Equipment and process for charging iron ore into a direct reduction shaft and / or discharging sponge iron from a direct reduction shaft

Abstract

The present disclosure relates to an installation and process for charging iron ore (207) into a direct reduction shaft (211) and an installation and process for discharging sponge iron (208) from the direct reduction shaft. Both processes each include a step of drawing a vacuum to evacuate the vessel and then refilling the vessel with a seal gas (223), the seal gas being a non-oxidant gas. Furthermore, the present disclosure relates to a system for the production of sponge iron, comprising such an installation for charging iron ore and / or an installation for discharging sponge iron. Furthermore, the present disclosure relates to a process for the direct reduction of iron ore, the process comprising introducing a seal gas consisting essentially of a gas selected from hydrogen, biogas, biosyngas, carbon dioxide, and combinations thereof, into the direct reduction shaft in conjunction with charging iron ore and / or discharging sponge iron.

Description

[Technical Field]

[0001] The present invention relates to an installation for charging iron ore into a direct reduction shaft and a process for charging iron ore into a direct reduction shaft using such an installation. The present invention further relates to an installation for discharging sponge iron from a direct reduction shaft and a process for discharging sponge iron from a direct reduction shaft using such an installation. Furthermore, the present invention relates to a system for producing sponge iron and a process for the direct reduction of iron ore, comprising such an installation. [Background technology]

[0002] Steel is the most important engineering and construction material in the world. It is difficult to find an object in the modern world that does not contain steel or that does not rely on steel for its production and / or transportation. As such, steel is intricately involved in nearly every aspect of our modern lives.

[0003] In 2018, total global production of crude steel was 1.81 billion tonnes, far exceeding any other metal, and is expected to reach 2.8 billion tonnes by 2050, of which 50% is expected to come from virgin iron sources. Steel is also the world's most recycled material at very high reuse grades due to the metal's ability to be used repeatedly after remelting, using electricity as the primary energy source.

[0004] Thus, steel is a foundation of modern society that will play an even more important role in the future.

[0005] Steel is produced mainly through three routes: i) An integrated process that uses virgin iron ore in a blast furnace (BF) to produce iron by reducing the iron oxide in the ore with carbon. The iron is further processed in the steelworks by oxygen blowing in a basic oxygen furnace (BOF) and subsequent refining to produce steel. This process is also commonly referred to as "oxygen steelmaking." ii) Scrap-based production using recycled steel melted in electric arc furnaces (EAFs) that use electricity as the primary energy source. This process is also commonly referred to as "electric steelmaking." iii) Direct reduction production based on virgin iron ore, which is reduced in a direct reduction (DR) process with carbonaceous reducing gases to produce sponge iron, which is subsequently melted with scrap in an EAF to produce steel.

[0006] The term crude iron is used herein to mean all iron produced for further processing into steel, whether obtained from a blast furnace (i.e., pig iron) or from a direct reduction shaft (i.e., sponge iron).

[0007] Although the above processes have been refined over decades and are approaching the theoretical minimum energy consumption, one fundamental problem remains unsolved: the reduction of iron ore using carbonaceous reductants produces CO2 as a by-product. In 2018, an average of 1.83 tons of CO2 was produced per ton of steel produced. The steel industry is one of the most CO2-producing industries, accounting for approximately 7% of global CO2 emissions. As long as carbonaceous reductants are used, excess CO2 generation is unavoidable in the steel production process.

[0008] The HYBRIT initiative was established to address this issue. HYBRIT, short for HYdrogen BReakthrough Ironmaking Technology, is a joint venture between SSAB, LKAB and Vattenfall, partly funded by the Swedish Energy Agency, and aims to reduce CO2 emissions and decarbonise the steel industry.

[0009] At the heart of the HYBRIT concept is the direct reduction-based production of sponge iron from virgin ore. However, instead of using a carbonaceous reductant gas such as natural gas, as in current commercial direct reduction processes, HYBRIT proposes using hydrogen gas as the reductant, termed hydrogen direct reduction (H-DR). Hydrogen gas can be produced, for example, by water electrolysis using primarily fossil-free and / or renewable primary energy sources, as is the case for electricity production in Sweden. Thus, the key step of reducing iron ore can be accomplished without the need for fossil fuels as an input and with water instead of CO2 as a by-product.

[0010] In both prior art fossil-based direct reduction systems and the proposed hydrogen-based direct reduction system, it is essential that the iron ore can be safely charged into the direct reduction shaft. Because the process gases passing through the shaft are highly flammable (typically containing hydrogen, carbon monoxide, and hydrocarbons in fossil-based processes), the formation of an explosive air / process gas mixture must be avoided when the ore is introduced into the shaft. This is typically achieved by ensuring that only inert (i.e., flammable, non-oxidizing) seal gases, and no air, are introduced into the shaft when the ore is being charged, and by ensuring that process gases do not exit the shaft uncontrolled via the charging equipment. The exact manner in which this is achieved depends on the design of the direct reduction system.

[0011] Typically, in DR shafts operating at low pressures (e.g., 2 bar or less), such as the Midrex process, dynamic gas seals are placed in the seal legs that connect the ore charging vessel directly to the reduction shaft. An inert seal gas is introduced at one or more points in the seal legs at a pressure above the operating pressure of the DR shaft. This high-pressure seal gas prevents air from being introduced into the DR shaft with the iron ore charge, while also preventing process gas from escaping the DR shaft through the seal legs.

[0012] Typically, in DR shafts operating at high pressures (e.g., greater than 2 bar), such as the Hyl ZR process, a charging vessel is located at the entrance to the direct reduction shaft. The ore is charged into a pressurizable charging vessel, which is first flushed with an inert seal gas to remove air and then pressurized using the seal gas to approximately the operating pressure of the DR shaft. Once pressurized, a valve separating the charge vessel from the DR shaft is opened, allowing the charge iron ore, along with the seal gas, to be introduced into the shaft. Once the charging vessel is empty of ore, it is resealed and flushed again with seal gas to evacuate the charging vessel from the process gas. Finally, the charging vessel can be opened to the atmosphere and refilled with ore. Typically, multiple charging vessels are arranged in parallel to supply ore to the DR shaft.

[0013] Similar equipment is also typically located at the discharge end of the direct reduction shaft to safely discharge the sponge iron produced.

[0014] There remains a need for improved means for charging iron ore to and / or discharging sponge iron from direct reduction shafts. Summary of the Invention [Problem to be solved by the invention]

[0015] Summary of the Invention The inventors of the present invention have identified several shortcomings in the prior art means of charging iron ore into a direct reduction shaft.

[0016] Prior art means of charging ore typically require the use of large amounts of seal gas, which is typically produced on-site, for example, using an air separation unit when the seal gas is nitrogen. The need for large amounts of seal gas contributes to the high capital and operating costs of direct reduction systems.

[0017] Additionally, when using conventional ore injection methods, the introduction of seal gas into the process gas is unavoidable. As mentioned above, commonly used seal gases, such as nitrogen, must be inert (i.e., they must not form explosive mixtures with the process gas) and therefore remain in the process gas. However, other components of the process gas are typically consumed by reaction (e.g., H2, CO, CH4) or removed from the circulation (e.g., H2O, CO2). This means that seal gas gradually accumulates in the process gas, and if nothing is done, its proportion will increase. To avoid this situation, a portion of the process gas is typically bled and flared from the process gas circuit to maintain an appropriate concentration of inert components in the process gas. This is economically detrimental, especially for the proposed hydrogen-based direct reduction process, because the reducing gas in such cases is expected to be more expensive than fossil-based reducing gas, at least initially. If the reducing gas is fossil-based, bleed-off of the process gas also leads to increased CO2 emissions, which is detrimental to the environment.

