Method and system for producing direct reduced iron products with multiple carbon levels from a single shaft furnace

Abstract

A method and system for producing a direct reduced iron product, including: producing hot direct reduced iron in a shaft furnace; receiving the hot direct reduced iron in a feed leg downstream of the shaft furnace; and adding carbon to the hot direct reduced iron in the feed leg downstream of the shaft furnace to form a direct reduced iron product. The method can also include receiving the hot direct reduced iron to which carbon has been added and briquetting it to form a direct reduced iron product. The method can also include receiving hot direct reduced iron in an additional (optionally parallel) feed leg downstream of the shaft furnace, and adding additional carbon (in different amounts) to the hot direct reduced iron in the additional feed leg, thereby utilizing the same hot direct reduced iron stream to form additional direct reduced iron products having different carbon contents.

Description

[0001] Stephen Brooks

[0002] Stephen C. Montagu

[0003] Hatakeyama Taiji

[0004] Cross-references to related applications

[0005] This disclosure claims priority to co-pending U.S. Patent Application No. 18 / 934,356, filed November 1, 2024, entitled “METHOD AND SYSTEM TO PRODUCE A DIRECT REDUCED IRON PRODUCT WITH MULTIPLE CARBON LEVELSFROM A SINGLE SHAFT FURNACE” and U.S. Provisional Patent Application No. 63 / 601,890, filed November 22, 2023, entitled “METHOD AND SYSTEM TO PRODUCE A DIRECT REDUCED IRON PRODUCT WITH MULTIPLE CARBON LEVELSFROM A SINGLE SHAFT FURNACE”, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0006] This disclosure generally relates to the fields of direct reduced iron (DRI) and steelmaking, particularly to the field of process and product improvement. More specifically, this disclosure relates to a method and system for producing hot DRI (HDRI), hot briquetted iron (HBI), etc., with multiple carbon levels from a single shaft furnace in a continuously operating direct reduction (DR) facility. Background Technology

[0007] HDRI or HBI is a common feedstock used in electric arc furnaces (EAFs) as clean iron units in steelmaking processes. In the case of smelting high-grade HDRI or HBI prepared from oxides with a high iron content (Fe > 67 wt%), HDRI or HBI can be fed into the smelting furnace to produce molten steel. The carbon content in the HDRI or HBI must be high enough to convert any remaining iron oxide (FeO) into iron (Fe) and provide the chemical energy for the smelting process.

[0008] In the case of smelting low-grade HDRI or HBI prepared from oxides with low iron content (Fe < 65 wt%), a two-step (2-step) process, as practiced in blast furnace (BF) combined steel plants, can be employed to reduce operating costs and improve iron yield during the smelting of HDRI or HBI to produce liquid steel. In the first smelting step, the target carbon content in the hot metal is typically >3% (C) while smelting HDRI or HBI and removing slag. In the second smelting step, the carbon in the hot metal is decarburized using oxygen blown in to produce liquid steel. A higher amount of carbon must then be added to the hot metal along with the HDRI or HBI, achieving the target carbon content at the first smelting step.

[0009] In any of the above situations, the amount of carbon in some existing HDRIs or HBIs is not high enough to achieve these target values ​​at the DRI melting process. Solid carbonaceous materials and fluxes are typically added at the melting furnace along with the HDRI or HBI, but the addition of loose solid carbonaceous materials results in significant losses due to entrainment by slag or exhaust gases discharged from the melting furnace, which significantly increases operating costs.

[0010] Furthermore, current advanced technologies introduce elemental carbon into DRI by using natural gas (NG) at and near the bottom of the shaft furnace and relying on thermochemical reactions to carburize DRI pellets. However, the amount of carbon added to DRI via NG is limited due to thermodynamic and chemical equilibrium constraints. Moreover, DRI with only a single carbon content can be discharged from a given shaft furnace, while DRI with different carbon levels may be desired in downstream processes (such as EAF or BOF in steel plants) or by market users outside steel plants. Therefore, a new technology is needed to simultaneously produce DRI with different, higher carbon levels from a single shaft furnace. Summary of the Invention

[0011] The embodiments of the present invention are designed to address the aforementioned and other needs.

[0012] Advantageously, embodiments of this disclosure address the aforementioned problems as follows: Instead of relying on carburizing chemistry in a shaft furnace to introduce carbon into the DRI product, embodiments of this disclosure incorporate carbon directly into the product downstream of the feed-leg (located downstream of the shaft furnace). This carbon product can be in various forms of graphitic carbon (including biochar) and can include processes for converting the graphitic carbon into cementite (Fe3C). Since the shaft furnace can supply multiple feed-legs simultaneously, different levels of carbon can be achieved for the HDRI or HBI output of each feed-leg.

