IP Library › Granted Patent US 12,692,563
Granted Patent B2
US 12,692,563 · App. 17/922,842 · Granted Jul 28, 2026

Process for the production of carburized sponge iron

Inventors: Jenny Anna Gunilla Hyllander (Södra Sunderbyn, SE); Magnus Tottie (Gällivare, SE)
Assignee: HYBRIT Development AB
C21B13/0073C21B13/004C21B13/02C21B13/146C25B1/04C21B2100/24C21B2100/282C21B2100/66
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Quick Facts
Patent No.
US 12,692,563
App. No.
17/922,842
Granted
Jul 28, 2026
Kind
B2
Abstract

The present disclosure relates to a process for the production of carburized sponge iron. The process comprises the steps of reducing iron ore pellets using a carbon-lean reducing gas in a direct reduction shaft reactor to provide a sponge iron intermediate; transferring the sponge iron intermediate to a carburization unit; and carburizing the sponge iron intermediate in the carburization unit using a carburizing gas to provide carburized sponge iron. The disclosure further relates to a system for the production of carburized sponge iron, a carburized sponge iron produced by the aforementioned process, and a sponge iron intermediate obtained during the production of such a carburized sponge iron.

Claims (13)

1 . A process for the production of carburized sponge iron ( 109 , 209 ), the process comprising the steps:

reducing (s 303 ) iron ore ( 107 , 207 ) using a carbon-lean reducing gas ( 115 , 215 ), said carbon-lean reducing gas comprising less than about 10 vol % of carbon-containing gases, in a direct reduction shaft ( 111 , 211 ) to provide a sponge iron intermediate ( 108 , 208 ), wherein the sponge iron intermediate has a degree of reduction from about 60% to about 80%;

transferring (s 305 ) the sponge iron intermediate to a carburization unit ( 112 , 213 ); and

carburizing (s 307 ) the sponge iron intermediate in the carburization unit using a carburizing gas ( 114 , 214 ) to provide carburized sponge iron.

2 . The process according to claim 1 , wherein the carburizing gas is derived from a renewable source.

3 . The process according to claim 1 , wherein the carburizing gas comprises bio-methane, biogas, gas from the pyrolysis of biomass, or a combination thereof.

4 . The process according to claim 1 , wherein the reducing gas comprises hydrogen produced by electrolysis.

5 . The process according to claim 1 , wherein hydrogen is separated from an off-gas ( 248 ) from the carburization unit.

6 . The process according to claim 1 , wherein carbon dioxide produced in the carburizing step is separated from an off-gas ( 248 ) from the carburization unit.

7 . The process according to claim 1 , wherein the carburization gas is pre-heated by heat exchange with an off-gas ( 248 ) from the carburization unit, and/or wherein the carburizing gas is mixed with an off-gas from the carburization unit prior to introduction into the carburization unit.

8 . The process according to claim 1 , wherein the sponge iron intermediate is transferred to the carburization unit at a temperature in excess of about 500° C.

9 . The process of claim 5 , wherein the hydrogen separated from the off-gas is introduced as reducing gas into the direct reduction shaft.

10 . The process of claim 6 , wherein the carbon dioxide is converted into carbon monoxide and introduced as a carburizing gas into the carburization unit.