a converter to produce second molten steel. The amount of carbon dioxide (K) emitted when producing 1 ton of the second molten steel is defined by the following equation 1. The amount of carbon dioxide (K) emitted when producing 1 ton of the second molten steel satisfies the following equation 2. [Formula 1] The amount of carbon dioxide emitted when producing 1 ton of second molten steel (K) = α × X + β × Y + γ × Z [Formula 2] The amount of carbon dioxide emitted when producing 1 ton of the second molten steel (K)

Description

[Technical Field]

[0001] The present invention relates to a method for producing steel. [Background technology]

[0002] Common methods for producing steel include the blast furnace-converter process and the electric furnace process.

[0003] The blast furnace-converter process includes a process of charging iron ore and bituminous coal (e.g., coke) into a blast furnace and melting them with hot air to produce molten iron, and a process of charging the molten iron tapped from the blast furnace into a converter to remove impurities such as carbon and produce molten steel.

[0004] The electric arc furnace process involves melting steel scrap in an electric arc furnace (EAF) to produce molten steel.

[0005] The molten steel produced by the above two methods is manufactured into semi-finished products through a continuous casting process, and the semi-finished products are then manufactured into finished products through a subsequent rolling process.

[0006] Meanwhile, rapid climate change caused by greenhouse gas emissions from various industries has become a hot topic of discussion internationally in recent years. The steel industry is currently conducting research and development to reduce emissions of carbon dioxide, a typical example of a greenhouse gas. Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a steelmaking method that can reduce the amount of carbon dioxide emitted during the steelmaking process. [Means for solving the problem]

[0008] A steelmaking method according to an embodiment of the present invention includes the steps of charging first raw materials into a blast furnace to produce molten pig iron, charging second raw materials into an electric furnace to produce first molten steel, and charging the molten pig iron, the first molten steel, and iron scrap into a converter to produce second molten steel, wherein an amount of carbon dioxide (K) emitted when producing 1 ton of the second molten steel is defined by the following equation 1, and the amount of carbon dioxide (K) emitted when producing 1 ton of the second molten steel satisfies the following equation 2: [Formula 1] The amount of carbon dioxide emitted when producing 1 ton of the second molten steel (K) = α × X + β × Y + γ × Z In the formula 1, X is a mass ratio of the molten pig iron among the molten pig iron, the first molten steel, and the iron scrap, Y is a mass ratio of the first molten steel among the molten pig iron, the first molten steel, and the iron scrap, Z is a mass ratio of the iron scrap among the molten pig iron, the first molten steel, and the iron scrap, and X+Y+Z=1; α, β, and γ are the carbon dioxide emission coefficient of the molten iron, the carbon dioxide emission coefficient of the first molten steel, and the carbon dioxide emission coefficient of the iron scrap, respectively; [Formula 2] The amount of carbon dioxide emitted when producing 1 ton of the second molten steel (K) < α In the formula 2, α is as defined in the formula 1.

[0009] In one embodiment, X may be greater than or equal to 0 and less than 1, Y may be greater than or equal to 0 and less than or equal to 1, and Z may be greater than or equal to 0 and less than or equal to 1.

[0010] In one embodiment, X may be greater than or equal to 0.4 and less than 1.

[0011] In one embodiment, the steelmaking method satisfies the following formula 3. [Formula 3] (X / (X+Z))×100(%)≦80(%) In the formula 3, X and Z are as defined in the formula 1.

[0012] In one embodiment, the amount of carbon dioxide (K) emitted when producing 1 ton of the second molten steel may be 1.7 tons or less.

[0013] In one embodiment, in the step of producing the second molten steel, the temperature of the first molten steel may be equal to or higher than the temperature of the molten pig iron.

[0014] In one embodiment, producing the second molten steel may include mixing the molten pig iron and the first molten steel to form an intermediate molten metal, and then mixing the intermediate molten metal and the iron scrap to form a final molten metal.

[0015] In one embodiment, the step of producing the second molten steel may include simultaneously mixing the molten pig iron, the first molten steel, and the iron scrap to produce the second molten steel.

[0016] In one embodiment, the first material may include iron ore, and the second material may include at least one of hot briquetted iron (HBI), direct reduced iron (DRI), and iron scrap.

[0017] In one embodiment, the method may further include continuously casting the second molten steel to produce a slab.