[0013] Advantageously, embodiments of this disclosure can generally be applied to any DR facility (plant), but are particularly advantageous to: (1) facilities requiring high-carbon products, (2) facilities whose customers have different carbon content requirements for HDRI or HBI, (3) facilities that must pay regulatory penalties for CO2 emissions or strive to provide environmentally friendly products; and (4) hydrogen-only plants that produce zero-carbon DRI, such facilities would require this type of secondary operation to add carbon to the product.

[0014] In some embodiments, this disclosure provides a method for producing direct reduced iron (DRI) products, the method comprising: generating hot DRI (also referred to as molten DRI) in a shaft furnace; receiving the hot DRI in a feed branch downstream of the shaft furnace; and adding carbon to the hot DRI in the feed branch downstream of the shaft furnace to form a DRI product.

[0015] In some implementations, hot direct reduced iron is produced in a shaft furnace using hydrogen as the sole reducing agent.

[0016] In some embodiments, the method further includes generating fines in the hot direct reduced iron downstream of the shaft furnace and reheating the hot direct reduced iron in the feed branch downstream of the shaft furnace.

[0017] In some implementations, adding carbon to the hot direct reduced iron in the feed branch downstream of the shaft furnace includes metering and mixing the carbon into the hot direct reduced iron.

[0018] In some embodiments, the carbon added to the hot direct reduced iron in the feed branch downstream of the shaft furnace is graphitic carbon. In some embodiments, the carbon added to the hot direct reduced iron in the feed branch downstream of the shaft furnace is graphitic carbon that has been converted into cementite. In some embodiments, the carbon added to the hot direct reduced iron in the feed branch downstream of the shaft furnace is biochar.

[0019] In some embodiments, the method further includes receiving hot direct reduced iron with added carbon and pressing it into blocks to form a direct reduced iron product.

[0020] In some embodiments, the method further includes receiving hot direct reduced iron in an additional (optionally parallel) feed branch downstream of the shaft furnace and adding additional carbon (in different amounts) to the hot direct reduced iron in the additional feed branch downstream of the shaft furnace, thereby using the same hot direct reduced iron stream from the same shaft furnace to form additional direct reduced iron products with different carbon contents.

[0021] In some embodiments, this disclosure provides a system for producing direct reduced iron (DRI) products, the system comprising: a shaft furnace for producing hot DRI; a feed branch downstream of the shaft furnace for receiving the hot DRI; and a carbon addition system for adding carbon to the hot DRI in the feed branch downstream of the shaft furnace to form DRI products.

[0022] In some implementations, hot direct reduced iron is produced in a shaft furnace using hydrogen as the sole reducing agent.

[0023] In some embodiments, the system further includes: a hot direct reduced iron crusher downstream of the shaft furnace for generating fine chips in the hot direct reduced iron; and a reheater system for reheating the hot direct reduced iron in the feed branch downstream of the shaft furnace.

[0024] In some implementations, adding carbon to the hot direct reduced iron in the feed branch downstream of the shaft furnace includes: metering and mixing the carbon added to the hot direct reduced iron using a carbon metering and mixing system.

[0025] In some embodiments, the carbon added to the hot direct reduced iron in the feed branch downstream of the shaft furnace is graphitic carbon. In some embodiments, the carbon added to the hot direct reduced iron in the feed branch downstream of the shaft furnace is graphitic carbon that has been converted into cementite. In some embodiments, the carbon added to the hot direct reduced iron in the feed branch downstream of the shaft furnace is biochar.

[0026] In some embodiments, the system further includes a briquetting machine for receiving hot direct reduced iron with added carbon and briquetting it to form a direct reduced iron product.

[0027] In some embodiments, the system further includes an additional (optionally parallel) feed branch downstream of the shaft furnace for receiving hot direct reduced iron, and a carbon addition system or additional carbon addition system for adding additional carbon (in different amounts) to the hot direct reduced iron in the additional feed branch downstream of the shaft furnace, thereby using the same hot direct reduced iron stream from the same shaft furnace to form additional direct reduced iron products with different carbon contents.

