Steelmaking method

Abstract

A steelmaking method according to one embodiment of the present invention comprises: a step for producing molten iron by introducing a first raw material into a blast furnace; a step for producing a first molten steel by introducing a second raw material into the electric furnace; and a step in which the molten iron, the first molten steel, and the scrap steel are introduced into a converter to produce a second molten steel. The amount (K) of carbon dioxide discharged when one ton of the second molten steel is produced is defined by the following formula 1. The amount (K) of carbon dioxide discharged when one ton of the second molten steel is produced satisfies the following formula 2. Formula 1: the amount (K) of carbon dioxide discharged when one ton of second molten steel is produced is equal to alpha * X + beta * Y + gamma * Z, and formula 2: the amount (Klt of carbon dioxide discharged when one ton of second molten steel is produced; alpha.

Description

Technical Field

[0001] The present invention relates to a method of manufacturing steel. Background Art

[0002] Generally, a method of manufacturing steel includes a blast furnace-converter process and an electric furnace process.

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

[0004] The electric furnace process includes a process of melting scrap steel in an electric 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 manufactured into finished products through a subsequent rolling process.

[0006] On the other hand, recently, due to greenhouse gases emitted in various industrial fields, climate change has become an international issue. In the steel industry, research and development is being conducted to reduce the emission of carbon dioxide, a representative example of greenhouse gas. Summary of the invention

[0007] Technical issues

[0008] An object of the present invention is to provide a steelmaking method capable of reducing the emission of carbon dioxide generated during the ironmaking process.

[0009] Solutions to the problem

[0010] According to one embodiment of the present invention, the steelmaking method includes: a step of adding a first raw material into a blast furnace to produce molten iron; a step of adding a second raw material into an electric furnace to produce a first molten steel; and a step of adding the molten iron, the first molten steel and scrap steel into a converter to produce a second molten steel, wherein the amount of carbon dioxide (K) emitted when producing 1 ton of the second molten steel is defined by the following formula 1, and the amount of carbon dioxide (K) emitted when producing 1 ton of the second molten steel satisfies the following formula 2.

[0011] Formula 1

[0012] The amount of carbon dioxide discharged when producing 1 ton of the second molten steel (K) = α×X+β×Y+γ×Z

[0013] In the above formula 1, X is the mass ratio of the molten iron among the molten iron, the first molten steel and the scrap steel, Y is the mass ratio of the first molten steel among the molten iron, the first molten steel and the scrap steel, and Z is the mass ratio of the scrap steel among the molten iron, the first molten steel and the scrap steel, X+Y+Z=1,

[0014] 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 scrap steel, respectively.

[0015] Formula 2

[0016] The amount of carbon dioxide discharged when producing 1 ton of the second molten steel (K) <α

[0017] In the above formula 2, α is as defined in the above formula 1.

[0018] 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.

[0019] In one embodiment, X may be greater than or equal to 0.4 and less than 1.

[0020] In one embodiment, the steelmaking method satisfies the following formula 3:

[0021] Formula 3

[0022] (X / (X+Z))×100(%)≤80(%)

[0023] In the above formula 3, X and Z are as defined in the above formula 1.

[0024] In one embodiment, the amount of carbon dioxide (K) discharged when producing 1 ton of the second molten steel may be less than 1.7 tons.

[0025] In one embodiment, in the step of producing the second molten steel, the temperature of the first molten steel may be higher than the temperature of the molten iron.

[0026] In one embodiment, the step of generating the second molten steel may include the steps of mixing the molten iron and the first molten steel to form an intermediate molten metal, and then mixing the intermediate molten metal and the scrap steel to form a final molten metal.

[0027] In one embodiment, the step of generating the second molten steel may include the step of simultaneously mixing the molten iron, the first molten steel and the scrap steel to generate the second molten steel.

[0028] In one embodiment, the first raw material may include iron ore, and the second raw material may include at least one of hot briquetted iron (HBI), direct reduced iron (DRI) and scrap steel.

[0029] In one embodiment, the method may further include a step of continuously casting the second molten steel to generate a slab.

[0030] According to one embodiment of the present invention, a steelmaking method includes: a step of producing a first molten metal; a step of producing a second molten metal having a carbon content lower than that of the first molten metal; and a step of putting the first molten metal, the second molten metal and scrap steel into a converter to produce molten steel, wherein the amount of carbon dioxide (K) emitted when producing 1 ton of the second molten steel is defined by the following formula 1, and the amount of carbon dioxide (K) emitted when producing 1 ton of the second molten steel satisfies the following formula 2.