[0018] The outlet of the direct reduction shaft, through which the produced sponge iron is discharged, also needs to be sealed, and the prior art means of discharging sponge iron suffers from the same drawbacks as the prior art means of charging ore.

[0019] It would be advantageous to provide a means for charging iron ore to and / or discharging sponge iron from a direct reduction shaft that overcomes or at least mitigates at least some of the above-mentioned disadvantages. In particular, it would be desirable to provide a means for charging iron ore to and / or discharging sponge iron from a direct reduction shaft that reduces the need for seal gas, potentially eliminates the need for process gas bleeding, and thus potentially reduces the cost of operating a direct reduction plant. [Means for solving the problem]

[0020] In order to better address one or more of these challenges, a process for charging iron ore into a direct reduction shaft is provided having the features defined in the independent claims.

[0021] This process is a) setting the ore outlet of the ore charging vessel to a sealed state; b) setting the ore inlet of the ore charging vessel to an open state; c) charging iron ore into the ore charging vessel via the ore inlet; d) setting the ore inlet to a sealed state; e) drawing a vacuum to remove gas from the ore charging vessel; f) refilling the ore charging vessel with a seal gas; g) setting the ore outlet to an open state and charging iron ore into the direct reduction shaft; Includes:

[0022] The seal gas is a non-oxidizing gas.

[0023] According to the disclosed process, the ore-filled charging vessel is evacuated and evacuated before being refilled with a selected non-oxidizing seal gas. Because the vacuum removes substantially all air from the charging vessel, flushing the charging vessel with large amounts of seal gas to ensure oxygen removal is not required. This may be contrasted with the amount of seal gas used to flush the charging vessel in prior art methods (i.e., typically about five times the volume of the charging vessel per charge).

[0024] According to another aspect of the invention, the object is achieved by a process for discharging sponge iron from a direct reduction shaft according to the attached independent claim.

[0025] The process for extracting sponge iron is as follows: i) setting the iron outlet and iron inlet of the iron discharge container to a sealed state; ii) drawing a vacuum to remove gas from the iron discharge vessel; iii) refilling the iron charge vessel with seal gas; iv) setting the iron inlet of the iron discharge container to an open state; v) charging sponge iron into the iron discharge vessel via the iron inlet; vi) setting the iron inlet to a sealed state; Including, The seal gas is a non-oxidizing gas.

[0026] Similar to the process for charging iron ore, the use of vacuum removes substantially all of the air from the discharge vessel, which means that less seal gas is required to ensure the atmosphere within the discharge vessel is sufficiently non-reactive before opening the vessel to the direct reduction shaft.

[0027] The following considerations apply independently to both the process for charging iron ore and the process for discharging sponge iron, unless otherwise specified.

[0028] By drawing a vacuum, the ore charging vessel (and alternatively or additionally, the iron discharge vessel) can be brought to a pressure of about 100 mbar or less, preferably about 10 mbar or less, and even more preferably about 1 mbar or less at ambient temperature (20° C.). The use of a stronger vacuum allows fewer evacuation / recharge cycles to be used before charging iron ore into (or discharging sponge iron from) the direct reduction shaft.

[0029] The seal gas can be selected from the list consisting of hydrogen, methane, biogas, syngas, carbon dioxide, nitrogen, refinery off-gas, and combinations thereof. That is, the seal gas can be a common inert gas (a flammable, non-oxidizing agent) such as carbon dioxide, nitrogen, or refinery off-gas. However, the process described herein allows substantially all of the seal gas used to be introduced directly into the reduction shaft, and therefore, seal gas is not wasted, in contrast to prior art methods in which large amounts of seal gas are used to purge the loading vessel or maintain a dynamic seal. Furthermore, the disclosed process empties the loading / unloading vessel substantially free of air before refilling with seal gas, thereby avoiding mixing of air with the seal gas. These combined features allow gases other than inert gases to be used as the seal gas, e.g., more expensive and / or potentially flammable gases. Thus, a pure reducing gas such as hydrogen gas, a reducing gas and a carburizing gas such as methane, biogas, or syngas, or an indirect carburizing gas such as carbon dioxide can be used as the seal gas. The use of such gases means that the introduction of inert gases into the direct reduction shaft can be avoided, and therefore no process gas bleeding is required to prevent the accumulation of inert components in the process gas. This can significantly improve process gas utilization and reduce operating costs. The methane can be biomethane and / or the syngas can be biosyngas. The carbon dioxide can be obtained from biological sources, i.e., non-fossil CO2.

[0030] In some cases, a single vacuum / recharge cycle may be sufficient to allow safe charging of iron ore into the direct reduction shaft (and alternatively or additionally to allow safe discharge of sponge iron from the direct reduction shaft). In such cases, only air is removed by vacuum and the charged gas is introduced into the direct reduction shaft, thereby avoiding the use of additional gas in the charging / discharge process beyond the amount of seal gas required to bring the relevant charging pressure to the charging / discharge vessel.

[0031] The process may further include the steps of drawing a vacuum to remove gas from the ore charging vessel (and, alternatively or additionally, the iron discharge vessel) and refilling the vessel with an inert gas. These steps may be performed after step d) of sealing the ore inlet but before step e) of drawing a vacuum to remove gas from the ore charging vessel (or after step i) but before step ii) in the sponge iron discharge process. That is, additional vacuum / refill cycles may be performed. This means that even when a relatively low vacuum, such as above about 100 mbar, is used, the process may be performed in stages by first performing an initial vacuum / refill cycle to provide a gas mixture into the vessel that contains primarily inert gas but some residual air. Subsequent vacuum / refill cycles should be sufficient to provide a gas mixture into the vessel that substantially contains the seal gas for the purposes of the present invention (i.e., to avoid the formation of a potentially explosive gas / air mixture).

[0032] Of course, multiple vacuum / refill cycles may be performed if desired, such as a total of three or four vacuum / refill cycles instead of the single and two vacuum / refill cycles already mentioned. However, since the total amount of inert gas required in the process increases with each vacuum / refill cycle, it is preferred that as few vacuum / refill cycles as possible be used. If more than one vacuum / refill cycle is performed, the refilling in the earlier cycle(s) is / are performed using inert gas, and refilling with seal gas is performed only in the final refill step.

[0033] The inert gas may be selected from the list consisting of carbon dioxide, nitrogen, refinery waste gas, and combinations thereof. The seal gas may be the same as or different from the inert gas. If the seal gas is different from the inert gas, the seal gas may be selected from the list consisting of hydrogen, methane, biogas, syngas, carbon dioxide, and combinations thereof. Using a seal gas that is not an inert gas helps prevent inert gases from accumulating in the process gas, thereby avoiding the need to bleed the process gas as described above. The methane may be biomethane and / or the syngas may be biosyngas. The carbon dioxide may be obtained from a biological source, i.e., non-fossil CO2.