[0028] It will be apparent to those skilled in the art that the elements, limitations, aspects and features of various embodiments of this disclosure may be included, omitted and combined as needed in the intended application, without limitation. Attached Figure Description

[0029] The present disclosure has been illustrated and described with reference to the accompanying drawings, wherein like reference numerals are used where appropriate to denote like method steps / system components, and wherein:

[0030] Figure 1 This is a schematic diagram illustrating one embodiment of the system disclosed herein, depicting a vertical shaft furnace and a briquetting machine;

[0031] Figure 2 It shows something similar to Figure 1 A schematic diagram of one embodiment of the system disclosed herein depicts a vertical shaft furnace and a briquetting machine, customized to further reduce or eliminate CO2 emissions during the DR production process;

[0032] Figure 3 It shows the relationship with Figure 1 and Figure 2 A schematic diagram of one embodiment of a system similar to that described in this disclosure depicts a vertical shaft furnace and a briquetting mill, further showing an overall diagram of multiple feed branches connected to the vertical shaft furnace, wherein each feed branch is capable of producing HBI with a specific and different carbon content; and

[0033] Figure 4 This is a flowchart illustrating one implementation of the method described in this disclosure.

[0034] It will be apparent to those skilled in the art that the elements, limitations, aspects and features in the various figures of this disclosure may be included, omitted and combined as needed in the particular application, without limitation. Detailed Implementation

[0035] Again, in its various embodiments, this disclosure generally relates to the fields of DRI and steelmaking, particularly to the areas of process and product improvement. More specifically, this disclosure relates to a method and system for producing DRI with multiple carbon levels from a single shaft furnace in a DR facility, thereby providing the DR facility with an option to deliver HDRI or HBI from the outlet of a continuously operating shaft furnace.

[0036] Instead of relying on carburizing chemistry in a shaft furnace to introduce carbon into the DRI product, embodiments of this disclosure incorporate carbon directly into the product downstream of the feed branch (which is downstream of the shaft furnace). This carbon product can be in various forms of graphitic carbon (including biochar) and can include processes for converting the graphitic carbon into cementite (Fe3C). Since the shaft furnace can supply multiple feed branches simultaneously, different levels of carbon can be output from each feed branch of the HBI.

[0037] The advantages of the embodiments of this disclosure arise from a mixer that: (1) operates within the process flow of existing DRI processing technology; (2) overcomes the tendency of graphite carbon segregation; and (3) produces high-carbon HBI products without compromising briquette quality requirements such as strength and density.

[0038] An advantageous feature of an embodiment of this disclosure is the ability to simultaneously output multiple carbon-containing HBI products from a single shaft furnace (from different feed branches). The current embodiment used in this disclosure is located within the feed branch section, upstream of the briquetting mill, so the mixer is suited to this location within each feed branch section (physically and technologically). Achieving uniform carbon coating to ensure the resulting briquettes retain their strength is a unique challenge addressed by this disclosure.

[0039] Furthermore, the design benefits include: the percentage of carbon in the HBI is no longer limited by the carburizing chemistry in the shaft furnace, allowing the production of products with up to 5% carbon or higher. Additionally, direct carbon incorporation at each feed branch has higher carbon efficiency compared to current state-of-the-art technologies (carburizing), so any CO2 emissions associated with the production of carbon-containing HBI are minimized or eliminated. If the carbon source is organic, CO2 offsetting or carbon credits are available.

[0040] Again, a key benefit of this design is that HBI products with different carbon percentages can be produced simultaneously using the same shaft furnace. Steel manufacturers' carbon requirements for HBI can vary from facility to facility, depending on other carbon inputs to the smelting and steelmaking processes. Under current state-of-the-art technology, if a DR facility expects to supply products to customers with different carbon requirements, the DR facility would have to fulfill one order with one carbon content requirement and then switch the process within the shaft furnace to produce the next order with a different carbon content requirement. This leads to inefficiency, which the implementation of this disclosure eliminates.

[0041] Now refer to the attached diagram, Figure 1-3 Various arrangements of embodiments of this disclosure are illustrated schematically. It should also be noted that embodiments of this disclosure share certain aspects with US 2022 / 0403481 and address similar issues, the contents of which are incorporated herein by reference in their entirety.

[0042] Figure 1 This is a schematic diagram illustrating one embodiment of System 1 of this disclosure, depicting a vertical shaft furnace 5 and a briquetting machine 40. Specifically, Figure 1 A schematic diagram of one embodiment of the present disclosure is shown, which includes a vertical shaft furnace 5, a briquetting machine 40, conventional components between the inlet and outlet of a feed branch 50, and process components of the carbon addition system 60 of the present disclosure downstream of the feed branch 50.