[0031] Formula 1

[0032] The amount of carbon dioxide discharged when producing 1 ton of the second molten steel (K) = α×X+β×Y+γ×Z

[0033] In the above formula 1, X is the mass ratio of the molten iron among the molten iron, the first molten steel and the scrap steel, Y is the mass ratio of the first molten steel among the molten iron, the first molten steel and the scrap steel, and Z is the mass ratio of the scrap steel among the molten iron, the first molten steel and the scrap steel, X+Y+Z=1,

[0034] 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 scrap steel, respectively.

[0035] Formula 2

[0036] The amount of carbon dioxide discharged when producing 1 ton of the second molten steel (K) <α

[0037] In the above formula 2, α is as defined in the above formula 1.

[0038] In one embodiment, the carbon content of the first molten metal may be greater than 2 wt %, and the carbon content of the second molten metal may be less than 2 wt %.

[0039] 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 scrap steel in an electric furnace.

[0040] According to one embodiment of the present invention, the steelmaking method includes: a step of adding a first raw material into a blast furnace to produce molten iron; a step of adding a second raw material into an electric furnace to produce a first molten steel; and a step of adding the molten iron, the first molten steel and scrap steel into a converter to produce a second molten steel.

[0041] Effects of the Invention

[0042] In the method for manufacturing steel according to an embodiment of the present invention, the second molten steel is manufactured by mixing molten iron, first molten steel and scrap steel, thereby reducing the emission of carbon dioxide generated in the process of manufacturing steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 FIG. 1 is a flow chart showing a steelmaking method according to an embodiment of the present invention.

[0044] Figure 2 For the general Figure 1 The flowchart shown is a concrete process for preparing molten iron, molten steel in an electric furnace and scrap steel.

[0045] Figure 3 For the general Figure 1 The flowchart shown is a concrete process for mixing molten iron, molten electric furnace steel and scrap steel. DETAILED DESCRIPTION

[0046] All terms (including technical terms and scientific terms) used in this specification have the same meanings as those commonly understood by ordinary technicians in the technical field to which the present invention belongs.

[0047] And, terms such as those defined in commonly used dictionaries should be interpreted as having meanings consistent with the meanings in the context of the relevant technology, unless interpreted as ideal or overly formal meanings, which are clearly defined herein.

[0048] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0049] Figure 1 FIG. 1 is a flow chart showing a steelmaking method according to an embodiment of the present invention. Figure 2 For the general Figure 1 The flowchart shown is a concrete process for preparing molten iron, molten steel in an electric furnace and scrap steel. Figure 3 For the general Figure 1 The flowchart shown is a concrete process for mixing molten iron, molten electric furnace steel and scrap steel.

[0050] Reference Figure 1The steelmaking method according to one embodiment of the present invention refers to a process of extracting iron from raw materials such as iron ore and steel scrap to produce steel products. The electric furnace molten steel means molten steel produced in an electric furnace, and may be referred to as the first molten steel in this specification. The converter molten steel described later means molten steel produced in a converter, and may be referred to as the second molten steel in this specification.

[0051] The steelmaking method S10 according to an embodiment of the present invention includes a step S100 of preparing molten iron, molten steel from an electric furnace and scrap steel, a step S200 of mixing the molten iron, molten steel from an electric furnace and scrap steel, a step S300 of tapping the molten steel from a converter and a step S400 of manufacturing a product.

[0052] Reference Figure 1 and Figure 2 , describing step S100 of preparing molten iron, molten steel in an electric furnace and scrap steel.

[0053] Reference Figure 1 and Figure 2 , the step S100 of preparing molten iron, molten steel in an electric furnace and scrap steel includes the step S110 of preparing molten iron, the step S120 of preparing molten steel in an electric furnace and the step S130 of preparing scrap steel.

[0054] In one embodiment, the step of preparing molten iron S110 may include a step of manufacturing molten iron S111 , a step of receiving molten iron S112 , and a step of moving molten iron S113 .

[0055] For example, in the step S111 of manufacturing molten iron, the molten iron may be manufactured using a first raw material including iron ore.

