ARRANGEMENT AND PROCESS FOR LOADING IRON ORE AND / OR UNLOADING SPONGE IRON FROM A DIRECT REDUCTION PAN

Abstract

This description relates to an arrangement and process for loading iron ore (207) into a direct reduction vessel (211), as well as an arrangement and process for unloading sponge iron (208) from a direct reduction vessel. Each process comprises steps of evacuating gas from a vessel by applying a vacuum followed by refilling the vessel with a sealing gas (223), wherein the sealing gas is a non-oxidizing gas. Furthermore, the description relates to a system for the production of sponge iron comprising such an arrangement for loading iron ore and / or unloading sponge iron.Furthermore, the description refers to a process for the direct reduction of iron ore, wherein the process comprises introducing a sealing gas consisting essentially of a gas selected from hydrogen, biogas, synthesis biogas, carbon dioxide and combinations thereof into a direct reduction tank together with the iron ore load and / or the sponge iron discharge.

Description

ARRANGEMENT AND PROCESS FOR LOADING IRON ORE AND / OR UNLOADING SPONGE IRON FROM A DIRECT REDUCTION PAN TECHNICAL FIELD The present invention relates to an arrangement for loading iron ore into a direct reduction vessel, as well as to a process for loading iron ore into a direct reduction vessel using such an arrangement. The invention further relates to an arrangement for unloading sponge iron from a direct reduction vessel, as well as to a process for unloading sponge iron from a direct reduction vessel using such an arrangement. In addition, the invention relates to a system for the production of sponge iron comprising such arrangements, and a process for the direct reduction of iron ore. BACKGROUND OF THE TECHNIQUE Steel is the world's most important engineering and construction material. It is difficult to find any object in the modern world that does not contain steel, or that does not depend on steel for its manufacture and / or transport. In this way, steel is intimately involved in almost every aspect of our modern lives. In 2018, total global crude steel production was 1.81 billion tons, far exceeding any other metal, and is expected to reach 2.8 billion tons by 2050, of which 50% is expected to come from virgin iron ore sources. Steel is also the most recycled material in the world, with a very high recycling rate due to the metal's ability to be reused repeatedly after remelting, using electricity as the primary energy source. Therefore, steel is a cornerstone of modern society with an even more important role to play in the future. Steel is produced primarily through three routes: i) Integrated production using virgin iron ore in a blast furnace (BF), where the iron oxide in the ore is reduced by carbon to produce iron. The iron is further processed in the steel plant by oxygen blowing in a basic oxygen furnace (BOF), followed by refining to produce steel. This process is also commonly known as 'oxygen steelmaking'. ii) Scrap-based production using recycled steel, which is melted in a furnace QObonn / eznz / E / YiAi electric arc (EAF) using electricity as the primary energy source. This process is also commonly known as 'electric steelmaking'. iii) Direct reduction production from virgin iron ore, which is reduced in a direct reduction (DR) process with a carbonaceous reducing gas to produce sponge iron. Subsequently, the sponge iron is smelted together with scrap in an EAF to produce steel. The term pig iron is used herein to refer to all iron produced for further processing into steel, regardless of whether it is obtained from a blast furnace (i.e., pig iron) or a direct reduction furnace (i.e., sponge iron). Although the processes mentioned above have been refined over decades and are approaching their theoretical minimum energy consumption, a fundamental issue remains unresolved. Reducing iron ore using carbonaceous reducing agents results in the production of CO2 as a byproduct. For every tonne of steel produced in 2018, an average of 1,830 kg (1.83 tons) of CO2 was generated. The steel industry is one of the largest CO2 emitters, accounting for approximately 7% of global CO2 emissions. Excessive CO2 generation within the steel production process cannot be avoided as long as carbonaceous reducing agents are used. The HYBRIT initiative was founded to address this problem. 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 decarbonize the steel industry. The core element of the HYBRIT concept is a production process based on the direct reduction of sponge iron from virgin ore. However, instead of using carbonaceous reducing gases, such as natural gas, as in current commercial direct reduction processes, HYBRIT proposes the use of hydrogen gas as the reducing agent, a process known as hydrogen direct reduction (H-DR). Hydrogen gas can be produced by water electrolysis using primarily fossil-free and / or renewable primary energy sources, such as those used in Swedish electricity generation. Therefore, the critical iron ore reduction stage can be achieved without requiring fossil fuels as an input, and with water as a byproduct instead of CO2. In state-of-the-art fossil fuel-based direct reduction systems, as well as in the proposed hydrogen-based direct reduction systems, it is imperative that the iron ore can be safely loaded into the direct reduction vessel. Since Since the process gases passing through the pulp chamber are highly flammable (typically comprising hydrogen, carbon monoxide, and hydrocarbons in fossil fuel-based processes), it is essential to prevent the formation of explosive air / process gas mixtures when the ore is introduced into the pulp chamber. Typically, this is achieved by ensuring that only an inert (i.e., non-flammable oxidizing) sealing gas, and not air, is introduced into the pulp chamber when the ore is charged, and that no process gas escapes uncontrolled from the pulp chamber through the charging arrangement. Exactly how this is achieved depends on the design of the direct reduction system. Typically, in DR vessels operating at low pressure (e.g., < 200,000 Pa (2 bar)), such as the Midrex process, a dynamic gas seal is provided in a seal leg connecting a charge vessel loaded with ore to the direct reduction vessel. Inert sealing gas is introduced at a pressure exceeding the DR vessel's operating pressure at one or more points on the seal leg. This higher-pressure sealing gas prevents air from entering the DR vessel with the iron ore charge and also prevents process gas from escaping the DR vessel through the seal leg. Typically, in direct reduction (DR) vessels operating at higher pressures (e.g., >200,000 Pa (2 bar)), such as the Hyl ZR process, a charge vessel is located at the inlet of the DR vessel. The ore is charged into the pressurizable charge vessel, which is first purged with an inert sealing gas to exclude air, then pressurized to approximately the operating pressure of the DR vessel using the same sealing gas. Once pressurized, the valve separating the charged charge vessel from the DR vessel is opened to allow the iron ore charge to be introduced into the vessel, along with the sealing gas. After the charge vessel is emptied of ore, it is resealed and purged again with sealing gas to evacuate process gases from the vessel. Finally, the charge vessel can be opened to the atmosphere and refilled with ore.Typically, several loading vessels are arranged in parallel to supply ore to the DR tank. Similar arrangements are also typically located at the discharge end of the direct reduction tank to safely discharge the sponge iron produced. There remains a need for improved means for loading iron ore and / or unloading sponge iron from a direct reduction tank. BRIEF DESCRIPTION OF THE INVENTION QObonn / eznz / E / YiAi The inventors of the present invention have identified a number of deficiencies in the prior art means of loading iron ore into a direct reduction tank. State-of-the-art methods for loading ore typically require the use of large volumes of sealing gas. This sealing gas is usually produced on-site, for example, using an air separation unit when the sealing gas is nitrogen. The large volume of sealing gas required results in higher capital and operating costs for the direct reduction system. Additionally, sealing gas is inevitably introduced into the process gas through the use of state-of-the-art ore loading methods. As described above, the sealing gases typically used, such as nitrogen, must be inert (i.e., not form explosive mixtures with the process gas) and are therefore retained in the process gas. However, the other components of the process gas are typically consumed by reaction (e.g., H₂O, CO, CH₄) or removed from circulation (e.g., H₂O, CO₂). This means that the sealing gas gradually accumulates in the process gas and would comprise an increasingly larger proportion if no action is taken. To prevent such a situation, a portion of the process gas is typically purged from the process gas circuit and flared to maintain an appropriate concentration of inert components in the process gas.This is economically detrimental, particularly for the proposed hydrogen-based direct reduction processes, as the reducing gas in such a case is expected to be more expensive, at least