[0034] Specifically, the process for charging iron ore into the direct reduction shaft may further include setting the ore outlet to a sealed state, drawing a vacuum to remove process gas from the ore charging vessel, backfilling the ore charging vessel with a gas selected from air, an inert gas, and combinations thereof, and setting the ore inlet to an open state. The inert gas may be selected from carbon dioxide, nitrogen, refinery off-gas, and combinations thereof. In this way, the charging vessel may be prepared for the introduction of a further charge of iron ore while ensuring efficient utilization of the gas.

[0035] According to another aspect of the present invention, the object is achieved by a process for the direct reduction of iron ore to sponge iron according to the attached independent claims. The process comprises introducing a seal gas consisting essentially of a gas selected from hydrogen, methane, biogas, and syngas, or a combination of hydrogen, methane, biogas, or biosyngas with carbon dioxide, or a combination thereof, into a direct reduction shaft in conjunction with charging iron ore to the direct reduction shaft and / or discharging sponge iron from the direct reduction shaft. The methane may be biomethane and / or the syngas may be biosyngas. The carbon dioxide may be obtained from a biological source, i.e., non-fossil CO2. By "introducing in conjunction with," it is meant that the seal gas may be introduced into the direct reduction shaft using a process for charging iron ore to the direct reduction shaft and / or discharging sponge iron from the direct reduction shaft, for example, as described herein and in the attached independent claims.

[0036] Since gas is inevitably introduced into the direct reduction shaft in conjunction with the charging and / or discharging of solids therefrom, by introducing a seal gas that reduces and / or optionally carburizes the iron ore, the process introduces only gases that serve the purpose in the direct reduction and avoids the introduction of gases that may adversely affect the process. Gases that may adversely affect the process are, for example, inert gases such as nitrogen, which may accumulate in the process gas and, if accumulated to excessive concentrations, may reduce the reducing ability of the process gas. Typically, bleeding of the process gas is required to ameliorate the effects of such accumulation. Therefore, the disclosed process allows for more efficient use of the process gas, which may reduce the operating costs of the process.

[0037] The process may include introducing a makeup gas into the direct reduction shaft countercurrent to the iron ore. The makeup gas may be selected from hydrogen and biosyngas and may be the same as or different from the seal gas. The makeup gas may ensure that sufficient reducing gas is introduced into the process to fully reduce the iron ore to sponge iron.

[0038] According to a further aspect of the invention, the object is achieved by an installation for charging iron ore into a direct reduction shaft according to the attached independent claim, comprising: an ore charging vessel; a vacuum source; -Seal gas supply source Equipped with.

[0039] A vacuum source and a source of seal gas are each disposed in controllable fluid communication with the ore charging vessel.

[0040] The seal gas is a non-oxidizing gas.

[0041] Such equipment helps to carry out a process for charging iron ore into a direct reduction shaft as described in this specification and in the accompanying independent claims. The ore charging vessel, or more specifically the ore outlet of the ore charging vessel, is typically arranged in communication with the inlet of the direct reduction shaft, allowing the ore to pass directly from the ore charging vessel into the reduction shaft.

[0042] According to yet a further aspect of the invention, the object is achieved by an installation for discharging sponge iron from a direct reduction shaft according to the attached independent claim.

[0043] The equipment for discharging sponge iron is as follows: an iron discharge container; a vacuum source; -Seal gas supply source Equipped with.

[0044] A vacuum source and a source of seal gas are each disposed in controllable fluid communication with the iron discharge vessel.

[0045] The seal gas is a non-oxidizing gas.

[0046] Such equipment facilitates carrying out a process for discharging sponge iron from a direct reduction shaft as described in this specification and in the accompanying independent claims. The iron discharge vessel, or more specifically the iron inlet of the iron discharge vessel, is typically positioned in communication with the outlet of the direct reduction shaft to allow the sponge iron to pass from the direct reduction shaft to the iron discharge vessel.

[0047] The following considerations apply independently to both installations for charging iron ore and installations for discharging sponge iron, unless otherwise specified.

[0048] The ore charging vessel may include a sealable ore inlet, a sealable ore outlet, and at least one gas conduit. The iron discharge vessel may include a sealable iron inlet, a sealable iron outlet, and at least one gas conduit. A vacuum source and / or a source of seal gas may be disposed in fluid connection with the gas conduit.

[0049] Regarding the source of the seal gas, the seal gas may be selected from the list consisting of hydrogen, methane, biogas, syngas, carbon dioxide, nitrogen, refinery waste gas, and combinations thereof. The methane may be biomethane and / or the syngas may be biosyngas. The carbon dioxide may be obtained from a biological source, i.e., non-fossil CO2.

[0050] The facility(ies) may further comprise a source of inert gas. The source of inert gas may be disposed in controllable fluid communication with the ore charging vessel and / or the iron discharging vessel. The inert gas may be different from the seal gas.

[0051] If the facility(ies) further comprises a source of inert gas, the inert gas may be selected from the list consisting of carbon dioxide, nitrogen, refinery exhaust gas, and combinations thereof, and the seal gas may be selected from the list consisting of hydrogen, methane, biogas, syngas, carbon dioxide, and combinations thereof. The methane may be biomethane and / or the syngas may be biosyngas. The carbon dioxide may be obtained from a biological source, i.e., non-fossil CO2.

[0052] The equipment(s) may be configured to obtain a pressure in the ore charging vessel (and alternatively or additionally, the iron discharge vessel) of about 100 mbar or less, preferably about 10 mbar or less, and even more preferably about 1 mbar or less at ambient temperature (20° C.). The vacuum source is strong enough to bring the vessel to the desired pressure, and / or the vessel is configured to withstand such low pressures (i.e. the vessel may be a vacuum vessel); and / or Openings in the vessel, such as a sealable inlet, a sealable outlet, and / or a gas conduit(s), are sealable to the extent that a vacuum source can maintain pressure within the vessel. may be required.

[0053] According to yet another aspect of the present invention, the object is achieved by a system for producing sponge iron according to the attached independent claim. The system comprises an equipment for charging iron ore as described herein and / or an equipment for discharging sponge iron as described herein. That is, the system comprises an equipment for charging iron ore as described herein, or an equipment for discharging sponge iron as described herein, or an equipment for charging iron ore and an equipment for discharging sponge iron as described herein. The system may further comprise charging equipment and / or discharging equipment known in the art. The system may further comprise a direct reduction shaft and a source of make-up gas arranged in fluid connection with the direct reduction shaft. If the system comprises an equipment for charging iron ore, the ore charging vessel may be arranged in communication with an inlet of the direct reduction shaft. If the system comprises an equipment for discharging sponge iron, the iron discharge vessel may be arranged in communication with an outlet of the direct reduction shaft. If the system includes both an installation for charging iron ore and an installation for discharging sponge iron, the system may require only a single vacuum source, a single source of seal gas, and / or a single source of inert gas, i.e., separate gas and / or vacuum sources are not required for the charging and discharging installations, but rather these sources may be integrated.

[0054] The source of the make-up gas may be an electrolytic cell. The electrolytic cell may produce hydrogen by electrolysis of water, or may produce syngas (a mixture of carbon monoxide and hydrogen) by co-electrolysis of water and carbon dioxide. Thus, the make-up gas may be hydrogen or a synthetic gas, such as biosyngas. In this way, it is possible to produce sponge iron without requiring the use of fossil fuels as a source of reducing gas.

[0055] Additional objects, advantages, and novel features of the present invention will become apparent to those skilled in the art upon reading the following detailed description.