[0056] Specifically, in step S111 of producing molten iron, iron ore and coke (COKE) are loaded into a blast furnace. Then, hot air may be injected into the blast furnace to reduce and melt the iron ore to produce molten iron. In another embodiment, the iron ore may also be put into the blast furnace in the form of reduced iron (e.g., DRI, HBI, etc.). In another embodiment, hydrogen may be used instead of coke as a reducing agent.

[0057] The molten iron may include carbon, and the carbon content in the molten iron may be greater than 2 wt % based on the total weight of the molten iron.

[0058] In the step S112 of receiving molten iron, the molten iron produced in the blast furnace may be moved to a first transport vehicle. The first transport vehicle may be a torpedo tank car (TLC). However, the first transport vehicle is not limited thereto, and the first transport vehicle may be an open tank car (OLC).

[0059] In the step S113 of moving the molten iron, the first transport vehicle receiving the molten iron may be moved to the vicinity of a subsequent converter (CONVERTER) facility.

[0060] The above content is an example of step S110 of preparing molten iron, and the method of manufacturing molten iron is not limited to the above content. For example, in the above embodiment of the present invention, it is described that molten iron is produced in a blast furnace, but molten iron can also be produced in an electric furnace.

[0061] In one embodiment, the step S120 of preparing the molten steel in the electric furnace may include the step S121 of manufacturing the molten steel in the electric furnace, the step S122 of treating the molten steel in the electric furnace, and the step S123 of moving the molten steel in the electric furnace.

[0062] Specifically, in the step S121 of manufacturing molten steel in an electric furnace, the second raw material may be melted in an electric furnace (EAF) to manufacture molten iron. The second raw material may include at least one of HBI (Hot Briquetted Iron), DRI (Direct Reduced Iron) and scrap steel.

[0063] The molten steel in the electric furnace may contain carbon. Based on the total mass of the molten steel in the electric furnace, the carbon content of the molten steel in the electric furnace may be less than 2 wt%.

[0064] The above content is an example of step S121 of manufacturing molten steel in an electric furnace, and the method for manufacturing molten steel in an electric furnace is not limited to the above content.

[0065] In step S122 of treating the molten steel in the electric furnace, the molten steel in the electric furnace may be heated or a carburizer may be added by judging whether the molten steel in the electric furnace is solidified. For example, the heating of the molten steel in the electric furnace may be performed by a ladle furnace (LF) refining machine.

[0066] In the step S123 of moving the molten steel from the electric furnace, the molten steel from the electric furnace may be received into a ladle, and the ladle may be moved to the vicinity of the converter equipment. The ladle may be a container with an open top and a defined space inside.

[0067] In one embodiment, the step of preparing the scrap steel ( S130 ) may include a step of moving the scrap steel to the vicinity of a converter device.

[0068] After the step S100 of preparing molten iron, molten steel from an electric furnace, and scrap steel, the step S200 of mixing the molten iron, molten steel from an electric furnace, and scrap steel is performed.

[0069] Specifically, the step S200 of mixing molten iron, molten steel from an electric furnace and scrap steel may be a step of mixing molten iron, molten steel from an electric furnace (hereinafter referred to as first molten steel) and scrap steel in a converter to produce converter steel.

[0070] In the steelmaking method of the present invention, the amount (K) of carbon dioxide discharged when producing 1 ton (ton) of converter molten steel (hereinafter referred to as second molten steel) is defined by the following formula 1.

[0071] Formula 1

[0072] The amount of carbon dioxide discharged when producing 1 ton of the second molten steel (K) = α×X+β×Y+γ×Z

[0073] In the above formula 1, X is the mass ratio of molten iron among molten iron, first molten steel and scrap steel, Y is the mass ratio of first molten steel among molten iron, first molten steel and scrap steel, Z is the mass ratio of scrap steel among molten iron, first molten steel and scrap steel, and X+Y+Z=1. That is, X, Y and Z are the respective mixing ratios of molten iron, first molten steel and scrap steel in the step S200 of mixing molten iron, electric furnace molten steel and scrap steel.

[0074] In the above formula 1, α, β and γ are the carbon dioxide emission coefficient of the above molten iron, the carbon dioxide emission coefficient of the above first molten steel and the carbon dioxide emission coefficient of the above scrap steel, respectively.

[0075] In the steelmaking method of the present invention, the amount (K) of carbon dioxide discharged when producing 1 ton of converter molten steel (hereinafter referred to as second molten steel) satisfies the following formula 2.