initially, than fossil fuel-based reducing gases. If the reducing gas is fossil fuel-based, purging the process gas also has negative environmental consequences, as it leads to increased CO2 emissions. The outlet of the direct reduction tank, from where the produced sponge iron is discharged, also requires sealing, and the state-of-the-art sponge iron discharge means suffer from the same disadvantages as the state-of-the-art ore loading means. It would be advantageous to achieve a means of loading iron ore into a direct reduction vessel and / or unloading sponge iron from a direct reduction vessel that overcomes, or at least alleviates, at least some of the deficiencies mentioned above. In particular, it would be desirable to enable a means of loading iron ore into a direct reduction vessel and / or unloading sponge iron from a direct reduction vessel that decreases the need for sealing gas and potentially eliminates the need to purge process gas, thereby potentially reducing the operating costs of the direct reduction plant. QObonn / eznz / E / YiAi To better address one or more of these concerns, a process is provided for loading iron ore into a direct reduction tank having the features defined in the independent claim. The process comprises the following stages: a) putting an ore outlet of an ore loading vessel into a sealed state; b) put an ore inlet of the ore loading vessel into an open state; c) load the ore loading container with iron ore through the ore inlet; d) put the ore inlet in a sealed state; e) evacuate the gas from the ore loading vessel by applying a vacuum; f) fill the ore loading container with a sealing gas; and g) put the ore outlet in an open state to load iron ore into the direct reduction tank. Sealing gas is a non-oxidizing gas. According to the described process, the ore-filled cargo vessel is evacuated by applying a vacuum before being refilled with a selected non-oxidizing sealing gas. Since applying a vacuum removes virtually all the air from the cargo vessel, it is not necessary to flush the vessel with multiple volumes of sealing gas to ensure oxygen removal. This is in stark contrast to the sealing gas volumes used to flush the cargo vessel in prior art methods, which are typically approximately five times the cargo vessel volume per batch. According to another aspect of the present invention, the objectives of the invention are achieved by a process for unloading sponge iron from a direct reduction tank according to the appended independent claim. The process for unloading sponge iron comprises the following stages: i) putting an iron outlet and an iron inlet of an iron discharge vessel in a sealed state; ii) evacuate the gas from the iron discharge vessel by applying a vacuum; iii) fill the iron loading container with a sealing gas; iv) putting an iron inlet of the iron discharge vessel in an open state; v) loading the iron discharge container with sponge iron through the iron inlet; and vi) putting the iron inlet in a sealed state; where the sealing gas is a non-oxidizing gas. QObonn / eznz / E / YiAi Similar to the iron ore loading process, the use of vacuum removes substantially all the air from the discharge vessel, meaning that a smaller volume of sealing gas is needed to ensure that the atmosphere in the discharge vessel is sufficiently non-reactive before opening the vessel to the direct reduction tank. The following considerations apply regardless of whether the process is for loading iron ore or for unloading sponge iron, unless specifically stated otherwise. A vacuum can be applied to bring the ore charging vessel (and alternatively, or additionally, the iron discharge vessel) to a pressure of approximately 10,000 Pa (100 mbar) or less, preferably approximately 1,000 Pa (10 mbar) or less, and even more preferably approximately 100 Pa (1 mbar) or less, at normal temperature (20 °C). The use of a relatively strong vacuum allows for fewer vacuum evacuation / refill cycles before charging iron ore into the direct reduction vessel (or discharging sponge iron from the direct reduction vessel). The sealing gas can be selected from a list consisting of hydrogen, methane, biogas, synthesis gas, carbon dioxide, nitrogen, purified combustion gas, and combinations thereof. That is, the sealing gas can be a typical inert gas (non-flammable oxidizer), such as carbon dioxide, nitrogen, or purified combustion gas. However, the processes described herein allow for the introduction of substantially all of the sealing gas used in the direct reduction vessel, and therefore, the sealing gas is not wasted, unlike prior art methods where large volumes of sealing gas are used to purge the charging vessel or maintain the dynamic seal. Furthermore, since the described processes substantially empty the charging / discharging vessel of air before refilling it with the sealing gas, mixtures of air and sealing gas are avoided.Together, these characteristics allow the use of gases other than inert gases as the sealing gas, for example, more expensive and / or potentially flammable gases. Therefore, purely reducing gases such as hydrogen, reducing and fuel gases such as methane, biogas, or synthesis gas, or indirectly fuel gases such as carbon dioxide can be used as the sealing gas. The use of such gases means that the introduction of inert gases into the direct reduction vessel can be avoided, and therefore, it may not be necessary to purge the process gas to prevent the accumulation of inert components. This can significantly improve the utilization of process gases and decrease operating costs. The methane can be biomethane and / or biogas. QObonn / eznz / E / YiAi synthesis can be synthesis biogas. Carbon dioxide can be derived from a biological source, i.e., non-fossil CO2. In some cases, a single vacuum evacuation / refill cycle may be sufficient to allow the safe charging of iron ore into the direct reduction vessel (and alternatively, or additionally, to allow the safe unloading of sponge iron from the direct reduction vessel). In such cases, since the vacuum only removes the air and the refill gas is introduced into the direct reduction vessel, this can prevent the use of any excess gas in the charging / unloading process, beyond the amount of sealing gas required to bring the charging / unloading vessel to the appropriate charging pressure. The process may further comprise steps of removing gas from the ore loading vessel (and alternatively, or additionally, from the iron discharge vessel) by applying a vacuum; 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 evacuating the gas from the ore loading vessel by applying a vacuum (or after step i, but before step ii in the process for discharging sponge iron). That is, an additional evacuation / refilling cycle may be performed. This means that even if a relatively weak vacuum is used, such as greater than approximately 10,000 Pa (100 mbar), the process may be carried out in stages by first performing an initial evacuation / refilling cycle to provide a gas mixture in the vessel comprising mainly the inert gas, but with some remaining air.The subsequent evacuation / vacuum refill cycle should be sufficient to provide a gas mixture in the container comprising essentially the sealing gas for the purpose of the invention (i.e., preventing the formation of potentially explosive gas / air mixtures). Of course, multiple vacuum evacuation / refilling cycles can be performed as needed, such as a total of three or four, instead of the single and double vacuum evacuation / refilling cycles already described. However, the total amount of inert gas required in the process increases with each vacuum evacuation / refilling cycle performed, and therefore, it is preferable to use as few vacuum evacuation / refilling cycles as possible. When more than one vacuum evacuation / refilling cycle is performed, the refilling in the initial cycle(s) is done using inert gas, and the refilling using sealing gas is done only in the final refilling stage. The inert gas can be selected from the list consisting of carbon dioxide, nitrogen, gas of 7 Purified combustion gases and their combinations. The sealing gas may be the same as or different from the inert gas. When the sealing gas is different from the inert gas, it can be selected from the list consisting of hydrogen, methane, biogas, synthesis gas, carbon dioxide, and their combinations. Using a sealing gas other than an inert gas helps prevent the accumulation of inert gas in the process gases and thus helps avoid the need to purge the process gas, as described above. The methane may be biomethane, and / or the synthesis gas may be synthesis biogas. The carbon dioxide may be derived from a biological source, i.e., non-fossil CO2. Specifically, the process for charging iron ore into a direct reduction vessel may include the following additional steps: sealing the ore outlet; removing a process gas from the ore charging vessel by applying a vacuum; filling the ore charging vessel with a gas selected from air, inert gas, or combinations thereof; and opening the ore inlet. The inert gas may be selected from carbon dioxide, nitrogen, purified flue gas, or combinations thereof. In this way, the charging vessel can be prepared for the introduction of an additional charge of iron ore while ensuring the efficient