[0043] Conventional components of each feed branch 50 include an HDRI crusher 10 disposed downstream of the shaft furnace 5. This HDRI crusher 10 is adapted to produce fine chips (required for proper compaction and strength) from the HDRI originating from the shaft furnace 5, and may be associated with a specific feed branch 50 or shared by all feed branches 50. Each feed branch 50 (individually or collectively) may also include a reheating system 20 operable to reheat the HDRI originating from the HDRI crusher 10 in each feed branch conduit 55. Each feed branch 50 (individually or collectively) also includes a briquetting machine 40 disposed downstream of one or more feed branches 50 and the carbon addition system 60 of this disclosure, operable to briquette the HDRI from one or more feed branches 50 to form HBI. If the desired product for some or all of the feed branches 50 is HDRI rather than HBI, the briquetting machine 40 may be omitted. In such cases, briquetting is unnecessary.

[0044] The process components of one or more carbon addition systems 60 of one or more feed branches 50 of this disclosure are disposed between one or more feed branches 50 and one or more briquetting machines 40, and include: (1) an HDRI crusher 30a for generating additional fines in the HDRI required for proper compaction and strength, (2) an optional additional reheating system 30b for compensating for heat loss associated with DRI processing and conveying, and (3) a dedicated carbon addition, metering and mixing system 30c for incorporating uniform carbon from the designated feed branch 50 into the DRI and HBI before / during briquetting. Figure 1 Only one feed branch 50 is depicted, but the process and equipment are reproducible for each feed branch 50; for example, one typical DR facility would have eight (8) feed branches 50. Therefore, customized carbon contents can be supplied to the DRI of multiple different feed branches 50, thus providing multiple HDRI or HBI outputs with different carbon contents, all using the same shaft furnace 5 upstream of one or more feed branches 50 to generate a single DRI stream.

[0045] Figure 2 This is a schematic diagram illustrating one implementation scheme of System 1, and... Figure 1 Similar to, but differing in that System 1 is customized to further reduce or eliminate CO2 emissions during the DR production process. Here, shaft furnace 5 uses hydrogen as the sole reducing agent, and the carbon material added to the DRI associated with each feed branch 50 is specified as biochar. It should be noted that... Figure 2 The intention is to depict implementation schemes including DR facilities using only hydrogen and / or carbon addition using biochar as described.

[0046] In particular, Figure 2 Also shown is a schematic diagram of one embodiment of the present disclosure, which includes a vertical shaft furnace 5, a briquetting machine 40, conventional components between the inlet and outlet of a feed branch 50, and process components of the carbon addition system 60 of the present disclosure downstream of the feed branch 50.

[0047] The conventional components of each feed branch 50 also include an HDRI crusher 10 disposed downstream of the shaft furnace 5. This HDRI crusher 10 is adapted to produce fine chips (required for proper compaction and strength) from the HDRI originating from the shaft furnace 5, and can be associated with a specific feed branch 50 or shared by all feed branches 50. Each feed branch 50 (individually or collectively) may also include a reheating system 20 operable to reheat the HDRI originating from the HDRI crusher 10 in each feed branch conduit 55. Each feed branch 50 (individually or collectively) also includes a briquetting machine 40 disposed downstream of one or more feed branches 50 and the carbon addition system 60 of this disclosure, operable to briquette the HDRI from one or more feed branches 50 to form HBI. If the desired product for some or all of the feed branches 50 is HDRI rather than HBI, the briquetting machine 40 can be omitted. In such cases, briquetting is not required.

[0048] The process components of one or more carbon addition systems 60 of one or more feed branches 50 of this disclosure are also disposed between one or more feed branches 50 and one or more briquetting machines 40, and include: (1) an HDRI crusher 30a for generating additional fines in HDRI required for proper compaction and strength, (2) an optional additional reheating system 30b for compensating for heat loss associated with DRI processing and conveying, and (3) a dedicated biochar addition, metering and mixing system 30c for incorporating uniform carbon from designated feed branches 50 into DRI and HBI before / during briquetting. Figure 2 Only one feed branch 50 is depicted, but the process and equipment are reproducible for each feed branch 50; for example, one typical DR facility would have eight (8) feed branches 50. Therefore, customized carbon contents can be supplied to the DRI of multiple different feed branches 50, resulting in multiple HDRI or HBI outputs with different carbon contents, all using the same shaft furnace 5 upstream of one or more feed branches 50 that generates a single DRI stream.

