Apparatus 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 apparatus and a process for charging iron ore (207) into a direct reduction shaft (211), and an apparatus and a process for discharging sponge iron (208) from the direct reduction shaft. Each of the processes includes a step of discharging gas from a container by applying a vacuum and then refilling the container with process gas from the direct reduction shaft. Further, the present disclosure relates to a system for producing sponge iron, comprising such an apparatus for charging iron ore and / or discharging sponge iron. Further, the present disclosure relates to a process for direct reduction of iron ore, the process including a step of introducing process gas from the direct reduction into the direct reduction shaft in conjunction with the step of charging iron ore and / or discharging sponge iron.

Description

Technical Field

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

Background Art

[0002] Steel is the most important industrial and construction material in the world. In the modern world, it is difficult to find an object that does not contain steel or that does not depend on steel for manufacturing and / or transportation. Thus, steel is intricately involved in almost every aspect of our modern life.

[0003] In 2018, the total global production of crude steel was 1.81 billion tons, which is far more than any other metal, and is expected to reach 2.8 billion tons by 2050, 50% of which is expected to be obtained from virgin iron sources. Steel is also the most recycled material in the world and has a very high recycling grade because it can be remelted using electricity as a primary energy source and used many times.

[0004] Therefore, steel is the cornerstone of modern society and will play an even more important role in the future.

[0005] Steel is mainly produced through three routes. i) The reduction of iron oxide in ore by carbon to produce iron, integrated production using virgin iron ore in a blast furnace (BF). The iron is further processed in a steel plant by blowing oxygen into a basic oxygen furnace (BOF), and then refined to produce steel. This process is generally also called "oxygen steelmaking". ii) Scrap-based production using recycled steel melted in an electric arc furnace (EAF) using electricity as the primary energy source. This process is generally also called "electric steelmaking". iii) Direct reduction (DR) production based on virgin iron ore reduced in a direct reduction process using a carbonaceous reducing gas to produce sponge iron. The sponge iron is then melted in an EAF together with scrap to produce steel.

[0006] In this specification, the term "crude iron" is used to denote all iron produced, whether obtained from a blast furnace (i.e., pig iron) or from a direct reduction shaft (i.e., sponge iron), for further processing into steel.

[0007] The processes named above have been improved over decades and are approaching the theoretical minimum energy consumption, but one fundamental problem remains unsolved. The use of a carbonaceous reducing agent to reduce iron ore results in the production of CO2 as a by-product. On average, 1.83 tons of CO2 were produced per ton of steel produced in 2018. The steel industry is one of the most CO2-emitting industries, accounting for approximately 7% of global CO2 emissions. As long as a carbonaceous reducing agent is used, it is impossible to avoid the generation of excessive CO2 in the steel production process.

[0008] To address this issue, the HYBRIT initiative was established. HYBRIT is an abbreviation for HYdrogen BReakthrough Ironmaking Technology (revolutionary ironmaking technology using hydrogen), a joint venture between SSAB, LKAB, and Vattenfall partially funded by the Swedish Energy Agency, aiming to reduce CO2 emissions and decarbonize the steel industry.

[0009] At the heart of the HYBRIT concept is the production of sponge iron based on the direct reduction of virgin ore. However, instead of using a carbonaceous reducing agent gas such as natural gas as in current commercial direct reduction processes, HYBRIT proposes using hydrogen gas as the reducing agent, called hydrogen direct reduction (H-DR). Hydrogen gas can be produced, for example, by electrolyzing water without using fossil fuels and / or mainly using renewable primary energy sources, as in the case of electricity production in Sweden. Therefore, the important process of reducing iron ore can be achieved without the need for fossil fuels as input materials, and water is produced as a by-product instead of CO2.