use of the gases. According to another aspect of the invention, the objectives of the invention are achieved by a process for the direct reduction of iron ore to sponge iron according to the appended independent claim. The process comprises introducing a sealing gas consisting essentially of a gas selected from hydrogen, methane, biogas, and synthesis gas, or combinations of carbon dioxide with hydrogen, methane, biogas, or synthesis gas, or combinations thereof, into a direct reduction vessel concurrently with loading iron ore into the direct reduction vessel and / or concurrently with unloading sponge iron from the direct reduction vessel. The methane may be biomethane and / or the synthesis gas may be synthesis biogas. The carbon dioxide may be derived from a biological source, i.e., non-fossil CO2. Introducing [...]] together with'; means that the sealing gas can, for example, be introduced into the direct reduction vessel by using the processes for loading iron ore into a direct reduction vessel and / or unloading sponge iron from the direct reduction vessel as described in the present description and in the appended independent claims. Since a gas is inevitably introduced into the direct reduction vessel along with the loading and / or unloading of solids into the direct reduction vessel, by introducing such sealing gases that reduce and / or optionally carburize the iron ore, the process introduces only QObonn / eznz / E / YiAi gases that serve a purpose in direct reduction and avoid the introduction of gases that can have a detrimental effect on the process. Gases that can have a detrimental effect on the process are, for example, inert gases such as nitrogen, which can accumulate in the process gas and decrease its reducing capacity if allowed to build up to excessive concentrations. Purging the process gas is usually necessary to mitigate the effects of such accumulation. Therefore, the described process allows for more effective use of the process gas and can thus decrease process operating costs. The process may involve introducing auxiliary gas into the direct reduction vessel in countercurrent flow to the iron ore. The auxiliary gas is selected from hydrogen and synthesis biogas and may be the same as or different from the sealing gas. This auxiliary gas ensures that sufficient reducing gas is introduced into the process to adequately reduce the iron ore to sponge iron. According to a further aspect of the invention, the objectives of the invention are achieved by an arrangement for loading iron ore into a direct reduction tank according to the appended independent claim. The arrangement for loading iron ore comprises - an ore loading container; - a vacuum source; and - a source of a sealing gas. The vacuum source and the sealing gas source are each arranged in controllable fluid connection with the ore loading vessel. Sealing gas is a non-oxidizing gas. This arrangement facilitates the process of loading iron ore into a direct reduction vessel as described herein and in the appended independent claim. The ore loading vessel, or more specifically the ore outlet of the ore loading vessel, is typically arranged in communication with the inlet of the direct reduction vessel, allowing the ore to pass from the ore loading vessel into the direct reduction vessel. According to another additional aspect of the invention, the objectives of the invention are achieved by an arrangement for discharging sponge iron from a direct reduction tank according to the appended independent claim. The arrangement for unloading sponge iron comprises: - an iron discharge container; QObonn / eznz / E / YiAi - a vacuum source; and - a source of a sealing gas; The vacuum source and the sealing gas source are each arranged in controllable fluid connection with the iron discharge vessel. Sealing gas is a non-oxidizing gas. This arrangement facilitates the process of discharging sponge iron from a direct reduction tank as described herein and in the appended independent claim. The iron discharge vessel, or more specifically the iron inlet of the iron discharge vessel, is typically arranged in communication with the outlet of the direct reduction tank, allowing the sponge iron to pass from the direct reduction tank into the iron discharge vessel. The following considerations apply regardless of whether the arrangement is for loading iron ore or for unloading sponge iron, unless specifically stated otherwise. The ore loading vessel may comprise a sealable ore inlet, a sealable ore outlet, and at least one gas conduit. The iron discharge vessel may comprise a sealable iron inlet, a sealable iron outlet, and at least one gas conduit. The vacuum source and / or the sealing gas source may be arranged in fluid connection with the gas conduit. Regarding the source of a sealing gas, the sealing gas can be selected from the list consisting of hydrogen, methane, biogas, synthesis gas, carbon dioxide, nitrogen, purified flue gas, and combinations thereof. The methane can be biomethane, and / or the synthesis gas can be biogas. The carbon dioxide can be derived from a biological source, i.e., non-fossil CO2. The arrangement(s) may further comprise a source of an inert gas. The source of the inert gas may be arranged in a controllable fluid connection with the ore loading vessel and / or the iron discharge vessel. The inert gas may be different from the sealing gas. If the arrangement(s) further comprise a source of an inert gas, then the inert gas may be selected from the list consisting of carbon dioxide, nitrogen, purified flue gas, and combinations thereof; and the sealing gas may be selected from the list consisting of hydrogen, methane, biogas, synthesis gas, carbon dioxide, and combinations thereof. The methane may be biomethane and / or the synthesis gas may be synthesis biogas. QObonn / eznz / E / YiAi carbon can be derived from a biological source, i.e., CO: non-fossil. The arrangement(s) may be configured to achieve a pressure of approximately 10,000 Pa (100 mbar) or less at normal temperature (20 °C) in the ore loading vessel (and alternatively, or additionally, in the iron discharge vessel), preferably approximately 1,000 Pa (10 mbar) or less, and even more preferably approximately 100 Pa (1 mbar) or less. This may require that: The vacuum source is strong enough to bring the vessel to the desired pressure, and / or the vessel is configured to tolerate such a low pressure (i.e., the vessel may be a vacuum vessel), and / or any openings in the vessel such as the sealable inlet, sealable outlet, and / or gas conduit(s) are sealable to such an extent that they can allow the vacuum source to maintain such pressure in the vessel. According to another aspect of the invention, the objectives of the invention are achieved by a system for the production of sponge iron according to the appended independent claim. The system comprises an arrangement for loading iron ore as described herein, and / or an arrangement for unloading sponge iron as described herein. That is to say, the system comprises an arrangement for loading iron ore as described herein; or an arrangement for unloading sponge iron as described herein; or an arrangement for loading iron ore and an arrangement for unloading sponge iron as described herein. The system may further comprise a loading arrangement and / or an unloading arrangement as conventionally known in the art.The system further comprises a direct reduction vessel and an auxiliary gas source arranged in fluid connection with the direct reduction vessel. If the system includes an arrangement for loading iron ore, the ore loading vessel may be arranged in communication with an inlet of the direct reduction vessel. If the system includes an arrangement for unloading sponge iron, the iron unloading vessel may be arranged in communication with an outlet of the direct reduction vessel. If the system includes both an iron ore loading arrangement and a sponge iron unloading arrangement, the system may require only one vacuum source, one sealing gas source, and / or one inert gas source. That is, separate gas and / or vacuum sources are not required for the loading and unloading arrangements, and these sources can be consolidated. QObonn / eznz / E / YiAi The auxiliary gas source can be an electrolyzer. The electrolyzer can produce hydrogen through water electrolysis or synthesis gas (a mixture of carbon monoxide and hydrogen) through the co-electrolysis of water and carbon dioxide. Therefore, the auxiliary gas can be either hydrogen or synthesis gas, such as biogas. In this way, it is possible to produce sponge iron without using fossil fuels as a reducing gas source. The objectives, advantages, and additional novel features of the present invention will become evident to a person skilled in the art from the following detailed description. BRIEF DESCRIPTION OF THE FIGURES For a more complete understanding of the present invention and its additional objectives and advantages, the detailed description set forth below should be read in conjunction with the accompanying figures, in which the same reference annotations indicate similar elements in the various diagrams, and in which: Figure 1 schematically illustrates a steelmaking value chain based on minerals according to the Hybrit concept; Figure 2 