[0018] A steelmaking method according to an embodiment of the present invention includes the steps of producing a first molten metal, producing a second molten metal having a carbon content lower than that of the first molten metal, and producing molten steel by charging the first molten metal, the second molten metal, and scrap iron into a converter, wherein an amount of carbon dioxide (K) emitted when producing 1 ton of the second molten steel is defined by the following equation 1, and the amount of carbon dioxide (K) emitted when producing 1 ton of the second molten steel satisfies the following equation 2: [Formula 1] The amount of carbon dioxide emitted when producing 1 ton of the second molten steel (K) = α × X + β × Y + γ × Z In the formula 1, X is a mass ratio of the molten pig iron among the molten pig iron, the first molten steel, and the iron scrap, Y is a mass ratio of the first molten steel among the molten pig iron, the first molten steel, and the iron scrap, Z is a mass ratio of the iron scrap among the molten pig iron, the first molten steel, and the iron scrap, and X+Y+Z=1; α, β, and γ are the carbon dioxide emission coefficient of the molten iron, the carbon dioxide emission coefficient of the first molten steel, and the carbon dioxide emission coefficient of the iron scrap, respectively; [Formula 2] The amount of carbon dioxide emitted when producing 1 ton of the second molten steel (K) < α In the formula 2, α is as defined in the formula 1.

[0019] In one embodiment, the carbon content of the first molten metal may be 2 wt% or more, and the carbon content of the second molten metal may be 2 wt% or less.

[0020] In one embodiment, the first molten metal may be produced by melting raw materials including iron ore in a blast furnace, and the second molten metal may be produced by melting raw materials including iron scrap in an electric furnace.

[0021] A steelmaking method according to one embodiment of the present invention includes the steps of charging a first raw material into a blast furnace to produce molten pig iron, charging a second raw material into an electric furnace to produce a first molten steel, and charging the molten pig iron, the first molten steel, and iron scrap into a converter to produce a second molten steel. [Effects of the Invention]

[0022] A method for producing steel according to an embodiment of the present invention can reduce carbon dioxide emissions generated during the steel production process by combining molten pig iron, first molten steel, and iron scrap to produce second molten steel. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a flowchart illustrating a steelmaking method according to one embodiment of the present invention. [Figure 2] FIG. 2 is a flowchart embodying the steps for preparing the molten pig iron, electric furnace molten steel, and iron scrap shown in FIG. [Figure 3] FIG. 3 is a flowchart showing the steps of combining the molten pig iron, the molten steel in the electric furnace, and the iron scrap shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0024] All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0025] Additionally, terms such as those defined in commonly used dictionaries should be construed to have a meaning consistent with the meaning in the context of the relevant art, and are not to be construed in an idealized or overly formal sense unless expressly defined herein.

[0026] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0027] Fig. 1 is a flowchart showing a steelmaking method according to one embodiment of the present invention. Fig. 2 is a flowchart embodying the steps of preparing molten pig iron, molten steel in an electric furnace, and iron scrap shown in Fig. 1. Fig. 3 is a flowchart embodying the steps of combining the molten pig iron, molten steel in an electric furnace, and iron scrap shown in Fig. 1.

[0028] Referring to FIG. 1, a steelmaking method according to an embodiment of the present invention refers to a process of extracting iron from raw materials such as iron ore and steel scrap to manufacture steel products. Electric furnace molten steel refers to molten steel produced in an electric furnace, and may be referred to as first molten steel in this specification. Converter furnace molten steel, which will be described later, refers to molten steel produced in a converter, and may be referred to as second molten steel in this specification.

[0029] A steelmaking method S10 according to one embodiment of the present invention includes step S100 of preparing molten pig iron, molten steel in an electric furnace, and scrap iron, step S200 of combining the molten pig iron, molten steel in an electric furnace, and scrap iron, step S300 of tapping molten steel in a converter, and step S400 of manufacturing a product.

[0030] To explain step S100 of preparing hot metal, electric furnace molten steel, and scrap iron, reference is made to FIGS. 1 and 2. FIG.

[0031] 1 and 2, step S100 of preparing molten pig iron, electric furnace molten steel, and iron scrap includes step S110 of preparing molten pig iron, step S120 of preparing electric furnace molten steel, and step S130 of preparing iron scrap.

[0032] In one embodiment, the step S110 of preparing the hot metal may include a step S111 of producing the hot metal, a step S112 of repairing the hot metal, and a step S113 of transferring the hot metal.

[0033] For example, in step S111 of producing molten iron, the molten iron may be produced using a first raw material including iron ore.