[0010] In the prior art fossil-based direct reduction systems as well, it is essential that the iron ore can be safely charged into the direct reduction shaft, similar to the proposed hydrogen-based direct reduction system. Since the process gas passing through the shaft is highly flammable (typically containing hydrogen, carbon monoxide, and hydrocarbons in a fossil-based process), it is crucial to avoid the formation of an explosive air / process gas mixture when introducing the ore into the shaft. This is typically achieved by ensuring that only an inert (i.e., non-oxidizing and non-flammable) sealing gas is introduced into the shaft when charging the ore, and air is not introduced into the shaft, and that the process gas does not leak out of the shaft uncontrollably through the charging device. Exactly how this is achieved depends on the design of the direct reduction system.

[0011] Typically, in a DR shaft operating at a low pressure (e.g., 2 bar or less) such as the Midrex process, a dynamic gas seal is arranged in a seal leg that connects the ore charging vessel directly to the direct reduction shaft. An inert seal gas is introduced at one or more locations in the seal leg at a pressure exceeding the operating pressure of the DR shaft. This high-pressure seal gas prevents air from being introduced into the DR shaft together with the charged iron ore and also prevents process gas from flowing out of the DR shaft through the seal leg.

[0012] Typically, in a DR shaft operating at a high pressure (e.g., exceeding 2 bar) such as the Hyl ZR process, the charging vessel is arranged 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 to a pressure higher than the operating pressure of the DR shaft using the seal gas. Once pressurized, a valve separating the charging vessel and the DR shaft is opened to allow the charged iron ore to be introduced into the shaft together with the seal gas. Typically, a plurality of charging vessels are arranged in parallel to supply ore to the DR shaft.

[0013] A similar device is also typically arranged at the discharge end of the direct reduction shaft to safely discharge the produced sponge iron.

[0014] There is still a need to improve the means for charging iron ore into the direct reduction shaft and / or discharging sponge iron from the direct reduction shaft. SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0015] The inventors of the present invention have found that there are several drawbacks in the prior art means for charging iron ore into the direct reduction shaft.

[0016] Conventional means of charging ore typically require the use of large amounts of sealing gas. The sealing gas is typically produced on-site using an air separation unit, for example, when the sealing gas is nitrogen. The need for large amounts of sealing gas leads to increased capital and operating costs for the direct reduction system.

[0017] In addition to this, when using conventional ore charging means, the sealing gas cannot be avoided from being introduced into the process gas. As described above, the typically used sealing gas, such as nitrogen, must be inert (i.e., it must not form an explosive mixture with the process gas), so it remains in the process gas. However, the other components of the process gas are typically consumed by the reaction (e.g., H2, CO, CH4) or removed from the circulation (e.g., H2O, CO2). This means that the sealing gas gradually accumulates in the process gas and, if no measures are taken, its proportion will continue to increase. To avoid such a situation, typically, a part of the process gas is extracted from the process gas circuit and incinerated to appropriately maintain the concentration of the inert component in the process gas. In particular, in the proposed hydrogen-based direct reduction process, this is economically disadvantageous because the reduction gas in such cases is expected to be more expensive than the fossil-based reduction gas, at least initially. When the reduction gas is fossil-based, extracting the process gas leads to an increase in CO2 emissions, which also has an adverse environmental impact.

[0018] It is also necessary to seal the outlet of the direct reduction shaft from which the produced sponge iron is discharged, and the conventional means of discharging sponge iron have the same drawbacks as the conventional means of charging ore.

[0019] It would be advantageous to implement means for charging iron ore into a direct reduction shaft and / or means for discharging sponge iron from the direct reduction shaft that overcome or at least mitigate at least some of the above-mentioned drawbacks. In particular, it is desirable to enable means for charging iron ore into a direct reduction shaft and / or means for discharging sponge iron from the direct reduction shaft that reduce the need for sealing gas and potentially eliminate the need to extract process gas, thus potentially reducing the operating costs of the direct reduction plant.

Means for Solving the Problems

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

[0021] The process comprises a) setting the ore outlet of the ore charging container to a sealed state; b) setting the ore inlet of the ore charging container to an open state; c) charging iron ore into the ore charging container through the ore inlet; d) setting the ore inlet to a sealed state; e) discharging gas from the ore charging container by applying a vacuum; f) refilling the ore charging container with process gas from the direct reduction shaft; g) setting the ore outlet to an open state and charging the iron ore into the direct reduction shaft and includes.