schematically illustrates an illustrative modality of a system suitable for carrying out a process as described in this description; Figure 3 is a flow diagram that schematically illustrates one illustrative modality of a process for loading iron ore as described herein; and Figure 4 is a flow diagram that schematically illustrates one illustrative modality of a process for unloading sponge iron as described in this description. DETAILED DESCRIPTION The present invention is based on the inventors' idea that, when iron ore is charged into a direct reduction vessel, removing the air from the charging vessel by vacuum followed by refilling with a selected sealing gas provides a wide range of potential advantages. Smaller volumes of sealing gas are required because, unlike prior art methods that rely on diluting the atmosphere within the charging vessel (corresponding to multiple "vessel volumes" of sealing gas that must be purged) until the atmosphere is sufficiently inert, the process described herein first removes the air atmosphere and replaces it with the sealing gas. Since smaller volumes of sealing gas are required and intermediate mixtures of sealing gas and air are avoided, it is not necessary to limit the sealing gas to inert gases (i.e., gases that do not repel). QObonn / eznz / E / YiAi form flammable or explosive mixtures with air or process gas). Instead, if desired, potentially flammable non-oxidizing gases such as hydrogen, methane, biogas, or synthesis gas can be used. This means that the accumulation of inert gases in the process gas can be avoided, and the need to purge the process gas can be reduced or completely eliminated. The methane can be biomethane, and / or the synthesis gas can be synthesis biogas. The carbon dioxide can be derived from a biological source, i.e., non-fossil CO2. The same concept can be applied when unloading sponge iron from the direct reduction tank, and the same or similar advantages are obtained. The term "process gas" is used in this description to refer to the gas mixture in the direct reduction process, regardless of the stage. That is, process gas refers to the gas that is introduced into, passes through, exits, and is recycled back to the direct reduction vessel. More specific terms are used to describe the process gas at various points in the process, or to describe the component gases that are added to the process gas to form part of it. The reducing gas is a gas that is introduced at a lower point than the inlet of the tank and which flows upwards against the moving bed of ore in order to reduce the ore and optionally carburize the sponge iron. The overhead gas is partially spent process gas that is removed from the upper end of the furnace, near the ore inlet. After treatment, the overhead gas can be recycled back to the direct reduction furnace as a component of the reducing gas. Auxiliary gas is fresh gas added to the process gas to maintain reducing capacity. Typically, auxiliary gas is added to recycled overhead gas before it is reintroduced into the direct reduction vessel. Therefore, reducing gas typically comprises auxiliary gas along with recycled overhead gas. The auxiliary gas and recycled overhead gas may be mixed before being introduced into the direct reduction vessel, or they may be introduced separately and mixed in the vessel. Sealing gas is gas that enters the direct reduction vessel from the ore charging arrangement at the inlet of the direct reduction vessel. The outlet end of the direct reduction vessel can also be sealed using sealing gas, and therefore, sealing gas can enter the DR vessel from a discharge arrangement at the outlet of the direct reduction vessel. Thus, the variations of the present invention are equally applicable when using sealing gas introduced during the discharge of sponge iron from the vessel. QObonn / eznz / E / YiAi direct reduction. The sealing gas used in prior art processes is typically inert, and inert sealing gas can also be used in the process described herein. However, unlike prior art processes, the sealing gas in the process described herein can instead be a reducing and / or fuel gas and can therefore be considered as a supplement to the auxiliary gas. An inert gas is a gas that does not form potentially flammable or explosive mixtures with either air or process gas; that is, a gas that cannot act as an oxidizer or fuel in a combustion reaction under the prevailing process conditions. Although carbon dioxide is referred to as an inert gas in this description, it should be noted that it can be converted to carbon monoxide via a reverse water-gas exchange reaction and can subsequently participate in reduction and / or fuel reactions. Therefore, while inert for the purpose of not forming flammable / explosive mixtures, it can still be consumed and will not accumulate in the process gas under certain conditions. Iron ore load The iron ore charge typically consists predominantly of iron ore pellets, although some lump iron ore may also be introduced. The iron ore pellets typically comprise mainly hematite, along with additional additives or impurities such as gangue, fluxes, and binders. However, the pellets may also contain other metals and minerals such as magnetite. Iron ore pellets specified for direct reduction processes are commercially available, and such pellets can be used in the present process. The ore loading vessel is typically a vessel comprising a sealable ore inlet, a sealable ore outlet, and at least one gas conduit suitable for the evacuation and / or introduction of gases. Naturally, the vessel may comprise multiple gas conduits, for example, separate conduits for gas evacuation and introduction, or multiple conduits for the introduction of a variety of gases. The ore loading vessel is constructed to withstand the pressures to which it is subjected: both the sub-atmospheric pressure (approximately 10,000 Pa (100 mbar) or less, preferably approximately 1,000 Pa (10 mbar) or less) prevailing during the evacuation stages and the supra-atmospheric pressure resulting from filling with sealing gas (often greater than 200,000 Pa (2 bar), such as from approximately 200,000 Pa (2 bar) to approximately 1,000,000 Pa (10 bar)).A plurality of ore loading containers can be arranged in parallel 14. QObonn / eznz / E / YiAi to supply ore to a single direct reduction tank. For example, two, three, or four ore loading vessels can be arranged to supply ore to a single direct reduction tank. Before loading the ore into the loading vessel, the ore outlet is sealed to contain the incoming ore. "Putting into a state" means that a component is brought into the relevant state if it is not already in that state, or maintained in that state if it is already in that state. Therefore, the term "putting into a state" does not necessarily imply a change of state. The ore is loaded into the vessel through the inlet, which is then sealed. A vacuum source, connected in fluid connection with a gas line, is then used to evacuate the atmosphere from the loading vessel. The vacuum source can be, for example, a vacuum pump. Such pumps are known in the art.Preferably, the charging vessel and pump are configured so that the charging vessel can be brought to a pressure of approximately 10,000 Pa (100 mbar) or less, preferably approximately 1,000 Pa (10 mbar) or less, and even more preferably approximately 100 Pa (1 mbar) or less, at room temperature (20 °C). Therefore, substantially all the air is evacuated from the charging vessel. If the achievable vacuum during the evacuation stage is sufficiently low, the charging vessel can be subsequently filled with sealing gas to a charging pressure, i.e., the desired charging vessel pressure for introducing the ore into the direct reduction tank. The charging pressure can typically be higher than the operating pressure of the direct reduction tank and can be, for example, from approximately 200,000 Pa (2 bar) to approximately 1,000,000 Pa (10 bar).If the vacuum achievable during the evacuation stage is not low enough, unwanted amounts of air may be retained in the charging vessel. In such a case, the charging vessel can be initially filled with an inert gas, followed by an additional evacuation stage. This reduces the remaining air to safe levels. The evacuation and inert gas refill stages can be repeated as many times as necessary to ensure safety. In the final refill stage, the charging vessel is filled with the sealing gas that will be introduced into the direct reduction vessel during charging. Once filled with ore and sealing gas, the ore outlet of the charging vessel is opened to allow the ore and sealing gas mixture to be charged into the direct reduction vessel. Once the ore has been loaded into the direct reduction tank, the ore charging vessel must be restarted to safely remove any process gas contained in the 15 QObonn / eznz / E / YiAi vessel and prepare the vessel for a new charge of ore. This can be done by sealing the ore outlet, evacuating the charge vessel using a vacuum to remove the process gas, and then subsequently refilling the charge vessel with a suitable gas such as air, nitrogen, purified combustion gas, or carbon dioxide. The process gases evacuated at this stage can be recycled to the direct reduction vessel. The vessel is refilled to approximately