[0049] Figure 3 This is a schematic diagram illustrating one implementation scheme of System 1, which is related to... Figure 1 and Figure 2Similarly, and further shown is an overall diagram of multiple feed branches 50 exiting the shaft furnace 5, each of which is capable of producing specific and different carbon content HDRI or HBI products.

[0050] In particular, Figure 3 Also shown is a schematic diagram of one embodiment of the present disclosure, which includes a vertical shaft furnace 5, a briquetting machine 40, conventional components between the inlet and outlet of a feed branch 50, and process components of the carbon addition system 60 of the present disclosure downstream of the feed branch 50.

[0051] The conventional components of each feed branch 50 also include an HDRI crusher 10 disposed downstream of the shaft furnace 5. This HDRI crusher 10 is adapted to produce fine chips (required for proper compaction and strength) from the HDRI originating from the shaft furnace 5, and can be associated with a specific feed branch 50 or shared by all feed branches 50. Each feed branch 50 (individually or collectively) may also include a reheating system 20 operable to reheat the HDRI originating from the HDRI crusher 10 in each feed branch conduit 55. Each feed branch 50 (individually or collectively) also includes a briquetting machine 40 disposed downstream of one or more feed branches 50 and the carbon addition system 60 of this disclosure, operable to briquette the HDRI from one or more feed branches 50 to form HBI. If the desired product for some or all of the feed branches 50 is HDRI rather than HBI, the briquetting machine 40 can be omitted. In such cases, briquetting is unnecessary.

[0052] The process components of one or more carbon addition systems 60 of one or more feed branches 50 of this disclosure are also disposed between one or more feed branches 50 and one or more briquetting machines 40, and include: (1) an HDRI crusher 30a for generating additional fines in the HDRI required for proper compaction and strength, (2) an optional additional reheating system 30b for compensating for heat loss associated with DRI processing and conveying, and (3) a dedicated carbon (or biochar) addition, metering and mixing system 30c for incorporating uniform carbon from the designated feed branch 50 into the DRI and HBI before / during briquetting. Figure 3 A feed branch 50 is also depicted, but the process and equipment are reproducible for each feed branch 50; for example, one typical DR facility would have eight (8) feed branches 50. Therefore, customized carbon contents can be supplied to the DRI of multiple different feed branches 50, thus providing multiple HDRI or HBI outputs with different carbon contents, all using the same shaft furnace 5 upstream of one or more feed branches 50 to generate a single DRI stream.

[0053] As shown, by way of example only, process components of one or more carbon addition systems 60 via one or more feed branches 50 of this disclosure have HDRI or HBI of 1.5%C, 2%C, 2.5%C, 3%C, 3.5%C, 4%C and 5%C from different feed branches 50.

[0054] Figure 4 This is a flowchart illustrating one embodiment of method 100 of this disclosure. At step 110, method 100 includes first generating HDRI via a reduction reaction in a shaft furnace 5, optionally using hydrogen as the sole reducing agent. At step 120, using an HDRI crusher 10, fine chips (required for proper compaction and strength) are generated from the HDRI originating from the shaft furnace 5. At step 130, using an associated reheating system 20, the HDRI originating from the HDRI crusher 10 is reheated in each feed branch 55 pipe. At step 140, in one or more carbon addition systems 60 of one or more feed branches 50 of this disclosure, located between one or more feed branches 50 and one or more briquetting machines 40, (1) additional fines required for proper compaction and strength are generated in the HDRI using an HDRI crusher 30a, (2) optionally using an additional reheating system 30b to compensate for heat losses associated with DRI processing and conveying, and (3) uniform carbon from the designated feed branch 50 is incorporated into the DRI and HBI before or during briquetting using a dedicated carbon (or biochar) addition, metering, and mixing system 30c. This process and equipment are reproducible for each feed branch 50; for example, one typical DR facility would have eight (8) feed branches 50. Therefore, customized carbon contents can be provided to the DRI of multiple different feed branches 50, resulting in multiple HDRI or HBI outputs with different carbon contents, all using the same shaft furnace 5 upstream of one or more feed branches 50 that generates a single DRI stream. At step 150, the carbon-reinforced HDRI is optionally briquetteed using briquetting machine 40 to form HBI. Similarly, if the desired product for some or all feed branches 50 is HDRI rather than HBI, briquetting machine 40 can be omitted. In such cases, briquetting is unnecessary.