[0022] According to the disclosed process, the charging container filled with ore is evacuated by applying a vacuum through a gas transfer conduit connecting the direct reduction shaft or its process gas circuit to the ore charging container before being refilled with process gas from the direct reduction shaft. Since substantially all the air is removed from the charging container by applying a vacuum, the container can be directly filled with the process gas from the direct reduction shaft, and there is no need to flush the charging container with a large amount of sealing gas to reliably remove oxygen. This can be compared with the amount of sealing gas used to flush the charging container in the prior art methods, typically about five times the volume of the charging container per charge. Further, since the container is refilled with the process gas from the direct reduction shaft, no inert gas is introduced into the process gas when loading the ore into the shaft, and thus the accumulation of inert gas in the direct reduction process gas is small and the need for incineration is low.

[0023] The process gas from the direct reduction shaft means the process gas taken out from the direct reduction shaft or the process gas taken out from the process gas circuit of the direct reduction shaft. When the process gas is taken out from the process gas circuit, it is preferably taken out from a location in the process gas circuit before the used process gas is mixed with the makeup gas.

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

[0025] The process for discharging sponge iron is i) setting the iron outlet and iron inlet of the iron discharge container in a sealed state; ii) discharging gas from the iron discharge container by applying a vacuum; iii) refilling the iron charging container with the process gas from the direct reduction shaft; iv) setting the iron inlet of the iron discharge container in an open state; v) loading sponge iron into the iron discharge container through the iron inlet. vi) setting the iron inlet to a sealed state and including.

[0026] Similar to the process for charging iron ore, by using a vacuum, substantially all air is removed from the discharge vessel, which means that it can be refilled using the process gas from the direct reduction shaft without the risk of forming an explosive mixture. Therefore, when the vessel is opened to the direct reduction shaft to discharge the sponge iron, no dilution of the process gas occurs.

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

[0028] A vacuum can be applied to bring the ore charging vessel (and, alternatively or in addition, the iron discharge vessel) 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). By using a relatively strong vacuum, air (oxidizing agent) is sufficiently discharged from the vessel, avoiding the formation of an explosive mixture when refilling with the process gas (reducing agent) from the direct reduction shaft.

[0029] This process can further include a step of removing gas from the ore charging vessel (alternatively or in addition to this, from the iron discharge vessel) by application of a vacuum, and a step of refilling the vessel with an inert gas. These steps can be carried out after step d) of setting the ore inlet in a sealed state, but before step e) of discharging gas from the ore charging vessel by application of a vacuum (or, in the process for discharging sponge iron, after step i but before step ii). That is, additional vacuum evacuation / refilling cycles may be carried out. This means that, even when a relatively poor vacuum is used, such as exceeding about 100 mbar, the process may be carried out stepwise by first carrying out the first vacuum evacuation / refilling cycle and supplying a gas mixture into the vessel that mainly contains inert gas but some air remains. Subsequent vacuum evacuation / refilling cycles should be sufficient to supply a gas mixture containing process gas from the direct reduction shaft into the vessel for the purpose of the present invention (i.e., to avoid the formation of a potentially explosive gas / air mixture).

[0030] Of course, instead of the single and double vacuum evacuation / refilling cycles already described, a plurality of vacuum evacuation / refilling cycles, such as a total of three or four vacuum evacuation / refilling cycles, may be carried out as required. However, the total amount of inert gas required in the process increases each time a vacuum evacuation / refilling cycle is carried out, and therefore it is preferable to use as few vacuum evacuation / refilling cycles as possible. When more than two vacuum evacuation / refilling cycles are carried out, the refilling in the initial cycle is carried out using an inert gas, and the refilling using process gas from the direct reduction shaft is carried out only in the last refilling step.

[0031] The inert gas may be selected from the list consisting of carbon dioxide, nitrogen, purified flue gas, and combinations thereof. The carbon dioxide may be of biological origin, i.e., non-fossil CO2.