atmospheric pressure. Alternatively, the vessel can simply be purged with inert gas to remove the process gas before opening it, in accordance with prior art methods. When the potentially flammable contents of the vessel have been evacuated and the vessel is back at or near atmospheric pressure, the vessel inlet can be opened to allow a new charge of iron to be received. Direct reduction The direct reduction tank can be of any type commonly known in the art. "Tank" refers to a countercurrent moving-bed solid-gas reactor, such that an iron ore charge is introduced at an inlet at the top of the reactor and flows down by gravity to an outlet at the bottom. The reducing gas is introduced at a lower point in the tank than the ore inlet, and flows upward to reduce and optionally carburize the iron ore. The reduction is typically carried out at temperatures of approximately 900 °C to approximately 1100 °C. The required temperatures are typically maintained by preheating the process gases before they enter the reactor, for example, by using a preheater such as an electric preheater. Further heating of the gases after they leave the preheater and before they enter the reactor can be achieved by exothermic partial oxidation of the gases with oxygen or air. The reduction can be carried out at a pressure of approximately 100,000 Pa (1 bar) to approximately 1,000,000 Pa (10 bar) in the DR vessel, preferably from approximately 300,000 Pa (3 bar) to approximately 800,000 Pa (8 bar). In conventional direct reduction processes, the auxiliary gas used to replenish the process gas is fossil fuel-based and typically comprises synthesis gas and natural gas in varying proportions. This description applies to processes using such a fossil fuel-based auxiliary gas. However, preferably the auxiliary gas is not derived from fossil fuels to provide a fossil fuel-free process for obtaining sponge iron. QObonn / eznz / E / YiAi The auxiliary gas may consist primarily of hydrogen. For example, the auxiliary 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 percentage determined under standard conditions of 1 atm and 0 °C). The described process allows the production of essentially carbon-free sponge iron by using hydrogen as the auxiliary gas and by not introducing carbonaceous gases into the process gas. However, in some cases, it may be desirable to obtain carburized sponge iron. Therefore, to achieve adequate levels of carburization of the sponge iron, some quantities of fuel gas and / or carbon dioxide may be added as auxiliary gas.Carburizing gases are carbon-containing gases capable of directly carburizing sponge iron, such as all incompletely oxidized carbon compounds, including hydrocarbons and carbon monoxide. These gases include, but are not limited to, methane, biogas, synthesis gas, and mixtures thereof. However, a carburizing effect in the present process can be achieved alternatively or additionally by introducing carbon dioxide. Under the prevailing carbon-scarce conditions of the direct reduction vessel, the carbon dioxide can be converted to carbon monoxide and subsequently carburize the sponge iron. The methane can be biomethane, and / or the synthesis gas can be biogas. The carbon dioxide can be derived from a biological source, i.e., non-fossil CO2. In addition to hydrogen, the remaining auxiliary gas may therefore comprise, or essentially consist of, carbon dioxide and / or fuel gas. If carbon dioxide and / or fuel gas constitute part of the auxiliary gas, they may be introduced into the direct reduction vessel along with the hydrogen auxiliary gas. Alternatively, some or all of the carbon dioxide and / or fuel gas that constitutes part of the auxiliary gas may be added to the direct reduction vessel separately from the main volume of auxiliary gas. For example, fuel gas may be added to a cooling or carburizing zone of the direct reduction vessel. The process gas can be at least partially recycled, so that the overhead (spent) gas from the DR vessel can be cleaned and treated to remove byproducts such as water and / or dust before being reintroduced into the DR vessel. This recycled overhead gas can be mixed with fresh auxiliary gas before being reintroduced into the reactor, or it can be introduced separately from any fresh auxiliary gas supply. QObonn / eznz / E / YiAi The sealing gas introduced along with the iron ore charge is also part of the process gas components. As described earlier, the sealing gas can be an inert gas such as nitrogen or purified combustion gas. In such cases, it may be necessary to continuously remove a portion of the process gas from the process cycle to maintain process gas balance and prevent the accumulation of inert components. This is known as process gas purging. The process gas purged from the process cycle can, for example, be burned to provide process heating, such as in conjunction with preheating. Alternatively, the sealing gas may comprise, consist essentially of, or consist of a non-oxidizing gas that serves a purpose in the process, such as the gases described above as potential auxiliary gases. These include hydrogen, methane, biogas, synthesis gas, carbon dioxide, and combinations thereof. The methane may be biomethane, the synthesis gas may be biogas from synthesis, and the carbon dioxide may be bio-CO2. In such a case, no inert gas is added to the process gas, and therefore, purging the process gas can be avoided. The need to produce inert gas as sealing gas also disappears, and capital equipment, such as an air separation unit, can be reduced or entirely eliminated. Sponge iron is obtained as a product of iron ore reduction and is discharged from the outlet at the bottom of the direct reduction vessel. The vessel may have a cooling and discharge cone at the bottom to allow the sponge iron to cool before being discharged. Sponge iron discharge The discharge of sponge iron from the direct reduction furnace has requirements similar to those for charging iron ore into the furnace. It is essential that no mixtures of combustible / explosive gases form during discharge, and it is preferable to avoid introducing inert gases into the process gas as much as possible. Therefore, the principles of the present invention can also be applied to an apparatus and process for discharging sponge iron. An iron discharge vessel typically comprises a sealable iron inlet, a sealable iron outlet, and at least one gas conduit suitable for the evacuation and / or introduction of gases. Naturally, the vessel may include multiple gas conduits, for example, separate conduits for gas evacuation and introduction, or multiple conduits for the introduction of a variety of gases. The iron discharge vessel is suitably constructed to withstand the pressures to which it is subjected. QObonn / eznz / E / YiAi Both the subatmospheric pressure (approximately 10,000 Pa (100 mbar) or less, preferably approximately 1,000 Pa (10 mbar) or less) prevailing during the evacuation stages and the supra-atmospheric pressure resulting from packing with sealing gas (often greater than 200,000 Pa (2 bar), such as from approximately 200,000 Pa (2 bar) to approximately 1,000,000 Pa (10 bar)) are considered. A plurality of iron discharge vessels may be arranged in parallel to receive iron from a single direct reduction vessel. For example, two, three, or four ore discharge vessels may be arranged to discharge iron from a single direct reduction vessel. Before the iron is discharged into the discharge vessel, the iron inlet and outlet are sealed. A vacuum source, connected in fluid connection with a gas line, is used to evacuate the atmosphere from the discharge vessel. The vacuum source can be, for example, a vacuum pump. Such pumps are known in the art. Preferably, the discharge vessel and pump are configured so that the discharge vessel can be brought to a pressure of approximately 10,000 Pa (100 mbar) or less, preferably approximately 1,000 Pa (10 mbar) or less, and even more preferably approximately 100 Pa (1 mbar) or less, at room temperature (20 °C). Therefore, substantially all the air is evacuated from the discharge vessel.If the achievable vacuum during the evacuation stage is sufficiently low, the discharge vessel can be subsequently refilled with sealing gas at a discharge pressure—that is, the discharge vessel pressure required to receive sponge iron from the direct reduction vessel. The discharge pressure can typically be equal to or greater than the operating pressure of the direct reduction vessel and can be, for example, from approximately 200,000 Pa (2 bar) to approximately 1,000,000 Pa (10 bar). If the achievable vacuum during the evacuation stage is not sufficiently low, unwanted amounts of air may be retained in the discharge vessel. In such a case, the discharge vessel can be initially refilled with an inert gas, followed by an additional evacuation stage. In this way, the amount of remaining air can be reduced to safe levels.The evacuation and inert gas refilling stages can be repeated as many times as necessary to ensure safety. In the final refilling stage, the discharge vessel is filled with the sealing gas that will be introduced into the direct reduction vessel when the sponge iron is discharged. Once a suitable atmosphere is established inside the discharge vessel, the iron inlet