[0056] BRIEF DESCRIPTION OF THE DRAWINGS For a more complete understanding of the present invention, together with further objects and advantages thereof, the following detailed description should be read in conjunction with the accompanying drawings, in which like reference numerals designate like items in the various drawings. [Brief explanation of the drawings]

[0057] [Figure 1] This diagram shows an outline of the ore-based steelmaking value chain under the HYBRIT initiative. [Figure 2] 1 illustrates generally an exemplary embodiment of a system suitable for carrying out the processes disclosed herein. [Figure 3] 1 is a flow chart that schematically illustrates an exemplary embodiment of a process for charging iron ore as disclosed herein. [Figure 4] 1 is a flow chart that schematically illustrates an exemplary embodiment of a process for discharging sponge iron disclosed herein. DETAILED DESCRIPTION OF THE INVENTION

[0058] Detailed Description The present invention is based on the inventors' insight that using a vacuum to remove air from a charging vessel and then refilling it with a selected seal gas when charging iron ore into a direct reduction shaft offers a wide range of potential advantages. In contrast to prior art methods that rely on diluting the atmosphere inside the charging vessel until it is sufficiently inert (requiring many times the "vessel volume" of seal gas to be flushed out), the disclosed process first removes the air and replaces it with seal gas, thereby requiring less seal gas. Because less seal gas is required and there is no intermediate mixing between the seal gas and air, the seal gas does not need to be limited to inert gases (i.e., gases that do not form flammable or explosive mixtures with air or process gas). Instead, if desired, potentially flammable non-oxidant gases such as hydrogen, methane, biogas, or syngas may be used. This means that the accumulation of inert gases in the process gas can be avoided and the need for process gas bleeding can be reduced or completely avoided. The methane can be biomethane and / or the syngas can be biosyngas. Carbon dioxide may be obtained from biogenic sources, i.e., non-fossil CO2.

[0059] The same concept can be applied to the discharge of sponge iron from a direct reduction shaft with the same or similar advantages.

[0060] The term process gas is used herein to refer to the mixture of gases in a direct reduction process, regardless of the stage in the process. That is, process gas refers to the gas introduced into, passing through, exiting, and being recycled back to the direct reduction shaft. More specific terms are used to refer to the process gas at various points in the process or to refer to component gases added to the process gas to form part of the process gas.

[0061] Reducing gas is gas introduced at a point below the entrance of the shaft, the reducing gas flowing upwardly against the moving bed of ore to reduce the ore and possibly carburize the sponge iron.

[0062] Top gas is partially spent process gas that is extracted from the top end of the shaft adjacent the ore inlet. After processing, the top gas can be recycled directly back to the reduction shaft as a component of the reducing gas.

[0063] Make-up gas is a new gas added to the process gas to maintain its reducing capacity. Typically, make-up gas is added to the recycled top gas before it is reintroduced into the direct reduction shaft. Thus, the reducing gas typically includes the recycled top gas and make-up gas. The make-up gas and the recycled top gas may be mixed before being introduced into the direct reduction shaft, or they may be introduced separately and mixed within the shaft.

[0064] The seal gas is the gas that enters the direct reduction shaft from the ore charging facility at the inlet of the direct reduction shaft. The outlet end of the direct reduction shaft can also be sealed using seal gas, so seal gas can enter the DR shaft from the discharge facility at the outlet of the direct reduction shaft. Therefore, variations of the present invention using seal gas introduced during the discharge of sponge iron from the direct reduction shaft are equally applicable. The seal gas used in prior art processes is typically inert, and an inert seal gas can also be used in the process disclosed herein. However, in contrast to prior art processes, the seal gas in the process disclosed herein can instead be a reducing gas and / or a carburizing gas and can therefore be considered complementary to the make-up gas.

[0065] An inert gas is a gas that does not form potentially flammable or explosive mixtures with either air or the process gas, i.e., does not act as an oxidizer or fuel in a combustion reaction under the conditions governing the process. While carbon dioxide is referred to herein as an inert gas, it should be noted that it can be converted to carbon monoxide via the reverse water-gas shift reaction and subsequently participate in reduction and / or carburization reactions. Thus, while inert for purposes of not forming flammable / explosive mixtures, it is nonetheless consumed under certain conditions and does not accumulate in the process gas.

[0066] Iron ore charging The iron ore charge typically consists primarily of iron ore pellets, although some lump iron ore may also be introduced. The iron ore pellets typically contain mostly hematite, along with further additives or impurities such as gangue, flux, and binders. However, the pellets may also contain some other metals and other ores, such as magnetite. Iron ore pellets specifically designed for direct reduction processes are commercially available, and such pellets may be used in the present process.

[0067] The ore charging vessel is typically a vessel having a sealable ore inlet, a sealable ore outlet, and at least one gas conduit suitable for venting and / or introducing gas. Naturally, the vessel may have multiple gas conduits, e.g., separate conduits for venting and introducing gas, or multiple conduits for introducing various gases. The ore charging vessel is suitably constructed to withstand both the subatmospheric pressures (about 100 mbar or less, preferably about 10 mbar or less) generated during the evacuation step and the superatmospheric pressures (often greater than 2 bar, e.g., about 2 bar to about 10 bar) generated by recharging the seal gas. Multiple ore charging vessels may be arranged in parallel to supply ore to a single direct reduction shaft. For example, two, three, or four ore charging vessels may be arranged to supply ore to a single direct reduction shaft.

[0068] Before ore is charged into the charging vessel, the ore outlet is set to a sealed state to accommodate the ore being introduced. "Setting to a state" means bringing a component into that state if it is not already in that state, or maintaining that state if it is already in that state. Thus, the term "setting to a state" does not necessarily involve a change of state. The ore is charged into the vessel through the inlet, which is then sealed. A vacuum source disposed in fluid communication with the gas conduit is then used to evacuate the atmosphere from the charging vessel. The vacuum source may be, for example, a vacuum pump. Such pumps are known in the art. The charging vessel and pump are preferably configured so that the charging vessel can be brought to a pressure of about 100 mbar or less, preferably about 10 mbar or less, and even more preferably about 1 mbar or less at ambient temperature (20°C). Thus, substantially all air is evacuated from the charging vessel. If the vacuum achievable during the evacuation step is sufficiently low, the charging vessel can subsequently be refilled with a seal gas up to the charging pressure, i.e., the pressure of the charging vessel desired for introducing the ore into the direct reduction shaft. The charging pressure may typically be a pressure above the operating pressure of the direct reduction shaft, for example, a pressure of about 2 bar to about 10 bar. If the vacuum achievable during the evacuation step is not low enough, an undesirable amount of air may remain in the charging vessel. In such cases, the charging vessel may first be refilled with inert gas, followed by a further evacuation step. In this way, the amount of remaining air can be reduced to a safe level. The evacuation and inert gas refill steps may be performed as many times as necessary to ensure safety. In the final refill step, the charging vessel is filled with a seal gas that is introduced into the direct reduction shaft during charging. After filling with the ore and seal gas, the ore outlet of the charging vessel is set to an open state so that the mixture of ore and seal gas can be charged into the direct reduction shaft.