[0034] Specifically, in step S111 of producing molten pig iron, iron ore and coke (COKE) are charged into a blast furnace. Next, hot air is injected into the blast furnace to reduce and melt the iron ore, producing the molten pig iron. In another embodiment, the iron ore may be charged into the blast furnace in the form of reduced iron (e.g., DRI, HBI, etc.). In another embodiment, hydrogen gas may be used as a reducing agent instead of coke.

[0035] The hot metal may contain carbon. The carbon content of the hot metal may be 2 wt% or more based on the total weight of the hot metal.

[0036] In step S112 of repairing the molten iron, the molten iron produced in the blast furnace can be transferred to a first transport vehicle. The first transport vehicle may be a TLC (torpedo ladle car). However, the first transport vehicle is not limited to this, and the first transport vehicle may be an OLC (open ladle car).

[0037] In step S113 of moving the molten iron, the first transport vehicle in which the molten iron has been repaired can be moved to the vicinity of the subsequent converter facility.

[0038] The above is an example of step S110 of preparing molten pig iron, and the method of producing molten pig iron is not limited to the above. For example, in the above-described embodiment of the present invention, the molten pig iron is produced in a blast furnace, but it is also possible to produce the molten pig iron using an electric furnace.

[0039] In one embodiment, the step S120 of preparing molten electric furnace steel may include the step S121 of producing molten electric furnace steel, the step S122 of treating the molten electric furnace steel, and the step S123 of transferring the molten electric furnace steel.

[0040] Specifically, in step S121 of producing molten steel in an electric arc furnace, a second raw material may be melted in an electric arc furnace (EAF) to produce molten metal. The second raw material may include at least one of hot briquetted iron (HBI), direct reduced iron (DRI), and iron scrap.

[0041] The molten electric furnace steel may contain carbon. The carbon content of the molten electric furnace steel may be 2 wt% or less based on the total mass of the molten electric furnace steel.

[0042] The above is an example of step S121 for producing electric furnace molten steel, and the method for producing electric furnace molten steel is not limited to the above.

[0043] In step S122 of treating the molten steel in the electric furnace, whether or not the molten steel in the electric furnace has solidified may be determined, and the temperature of the molten steel in the electric furnace may be increased or a recarburizer may be added. For example, the temperature of the molten steel in the electric furnace may be increased by an LF (Ladle Furnace) refining machine.

[0044] In step S123 of moving the molten steel from the electric furnace, the molten steel from the electric furnace is received in a ladle, and the ladle can be moved to the vicinity of the converter equipment. The ladle may be a bowl with an open top and a defined space inside.

[0045] In one embodiment, the step S130 of preparing the scrap iron may include moving the scrap iron to a location adjacent to the converter facility.

[0046] After step S100 of preparing molten pig iron, molten steel from an electric furnace, and scrap iron, step S200 of combining the molten pig iron, molten steel from an electric furnace, and scrap iron is performed.

[0047] Specifically, step S200 of combining molten pig iron, electric furnace molten steel, and iron scrap may be a step of combining molten pig iron, electric furnace molten steel (hereinafter referred to as first molten steel), and iron scrap in a converter to produce converter molten steel.

[0048] In the steelmaking method of the present invention, the amount of carbon dioxide (K) emitted to produce 1 ton of converter molten steel (hereinafter referred to as second molten steel) is defined by the following formula 1.

[0049] [Formula 1] The amount of carbon dioxide emitted when producing 1 ton of the second molten steel (K) = α × X + β × Y + γ × Z

[0050] In the above formula 1, X is the mass ratio of the molten pig iron among the molten pig iron, the first molten steel, and the iron scrap, Y is the mass ratio of the first molten steel among the molten pig iron, the first molten steel, and the iron scrap, and Z is the mass ratio of the iron scrap among the molten pig iron, the first molten steel, and the iron scrap, where X+Y+Z=1. That is, X, Y, and Z are the respective blending ratios of the molten pig iron, the first molten steel, and the iron scrap in step S200 of combining the molten pig iron, the electric furnace molten steel, and the iron scrap.

[0051] In the above formula 1, α, β, and γ are the carbon dioxide emission coefficient of the molten iron, the carbon dioxide emission coefficient of the first molten steel, and the carbon dioxide emission coefficient of the iron scrap, respectively.

[0052] In the steelmaking method of the present invention, the amount of carbon dioxide (K) emitted to produce 1 ton of converter molten steel (hereinafter referred to as second molten steel) satisfies the following formula 2.

[0053] [Formula 2] The amount of carbon dioxide emitted when producing 1 ton of the second molten steel (K) < α

[0054] In the formula 2, α is as defined in the formula 1.