can be opened to allow sponge iron to be received from the direct reduction vessel. Once loaded with sponge iron, inlet 19 can be closed. QObonn / eznz / E / YiAi of the discharge vessel. The sealed vessel then contains a mixture of hot sponge iron and process gases. Preferably, the gaseous contents of the vessel should be removed once more by applying a vacuum and replaced with an inert gas at a suitable pressure before opening the discharge vessel outlet to release the contained sponge iron. The process gases evacuated at this stage can be recycled to the direct reduction vessel. Sponge iron The term pig iron is used in this description to refer to all iron produced for further processing into steel, regardless of whether it is obtained from a blast furnace (i.e., pig iron) or, as in the process described, a direct reduction (DR) vessel (i.e., sponge iron). The sponge iron obtained from the DR vessel is typically predominantly in pellet form, due to the structural integrity of the direct reduction pellets and the conditions prevailing in the DR vessel. Such sponge iron is typically called direct reduction iron (DRI). Depending on the process parameters, it can be provided hot (HDRI) or cold (CDRI). Cold DRI may also be referred to as type (B) DRI. DRI can be prone to reoxidation and, in some cases, is pyrophoric. However, there are several known means of passivating DRI.One commonly used passivation method to facilitate product transport is pressing the hot DRI into briquettes. These briquettes are commonly called hot briquetted iron (HBI) and may also be known as type (A) DRI. The sponge iron product obtained by the process described herein can be essentially fully metallized sponge iron, that is, sponge iron having a degree of reduction (DoR) greater than 90%, such as greater than 94% or greater than 96%. The degree of reduction is defined as the amount of oxygen removed from the iron oxide, expressed as a percentage of the initial amount of oxygen present in the iron oxide. It is often not commercially advantageous to obtain sponge irons with a DoR greater than approximately 96% due to reaction kinetics, although such sponge irons can be produced if desired. As described above, the process described herein is suitable for producing either carburized or carbon-free sponge iron, as desired. Carburized sponge iron means sponge iron that contains carbon. The carbon present in the sponge iron product can typically be in the form of cementite (Fe3C) and / or graphite. 20 Graphite tends to scatter and disappear from sponge iron before reaching the molten mass of the EAF. For this reason, it may be preferable for the carbon to be present in sponge iron as cementite. Carburized sponge iron may comprise from 0.1 to 5 percent carbon by weight, such as from 0.5 to 3 percent carbon by weight, such as approximately 1 to 2 percent carbon by weight. However, it is typically convenient for further processing that the sponge iron have a carbon content of 0.5 to 5 percent carbon by weight, preferably from 1 to 4 percent by weight, such as approximately 3 percent by weight, although this may depend on the ratio of sponge iron to scrap used in a subsequent EAF processing stage. If desired, the carburized sponge iron product of the present process may be subsequently carburized by other means before further processing. Gases Hydrogen gas can preferably be obtained, at least in part, by electrolysis of water. If the water electrolysis is carried out using renewable energy, then this allows for the supply of a reducing gas from renewable sources. The electrolytic hydrogen can be transported via a pipeline directly from the electrolyzer to the DR cell, or the hydrogen can be stored during production and transported to the DR cell as needed. If carbon dioxide is used in the process described herein, whether as a sealing gas, auxiliary gas, or inert gas, it is preferable that the carbon dioxide source be essentially pure carbon dioxide, for example, 95% by volume or higher, preferably 98% by volume or higher. The carbon dioxide source may preferably be a high-concentration source, preferably a high-concentration biogenic source. For example, concentrated "green" CO₂ may be obtained as a byproduct of biogas production through anaerobic digestion, or as a byproduct of bioethanol production. If the carbon dioxide used in the process is from a renewable source, then the process may be net negative with respect to CO₂ emissions.However, even using a carbon dioxide source from a fossil fuel that would otherwise have been emitted directly means that the process may not result in any increased CO2 emissions. An alternative means of supplying carbon dioxide is to preheat the reducing gas before introducing it into the direct reduction vessel using biomass combustion. Oxygen and fuel combustion. The principle of oxygen and fuel combustion is simple: biomass is burned using essentially pure oxygen as the oxidant. The resulting flue gas stream consists essentially of carbon dioxide and steam. The steam can be removed by simple condensation to provide an essentially pure source of carbon dioxide. Conventionally, the supply of essentially pure oxygen is an economic impediment to the use of oxygen and fuel combustion. However, in the present case, an immediate supply of oxygen may be available at low additional cost from water electrolysis, making oxygen and fuel preheating of the reducing gas economically feasible. A fuel gas can be used as a sealing gas and / or auxiliary gas. The fuel gas can be any gas known or expected in the art to provide carburization. Gas in this context refers to a substance that is gaseous at the high temperatures prevailing in the carburizing reactor, although it may be liquid or solid at ambient temperature. Suitable fuel gases include hydrocarbons such as methane, natural gas, LPG, or petroleum, or other carbonaceous substances such as synthesis gas, alcohols, esters, and lower ethers (C1-C6). The fuel gas can be of fossil origin, but it is preferable that it be obtained partially or entirely from a renewable source to reduce net CO₂ emissions. Renewable means a resource that is naturally replenished on a human timescale.The high carbon content of fuel gas allows for the use of renewable fuel gases, despite their relative scarcity and high cost compared to fossil fuel equivalents. Suitable renewable fuel gases include biomethane, biogas, gas obtained from the pyrolysis or partial combustion of biomass (e.g., synthetic biogas), lower alcohols or ethers such as methanol, DME, or ethanol derived from renewable feedstocks, or combinations thereof. Fuel gases containing sulfur can be used, as sulfur is known to inhibit graphite nucleation and passivate the sponge iron product. The composition of the fuel gas can be chosen to suit the final carburized sponge iron to be obtained. The carburization reaction with hydrocarbons is relatively endothermic, resulting in a relatively cool end product, whereas the reaction with fuel gases containing CO is more exothermic, resulting in a hotter end product. This effect can be used to tailor the temperature of the final product obtained. For example, if a hot product for making briquettes (HBI) is desired, a gas comprising some partially oxidized carbon (e.g., in the form of CO, ketones, 22) can be used. QObonn / eznz / E / YiAi aldehydes), whereas if a cold sponge iron (CDRI) is desired, then biomethane can be used. When considering the total amounts of carbon dioxide and / or suitable auxiliary fuel gas to add to the process gas, either as a sealing gas or in the auxiliary gas, the factors to consider are the desired degree of carburization, the effect of the added carbon on the water-gas equilibrium change, and the effect of the added carbon on the reducing capacity of the reducing gas. For example, excessive carbon addition can result in a significant buildup of carbon dioxide in the process gas, which could decrease the reducing capacity of the reducing gas and necessitate purging the process gas. Inert gases such as nitrogen or purified flue gas can be used as sealing gas. Nitrogen can be obtained, for example, by cryogenic distillation of air using an air separation unit (ASU). Purified flue gas means flue gas that has been treated to ensure it is suitable for use as a sufficiently inert sealing gas. Such treatment may include post-combustion to remove excess oxygen and / or drying of the flue gas. Modalities The invention will now be described in more detail with reference to certain illustrative embodiments and figures. However, the invention is not limited to the illustrative embodiments discussed herein and / or shown in the accompanying figures, but may vary within the scope of the appended claims. Furthermore, the figures are not to be considered drawn to scale, as some features may be exaggerated to illustrate certain characteristics more clearly. Figure 1 schematically illustrates a state-of-the-art embodiment of the mineral-based steelmaking value chain according to the Hybrit concept. The mineral-based steelmaking value chain begins at the iron ore mine 101. After extraction, the iron ore 103 is concentrated and processed in a granulation plant 105, producing iron ore pellets 107. These pellets, along with any lump ore used in the process, are converted