[0069] Once the ore has been charged into the direct reduction shaft, the ore charging vessel should be reset to safely remove any process gas contained therein and prepare the vessel for a new charge of ore. This can be done by sealing the ore outlet, evacuating the charging vessel to remove the process gas, and then refilling the charging vessel with a suitable gas, such as air, nitrogen, refinery off-gas, or carbon dioxide. The process gas evacuated in this step can be recycled to the direct reduction shaft. The vessel is then refilled to a pressure near atmospheric pressure. Alternatively, as with prior art methods, the vessel can simply be flushed with an inert gas to remove the process gas before opening. Once the vessel has been emptied of its potentially flammable contents and the vessel is again at or near atmospheric pressure, the vessel's inlet can be opened to accept a new charge of iron.

[0070] Direct reduction The direct reduction shaft may be of any type commonly known in the art. By shaft is meant a solid-gas countercurrent moving bed reactor, whereby the iron ore charge is charged to an inlet at the top of the reactor and flows downward by gravity to an outlet located at the bottom of the reactor. Reducing gas is introduced into the shaft at point I below the ore inlet, and the reducing gas flows upward to reduce and optionally carburize the ore.

[0071] The reduction is typically carried out at a temperature of about 900°C to about 1100°C. The required temperature is typically maintained by preheating the process gases introduced into the reactor using a preheater, for example an electric preheater. Further heating of the gases may be obtained by exothermic partial oxidation of the gases with oxygen or air after they leave the preheater and before they are introduced into the reactor. The reduction may be carried out in the DR shaft at a pressure of about 1 bar to about 10 bar, preferably about 3 bar to about 8 bar.

[0072] In conventional direct reduction processes, the make-up gas used to supplement the process gas is fossil-based and typically contains varying proportions of syngas and natural gas. The present disclosure is applicable to processes that utilize such fossil-based make-up gas. However, to provide a fossil-free process for obtaining sponge iron, it is preferred that the make-up gas not be derived from a fossil fuel.

[0073] The makeup gas may be primarily composed of hydrogen. For example, the makeup gas may comprise, consist essentially of, or consist of at least 80% by volume, preferably greater than 90% by volume, and even more preferably greater than 95% by volume of hydrogen gas (volume percentages measured at 1 atmosphere and normal conditions at 0°C). The disclosed process enables the production of substantially carbon-free sponge iron by using hydrogen as the makeup gas and not introducing a carbonaceous gas into the process gas. However, in some cases, it may be desirable to obtain carburized sponge iron. Therefore, some amount of carburizing gas and / or carbon dioxide may be added as makeup gas to achieve an appropriate level of carburization of the sponge iron. Carburizing gas is a carbon-containing gas capable of directly carburizing sponge iron, such as any carbon compound that is not fully oxidized, such as hydrocarbons or carbon monoxide. Such gases include, but are not limited to, methane, biogas, synthetic gas, and mixtures thereof. However, the carburizing effect in the present process may alternatively or additionally be achieved by introducing carbon dioxide. Under the prevailing carbon-lean conditions of the direct reduction shaft, the carbon dioxide is converted to carbon monoxide, which can then carburize the sponge iron. The methane may be biomethane and / or the syngas may be biosyngas. The carbon dioxide may be obtained from a biological source, i.e., non-fossil CO2.

[0074] In addition to hydrogen, the remainder of the makeup gas may therefore include, consist essentially of, or consist of carbon dioxide and / or carburizing gas. When carbon dioxide and / or carburizing gas constitute part of the makeup gas, they may be introduced directly into the reduction shaft along with the hydrogen makeup gas. Alternatively, some or all of the carbon dioxide and / or carburizing gas that constitutes part of the makeup gas may be added directly to the reduction shaft separately from the majority of the makeup gas. For example, the carburizing gas may be added directly to the carburizing zone or cooling zone of the reduction shaft.

[0075] The process gas may be at least partially recycled, whereby the top (spent) gas from the DR shaft may be scrubbed and treated to remove by-products such as water and / or dust before being reintroduced into the DR shaft. This recycled top gas may be mixed with fresh make-up gas before being reintroduced into the reactor, or it may be introduced separately from the fresh make-up gas supply.

[0076] The seal gas introduced with the iron ore charge also forms part of the process gas. As mentioned above, the seal gas may be an inert gas such as nitrogen or refinery off-gas. In such cases, it may be necessary to continuously remove a portion of the process gas from the process cycle to maintain a balance in the process gas and prevent the buildup of inert components. This is known as process gas bleeding. Process gas bled from the process cycle may be combusted, for example, to provide process heat in conjunction with preheating.

[0077] Alternatively, the seal gas may include, consist essentially of, or consist of non-oxidant gases that serve a purpose in the process, such as those gases described above as potential makeup gases. These include hydrogen, methane, biogas, syngas, carbon dioxide, and combinations thereof. The methane may be biomethane, and / or the syngas may be biosyngas, and / or the carbon dioxide may be bio-CO2. In such cases, no inert gas is added to the process gas, and therefore, process gas bleeding may be eliminated. The need to produce inert gas as a seal gas is also reduced, and capital equipment such as an air separation unit may be downsized or eliminated entirely.

[0078] Sponge iron is obtained as a product of the reduction of iron ore and is discharged directly from an outlet at the lower end of the reduction shaft. The shaft may have a cooling cone located at the bottom so that the sponge iron can be cooled before being discharged from the outlet.

[0079] Sponge iron excretion Discharging sponge iron from a direct reduction shaft has similar requirements to charging iron ore into the shaft. It is essential that no flammable / explosive gas mixtures are formed during discharge, and it is preferable to avoid introducing inert gases into the process gas whenever possible. Therefore, the principles of the present invention can also be applied to sponge iron discharge devices and processes.

[0080] The iron discharge vessel is typically a vessel equipped with a sealable iron inlet, a sealable iron outlet, and at least one gas conduit suitable for venting and / or introducing gas. Naturally, the vessel may be equipped with multiple gas conduits, e.g., separate conduits for venting and introducing gas, or multiple conduits for introducing various gases. The iron discharge vessel is suitably constructed to withstand both the subatmospheric pressures (about 100 mbar or less, preferably about 10 mbar or less) generated during the evacuation step and the superatmospheric pressures (often greater than 2 bar, e.g., about 2 bar to about 10 bar) generated by recharging the seal gas. Multiple iron discharge vessels may be arranged in parallel to receive iron from a single direct reduction shaft. For example, two, three, or four ore discharge vessels may be arranged to discharge iron from a single direct reduction shaft.

[0081] Before discharging the iron into the discharge vessel, the iron inlet and outlet are set to a sealed state. A vacuum source, fluidly connected to the gas conduit, is used to evacuate the atmosphere from the discharge vessel. The vacuum source may be, for example, a vacuum pump. Such pumps are known in the art. The discharge vessel and pump are preferably configured so that the discharge vessel can be pressurized to a pressure of about 100 mbar or less, preferably about 10 mbar or less, and even more preferably about 1 mbar or less at room temperature (20°C). Thus, substantially all air is evacuated from the discharge vessel. If the vacuum achievable during the evacuation step is sufficiently low, the discharge vessel can subsequently be refilled with a seal gas up to the discharge pressure, i.e., the pressure of the discharge vessel desired for receiving sponge iron from the direct reduction shaft. The discharge pressure may typically be equal to or greater than the operating pressure of the direct reduction shaft, for example, a pressure of about 2 bar to about 10 bar. If the vacuum achievable during the evacuation step is not sufficiently low, an undesirable amount of air may remain in the discharge vessel. In such cases, the discharge vessel may first be refilled with an inert gas, followed by a further evacuation step. In this way, the amount of remaining air can be reduced to a safe level. The vacuuming and inert gas refilling steps can be performed as many times as necessary to ensure safety. In the final refilling step, the discharge vessel is filled with a seal gas that is introduced into the direct reduction shaft when the sponge iron is discharged. Once a suitable atmosphere is established inside the discharge vessel, the iron inlet can be opened to accept the sponge iron into the vessel from the direct reduction shaft. Once the sponge iron is loaded, the inlet of the discharge vessel can be closed. The closed vessel then contains a mixture of hot sponge iron and process gas. Preferably, the gaseous contents of the vessel should be removed by vacuuming again and replaced with inert gas at an appropriate pressure before opening the outlet of the discharge vessel to release the contained sponge iron. The process gas evacuated in this step can be recycled to the direct reduction shaft.