[0055] Specifically, when X = 1, Y = 0, and Z = 0 in Equation 1, α corresponds to the amount of carbon dioxide (K) emitted when producing 1 ton of second molten steel. The steelmaking method of the present invention uses only molten pig iron (when X = 1, Y = 0, and Z = 0 in Equation 1) to emit an amount of carbon dioxide lower than the amount of carbon dioxide (= α) emitted when producing second molten steel, thereby reducing the amount of carbon dioxide emitted in the steelmaking process. Specifically, the steelmaking method of the present invention minimizes the blending ratio of molten pig iron, which emits a large amount of carbon dioxide, in the process of producing second molten steel, thereby reducing the amount of carbon dioxide (K) emitted when producing second molten steel.

[0056] For example, in the steelmaking method of the present invention, the amount of carbon dioxide (K) emitted when producing 1 ton of second molten steel may be 1.7 tons or less, although the present invention is not limited thereto.

[0057] In the steelmaking method of the present invention, X in formula 1 may be 0 or more and less than 1, Y may be 0 or more and 1 or less, and Z may be 0 or more and 1 or less.

[0058] In one embodiment, X in Formula 1 may be 0 or more and less than 1, Y may be more than 0 and 1 or less, and Z may be 0 or more and 1 or less. That is, the molten pig iron and the first molten steel may always be used when producing the second molten steel.

[0059] In one embodiment, X in Formula 1 may be 0.4 or more and less than 1, Y may be 0 or more and 1 or less, and Z may be 0 or more and 1 or less. If X is less than 0.4, the heat source may be insufficient, making operation substantially difficult.

[0060] The steelmaking method of the present invention can satisfy the following formula 3.

[0061] [Formula 3] (X / (X+Z))×100(%)≦80(%)

[0062] In the formula 3, X and Z are as defined in the formula 1.

[0063] That is, Equation 3 means that in the steelmaking method of the present invention, when the second molten steel is produced, (mass of molten pig iron / (mass of molten pig iron+mass of iron scrap))×100(%) satisfies 80% or less. This means that, compared to the conventional hot metal ratio (HMR) of 85% or more when molten steel is produced by charging molten pig iron and iron scrap into a blast furnace, the blending ratio of molten pig iron to iron scrap is reduced in the steelmaking method of the present invention.

[0064] As a result, the steelmaking method of the present invention can reduce carbon dioxide emissions when producing the second molten steel.

[0065] Meanwhile, referring to FIGS. 1 and 3, the step S200 of combining molten pig iron, electric furnace molten steel, and iron scrap according to one embodiment may include a step S210 of combining the molten pig iron and electric furnace molten steel to produce an intermediate molten metal, and a step S200 of combining the intermediate molten metal and iron scrap to produce a final molten metal.

[0066] Specifically, step S210 of combining molten pig iron and molten steel from an electric furnace to produce an intermediate molten metal may be a step of first combining the molten pig iron and molten steel from an electric furnace without iron scrap. In this case, the composition of the produced intermediate molten metal may be adjusted before combining with the iron scrap. For example, impurities (e.g., silicon, phosphorus, sulfur) present in the intermediate molten metal may be removed from the intermediate molten metal in a hot metal pretreatment machine.

[0067] Thereafter, step S220 may be performed in which the intermediate molten metal and the scrap iron are combined to produce a final molten metal. Specifically, the intermediate molten metal and the scrap iron from which impurities have been removed may be charged into a converter to produce the final molten metal.

[0068] The temperature and composition of the final molten metal may then be adjusted by an LF refining machine. However, the present invention is not limited to the above, and a vacuum degassing process may be further performed.

[0069] However, the embodiment of the present invention is not limited to Fig. 3. In another embodiment of the present invention, step S200 of combining the molten pig iron, the molten steel from the electric furnace, and the scrap iron may include a step of simultaneously charging the molten pig iron, the molten steel from the electric furnace, and the scrap iron into a converter and combining them.

[0070] Step S200 of combining the molten pig iron, the molten steel from the electric furnace, and the iron scrap may be followed by step S300 of tapping the molten steel from the converter, and then step S400 of continuously casting the molten steel from the electric furnace to produce a product.

[0071] Specifically, the step S400 of manufacturing a product may include manufacturing a semi-finished product from molten steel in an electric furnace and manufacturing a finished product from the semi-finished product.