[0032] Specifically, the process for charging iron ore into the direct reduction shaft can further include a step of setting the ore outlet in a sealed state, a step of removing process gas from the ore charging container by applying ventilation and / or vacuum, a step of refilling the ore charging container with a gas selected from air, an inert gas, and combinations thereof, and a step of setting the ore inlet in an open state. The inert gas may be selected from carbon dioxide, nitrogen, purified flue gas, and combinations thereof. In this way, the charging container can be prepared for the introduction of further iron ore charge while ensuring effective use of the gas.

[0033] According to another aspect of the present invention, the object of the present invention is achieved by a process for the direct reduction of iron ore to sponge iron according to the appended independent claims. This process includes a step of introducing process gas from direct reduction into the direct reduction shaft in conjunction with the step of charging iron ore into the direct reduction shaft and / or in conjunction with the step of discharging sponge iron from the direct reduction shaft. "In conjunction with the step of charging iron ore into the direct reduction shaft" means that the process gas from direct reduction is introduced together with the iron ore charged into the shaft. "In conjunction with the step of discharging sponge iron from the direct reduction shaft" means that when the discharge container is opened and sponge iron can be discharged from the shaft, the process gas from direct reduction is introduced from the discharge container. "Introducing... in conjunction with" means that, for example, as described in the present specification and the appended independent claims, the gas can be introduced into the direct reduction shaft using the process for charging iron ore into the direct reduction shaft and / or discharging sponge iron from the direct reduction shaft.

[0034] Since it is inevitable that gas is introduced into the direct reduction shaft in connection with the charging and / or discharging of solids into / from the direct reduction shaft, by introducing such gas for reducing the iron ore and / or, optionally, carburizing it, the process avoids introducing only the gases useful for direct reduction and avoids introducing gases that may have an adverse effect on the process. Gases that may have an adverse effect on the process are, for example, inert gases such as nitrogen that accumulate in the process gas and, if accumulated to an excessive concentration, may reduce the reduction ability of the process gas. Usually, in order to improve the effect of such accumulation, extraction of the process gas is necessary. Therefore, the disclosed process makes it possible to use the process gas more effectively and thus reduce the operating costs of the process.

[0035] The process can include the step of introducing makeup gas countercurrently to the iron ore into the direct reduction shaft. The makeup gas is selected from hydrogen, methane (such as natural gas or biomethane), and synthesis gas (such as biogas synthesis gas). This makeup gas can ensure that a sufficient amount of reducing gas for fully reducing the iron ore to sponge iron is introduced into the process.

[0036] According to a further aspect of the invention, the object of the invention is achieved by a device for charging iron ore into a direct reduction shaft according to the appended independent claims. The device for charging iron ore comprises - an ore charging container, - a direct reduction shaft, - a vacuum source and is provided with.

[0037] The vacuum source is arranged in controllable fluid communication with the ore charging container.

[0038] The ore charging vessel is arranged to be controllably in fluid communication with the direct reduction shaft via a gas transfer conduit arranged to extend between the direct reduction shaft or its process gas circuit and the ore charging vessel. The gas transfer conduit can extend, for example, from the upper part of the direct reduction shaft, for example, in the vicinity of the top gas outlet of the direct reduction shaft.

[0039] Such a device facilitates performing a process for charging iron ore into a direct reduction shaft, as described in this specification and the appended independent claims. The ore charging vessel, more specifically the ore outlet of the ore charging vessel, is typically arranged in communication with the inlet of the direct reduction shaft, enabling ore to flow from the ore charging vessel into the direct reduction shaft.

[0040] According to a further aspect of the invention, the object of the invention is achieved by a device for discharging sponge iron from a direct reduction shaft according to the appended independent claims.

[0041] The device for discharging sponge iron comprises - a sponge iron discharge vessel, - a direct reduction shaft, - a vacuum source and is provided with.

[0042] The vacuum source is arranged to be controllably in fluid communication with the iron discharge vessel.

[0043] The sponge iron discharge vessel is arranged to be controllably in fluid communication with the direct reduction shaft via a gas transfer conduit arranged to extend between the direct reduction shaft or its process gas circuit and the sponge iron discharge vessel.