[0082] Sponge iron The term crude iron is used herein to refer to any iron produced for further processing into steel, whether obtained from a blast furnace (i.e., pig iron) or, as in the disclosed process, from a direct reduction shaft (i.e., sponge iron). The sponge iron obtained at the outlet of the direct reduction shaft is usually primarily in the form of pellets due to the structural integrity of the direct reduction pellets and the conditions prevailing in the DR shaft. Such sponge iron is commonly referred to as direct reduced iron (DRI). Depending on the process parameters, it can be provided as high-temperature (HDRI) or low-temperature (CDRI). Low-temperature DRI is also known as Type (B) DRI. DRI is prone to reoxidation and, in some cases, is pyrophoric. However, several known means exist for passivating DRI. One such passivation method, commonly used to facilitate overseas transportation of the product, involves compressing high-temperature DRI into briquettes. Such briquettes are commonly referred to as high-temperature briquetted iron (HBI), also known as Type (A) DRI.

[0083] The sponge iron product obtained by the process herein can be essentially fully metallized sponge iron, i.e., sponge iron having a degree of reduction (DoR) of greater than about 90%, such as greater than about 94% or greater than about 96%. The degree of reduction is defined as the amount of oxygen removed from the iron oxide and is expressed as a percentage of the initial amount of oxygen present in the iron oxide. Due to reaction kinetics, obtaining sponge iron with a DoR of greater than about 96% is often commercially undesirable, although such sponge iron can be produced if desired.

[0084] As mentioned above, the processes described herein are suitable for producing carbon-free or carburized sponge iron, as desired. By carburized sponge iron, we mean sponge iron containing carbon. The carbon present in the sponge iron product may typically be in the form of cementite (FeC) and / or graphite. Graphite tends to become dust and is easily lost from the sponge iron before it reaches the melt in the EAF. For this reason, it may be preferable for the carbon to be present in the sponge iron as cementite.

[0085] The carburized sponge iron may contain 0.1% to 5% by weight carbon, such as 0.5% to 3% by weight carbon, such as about 1% to 2% by weight carbon. This may depend on the ratio of sponge iron to scrap used in the subsequent EAF processing step, but it is generally desirable for the sponge iron to have a carbon content of 0.5% to 5% by weight, preferably 1% to 4% by weight, such as about 3% by weight, for further processing. If desired, the carburized sponge iron product of the present process may then be further carburized by other means before further processing.

[0086] gas Preferably, hydrogen gas can be obtained at least in part by electrolysis of water. When the electrolysis of water is carried out using renewable energy, the reducing gas can be provided from a renewable source. The electrolytic hydrogen can be transported directly from the electrolyzer to the DR shaft by a conduit, or the hydrogen can be stored during production and transported to the DR shaft as needed.

[0087] When carbon dioxide is used as a seal gas, makeup gas, or inert gas in the processes described herein, the source of carbon dioxide is preferably substantially pure carbon dioxide, e.g., 95% or more by volume carbon dioxide, preferably 98% or more by volume. The source of carbon dioxide may preferably be a highly concentrated source, preferably a highly concentrated biogenic source. For example, concentrated "green" CO2 may be obtained as a by-product of biogas production by anaerobic digestion or as a by-product of bioethanol production. If the carbon dioxide used in the process is derived from a renewable source, the process may be net negative in terms of CO2 emissions. However, using a source of carbon dioxide derived from a fossil source that would otherwise be emitted directly means that the process cannot result in excessive CO2 emissions. An alternative means of providing carbon dioxide is to utilize oxy-fuel combustion of biomass to preheat the reducing gas before introducing it into the direct reduction shaft. The principle of oxy-fuel combustion is simple: biomass is burned using substantially pure oxygen as the oxidant. The resulting exhaust stream consists essentially of carbon dioxide and steam. The vapor can be removed by simple condensation to provide a source of substantially pure carbon dioxide. Previously, providing substantially pure oxygen was an economic obstacle to utilizing oxyfuel combustion. However, in this case, oxygen can be readily provided from water electrolysis at low additional cost, making oxyfuel preheating of the reducing gas economically feasible.

[0088] Carburizing gas can be used as a seal gas and / or a makeup gas. The carburizing gas can be any gas known or anticipated in the art to provide carburizing. In this context, gas refers to a substance that is gaseous at the high temperatures prevailing in the carburizing reactor, but may be liquid or solid at room temperature. Suitable carburizing gases include hydrocarbons such as methane, natural gas, LPG, or petroleum, or other carbonaceous substances such as synthetic gas, lower (C1-C6) alcohols, esters, and ethers. Carburizing gas can be of fossil origin, but is preferably derived partially or entirely from renewable sources to reduce net CO2 emissions. Renewable refers to a resource that is naturally replenished on a human timescale. The high utilization of carbon present in carburizing gas allows for the use of renewable carburizing gas, despite its relative scarcity and higher cost compared to fossil equivalents. Suitable renewable carburizing gases include biomethane, biogas, gases obtained from the pyrolysis or partial combustion of biomass (e.g., biosyngas), lower alcohols or ethers such as methanol, DME or ethanol derived from renewable sources, or combinations thereof. Sulfur-containing carburizing gases may be used, as sulfur is known to prevent graphite nucleation and passivate sponge iron products.

[0089] The composition of the carburizing gas can be selected to suit the final carburized sponge iron. While the carburizing reaction with hydrocarbons is relatively endothermic, resulting in a relatively low-temperature end product, the reaction with CO2-containing carburizing gases is more exothermic, resulting in a higher-temperature end product. This effect can be exploited to tailor the temperature of the resulting final product. For example, if a high-temperature product is desired for briquetting (HBI), gases containing partially oxidized carbon (e.g., in the form of CO, ketones, and aldehydes) can be used, while if low-temperature sponge iron (CDRI) is desired, biomethane can be used.

[0090] When considering the total amount of carbon dioxide and / or auxiliary carburizing gas suitable for addition to the process gas as a seal gas or in the make-up gas, factors to consider are the degree of carburization desired, the effect of the added carbon on the water-gas shift equilibrium, and the effect the added carbon has on the reducing ability of the reducing gas. For example, adding too much carbon can result in significant carbon dioxide accumulation in the process gas, reducing the reducing ability of the reducing gas and requiring bleeding of the process gas.