[0072] Specifically, in step S400 of manufacturing a product, the molten steel from the electric furnace may be manufactured into a semi-finished product by a continuous casting process. For example, the semi-finished product may be a slab or a billet. However, the semi-finished product is not limited thereto, and may also be a bloom.

[0073] The semi-finished product may then be manufactured into a finished product by a rolling process, which may be a hot rolling process or a cold rolling process, and the finished product may be a steel plate or a wire rod.

[0074] A steelmaking method according to an embodiment of the present invention produces steel by charging molten pig iron, molten steel from an electric furnace, and iron scrap into a converter, thereby reducing the amount of molten pig iron required and the amount of carbon dioxide emissions generated in the steelmaking process compared to conventional methods.

[0075] Meanwhile, the steelmaking method according to an embodiment of the present invention is not limited to the above.

[0076] A steelmaking method according to one embodiment includes producing a first molten metal, producing a second molten metal having a carbon content lower than the carbon content of the first molten metal, and charging the first molten metal, the second molten metal, and scrap iron into a converter to produce molten steel.

[0077] For example, the carbon content of the first molten metal may be 2 wt % or more based on the total mass of the first molten metal. For example, the first molten metal may be produced by melting raw materials including iron ore in a blast furnace, such as molten pig iron. However, examples of the first molten metal are not limited thereto.

[0078] For example, the carbon content of the second molten metal may be 2 wt % or less based on the total mass of the second molten metal. For example, the second molten metal may be produced by melting raw materials including iron scrap in an electric furnace, such as electric furnace molten steel. However, the second molten metal is not limited to this example.

[0079] For example, the molten steel produced by charging the first molten metal, the second molten metal, and iron scrap into a converter may be electric furnace molten steel.

[0080] The first molten metal, the second molten metal, and the molten steel can satisfy the above-mentioned [Formula 1], [Formula 2], and [Formula 3]. Specifically, in the above-mentioned [Formula 1], [Formula 2], and [Formula 3], the relationship between the molten pig iron, the molten steel in the electric furnace, and the molten steel in the converter may be the same as the relationship between the first molten metal, the second molten metal, and the molten steel.

[0081] As a result, the steelmaking method according to one embodiment of the present invention produces molten steel that includes not only a first molten metal having a relatively high carbon content but also a second molten metal having a relatively low carbon content, thereby reducing carbon dioxide emissions generated during the steelmaking process.

[0082] Tables 1 and 2 below show the calculated amount of carbon dioxide (K) emitted when producing 1 ton of second molten steel based on the blending ratios of molten pig iron, electric furnace molten steel, and iron scrap and the emission factors (α, β, γ).

[0083] The hot metal used in Tables 1 and 2 below was produced by mixing sinter, lump ore, and pallets in a mass ratio of sinter:lump ore:pallets = 90.6:7.2:0.6.

[0084] The compositions of the electric furnace molten steels used in Tables 1 and 2 below are different from each other.

[0085] Specifically, the electric furnace molten steel used in Table 1 below was produced by blending HBI and iron scrap in a mass ratio of HBI:iron scrap = 60:40. As a result, in Table 1 below, the carbon dioxide emission factor (α) of the molten iron was calculated to be 2.06, the carbon dioxide emission factor (β) of the first molten steel was calculated to be 0.912, and the carbon dioxide emission factor (γ) of the iron scrap was calculated to be 0.028.

[0086] The contents of Table 1 are as follows:

[0087] [Table 1]

[0088] Specifically, the electric furnace molten steel used in Table 2 below was produced with an HBI:iron scrap ratio of 0:100, i.e., it was produced using iron scrap without HBI. As a result, the carbon dioxide emission factor (α) of the molten pig iron in Table 2 below was calculated to be 2.06, the carbon dioxide emission factor (β) of the first molten steel was calculated to be 0.437, and the carbon dioxide emission factor (γ) of the iron scrap was calculated to be 0.028.

[0089] The contents of Table 2 are as follows:

[0090] [Table 2]

[0091] Referring to Tables 1 and 2, the steelmaking method of one embodiment produces steel by charging molten pig iron, electric furnace molten steel, and iron scrap into a converter, thereby reducing the amount of molten pig iron charged and reducing carbon dioxide emissions generated in the steelmaking process.

[0092] While preferred embodiments of the present invention have been described above, it will be obvious to those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or scope of the present invention.

[0093] That is, the above-described embodiments should be considered as illustrative rather than restrictive, and therefore the present invention is not limited to the above description, but may be modified within the scope of the appended claims and their equivalents.