[0044] Such a device facilitates performing a process for discharging sponge iron from a direct reduction shaft, as described in this specification and the appended independent claims. The iron discharge vessel, more specifically the iron inlet of the iron discharge vessel, is typically arranged in communication with the outlet of the direct reduction shaft, enabling sponge iron to flow from the direct reduction shaft into the iron discharge vessel.

[0045] The following considerations are applicable independently to both the apparatus for charging iron ore and the apparatus for discharging sponge iron, unless otherwise specified.

[0046] The ore charging container can be provided with a sealable ore inlet and a sealable ore outlet. The gas transfer conduit can be provided with a controllable valve. The iron discharge container can be provided with a sealable iron inlet and a sealable iron outlet. The gas transfer conduit can be provided with a controllable valve. The vacuum source and / or the seal gas source can be arranged in fluid communication with the gas transfer conduit.

[0047] These apparatuses can further include an inert gas source. The inert gas source can be arranged in controllable fluid communication with the ore charging container and / or the iron discharge container.

[0048] When these apparatuses further include an inert gas source, the inert gas may be selected from the list consisting of carbon dioxide, nitrogen, purified flue gas, and combinations thereof. The carbon dioxide may be of biological origin, i.e., non-fossil CO2.

[0049] These apparatuses can be configured to achieve 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) in the ore charging container (and, alternatively or in addition thereto, in the iron discharge container). This requires that the vacuum source is strong enough to bring the container to the desired pressure, and / or the container is configured to tolerate such a low pressure (i.e., the container may be a vacuum container), and / or any openings in the container, such as the sealable inlet, the sealable outlet, and / or the gas conduit, are sealable to such an extent that the vacuum source can maintain such a pressure inside the container in some cases.

[0050] According to yet another aspect of the present invention, the object of the present invention is achieved by a system for the production of sponge iron according to the appended independent claims. The system comprises an apparatus for charging the iron ore described herein and / or an apparatus for discharging the sponge iron described herein. That is, the system comprises an apparatus for charging the iron ore described herein, or an apparatus for discharging the sponge iron described herein, or an apparatus for charging the iron ore described herein and an apparatus for discharging the sponge iron described herein. The system can further comprise charging and / or discharging apparatuses as conventionally known in the art. The system further comprises a makeup gas source arranged to be in fluid communication with the direct reduction shaft. When the system comprises an apparatus for charging the iron ore, the ore charging container can be arranged to communicate with the inlet of the direct reduction shaft. When the system comprises an apparatus for discharging the sponge iron, the iron discharge container can be arranged to communicate with the outlet of the direct reduction shaft. When the system comprises both an apparatus for charging the iron ore and an apparatus for discharging the sponge iron, the system can require only a single vacuum source and optionally only a single inert gas source. That is, separate gas sources and / or vacuum sources for the charging and discharging apparatuses are not necessarily required, and one or more of these sources can be integrated.

[0051] The makeup gas source can be an electrolyzer. The electrolyzer can generate hydrogen by electrolysis of water or can generate synthesis gas (a mixture of carbon monoxide and hydrogen) by co-electrolysis of water and carbon dioxide. Thus, the makeup gas can be hydrogen or a synthesis gas such as biogas. In this way, it is possible to produce sponge iron without the need to use fossil fuels as a source of reducing gas.

[0052] Further objects, advantages, and novel features of the present invention will become apparent to those skilled in the art from the following detailed description.

[0053] For a more complete understanding of the present invention and its further objects and advantages, the following detailed description should be read in conjunction with the accompanying drawings. In the drawings, the same reference numerals indicate like items in the various drawings.