[0055] Although this disclosure has been illustrated and described with reference to preferred embodiments and specific examples, it will be apparent to those skilled in the art that other embodiments and implementations can perform similar functions and / or achieve the same results. All such equivalent embodiments and implementations are considered within the spirit and scope of this disclosure and are intended to be covered by the appended non-limiting claims for all purposes. Furthermore, all elements, limitations, and features described and claimed can be used in any combination in various embodiments.

Claims

1. A method for producing direct reduced iron products, the method comprising: Heat is generated in the vertical shaft furnace to directly reduce iron; The hot direct reduced iron is received in the feed branch downstream of the shaft furnace; Carbon is added to the hot direct reduced iron in the feed branch downstream of the shaft furnace to form the direct reduced iron product. The hot direct reduced iron is received in an additional feed branch downstream of the shaft furnace; as well as Additional carbon is added to the hot direct reduced iron in an additional feed branch downstream of the shaft furnace to form an additional direct reduced iron product, wherein the carbon content of the additional direct reduced iron product is different from that of the direct reduced iron product.

2. The method according to claim 1, wherein the hot direct reduced iron is produced in the shaft furnace using hydrogen as the sole reducing agent.

3. The method according to claim 1, further comprising generating fine shavings in the hot direct reduced iron downstream of the shaft furnace.

4. The method according to claim 1, further comprising reheating the hot direct reduced iron in the feed branch downstream of the shaft furnace.

5. The method of claim 1, wherein adding the carbon to the hot direct reduced iron in the feed branch downstream of the shaft furnace comprises: The carbon is metered and mixed into the thermally reduced iron.

6. The method of claim 1, wherein the carbon added to the hot direct reduced iron in the feed branch downstream of the shaft furnace is graphitic carbon.

7. The method of claim 1, wherein the carbon added to the hot direct reduced iron in the feed branch downstream of the shaft furnace is graphitic carbon that has been converted into cementite.

8. The method of claim 1, wherein the carbon added to the hot direct reduced iron in the feed branch downstream of the shaft furnace is biochar.

9. The method according to claim 1, further comprising: The hot direct reduced iron with added carbon is received and briquetted to form the direct reduced iron product.

10. The method of claim 1, wherein the additional feed branch downstream of the shaft furnace operates in parallel with the feed branch downstream of the shaft furnace to form another additional direct reduced iron product.

11. A system for producing direct reduced iron products, the system comprising: Vertical shaft furnace, used to generate direct reduced iron; A feed branch downstream of the vertical furnace is used to receive the hot direct reduced iron. A carbon addition system for adding carbon to hot direct reduced iron in the feed branch downstream of the shaft furnace to form the direct reduced iron product. An additional feed branch, located downstream of the shaft furnace, is used to receive the hot direct reduced iron; and The carbon addition system or additional carbon addition system is used to add additional carbon to the hot direct reduced iron in the additional feed branch downstream of the shaft furnace to form an additional direct reduced iron product, wherein the carbon content of the additional direct reduced iron product is different from that of the direct reduced iron product.

12. The system of claim 11, wherein the thermal direct reduced iron is produced in the shaft furnace using hydrogen as the sole reducing agent.

13. The system of claim 11, further comprising: A hot direct reduced iron crusher, located downstream of the vertical shaft furnace, is used to generate fine chips in the hot direct reduced iron.

14. The system of claim 11, further comprising: A reheater system for reheating the hot direct reduced iron in the feed branch downstream of the shaft furnace.

15. The system of claim 11, wherein adding the carbon to the hot direct reduced iron in the feed branch downstream of the shaft furnace comprises: The carbon is metered and mixed into the thermally reduced iron using a carbon metering and mixing system.

16. The system of claim 11, wherein the carbon added to the hot direct reduced iron in the feed branch downstream of the shaft furnace is graphitic carbon.

17. The system of claim 11, wherein the carbon added to the hot direct reduced iron in the feed branch downstream of the shaft furnace is graphitic carbon that is converted into cementite.

18. The system of claim 11, wherein the carbon added to the hot direct reduced iron in the feed branch downstream of the shaft furnace is biochar.

19. The system of claim 11, further comprising: A briquetting machine is used to receive the hot direct reduced iron with added carbon and briquette it to form the direct reduced iron product.

20. The system of claim 11, wherein the additional feed branch downstream of the shaft furnace operates in parallel with the feed branch downstream of the shaft furnace to form another additional direct reduced iron product.

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