[0076] Formula 2

[0077] The amount of carbon dioxide discharged when producing 1 ton of the second molten steel (K) <α

[0078] In the above formula 2, α is as defined in the above formula 1.

[0079] Specifically, in the above formula 1, when X=1, Y=0, and Z=0, α is equivalent to the amount of carbon dioxide (K) emitted when producing 1 ton of the second molten steel. In the steelmaking method of the present invention, the emission of carbon dioxide in the steelmaking process can be reduced by emitting carbon dioxide that is lower than the amount of carbon dioxide (=α) emitted when producing the second molten steel using only molten iron (in the above formula 1, when X=1, Y=0, and Z=0). Specifically, in the steelmaking method of the present invention, the amount of carbon dioxide (K) emitted when producing the second molten steel can be reduced by minimizing the proportion of molten iron with a high carbon dioxide emission during the production of the second molten steel.

[0080] For example, in the steelmaking method of the present invention, the amount of carbon dioxide (K) discharged when producing 1 ton of the second molten steel may be 1.7 tons or less. However, the embodiments of the present invention are not limited thereto.

[0081] In the steelmaking method of the present invention, X in Formula 1 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.

[0082] In one embodiment, in Formula 1, X may be greater than 0 and less than 1, Y may be greater than 0 and less than 1, and Z may be greater than 0 and less than 1. That is, when producing the second molten steel, the molten iron and the first molten steel may be used.

[0083] In one embodiment, in Formula 1, X may be greater than or equal to 0.4 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. When X is less than 0.4, it is substantially difficult to perform the operation due to insufficient heat source.

[0084] The steelmaking method of the present invention can satisfy the following formula 3.

[0085] Formula 3

[0086] (X / (X+Z))×100(%)≤80(%)

[0087] In the above formula 3, X and Z are as defined in the above formula 1.

[0088] That is, Formula 3 means that when the second molten steel is produced in the steelmaking method of the present invention, (molten iron mass / (molten iron mass+scrap steel mass))×100(%) satisfies 80% or less. This means that compared with the conventional method of producing molten steel by charging molten iron and scrap steel into a blast furnace, the molten iron ratio (HMR, Hot Metal Ratio) is 85% or more, and in the steelmaking method of the present invention, the blending ratio of molten iron to scrap steel is reduced.

[0089] Therefore, in the steelmaking method of the present invention, when the second molten steel is produced, the amount of carbon dioxide emitted can be reduced.

[0090] On the other hand, refer to Figure 1 and Figure 3 According to one embodiment, the step S200 of mixing molten iron, molten steel from an electric furnace and scrap steel may include a step S210 of mixing molten iron and molten steel from an electric furnace to generate an intermediate molten metal and a step S220 of mixing the intermediate molten metal and scrap steel to produce a final molten metal.

[0091] Specifically, the step S210 of mixing molten iron and molten steel in an electric furnace to generate an intermediate molten metal may be a step of preferentially mixing molten iron and molten steel in addition to scrap steel. The composition of the intermediate molten metal produced at this time may be adjusted before mixing with the scrap steel. For example, the intermediate molten metal may be removed of impurities (e.g., silicon, phosphorus, sulfur) present in the intermediate molten metal in a molten iron pre-treatment machine.

[0092] Afterwards, a step S220 of mixing the intermediate molten metal and the scrap steel to generate the final molten metal may be performed. Specifically, the intermediate molten metal and the scrap steel from which impurities are removed may be charged into a converter to generate the final molten metal.

[0093] Afterwards, the temperature and composition of the final molten metal can be adjusted using the LF refiner. However, the present invention is not limited to the above content, and a vacuum degassing process can also be performed.

[0094] However, the embodiments of the present invention are not limited to Figure 3 In another embodiment of the present invention, the step S200 of mixing the molten iron, molten steel from an electric furnace and scrap steel may include the step of simultaneously putting the molten iron, molten steel from an electric furnace and scrap steel into a converter for mixing.

[0095] After the step S200 of mixing the molten iron, the molten steel from the electric furnace and the scrap steel, the step S300 of tapping the molten steel from the converter may be performed. Furthermore, the step S400 of continuously casting the molten steel from the electric furnace to manufacture a product may be performed.

[0096] Specifically, the step S400 of manufacturing the product may include the steps of making a semi-finished product from molten steel in an electric furnace, and making a finished product from the semi-finished product.