Brief Description of the Drawings

[0054]

Figure 1

Figure 2

Figure 3

Figure 4

Mode for Carrying Out the Invention

[0055] The present invention is based on the inventors' insight that when charging iron ore into a direct reduction shaft, removing air from the charging vessel using a vacuum and then refilling with process gas (e.g., top gas) from the direct reduction shaft or from its process gas circuit provides a wide range of potential advantages. In contrast to prior art methods based on diluting the atmosphere inside the charging vessel until it is sufficiently inert (corresponding to multiple "vessel volumes" of seal gas that need to be flushed), the process of the present disclosure first removes the air atmosphere and replaces it with process gas from the direct reduction shaft, thus avoiding the use of an inert seal gas. Since the inert seal gas is not introduced into the direct reduction shaft, the accumulation of inert gas in the process gas is avoided, and the need for evacuation of the process gas may be reduced or completely avoided.

[0056] The same concept can be applied when discharging sponge iron from the direct reduction shaft, and the same or similar advantages can be obtained.

[0057] The term "process gas" is used herein to denote a gas mixture in the direct reduction process, regardless of whether it is in the stage of the direct reduction process. That is, the process gas refers to the gas that is introduced into the direct reduction shaft, passes through the direct reduction shaft, exits from the direct reduction shaft, and is recycled back to the direct reduction shaft. The process gas circuit of the direct reduction shaft means a series of gas lines that return the used process gas from the direct reduction shaft to the re-introduction point to the direct reduction shaft through a series of processes such as dust removal, heat exchange, compression, and mixing with makeup gas. More specific terms are used to denote the process gas at various locations in the process or the component gases that are added to the process gas to form part of the process gas.

[0058] The reducing gas is a gas that is introduced at a location lower than the inlet of the shaft, reduces the ore, and optionally flows upward in the opposite direction to the moving bed of the ore to carburize the sponge iron.

[0059] The top gas is a partially used process gas that is taken out from the upper end of the shaft close to the ore inlet. After treatment, the top gas can be recycled as a component of the reducing gas and returned to the direct reduction shaft.

[0060] The makeup gas is fresh gas that is added to the process gas to maintain the reducing ability. Typically, the makeup gas is added to the recycled top gas before being re-introduced into the direct reduction shaft. Therefore, the reducing gas typically includes the recycled top gas and the makeup gas. The makeup gas and the recycled top gas may be mixed before being introduced into the direct reduction shaft, or may be introduced separately and mixed within the shaft.

[0061] Seal gas is the gas that enters the direct reduction shaft from the ore charging device at the inlet of the direct reduction shaft. The outlet end of the direct reduction shaft can also be sealed using seal gas, and thus the seal gas can enter the DR shaft from the discharge device at the outlet of the direct reduction shaft. Therefore, a modification of the present invention is similarly applicable using seal gas introduced during the discharge of sponge iron from the direct reduction shaft. The seal gas used in prior art processes is typically an inert gas. The present disclosure is based on the idea of using the process gas from the direct reduction shaft as seal gas (i.e., instead of an inert seal gas).

[0062] An inert gas is a gas that cannot form a combustible or explosive mixture with either air or process gas, i.e., a gas that does not act as an oxidizing agent or fuel in a combustion reaction under the prevailing conditions of the process.

[0063] "Process gas from the direct reduction shaft or its process gas circuit" means the process gas supplied from inside the direct reduction shaft, or the process gas supplied from the process gas circuit of the direct reduction shaft such as a reduction gas circuit or a cooling gas (carburizing) circuit. The process gas supplied from inside the direct reduction shaft may be, for example, the top gas taken out from the upper part of the direct reduction shaft, or the cooling gas taken out from the lower cone part of the direct reduction shaft. When the process gas is used from the process gas circuit, it is preferably the process gas taken out from a location in the process gas circuit before mixing with the makeup gas. That is, the process gas supplied from the process gas circuit is preferably purely "recycled" process gas. Hereinafter, in the present application, the term "process gas from the direct reduction shaft" related to the gas used to fill the charging and / or discharging container is intended to include the process gas from the direct reduction shaft or the process gas from the process gas circuit of the direct reduction shaft unless otherwise explicitly stated.

