Method for reducing carbon footprint in operating a metallurgical plant for producing pig iron

Patent metadata

Field	Value
Publication number	US-2025011888-A1
Application number	US-202218702157-A
Country	US
Kind code	A1
Filing date	Oct 14, 2022
Priority date	Oct 19, 2021
Publication date	Jan 9, 2025
Grant date	—

Abstract

A method for reducing carbon footprint in operating a metallurgical plant for producing pig iron, including: pre-heating iron ore fines in a first electric pre-heater to obtain pre-heated iron ore fines partially reducing the pre-heated iron ore fines in one or more fluidized bed reactors in the presence of a hot reducing gas to obtain partially reduced iron; feeding the partially reduced iron to a submerged arc furnace; further reducing and melting the partially reduced iron within the submerged arc furnace in the presence of a carbonaceous material to obtain molten pig iron; where the hot reducing gas includes hydrogen, syngas, off-gas of the submerged arc furnace, other off-gases from the metallurgical plant, or mixtures of two or more thereof, where the syngas is produced from natural gas or biomethane, blast furnace gas, off-gas of the submerged arc furnace, other off-gases from the metallurgical plant, or mixtures of two or more thereof in the presence of air or oxygen enriched air, steam or carbon dioxide in one or more reforming reactors, where the hot reducing gas has a temperature above 550° C., and where the partially reduced iron has a metallization degree of 55 to 75%.

First claim

1 . A method for reducing carbon footprint in operating a metallurgical plant for producing pig iron, the method comprising the steps of:
a) pre-heating iron ore fines in a first electric pre-heater based on Joule effect and/or microwave heating to a temperature above 600° C. to obtain pre-heated iron ore fines; b) partially reducing the pre-heated iron ore fines in one or more fluidized bed reactors in presence of only hot reducing gas as a reductant to obtain partially reduced iron; c) feeding the partially reduced iron to a submerged arc furnace comprising a bath of molten metal with a top slag layer; d) further reducing and melting the partially reduced iron within the submerged arc furnace in the presence of a carbonaceous material to obtain molten pig iron;
wherein, in step b), the hot reducing gas comprises hydrogen, syngas, off-gas of the submerged arc furnace, other off-gases from the metallurgical plant, or mixtures of two or more thereof, wherein said syngas is produced from natural gas or biomethane, blast furnace gas, off-gas of the submerged arc furnace, other off-gases from the metallurgical plant, or mixtures of two or more thereof in one or more reforming reactors in the presence of air or oxygen-enriched air, steam or carbon dioxide; wherein, in step b), the hot reducing gas has a temperature above 550° C.; and wherein, in step b), the partially reduced iron has a metallization degree of 55 to 75%.

2 . The method according to claim 1 , wherein the one or more fluidized bed reactors is/are of a circulating type.

3 . The method according to claim 1 , wherein the hydrogen is pre-heated in a second electric pre-heater and off-gas of the submerged arc furnace and other off-gases from the metallurgical plant are pre-heated in a third electric pre-heater, both second and third pre-heaters being independently based on Joule effect and/or microwave heating to a temperature above 700° C.

4 . The method according to claim 1 , wherein the carbonaceous material in step d) comprises of bio-char produced by biomass, including demolition wood, up to 40 wt.-%, and/or waste plastics, up to 20 wt.-%.

5 . The method according to any claim 1 , wherein the iron ore fines have a grainsize distribution in the range 0.1-1 mm.

6 . The method according to claim 1 , wherein step b) further comprises hot briquetting partially reduced iron ore fines to obtain briquetted partially reduced iron.

7 . The method according to claim 6 , wherein the carbonaceous material is at least partially introduced into the briquetted partially reduced iron during hot briquetting and fed to submerged arc furnace in step d).

8 . The method according to claim 1 , wherein the other off-gases of the metallurgical plant comprise one or more of off-gases from a coke oven plant, a Direct Reduced Iron plant and basic oxygen furnace.