into sponge iron 109 by reduction in a direct reduction vessel 111 using hydrogen gas 115 as the main reducing agent, with water 117 being the main byproduct. Hydrogen gas 115 is produced by electrolysis of water 117 in an electrolyzer 119 using electricity 121 that is preferably derived from a fossil-free or renewable source 122. Hydrogen gas 115 can be stored 23 QObonn / eznz / E / YiAi in a hydrogen storage tank 120 before introduction into the direct reduction vessel 111. Sponge iron 109 is melted using an electric arc furnace 123, optionally together with a portion of iron scrap 125 or another iron source, to provide a molten mass 127. The molten mass 127 undergoes further downstream secondary metallurgical processes 129 and steel 131 is produced. The entire value chain, from ore to steel, is intended to be fossil fuel-free and produce only low or zero carbon emissions. Figure 2 schematically illustrates an illustrative modality of a system suitable for carrying out the process as described in this description. A direct reduction vessel 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 the upper gas 211d. A charging vessel 213 is provided in communication with the inlet 211a to the direct reduction vessel 211. A discharging vessel 231 is provided in communication with the outlet 211b of the direct reduction vessel 211. The loading vessel 213 comprises 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 loading vessel 213 is arranged in connection with an ore storage tank 227. The gas inlet 213c of the loading vessel 213 is arranged in connection with a sealing gas source 221, and the gas outlet 213d is arranged in connection with a vacuum pump 229. The discharge vessel 231 comprises an inlet 231a for sponge iron 208, an outlet 231b for sponge iron 208, a first gas inlet 231c, a second gas inlet 231e, and a gas outlet 23Id. The inlet 231a of the discharge vessel 231 is connected to the outlet 211b of the direct reduction vessel 211. The first gas inlet 231c of the charging vessel 231 is connected to a sealing gas source 221. The second gas inlet 231e of the charging vessel 231 is connected to a sealing gas source 233. The gas outlet 23Id is connected to a vacuum pump 229. Initially, the ore inlet 213a of the loading vessel 213 is open, and the ore outlet 213b, gas inlet 213c, and gas outlet 213d are closed. Iron ore 207 from the ore bin 227 is fed into the loading vessel 213. Once loaded with ore, the ore inlet 213a is sealed, the gas outlet 213d is opened, and the air is evacuated from the loading vessel 213 using the vacuum pump 229, as the pressure in the 24 QObonn / eznz / E / YiAi Charging vessel 213 is pressurized to approximately 10,000 Pa (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 sealing gas 223 to a pressure approaching the operating pressure of the direct reduction vessel 211. Once pressurized, the gas inlet 213c is closed, and the ore outlet 213b of the charging vessel 213 is opened to allow iron ore 207 to be charged into the inlet 211 of the direct reduction vessel 211. Sealing gas 223 is inevitably introduced concomitantly into the direct reduction vessel during the charging operation. The iron ore 207 loaded into the direct reduction tank 211 passes progressively through the tank to be discharged at outlet 21 Ib.During its passage through tank 211, the ore 207 is reduced by the reducing gas 217 in a countercurrent flow, so that sponge iron 208 is obtained at the discharge outlet 21 Ib of reactor 211. Before discharging the sponge iron 208, the discharge vessel 231 is first sealed at its inlets 231a and 231b, evacuated using the vacuum pump 229, and filled with sealing gas 223. The vessel 231 is then ready to receive the sponge iron 208. The inlet 231a of the vessel is opened, allowing the sponge iron 208 to fall into the vessel and displace the sealing gas from the vessel upwards into the direct reduction tank 211. The inlet 231a of the discharge vessel is then closed, the discharge vessel 231 is evacuated using the vacuum pump 229, and filled to atmospheric pressure using inert gas 235. The outlet 231b of the discharge vessel 231 can then be opened to release the sponge iron 208. Auxiliary gas 215 is supplied from an auxiliary gas source 220, such as a hydrogen gas tank or a water electrolyzer. Auxiliary gas 215 is mixed with the treated overhead gas 218 to form reducing gas 217. Reducing gas 217 passes through a preheater 241 before being introduced into the direct reduction vessel 211. Overhead gas 216 exiting outlet 21 Id passes through a plurality of treatment units 243 to prepare the gas for reintroduction into the direct reduction vessel 211. The plurality of treatment units may include a cleaning stage, such as passage through an electrostatic precipitator to remove solids from the gas, heat exchange with other process gases, such as reducing gas 217, and water separation.The treated upper gas 218 is mixed with the auxiliary gas 215 and passes through the preheater 241 before being reintroduced into the direct reduction vessel 211a through inlet 211c. The temperature of the gases entering inlet 211c can be further increased by partial oxidation. In this case, a supply of 25 can be provided. QObonn / eznz / E / YiAi oxygen (not shown) between preheater 241 and inlet 211c. Once the ore is discharged from the loading vessel 213, the vessel can be prepared for a new ore charge. First, the ore outlet 213b is closed. Subsequently, the gas outlet 213d is opened, and the process gases are evacuated from the loading vessel 213 using the vacuum pump 229. Then, the gas outlet 213d is closed, and the loading vessel is refilled with a gas at ambient pressure. In the illustrated example, the vessel 213 is refilled with sealing gas 223 by opening the gas inlet 213c, but it can instead be filled from an inert gas source (not illustrated) if the sealing gas is not inert. Finally, the gas inlet 213c is closed, and the ore inlet 213a is opened. In this way, the loading vessel 213 is restored to its initial configuration and is ready to receive an additional charge of iron ore. Figure 3 is a flow diagram schematically illustrating one embodiment of the process for charging iron ore into a direct reduction vessel as described herein. Step s301 indicates the start of the process. In step s303, the ore outlet 213b of the ore charging vessel 213 is placed in a sealed state. In step s305, an ore inlet 213a of the ore charging vessel 213 is placed in an open state. Note that if the ore outlet 213b and ore inlet 213a are already in a closed and open state, respectively, then these steps do not involve any change in the state of the charging arrangement. 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 placed in a sealed state.In step s312, the gas is evacuated from the ore charging vessel 213 by applying a vacuum. In step s313, the ore charging vessel is filled with a sealing gas 223. In step s315, the ore outlet 213b is opened to charge iron ore 207 to the direct reduction vessel 211. Step s317 marks the end of the process. The listed steps are performed sequentially, but intermediate steps may be necessary. For example, if for any reason the vacuum applied to the loading vessel is insufficient to remove substantially all the air—for example, if the loading vessel cannot tolerate such low pressures—one or more additional evacuation / refilling cycles may be performed between steps s309 and s312. One such evacuation / refilling cycle is illustrated in Figure 3. This involves a step s310 of evacuating the gas from the ore loading vessel 213 by applying a vacuum, and a step s311 of refilling the ore loading vessel with an inert gas. QObonn / eznz / E / YiAi Figure 4 is a flow diagram schematically illustrating one embodiment of the process for unloading iron ore from a direct reduction vessel as described herein. Step s401 marks the beginning of the process. In step s403, the iron 231a outlet and the iron 231b inlet of the iron 231 discharge vessel are brought into a sealed state. Note that if outlet 231b and inlet 231a are already in a closed state, then these steps do not involve any change in the state of the discharge arrangement. In step s405, gas is evacuated from the iron 231 discharge vessel by applying a vacuum. In step s407, the iron 231 charging vessel is filled with sealing gas 223. In step s409, the iron 231a inlet of the iron 231 discharge vessel is brought into an open state.In step s409, the iron discharge vessel 231 is charged with sponge iron 208 through the iron inlet 231a. In step s411, the iron inlet is sealed. This allows the sponge iron 208 to be discharged from the direct reduction vessel 211. Through a number of optional intermediate steps (not shown), the discharge vessel is prepared for the release of the sponge iron 208. In a final step, s413, the iron outlet 231b is opened, and the sponge iron 208 is released. Step s415 marks the end of the process. The listed steps are performed sequentially, but there may be intermediate steps. For example, if for some reason the vacuum applicable to the discharge vessel is not sufficient to substantially remove all the air, for example, if the discharge vessel does not tolerate such low pressures, one or more additional evacuation / refill cycles may be performed between stages s403 and s405 (not shown).