[0091] Inert gases such as nitrogen or purified exhaust gas can be used as the seal gas. Nitrogen can be obtained, for example, by cryogenic distillation of air using an air separation unit (ASU). By purified exhaust gas is meant exhaust gas that has been treated to ensure it is sufficiently inert for use as a seal gas. Such treatment can include post-combustion to remove excess oxygen and / or drying of the exhaust gas.

[0092] Embodiment The present invention will now be described in more detail with reference to certain exemplary embodiments and drawings. However, the present invention is not limited to the exemplary embodiments discussed herein and / or shown in the drawings, but may vary within the scope of the appended claims. Furthermore, the drawings should not be considered to scale, as some features may be exaggerated to more clearly show certain features.

[0093] FIG. 1 shows a schematic diagram of a prior art embodiment of an ore-based steelmaking value chain according to the HYBRIT concept. The ore-based steelmaking value chain begins at an iron ore mine 101. After mining, iron ore 103 is beneficiated and processed in a pelletizing plant 105 to produce iron ore pellets 107. These pellets, along with any agglomerated ore used in the process, are converted to sponge iron 109 by reduction in a direct reduction shaft 111 using hydrogen gas 115 as the primary reductant, producing water 117 as the primary by-product. The hydrogen gas 115 is produced by electrolysis of water 117 in an electrolyzer 119 using electricity 121, preferably derived primarily from fossil-free or renewable sources 122. The hydrogen gas 115 may be stored in a hydrogen storage tank 120 prior to introduction into the direct reduction shaft 111. The sponge iron 109 is melted using an electric arc furnace 123, possibly with a proportion of scrap iron 125 or other iron source, to provide a smelt 127. The smelt 127 is subjected to further downstream secondary metallurgical processes 129 to produce steel 131. It is intended that the entire value chain, from ore to steel, can be fossil-free and produce low or no carbon emissions.

[0094] FIG. 2 illustrates a schematic diagram of an exemplary embodiment of a system suitable for implementing the processes disclosed herein.

[0095] A direct reduction shaft 211 is provided with an inlet 211a for iron ore 207, an outlet 211b for discharging sponge iron 208, an inlet for reducing gas 211c, and an outlet for top gas 211d. A charging vessel 213 is disposed in communication with the inlet 211a to the direct reduction shaft 211. A discharging vessel 231 is disposed in communication with the outlet 211b of the direct reduction shaft 211.

[0096] The charging vessel 213 includes an inlet 213a for iron ore 207, an outlet 213b for iron ore 207, a gas inlet 213c, and a gas outlet 213d. The inlet 213a of the charging vessel 213 is connected to an ore bin 227. The gas inlet 213c of the charging vessel 213 is connected to a supply source 221 of a seal gas 223, and the gas outlet 213d is connected to a vacuum pump 229.

[0097] The discharge vessel 231 includes an inlet 231a for the sponge iron 208, an outlet 231b for the sponge iron 208, a first gas inlet 231c, a second gas inlet 231e, and a gas outlet 231d. The inlet 231a of the discharge vessel 231 is connected to the outlet 211b of the direct reduction shaft 211. The first gas inlet 231c of the loading vessel 231 is connected to a supply source 221 of a seal gas 223. The second gas inlet 231e of the loading vessel 231 is connected to a supply source 233 of a seal gas 235. The gas outlet 231d is connected to a vacuum pump 229.

[0098] Initially, the ore inlet 213a of the charging vessel 213 is open, and the ore outlet 213b, gas inlet 213c, and gas outlet 213d are closed. Iron ore 207 from an ore bin 227 is introduced into the charging vessel 213. Once the ore is loaded, the ore inlet 213a is sealed, the gas outlet 213d is opened, and the charging vessel 213 is evacuated using a vacuum pump 229, reducing the pressure within the charging vessel 213 to approximately 100 mbar or less. Once the target pressure is reached, the gas outlet 213d is closed, the gas inlet 213c is opened, and the charging vessel 213 is pressurized with a seal gas 223 to a pressure close to the operating pressure of the direct reduction shaft 211. Once pressurized, the gas inlet 213c is closed and the ore outlet 213b of the charging vessel 213 is opened to allow the iron ore 207 to be charged into the inlet 211a of the direct reduction shaft 211. A seal gas 223 is necessarily introduced into the direct reduction shaft during the charging operation. The iron ore 207 charged into the direct reduction shaft 211 gradually passes through the shaft and is discharged at the outlet 211b. While passing through the shaft 211, the ore 207 is reduced by the countercurrent reducing gas 217 so that sponge iron 208 is obtained at the outlet 211b of the reactor 211.

[0099] Before discharging the sponge iron 208, the discharge vessel 231 is first sealed at its inlets 231a and 231b, evacuated using a vacuum pump 229, and refilled with a seal gas 223. This makes the vessel 231 ready to receive the sponge iron 208. The inlet 231a of the vessel is opened to allow the sponge iron 208 to fall into the vessel and the seal gas in the vessel to move upward directly into the reduction shaft 211. Thereafter, the inlet 231a of the discharge vessel is closed, and the discharge vessel 231 is evacuated using a vacuum pump 229 and refilled with an inert gas 235 to atmospheric pressure. The outlet 231b of the discharge vessel 231 can then be opened to release the sponge iron 208.

[0100] Makeup gas 215 is supplied from a source of makeup gas 220, such as a hydrogen gas reservoir or a water electrolyzer. Makeup gas 215 is mixed with treated top gas 218 to form reduced gas 217. The reduced gas 217 is passed through a preheater 241 before being introduced into the direct reduction shaft 211. Top gas 216 exiting outlet 211d is passed through multiple treatment devices 243 to prepare the gas for reintroduction into the DR shaft 211. The multiple treatment devices may include cleaning steps, such as passing through an electrostatic precipitator to remove solids from the gas, heat exchange with other process gases, such as reduced gas 217, and water separation. Treated top gas 218 is mixed with makeup gas 215 and passed through a preheater 241 before being reintroduced into the direct reduction shaft 211 through inlet 211c. The temperature of the gas entering inlet 211c may be further increased by partial oxidation. In such a case, an oxygen supply (not shown) may be placed between preheater 241 and inlet 211c.

[0101] Once the ore has been discharged from the charging vessel 213, the vessel may be prepared for a new charge of ore. First, the ore outlet 213b is closed. Then, the gas outlet 213d is opened and process gas is evacuated from the charging vessel 213 using a vacuum pump 229. The gas outlet 213d is then closed and the charging vessel is recharged with gas to atmospheric pressure. In the illustrated example, the vessel 213 is recharged with seal gas 223 by opening the gas inlet 213c, but alternatively, if the seal gas is not an inert gas, it may be recharged from a source of inert gas (not shown). Finally, the gas inlet 213c is closed and the ore inlet 213a is opened. In this way, the charging vessel 213 is returned to its initial configuration and is ready to receive further charge of iron ore.

[0102] FIG. 3 is a flow chart that schematically illustrates an exemplary embodiment of a process for charging iron ore into a direct reduction shaft disclosed herein. Step s301 marks the start of the process. In step s303, the ore outlet 213b of the ore charging vessel 213 is set to a sealed state. In step s305, the ore inlet 213a of the ore charging vessel 213 is set to an open state. Note that these steps do not involve any change in the state of the charging equipment if the ore outlet 213b and the ore inlet 213a are already in a closed and open state, respectively. In step s307, the ore charging vessel 213 is charged with iron ore 207 through the ore inlet 213a. In step s309, the ore inlet 213a is set to a sealed state. In step s312, gas is evacuated from the ore charging vessel 213 by drawing a vacuum. In step s313, the ore charging vessel is refilled with seal gas 223. In step s315, the ore outlet 213b is set to an open state to charge the iron ore 207 into the direct reduction shaft 211. Step s317 marks the end of the process.