[0097] Specifically, in step S400 of manufacturing the product, the molten steel in the electric furnace can be made into a semi-finished product through a continuous casting process. For example, the semi-finished product can be a slab or a billet. However, it is not limited thereto, and the semi-finished product can also be a bloom.

[0098] Then, the semi-finished product can be made into a finished product through a rolling process. The rolling process can be a hot rolling process or a cold rolling process. The finished product can be a steel plate or a wire.

[0099] In a steelmaking method according to an embodiment of the present invention, steel is produced by feeding molten iron, molten steel from an electric furnace and scrap steel into a converter. Compared with the past, the amount of molten iron can be reduced and the emission of carbon dioxide generated in the steelmaking process can be reduced.

[0100] On the other hand, the steelmaking method according to an embodiment of the present invention is not limited to the above contents.

[0101] According to one embodiment, the steelmaking method includes: a step of producing a first molten metal; a step of producing a second molten metal having a carbon content lower than that of the first molten metal; and a step of feeding the first molten metal, the second molten metal and scrap steel into a converter to produce molten steel.

[0102] For example, the carbon content of the first molten metal may be greater than 2 wt% 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, for example, molten iron. However, the embodiment of the first molten metal is not limited thereto.

[0103] For example, the carbon content of the second molten metal may be less than 2 wt% based on the total mass of the second molten metal. For example, the second molten metal may be produced by melting raw materials including scrap steel in an electric furnace, for example, may be electric furnace molten steel. However, the embodiment of the second molten metal is not limited thereto.

[0104] For example, the molten steel produced by charging the first molten metal, the second molten metal, and the scrap steel into a converter may be electric furnace molten steel.

[0105] The first molten metal, the second molten metal and the molten steel may satisfy the above formula 1, formula 2 and formula 3. Specifically, in the above formula 1, formula 2 and formula 3, the relationship between the molten iron, the electric furnace molten steel and the converter molten steel may be the relationship between the first molten metal, the second molten metal and the molten steel.

[0106] Therefore, in a steelmaking method according to an embodiment of the present invention, in addition to a first molten metal with a relatively high carbon content, a second molten metal with a relatively low carbon content may be included to produce molten steel to reduce the emission of carbon dioxide generated in the steelmaking process.

[0107] In the following Tables 1 and 2, calculations are performed to show the amount of carbon dioxide (K) emitted when 1 ton of second molten steel is produced based on the blending ratio of molten iron, molten steel in electric furnaces and scrap steel and the emission coefficients (α, β, γ).

[0108] The molten iron used in the following Table 1 and Table 2 was produced by mixing sintered ore, lump ore and pellets in a mass ratio of sintered ore:lump ore:pellet ore=90.6:7.2:0.6.

[0109] The compositions of the electric furnace molten steel used in the following Tables 1 and 2 are different from each other.

[0110] Specifically, the electric furnace molten steel used in the following Table 1 was produced by blending HBI and scrap steel at a mass ratio of HBI: scrap steel = 60:40. Thus, the carbon dioxide emission coefficient (α) of the molten iron in the following Table 1 was calculated to be 2.06, the carbon dioxide emission coefficient (β) of the first molten steel was calculated to be 0.912, and the carbon dioxide emission coefficient (γ) of the scrap steel was calculated to be 0.028.

[0111] The contents of Table 1 are as follows.

[0112] Table 1

[0113]

[0114]

[0115] Specifically, the electric furnace molten steel used in the following Table 2 was produced with HBI: scrap steel = 0:100, that is, it was produced from scrap steel without HBI. Therefore, the carbon dioxide emission coefficient (α) of the molten iron in the following Table 2 was calculated to be 2.06, the carbon dioxide emission coefficient (β) of the first molten steel was calculated to be 0.437, and the carbon dioxide emission coefficient (γ) of the scrap steel was calculated to be 0.028.

[0116] The contents of Table 2 are as follows.

[0117] Table 2

[0118]

[0119]

[0120]

[0121] Referring to Tables 1 and 2 above, in a steelmaking method of one embodiment, by feeding molten iron, molten steel from an electric furnace and scrap steel into a converter to produce steel, the amount of molten iron input can be reduced, and the amount of carbon dioxide emissions generated in the steelmaking process can be reduced.