Claims

CLAIMS 1. An arrangement for loading iron ore (207) into a direct reduction vessel (211), the arrangement comprising: an ore loading vessel (213); a vacuum source (229); and a source of a sealing gas (221); wherein the vacuum source and the source of the sealing gas are each arranged in controllable fluid connection with the ore loading vessel; and wherein the sealing gas is a non-oxidizing gas.

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

3. The arrangement according to any of the preceding claims, wherein the sealing gas is selected from the list consisting of hydrogen, methane, biogas, synthesis gas, carbon dioxide, nitrogen, purified combustion gas and combinations thereof.

4. The arrangement according to any of the preceding claims, further comprising a source of an inert gas, wherein the source of the inert gas is arranged in controllable fluid connection with the iron ore loading arrangement, and wherein the inert gas is different from the sealing gas.

5. The arrangement according to claim 4, wherein the inert gas is selected from the list consisting of carbon dioxide, nitrogen, purified combustion gas and combinations thereof; and wherein the sealing gas is selected from the list consisting of hydrogen, methane, biogas, synthesis gas, carbon dioxide and combinations thereof.

6. The arrangement according to any of the preceding claims, configured to achieve a pressure of approximately 10,000 Pa (100 mbar) or less at normal temperature, preferably approximately 1000 Pa (10 mbar) or less, even more preferably approximately 100 Pa (1 mbar) or less.

7. An arrangement for unloading sponge iron from a direct reduction vessel, the arrangement comprising: a sponge iron unloading vessel (231); a vacuum source (229); and a source of a sealing gas (221); wherein the vacuum source and the source of the sealing gas are each arranged in controllable fluid connection with the iron unloading vessel; and wherein the sealing gas is a non-oxidizing gas.

8. A system for the production of sponge iron, the system comprising: an arrangement for loading iron ore according to any of claims 1-2, and / or an arrangement for unloading sponge iron according to claim 7; a direct reduction vessel (211); and a source of an auxiliary gas (220) arranged in fluid connection with the direct reduction vessel.

9. The system according to claim 8, wherein the auxiliary gas source is an electrolyzer and the auxiliary gas is hydrogen.

10. A process for charging iron ore to a direct reduction vessel, the process comprising the steps: a) putting (s3O3) an ore outlet of an ore charging vessel into a sealed state; b) putting (s3O5) an ore inlet of the ore charging vessel into an open state; c) charging (s307) the ore charging vessel with iron ore through the ore inlet; d) putting (s309) the ore inlet into a sealed state; e) evacuating (s312) the gas from the ore charging vessel by applying a vacuum; f) filling (s313) the ore charging vessel with a sealing gas; and g) putting (s315) the ore outlet into an open state to charge iron ore to the direct reduction vessel; QObonn / eznz / E / YiAi wherein the sealing gas is a non-oxidizing gas.

11. The process according to claim 10, wherein the sealing gas is selected from the list consisting of hydrogen, methane, biogas, synthesis gas, carbon dioxide, nitrogen, purified combustion gas and combinations thereof.

12. The process according to any of claims 10-11, further comprising the steps: eO) removing (s310) the gas from the ore loading vessel by applying a vacuum; and fO) filling (s311) the ore loading vessel with an inert gas; wherein steps eO) and fO) are performed after step d) but before step e).

13. The process according to claim 12, wherein the inert gas is selected from the list consisting of carbon dioxide, nitrogen, purified combustion gas and combinations thereof.

14. The process according to any of claims 12-13, wherein the sealing gas and the inert gas are the same.

15. The process according to any of claims 12-13, wherein the sealing gas and the inert gas are different; and wherein the sealing gas is selected from the list consisting of hydrogen, methane, biogas, synthesis gas, carbon dioxide and combinations thereof.

16. The process according to any of claims 10-15, further comprising the steps: (h) placing the ore outlet in a sealed state; (i) removing a process gas from the ore loading vessel by applying a vacuum; (j) filling the ore loading vessel with a gas selected from air, inert gas, and combinations thereof; and (k) placing the ore inlet in an open state. QObonn / eznz / E / YiAi 17. A process for unloading sponge iron from a direct reduction vessel, the process comprising the steps: i) placing (s403) an iron outlet and an iron inlet of an iron discharge vessel in a sealed state; ii) evacuating (s405) the gas from the iron discharge vessel by applying a vacuum; iii) filling (s407) the iron charging vessel with a sealing gas; iv) placing (s409) an iron inlet of the iron discharge vessel in an open state; v) charging (s411) the iron discharge vessel with sponge iron through the iron inlet; and vi) placing (s411) the iron inlet in a sealed state; wherein the sealing gas is a non-oxidizing gas.

18. A process for the direct reduction of iron ore, wherein the process comprises introducing a sealing gas consisting essentially of a gas selected from hydrogen, methane, biogas, synthesis gas, combinations of carbon dioxide with hydrogen, methane, biogas or synthesis biogas, and combinations thereof into a direct reduction vessel together with the loading of iron ore into the direct reduction vessel and / or together with the unloading of sponge iron from the direct reduction vessel.

19. A process according to claim 18, wherein the sealing gas is introduced by a process for loading iron ore according to any of claims 10-16, and / or by a process for unloading sponge iron according to claim 17.