Biomass direct reduced iron

Patent metadata

Field	Value
Publication number	US-2023332258-A1
Application number	US-202118027409-A
Country	US
Kind code	A1
Filing date	Sep 20, 2021
Priority date	Sep 22, 2020
Publication date	Oct 19, 2023
Grant date	—

Abstract

A method for producing direct reduced iron (“DRI”) from iron ore and biomass is disclosed. The method includes heating a batch of iron ore and biomass in each oven chamber of a non-recovery batch oven by a combination (i) the thermal mass of a lining of the oven chamber and (ii) combustion of a fuel gas from at least one other oven chamber and at least partially reducing the iron ore and forming DRI. The method also includes discharging gases from the oven chamber through passageways in a wall and a floor of the oven chamber and further combusting combustible gases and transferring heat to the wall and the floor of the oven chamber as the gases move through the passageways. The method also includes discharging at least a portion of gases from the oven chamber, without passing the gases through passageways in the floor of the oven chamber, and using these gases as a fuel gas in subsequent combustion heating in other batch oven chambers when a first predetermined trigger point is reached. A non-recovery batch oven is also disclosed.

First claim

1 . A method for producing direct reduced iron (DRI) from iron ore and biomass using a batch oven in a batch cycle mode of operation, with the oven having a plurality of separate batch ovens, with each batch oven having a chamber defined by a refractory-lined wall and floor having a thermal mass and a plurality of burners, and with the oven chambers having shared fuel gas and off-gas offtakes, with the method including the following steps in at least one batch oven:
a) charging a batch of composite of iron ore and biomass into the batch oven chamber; b) heating the charged iron ore and biomass in each oven chamber by a combination of heat from (i) the thermal mass of the lining of the oven chamber and (ii) combusting a fuel gas from at least one other oven chamber in a top space of the oven chamber in a flame of at least one oxygen-enriched burner in the oven chamber and at least partially reducing the iron ore and forming DRI and discharging gases from the oven chamber through passageways in a wall and a floor of the oven chamber and further combusting combustible gases in the discharged gases and transferring heat to the wall and the floor of the oven chamber as the gases move through the passageways and thereby contributing to the thermal mass of the non-recovery oven and heat transfer to the oven chamber; c) on reaching a first predetermined trigger point, discharging at least a portion of gases from the oven chamber, without passing the gases through passageways in the floor of the oven chamber, and using the gases as a fuel gas in subsequent combustion heating in other batch oven chambers; and d) on reaching a second predetermined trigger point in the batch oven, stopping discharging gases from the oven chamber in step c) and re-commencing step b); and e) at the end of the batch cycle discharging DRI from the oven chamber.

2 . The method defined in claim 1 includes discharging gases from the passageways through a flue gas system to the atmosphere.

3 . The method defined in claim 1 wherein step c) includes discharging at least a portion of the gases from the oven chamber without passing the gases through passageways in the wall and the floor of the oven chamber and using the gases as a fuel gas in subsequent combustion heating in other batch oven chambers.

4 . The method defined in claim 1 wherein step b) includes operating the oxygen-enriched burner(s) with a nominally cold oxygen-air mixture with a minimum of 25% oxygen in the air-oxygen mixture (calculated as a mixed stream regardless of whether or not air and oxygen are (a) actually pre-mixed or (b) fed independently as two individual streams to the gas burners).

5 . The method defined in claim 1 wherein the batch of the composite of iron ore and biomass charged into the batch oven in step a) includes 20-50% by weight biomass on a wet (as-charged) basis of the total weight of the batch.

6 . The method defined in claim 5 wherein the balance of the batch of the composite of iron ore and biomass charged into the batch oven in step a) includes (i) iron ore and (ii) flux/binder materials and (iii) optionally carbonaceous material, which may be coal or pre-charred biomass, in an amount of <5% by weight of the total weight of the batch.

7 . The method defined in claim 1 wherein the batch of composite of iron ore and biomass charged into the batch oven in step a) includes 30-40% by weight on a wet (as-charged) basis of the total weight of the batch.

8 . The method defined in claim 1 wherein step b) includes heating iron ore and biomass to a temperature in a range of 800-1300° C. in the batch cycle time.

9 . The method defined in claim 1 wherein the batch cycle time in step b) is in a range of 30-60 hours.

10 . The method defined in claim 1 includes forming the composite of iron ore and biomass for the batch for step a) by roll pressing an iron ore biomass mix into slab form (whether now remaining in such slab form or in broken pieces thereof).

11 . The method defined in claim 1 wherein step a) includes forming some of the biomass charged into the batch oven as a layer or a sheet.

12 . The method defined claim 1 wherein step a) includes forming the composite of iron ore and biomass on a discrete layer of biomass in the batch oven.

13 . The method defined claim 1 wherein the composite of iron ore and biomass in the batch charged into the batch oven in step a) includes briquettes.

14 . The method defined in claim 1 wherein step e) includes discharging DRI from the oven into a product handling system that is configured to prevent bulk ingress of oxygen-containing gases and allows transportation in a hot state away from the non-recovery oven.

15 . A non-recovery oven for producing direct reduced iron (DRI) from iron ore and biomass comprising a plurality of separate batch ovens, with each batch oven having a chamber defined by a refractory-lined wall and floor having a thermal mass and a plurality of oxygen-enriched burners, with the wall and the floor of each oven chamber having a plurality of passageways for transferring gases from the oven chamber and heating the refractories in the wall and the floor as the gases pass through the passageways, a gas collection and gas sharing assembly interconnecting the batch ovens, the gas collection and sharing assembly including a communal header and pipes extending between the batch ovens and the header for supplying fuel gas from the oven chambers to the header and for supplying fuel gas from the header to the oven chambers.

16 . The non-recovery oven defined in claim 15 wherein the plurality of the burners is spaced along the length of the oven chamber.

17 . The non-recovery oven defined in claim 16 wherein the plurality of the burners is spaced also across the width of the oven chamber.

18 . The non-recovery oven defined in claim includes a product handling system for DRI discharged from the batch oven chamber that is configured to prevent bulk ingress of oxygen-containing gases and allow transportation in a hot state away from the non-recovery oven.

19 . A method for producing direct reduced iron (“DRI”) from iron ore and biomass includes heating a batch of iron ore and biomass in each oven chamber of a non-recovery batch oven by a combination (i) the thermal mass of a lining of the oven chamber and (ii) combustion of a fuel gas from at least one other oven chamber and at least partially reducing the iron ore and forming DRI, discharging gases from the oven chamber through passageways in a wall and a floor of the oven chamber and further combusting combustible gases and transferring heat to the wall and the floor of the oven chamber as the gases move through the passageways, and discharging at least a portion of gases from the oven chamber, without passing the gases through passageways in the floor (and optionally the wall) of the oven chamber, and using these gases as a fuel gas in subsequent combustion heating in other batch oven chambers when a first predetermined trigger point is reached.

Assignees

• Tech Resources Pty Ltd

Inventors

• Dry Rodney James
• Farr Iain William

Classifications

• C21B13/004 Primary

  in a continuous way by reduction from ores · CPC title

• C21B13/0066

  Preliminary conditioning of the solid carbonaceous reductant · CPC title

• C21B13/10 Primary

  in hearth-type furnaces · CPC title

• C21B13/008 Primary

  Use of special additives or fluxing agents · CPC title

• C21B13/14

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