[0103] Although the recited steps are performed sequentially, there may be intervening steps. For example, if for some reason the vacuum applicable to the charging vessel is not sufficient to remove substantially all of the air, e.g., if the charging vessel does not tolerate such low pressure, one or more additional vacuum / refill cycles may be performed between steps s309 and s312. One such vacuum / refill cycle is shown in Figure 3. It includes step s310 of drawing a vacuum to evacuate the ore charging vessel 213 and step s311 of refilling the ore charging vessel with inert gas.

[0104] FIG. 4 is a flow chart that schematically illustrates an exemplary embodiment of a process for discharging iron ore from a direct reduction shaft disclosed herein. Step s401 indicates the start of the process. In step s403, the iron outlet 231a and iron inlet 231b of the iron discharge vessel 231 are set to a sealed state. Note that these steps do not involve any change in the state of the discharge equipment if the outlet 231b and inlet 231a are already in a closed state. In step s405, gas is evacuated from the iron discharge vessel 231 by drawing a vacuum. In step s407, the iron charging vessel 231 is refilled with the seal gas 223. In step s409, the iron inlet 231a of the iron discharge vessel 231 is set to an open state. In step s409, the iron discharge vessel 231 is charged with sponge iron 208 via the iron inlet 231a. In step s411, the iron inlet is set to a sealed state. In this manner, the sponge iron 208 is discharged from the direct reduction shaft 211. Through several optional intermediate steps (not shown), the discharge vessel is prepared for the discharge of the sponge iron 208. In the final step, s413, the iron outlet 231b is opened and the sponge iron 208 is discharged. Step s415 marks the end of the process. The listed steps are performed sequentially, although intervening steps may be present. For example, if for some reason the vacuum applicable to the discharge vessel is not sufficient to remove substantially all of the air, e.g., if the discharge vessel does not tolerate such low pressure, one or more additional vacuum / refill cycles may be performed (not shown) between steps s403 and s405.

Claims

1. 1. An installation for charging iron ore (207) into a direct reduction shaft (211), said installation comprising: an ore charging vessel (213); a vacuum source (229); a source of seal gas (221); Equipped with the vacuum source and the source of the seal gas are each disposed in controllable fluid communication with the ore charging vessel; The seal gas is selected from the list consisting of hydrogen, methane, biogas, syngas, carbon dioxide, nitrogen, refinery waste gas, and combinations thereof. Equipment.

2. 2. The installation according to claim 1, wherein the ore charging vessel comprises a sealable ore inlet (213a), a sealable ore outlet (213b), and at least one gas conduit (213c, 213d), and the vacuum source and / or the source of the sealing gas are arranged in fluid connection with the gas conduit.

3. 3. The installation of claim 1 or 2, further comprising a source of inert gas, the source of inert gas being arranged in controllable fluid connection with the installation for charging the iron ore (207) into the direct reduction shaft (211), the inert gas being different from the seal gas.

4. 4. The system of claim 3, wherein the inert gas is selected from the list consisting of carbon dioxide, nitrogen, refinery waste gas, and combinations thereof, and the seal gas is selected from the list consisting of hydrogen, methane, biogas, syngas, carbon dioxide, and combinations thereof.

5. 5. The installation according to any one of claims 1 to 4, configured to obtain a pressure of about 100 mbar or less, preferably about 10 mbar or less, even more preferably about 1 mbar or less at ambient temperature.

6. 1. An installation for discharging sponge iron from a direct reduction shaft, said installation comprising: a sponge iron discharge container (231); a vacuum source (229); a source of seal gas (221); Equipped with the vacuum source and the source of the seal gas are each disposed in controllable fluid communication with the iron discharge vessel; The seal gas is selected from the list consisting of hydrogen, methane, biogas, syngas, carbon dioxide, nitrogen, refinery waste gas, and combinations thereof. Equipment.

7. 1. A system for the production of sponge iron, said system comprising: An equipment for charging the iron ore according to any one of claims 1 to 5, and / or an equipment for discharging the sponge iron according to claim 6; A direct reduction shaft (211); a source of make-up gas (220) disposed in fluid communication with the direct reduction shaft; A system comprising:

8. 8. The system of claim 7, wherein the source of make-up gas is an electrolyzer and the make-up gas is hydrogen.

9. 1. A process for charging iron ore to a direct reduction shaft, said process comprising: a) setting the ore outlet of the ore charging vessel to a sealed state (s303); b) setting the ore inlet of the ore charging vessel to an open state (s305); c) charging iron ore into the ore charging vessel through the ore inlet (s307); d) setting the ore inlet to a sealed state (s309); e) drawing a vacuum to remove gas from the ore charging vessel (s312); f) refilling the ore charging vessel with a seal gas (s313); g) setting the ore outlet to an open state and charging iron ore into the direct reduction shaft (s315); Including, The seal gas is selected from the list consisting of hydrogen, methane, biogas, syngas, carbon dioxide, nitrogen, refinery waste gas, and combinations thereof. process.

10. e0) applying a vacuum to remove gas from the ore charging vessel (s310); f0) refilling the ore charging vessel with inert gas (s311); Further comprising:

10. The process of claim 9, wherein steps e0) and f0) are performed after step d) but before step e).

11. 11. The process of claim 10, wherein the inert gas is selected from the list consisting of carbon dioxide, nitrogen, refinery off-gas, and combinations thereof.

12. 12. The process of claim 10 or 11, wherein the seal gas and the inert gas are the same.

13. The seal gas and the inert gas are different.

12. The process of claim 10 or 11, wherein the seal gas is selected from the list consisting of hydrogen, methane, biogas, syngas, carbon dioxide, and combinations thereof.

14. h) setting the ore outlet to a sealed state; i) drawing a vacuum to remove process gas from the ore charging vessel; j) refilling the ore charging vessel with a gas selected from air, an inert gas, and combinations thereof; k) setting the ore inlet to an open state; The process of any one of claims 9 to 13, further comprising:

15. 1. A process for discharging sponge iron from a direct reduction shaft, said process comprising: i) setting the iron outlet and iron inlet of the iron discharge container to a sealed state (s403); ii) applying a vacuum to remove gas from the iron discharge vessel (s405); iii) refilling the iron discharge vessel with a seal gas (s407); iv) setting the iron inlet of the iron discharge container to an open state (s409); v) charging sponge iron into the iron discharge container through the iron inlet (s409); vi) setting the iron inlet to a sealed state (s411); Including, The seal gas is selected from the list consisting of hydrogen, methane, biogas, syngas, carbon dioxide, nitrogen, refinery waste gas, and combinations thereof. process.

16. 1. A process for the direct reduction of iron ore, said process comprising: hydrogen, methane, Biogas, Syngas, a combination of hydrogen, methane, biogas, or biosyngas with carbon dioxide; and A combination of these introducing a seal gas consisting essentially of a gas selected from the group consisting of: The sealing gas is introduced by the process for charging iron ore according to any one of claims 9 to 14 and / or by the process for discharging sponge iron according to claim 15. process.

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