[0122] As described above, while observing the preferred embodiments according to the present invention, it is obvious to those skilled in the art that the present invention can be embodied in different specific forms other than the embodiments described above without departing from the spirit or scope thereof.

[0123] That is, the above embodiments should be regarded as illustrative rather than restrictive, and thus the present invention is not limited to the above description but may be modified within the scope of the appended claims and the equivalent scope thereof.

Claims

1. A steelmaking method, include: A step of feeding a first raw material into a blast furnace to produce molten iron; The step of adding a second raw material into an electric furnace to produce a first molten steel; as well as The step of putting the molten iron, the electric furnace molten steel and scrap steel 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) discharged when producing 1 ton of the second molten steel satisfies the following formula 2: It is characterized in that Formula 1: The amount of carbon dioxide discharged when producing 1 ton of the second molten steel (K) = α×X+β×Y+γ×Z In the above formula 1, X is the mass ratio of the molten iron among the molten iron, the first molten steel and the scrap steel, Y is the mass ratio of the first molten steel among the molten iron, the first molten steel and the scrap steel, Z is the mass ratio of the scrap steel among the molten iron, the first molten steel and the scrap steel, 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 scrap steel, respectively. Formula 2: The amount of carbon dioxide discharged when producing 1 ton of the second molten steel (K) <α In the above formula 2, α is as defined in the above formula 1.

2. The steelmaking method according to claim 1, It is characterized in that 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, Z is greater than or equal to 0 and less than or equal to 1.

3. The steelmaking method according to claim 2, It is characterized in that X is 0.4 or more and less than 1.

4. The steelmaking method according to claim 2 satisfies the following formula 3, It is characterized in that Formula 3: (X / (X+Z))×100(%)≤80(%) In the above formula 3, X and Z are as defined in the above formula 1.

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

6. The steelmaking method according to claim 1, It is characterized in that In the step of producing the second molten steel, the temperature of the first molten steel is higher than the temperature of the molten iron.

7. The steelmaking method according to claim 1, It is characterized in that The step of generating the second molten steel includes the steps of mixing the molten iron and the first molten steel to form an intermediate molten metal, and then mixing the intermediate molten metal and the scrap steel to form a final molten metal.

8. The steelmaking method according to claim 1, It is characterized in that The step of generating the second molten steel includes the step of simultaneously mixing the molten iron, the first molten steel and the scrap steel to generate the second molten steel.

9. The steelmaking method according to claim 1, It is characterized in that The first raw material includes iron ore. The second raw material includes at least one of hot briquetted iron, direct reduced iron and scrap steel.

10. The steelmaking method according to claim 1, It is characterized in that The method also includes the step of continuously casting the second molten steel to generate a slab.

11. A method for making steel, include: a step of producing a first molten metal; a step of producing a second molten metal having a carbon content lower than that of the first molten metal; as well as The first molten metal, the second molten metal and scrap steel are put into a converter to produce molten steel. The amount of carbon dioxide (K) emitted when producing 1 ton of the above molten steel is defined by the following formula 1, The amount of carbon dioxide (K) emitted when producing 1 ton of the above molten steel satisfies the following formula 2, It is characterized in that Formula 1: The amount of carbon dioxide emitted when producing 1 ton of the above molten steel (K) = α×X+β×Y+γ×Z In the above formula 1, X is the mass ratio of the first molten metal, the second molten metal and the first molten metal in the scrap steel, Y is the mass ratio of the first molten metal, the second molten metal and the second molten metal in the scrap steel, Z is the mass ratio of the first molten metal, the second molten metal and the scrap steel, X+Y+Z=1, α, β and γ are the carbon dioxide emission coefficient of the first molten metal, the carbon dioxide emission coefficient of the second molten metal and the carbon dioxide emission coefficient of the scrap steel, respectively. Formula 2: The amount of carbon dioxide emitted when producing 1 ton of the above molten steel (K) <α In the above formula 2, α is as defined in the above formula 1.

12. The steelmaking method according to claim 11, It is characterized in that The carbon content of the first molten metal is greater than 2 wt%. The carbon content of the second molten metal is less than 2 wt %.

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

14. A method for making steel, It is characterized in that include: A step of feeding a first raw material into a blast furnace to produce molten iron; The step of adding a second raw material into an electric furnace to produce a first molten steel; as well as The step of putting the molten iron, the first molten steel and scrap steel into a converter to produce a second molten steel.

Images