[0064] Charging of iron ore The iron ore charging raw material typically consists mainly of iron ore pellets, although some lumpy iron ore may also be introduced. Iron ore pellets typically have hematite as the main component and are accompanied by additional additives or impurities such as gangue, fluxes, and binders. However, the pellets may contain any other metals and other ores such as magnetite. Iron ore pellets for direct reduction processes are commercially available and such pellets can be used in this process.

[0065] The ore charging container is typically a container equipped with a sealable ore inlet, a sealable ore outlet, and at least one gas conduit suitable for gas discharge and / or introduction. Of course, the container may be equipped with multiple gas conduits, for example, separate conduits for gas discharge and introduction, or multiple conduits for the introduction of various gases. The ore charging container is appropriately constructed to withstand both such pressures, i.e., pressures below atmospheric pressure (about 100 mbar or less, preferably about 10 mbar or less) that are dominant in the discharge process, and pressures above atmospheric pressure (often, such as about 2 bar to about 10 bar, higher than 2 bar) caused by the refill of the sealing gas. Multiple ore charging containers may be arranged in parallel to supply ore to a single direct reduction shaft. For example, 2, 3, 4, 5, 6, 7, 8, 9, or 10 ore charging containers may be arranged to supply ore to a single direct reduction shaft.

[0066] Before loading the ore into the loading container, the ore outlet is set to a sealed state to be able to accommodate the ore to be introduced. "Setting to a certain state" means making the component in that state if it is not already in such a state, or maintaining that state if it is already in such a state. Therefore, the term "setting to a certain state" does not necessarily imply a change in state. The ore is loaded into the container through the inlet, and then the inlet is sealed. Then, a vacuum source arranged in fluid communication with the gas conduit is used to evacuate the atmosphere from the loading container. The vacuum source may be, for example, a vacuum pump. Such pumps are known in the art. The loading container and the pump are preferably configured such that the loading container can reach 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 of the air is evacuated from the loading container. If the achievable vacuum level at the evacuation stage is low enough, then the loading container can be directly refilled with the process gas from the direct reduction shaft subsequently.

[0067] The process gas can be supplied through a gas transfer conduit connecting the direct reduction shaft to the loading container. Since the gas transfer line provides direct fluid communication between the loading container and the direct reduction shaft, if the gas transfer conduit is held open for a sufficient time, the pressure obtained within the loading container will be equal to the dominant pressure within the direct reduction shaft. Alternatively, the process gas may be supplied from a location within the process gas circuit having a pressure equal to or higher than the dominant pressure within the direct reduction shaft. For example, the gas transfer line may extend from a location where the outlet of a compressor arranged in the process gas circuit is located. In such a case, the pressure obtained in the loading circuit will exceed the pressure within the direct reduction shaft.

[0068] If the achievable vacuum level during the evacuation stage 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 an inert gas and then a further evacuation step may be performed. In this way, the remaining amount of air can be reduced to a safe level. The evacuation and refilling with an inert gas steps can be performed as many times as necessary to ensure safety. In the final refilling step, the charging vessel is filled with process gas from the direct reduction shaft that is reintroduced directly into the direct reduction shaft during charging. When the ore and the process gas are filled, the ore outlet of the charging vessel is set to an open state so that a mixture of the ore and the process gas can be charged into the direct reduction shaft.

[0069] When the ore is charged into the direct reduction shaft, the ore charging vessel should be reset to safely remove the process gas contained in the vessel and prepare the vessel for new ore charging. This can be done by sealing the ore outlet and evacuating the charging vessel using ventilation, flushing with an inert gas, and / or vacuum to remove the process gas, and then refilling the charging vessel with an appropriate gas such as air, nitrogen, purified flue gas, or carbon dioxide. The process gas discharged in this step may be reused in the direct reduction shaft. The vessel is refilled to a pressure of about atmospheric pressure. Once the potentially flammable contents of the vessel are discharged and the vessel reaches about atmospheric pressure again, the inlet of the vessel can be opened to accept new charged iron.

[0070] Direct reduction The direct reduction shaft may be of any type commonly known in the art. The shaft means a solid-gas countercurrent moving bed reactor, and the iron ore charging raw material is charged at the inlet at the top of the reactor and descends by gravity toward the outlet located at the bottom of the reactor. The reducing gas is introduced at location I below the ore inlet of the shaft, and the reducing gas flows upward to reduce the iron ore and optionally carburize it.

