Biomass Direct Reduced Iron

Patent metadata

Field	Value
Publication number	US-2023366051-A1
Application number	US-202118038099-A
Country	US
Kind code	A1
Filing date	Nov 24, 2021
Priority date	Nov 24, 2020
Publication date	Nov 16, 2023
Grant date	—

Abstract

A method and an apparatus method for producing direct reduced iron (DRI) from iron ore using biomass as a source of reductant and as a heating source of the iron ore and electromagnetic energy as a further heating source in a furnace having multiple zones. The zones include a preheat zone and a reduction zone between an inlet for briquettes of iron ore and biomass and an outlet for direct reduced iron. The method includes counter-current movement of (a) briquettes of iron ore and biomass in a direction from the inlet to the outlet and (b) combustible gases in an opposite direction in the furnace.

First claim

1 . A method for producing direct reduced iron (DRI) from iron ore using biomass as a source of reductant and as a heating source of the iron ore and electromagnetic energy as a heating source in a furnace having multiple zones including a preheat zone and a reduction zone between an inlet for briquettes of iron ore fragments and biomass and an outlet for direct reduced iron produced in the furnace, the method including counter-current movement of (a) briquettes of iron ore fragments and biomass in a direction from the inlet to the outlet and (b) combustible gases in an opposite direction in the furnace, with the combustible gases including combustible gases produced under anoxic conditions in the reduction zone flowing to the preheat zone, counter-current to movement of briquettes in the furnace, and air or oxygen-enriched air fed burners combusting combustible gases in the preheat zone and producing heat that heats briquettes in the preheat zone before preheated briquettes move to the reduction zone.

2 . A method for producing direct reduced iron (DRI) from briquettes of a composite of iron ore fragments and biomass in a furnace including a chamber having the following zones along the length of the furnace between an inlet for briquettes of iron ore fragments and biomass and an outlet for direct reduced iron: a feed zone that includes the inlet, a preheat zone, a final reduction zone and a discharge zone that includes the outlet, and a conveyor that is movable through the zones, the method including:
(a) feeding briquettes onto the conveyor in the feed zone; (b) transporting briquettes on the conveyor through the preheat zone and heating briquettes and reducing iron ore in briquettes and releasing volatiles in biomass in briquettes, with heating including generating heat by burning combustible gases in a top space of the preheat zone via a plurality of air or oxygen-enriched air fed burners, with the combustible gases including combustible gases generated within the furnace, and (c) transporting heated briquettes on the conveyor from the preheat zone through the final reduction zone, with the final reduction zone being an anoxic environment, and supplying electromagnetic energy, such as microwave energy, into the final reduction zone and heating briquettes and reducing iron ore in briquettes and forming DRI; (d) causing gases generated in the final reduction zone to flow counter-current to the direction of movement of briquettes on the conveyor through the furnace; and (e) transporting DRI on the conveyor to the discharge zone at the outlet and discharging DRI from the discharge zone.

3 . The method defined in claim 2 wherein step (a) includes forming a relatively uniform bed of briquettes on the conveyor.

4 . The method defined in claim 2 includes generating heat in step (b) by burning combustible gases in a plurality of burners that are spaced apart along the length of the top space of the preheat zone of the furnace and/or spaced across the width of the preheat zone of the furnace.

5 . (canceled)

6 . The method defined in claim 2 includes adjusting the amount of air or oxygen-enriched air fed to each burner in step (b) to compensate for variations in combustible gases in the top space of the preheat zone.

7 . (canceled)

8 . The method defined in claim 2 wherein the mass percentage of biomass in briquettes is 20-45% by weight on a wet (as-charged) basis.

9 . The method defined in claim 8 wherein the balance of the composition of briquettes is (a) iron ore fragments (b) optionally flux/binder materials and (c) optionally additional carbonaceous material, which may be coal or pre-charred biomass, in an amount of < 5% by weight of the total weight of briquettes.

10 . (canceled)

11 . The method defined in claim 2 includes controlling the method so that the bulk temperature of briquettes is at least 500° C. when briquettes leave the preheat zone and pass to the final reduction zone.

12 . The method defined in claim 2 wherein step (c) includes electromagnetic energy heating briquettes by at least 250° C. in the final reduction zone.

13 . The method defined in claim 2 includes releasing at least 90% of volatiles in biomass in the briquettes as a gas in the preheat zone.

14 . The method defined in claim 2 wherein step (d) includes generating a higher pressure of gases in the final reduction zone compared to gas pressure in the preheat zone and thereby causing gases generated in the final reduction zone to flow counter-current to the direction of movement of briquettes on the conveyor through the furnace.

15 . The method defined in claim 14 includes generating the higher pressure in the final reduction zone as a consequence of reduction of iron ore in briquettes in the final reduction zone generating gases in the zone and/or by supplying an inert gas into the final reduction zone and/or by means of a gas flow “choke” in the reduction zone.

16 . (canceled)

17 . (canceled)

18 . The method defined in claim 15 wherein the gas flow “choke” in the reduction zone increases the gas velocity of gases generated in the final reduction zone from the reduction zone to the preheat zone by a factor of 2-3 compared to what would have been the gas velocity without the gas flow “choke” in order to ensure that there is no substantial gas flow from the reduction zone side to the reduction zone side of the furnace.

19 . The method defined in claim 2 includes discharging gas produced in the furnace by heating and/or combustion within the furnace as a flue gas through a flue gas outlet in the feed zone.

20 . (canceled)

21 . (canceled)

22 . The method defined in claim 2 includes feeding briquettes onto the conveyor in the feed zone while restricting outflow of furnace gases through such feeding process.

23 . The method defined in claim 2 includes moving the conveyor in an endless path and returning the conveyor to the feed zone of the furnace from the discharge zone of the furnace with the conveyor having residual heat as a result of passing through the furnace that contributes to heating briquettes loaded onto the conveyor in step (a).

24 . (canceled)

25 . The method defined in claim 2 wherein step (e) includes discharging DRI from the discharge zone and transporting the DRI in a hot state away from the furnace at a temperature in a range of 900-11500° C.

26 . (canceled)

27 . An apparatus for producing direct reduced iron (DRI) from briquettes of a composite of iron ore fragments and biomass, the apparatus including a furnace that includes a chamber having:
(a) an inlet for briquettes of iron ore and biomass at one end and an outlet for direct reduced iron at the other end, (b) the following zones:
(i) a feed zone that includes the inlet,
(ii) a preheat zone for heating briquettes and reducing iron ore in briquettes and releasing volatiles in biomass in briquettes, the preheat zone including a plurality of air or oxygen-enriched air fed burners for generating heat by burning combustible gases in a top space of the preheat zone, with the combustible gases including combustible gases generated within the furnace,
(iii) a final reduction zone for heating briquettes and reducing iron ore in briquettes and forming DRI, the final reduction zone including a means for supplying electromagnetic energy, such as microwave energy, into the final reduction zone for heating briquett

Assignees

• Tech Resources Pty Ltd

Inventors

• Farr Iain William
• Dry Rodney James
• Buckley Michael

Classifications

• Y02P10/134

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

• C21B13/004 Primary

  in a continuous way by reduction from ores · CPC title

• C21B13/0086

  Conditioning, transformation of reduced iron ores · CPC title

• C21B2100/60

  Process control or energy utilisation in the manufacture of iron or steel · CPC title

• C21B13/14 Primary

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