Methods for manufacturing steel, and corresponding plants

Abstract

A method and plant (10) for producing steel includes at least a first direct reduction step in which iron ore (20) is reduced by gas using a direct reduction plant (11) to obtain an iron material (30), and at least a second melting step, wherein only in the second melting step, the iron material (30) is melted using an electric melting furnace (12) to produce a certain volume of slag (21) and a certain volume of liquid metal (40) with a carbon content of about 1% or less.

Claims

[Claim 1] A method for manufacturing steel (50b), The method includes at least a first direct reduction step in which iron ore (20) is reduced by gas using a direct reduction plant (11) to obtain iron material (30), The method comprises at least a second dissolution step after the first direct reduction step, Only in the second melting step, the iron material (30) is melted using an electric melting furnace (12) to produce a certain volume of slag (21) and a certain volume of liquid metal (40) with a carbon content of approximately 1% or less. A method characterized by the following: [Claim 2] If at least one blast furnace (110) is provided to supply a portion of the material for producing the steel (50b), then a third recarbonization step is at least to be included in which a desired amount of carbon is added to the liquid metal (40) in a recarbonization station (13) to produce a metal carbide (50c) having a desired carbon content of 1% to 3%, The method according to claim 1. [Claim 3] The process further includes a fourth oxidation step of mixing the metal carbide (50c) with a predetermined amount of cast iron (50a) produced in at least one blast furnace (110) using at least one converter (120), and oxidizing excess carbon to produce the steel (50b) by subjecting both the metal carbide (50c) and the cast iron (50a) to at least one desired oxygen addition, The steel (50b) is then sent to a continuous casting step. The method according to claim 2. [Claim 4] The mixing step includes mixing the metal carbide (50c) with a predetermined amount of cast iron (50a) produced in at least one blast furnace (110) at a mixing station (14) before introducing it into the converter (120), The method according to claim 3. [Claim 5] After the removal of at least one blast furnace (110), the third recarbonization step is eliminated along with the converter (120), a secondary metallurgical process is carried out in the recarbonization station (13) to produce the steel (50b), and the steel (50b) is cast in the continuous casting step. The method according to claim 3 or 4. [Claim 6] In the second melting step, the process of refining the liquid metal (40) is also carried out in the electric furnace (12). The method according to claim 5. [Claim 7] The iron ore (20) used in the first direct reduction step has an iron concentration of 62% to 68%. The method according to any one of claims 1 to 6. [Claim 8] The reducing gas includes a combination or together of hydrogen gas with a mixed gas substantially composed of carbon monoxide, methane, light hydrocarbons, and other gases in small amounts. The method according to any one of claims 1 to 7. [Claim 9] The oxidation applied to the DRI produced by the direct reduction (30) is performed only in the second dissolution step, and is approximately 5 Nm ３ / t ~ approx. 15Nm ３ / t's O ２ Use The slag (21) has an iron oxide concentration of about 10% to about 15%. The method according to any one of claims 1 to 8. [Claim 10] In the third recarbonization step, graphite is used in the lump ore or flux-cored wire, and graphite or CaC ２ including, The method according to any one of claims 2 to 9. [Claim 11] In the second melting step, scrap metal (15) is also supplied only to the electric furnace (12). The method according to any one of claims 1 to 10. [Claim 12] A plant (10, 110) for manufacturing steel (50b), The system includes at least one direct reduction plant (11) configured to reduce iron ore (20) using natural gas in order to obtain iron material (30), The plant (10, 110) is equipped with at least one electrolytic melting furnace (12) downstream of the direct reduction plant (11), The electric melting furnace (12) is suitable for melting the iron material (30) to produce a certain volume of slag (21) and a certain volume of liquid metal (40) with a carbon content of approximately 1% or less. A plant characterized by (10,110). [Claim 13] The aforementioned plant (10, 110) has a first configuration, A recarbonization station (13) is located downstream of the at least one electrolytic melting furnace (12) and adds a desired amount of carbon to the liquid metal (40) to produce a metal carbide (50c) containing a desired amount of carbon, A blast furnace (110) suitable for supplying a predetermined amount of cast iron (50a) to produce the steel (50b), A converter (120) suitable for receiving the metal carbide (50c), the cast iron (50a), and optionally scrap, and for oxidizing at least the excess carbon contained in the metal carbide (50c), the cast iron (50a), and optionally scrap, It is equipped with, In the second configuration, the at least one electric furnace (12) is converted from the first configuration to be suitable for performing a smelting process on the liquid metal (40), and the recarbonization station (13) is suitable for performing a secondary metallurgical process on the smelted liquid metal (40) to produce the steel (50b). The plant (10, 110) according to claim 12. [Claim 14] The plant (10) in the second configuration does not include a blast furnace (110) and a converter (120). The plant (10) according to claim 13.

Images