Claims

1. charging a first raw material into a blast furnace to produce molten iron; charging a second raw material into the electric furnace to produce a first molten steel; and charging the molten pig iron, the electric furnace molten steel, and iron scrap into a converter to produce a second molten steel, The amount of carbon dioxide (K) emitted when producing 1 ton of the second molten steel is defined by the following formula 1: the amount of carbon dioxide (K) emitted during the production of 1 ton of the second molten steel satisfies the following formula 2. [Formula 1] The amount of carbon dioxide emitted when producing 1 ton of the second molten steel (K) = α x X + β x Y + γ x Z In the formula 1, X is a mass ratio of the molten pig iron to the first molten steel and the iron scrap, Y is a mass ratio of the first molten steel in the molten pig iron, the first molten steel, and the iron scrap, Z is a mass ratio of the iron scrap in the molten pig iron, the first molten steel, and the iron scrap, X+Y+Z=1, α, β, and γ are the carbon dioxide emission coefficient of the molten iron, the carbon dioxide emission coefficient of the first molten steel, and the carbon dioxide emission coefficient of the iron scrap, respectively; [Formula 2] The amount of carbon dioxide emitted when producing 1 ton of the second molten steel (K) < α In the formula 2, α is as defined in the formula 1.

2. X is greater than or equal to 0 and less than 1; Y is greater than or equal to 0 and less than or equal to 1, The steelmaking method according to claim 1 , wherein Z is 0 or more and 1 or less.

3. The steelmaking method according to claim 2, wherein X is equal to or greater than 0.4 and less than 1.

4. The steelmaking method according to claim 2, wherein the following formula 3 is satisfied: [Formula 3] (X / (X+Z))×100(%)≦80(%) In the formula 3, X and Z are as defined in the formula 1.

5. The steelmaking method according to claim 1 , wherein the amount of carbon dioxide (K) emitted when producing 1 ton of the second molten steel is 1.7 tons or less.

6. In the step of producing the second molten steel, The steelmaking method according to claim 1 , wherein the temperature of the first molten steel is equal to or greater than the temperature of the molten pig iron.

7. The step of producing the second molten steel comprises: The steelmaking method of claim 1 , comprising mixing the molten steel and the first molten steel to form an intermediate molten metal, and thereafter mixing the intermediate molten metal and the scrap iron to form a final molten metal.

8. The step of producing the second molten steel comprises: The steelmaking method of claim 1 , comprising simultaneously mixing the hot metal, the first molten steel, and the scrap iron to produce the second molten steel.

9. the first raw material comprises iron ore; The steelmaking method of claim 1 , wherein the second raw material comprises at least one of hot briquette iron (HBI), direct reduced iron (DRI), and iron scrap.

10. The steelmaking method of claim 1 further comprising the step of continuously casting the second molten steel to produce a slab.

11. Producing a first molten metal; producing a second molten metal having a carbon content lower than the carbon content of the first molten metal; and charging the first molten metal, the second molten metal, and scrap iron into a converter to produce molten steel, The amount of carbon dioxide (K) emitted when producing 1 ton of molten steel is defined by the following formula 1: The steelmaking method, wherein the amount of carbon dioxide (K) emitted during the production of 1 ton of molten steel satisfies the following formula 2: [Formula 1] The amount of carbon dioxide emitted when producing 1 ton of molten steel (K) = α x X + β x Y + γ x Z In the formula 1, X is a mass ratio of the first molten metal to the second molten metal and the iron scrap, Y is a mass ratio of the second molten metal to the first molten metal and the second molten metal to the iron scrap, Z is a mass ratio of the first molten metal, the second molten metal, and the iron scrap to the iron scrap, X+Y+Z=1, α, β, and γ are the carbon dioxide emission coefficients of the first molten metal, the second molten metal, and the iron scrap, respectively; [Formula 2] The amount of carbon dioxide emitted when producing 1 ton of molten steel (K) < α In the formula 2, α is as defined in the formula 1.

12. The carbon content of the first molten metal is 2 wt % or more, The steelmaking method according to claim 11, wherein the carbon content of the second molten metal is 2 wt% or less.

13. the first molten metal is produced by melting raw materials including iron ore in a blast furnace; The steelmaking method according to claim 11, wherein the second molten metal is produced by melting raw materials including iron scrap in an electric furnace.

14. charging a first raw material into a blast furnace to produce molten iron; charging a second raw material into the electric furnace to produce a first molten steel; and charging the molten pig iron, the first molten steel, and iron scrap into a converter to produce a second molten steel.

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