9 . The method according to claim 1 , wherein all electrical energy needed in the pre-heater(s) and the submerged arc furnace is renewable electricity.

10 . A metallurgical plant for producing pig iron with a reduced carbon footprint, by implementing the method according any of claim 1 , the metallurgical plant comprising:
a first electric pre-heater configured for pre-heating iron ore fines based on Joule effect and/or microwave heating into pre-heated iron ore fines at a temperature above 600° C.; one or more fluidized bed reactors configured for partially reducing the pre-heated iron ore fines in the presence of only hot reducing gas as a reductant into partially reduced iron to a metallization degree of 55 to 75%; a submerged arc furnace comprising a bath of molten metal with a top slag layer, configured for receiving the partially reduced iron and further reducing and melting the partially reduced iron in the presence of a carbonaceous material to obtain molten pig iron;
wherein the metallurgical plant further comprises one or more reforming reactors configured for producing a syngas from a feed of natural gas or biomethane, a feed of blast furnace gas, one or more feeds of off-gas of the submerged arc furnace and other off-gases from the metallurgical plant, or a feed of mixtures of two or more thereof, and a feed of air or oxygen-enriched air, steam or carbon dioxide; wherein the metallurgical plant further comprises a feed of hydrogen; a hot reducing gas mixing device fluidly connected upstream to the one or more reforming reactors and to the feed of hydrogen, and to one or more of said feeds of an off-gas of the submerged arc furnace and of other off-gases of the metallurgical plant, or a feed of mixtures of two or more thereof, and downstream to an inlet of the one or more fluidized bed reactors, said hot reducing gas mixing device being configured for providing hot reducing gas at a temperature above 550° C. comprising hydrogen, syngas, off-gas of the submerged arc furnace, other off-gases of the metallurgical plant, or mixtures of two or more thereof.

11 . The metallurgical plant according to claim 10 , wherein the one or more fluidized bed reactors is/are of a circulating type.

12 . The metallurgical plant according to claim 10 , comprising a second electric pre-heater based on Joule effect and/or microwave heating fluidly connected between said feed of hydrogen and the hot reducing gas mixing device, and a third electric pre-heater based on Joule effect and/or microwave heating fluidly connected between said one or more feeds of off-gas of the submerged arc furnace and other off-gases of the metallurgical plant and the hot reducing gas mixing device, said second and third electric pre-heaters being configured for pre-heating the relevant off-gas(es) and syngas to a temperature above 700° C.

13 . The metallurgical plant according to claim 10 , wherein the carbonaceous material is provided from a source comprising of bio-char produced by biomass, including demolition wood, up to 40 wt.-%, and/or waste plastics, up to 20 wt.-%.

14 . The metallurgical plant according to claim 10 , further comprising a hot briquetting apparatus configured for briquetting partially reduced iron ore fines into briquetted partially reduced iron.

15 . The metallurgical plant according to claim 10 , wherein the metallurgical plant comprises one or more among, a coke oven plant, a Direct Reduced Iron plant, a blast furnace and basic oxygen furnace, providing said other off-gases of the metallurgical plant.

16 . The metallurgical plant according to claim 10 , wherein all electrical energy needed in the pre-heater(s) and the submerged arc furnace is renewable electricity.

Assignees

• Wurth Paul Sa

Inventors

• Krull Jan
• Hansmann Thomas
• PAPALIA Katia

Classifications

• C21B2100/00

  Handling of exhaust gases produced during the manufacture of iron or steel · CPC title

• C21B13/0033

  In fluidised bed furnaces or apparatus containing a dispersion of the material · CPC title

• Y02P10/134

  by avoiding CO2, e.g. using hydrogen · CPC title

• C21B13/14

  Multi-stage processes {processes carried out in different vessels or furnaces} · CPC title

• C21B13/12

  in electric furnaces · CPC title