[0071] 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 gas introduced into the reactor using a preheater such as an electric preheater. Further heating of the gas can be obtained by exothermic partial oxidation of the gas with oxygen or air after leaving the preheater and before introducing it into the reactor. Reduction can 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 makeup gas used for supplementing the process gas is fossil-based and typically contains synthesis gas and natural gas in various proportions. This disclosure is applicable to processes utilizing such fossil-based makeup gas. However, in order to provide a process that does not use fossil fuels to obtain sponge iron, it is preferable that the makeup gas is not derived from fossil fuels.

[0073] The makeup gas may mainly consist of hydrogen. For example, the makeup gas may contain at least 80% by volume, preferably more than 90% by volume, and even more preferably more than 95% by volume of hydrogen gas (volume % measured under normal conditions of 1 atm and 0 °C), may be substantially composed of such hydrogen gas, or may be composed of such hydrogen gas. The disclosed process enables the production of substantially carbon-free sponge iron by using hydrogen as the makeup gas and not introducing carbonaceous gas into the process gas. However, in some cases, it may be desirable to obtain carburized sponge iron. Therefore, in order to achieve an appropriate level of carburization of the sponge iron, some amount of carburizing gas and / or carbon dioxide may be added as the makeup gas. The carburizing gas is a gas containing carbon that can directly carburize the sponge iron, for example, all carbon compounds that are not fully oxidized such as hydrocarbons or carbon monoxide. Such gases include, but are not limited to, methane, biogas, synthesis gas, and mixtures thereof. However, the carburizing effect in this process can be achieved by introducing carbon dioxide instead of or in addition to this. In the dominant carbon-lean state of the direct reduction shaft, carbon dioxide is converted to carbon monoxide, which can then carburize the sponge iron. Methane may be biomethane, and / or synthesis gas may be biosynthesis gas. Carbon dioxide may be of biological origin, i.e., non-fossil CO2.

[0074] Therefore, the remainder of the makeup gas may, in addition to hydrogen, contain carbon dioxide and / or carburizing gas, may be substantially composed of such gases, or may be composed of such gases. When carbon dioxide and / or carburizing gas constitute a part of the makeup gas, they may be introduced directly into the direct reduction shaft together with the hydrogen makeup gas. Alternatively, some or all of the carbon dioxide and / or carburizing gas that constitute a part of the makeup gas may be added to the direct reduction shaft separately from the main part of the makeup gas. For example, the carburizing gas may be added to the carburizing region or the cooling region of the direct reduction shaft.

[0075] The process gas can be recycled at least partially, so that the top-of-furnace (used) gas from the DR shaft can be cleaned and treated to remove by-products such as water and / or dust before being reintroduced into the DR shaft. This recycled top-of-furnace gas may be mixed with fresh makeup gas before being reintroduced into the reactor, or may be introduced separately from the supply of fresh makeup gas.

[0076] In the process of the present disclosure, since an inert gas is not added to the process gas, in contrast to the prior art processes, the extraction / incineration of the process gas can be reduced or avoided. The need to produce an inert gas as seal gas is also reduced, and capital equipment such as an air separation unit can be downsized or eliminated completely.

[0077] Sponge iron is obtained as a reduction product of iron ore and is discharged from an outlet at the lower end of the direct reduction shaft. The shaft may be provided with a cooling and discharge cone at the bottom so that the temperature of the sponge iron can be lowered before it is discharged from the outlet.

[0078] Discharge of Sponge Iron Discharging sponge iron from the direct reduction shaft has the same requirements as charging iron ore into the shaft. It is essential that no combustible / explosive gas mixture is formed during discharge, and it is preferable to avoid introducing an inert gas into the process gas as much as possible. Therefore, the principles of the present invention can also be applied to the sponge iron discharge device and process.

[0079] The iron discharge container is typically a container comprising a sealable iron inlet, a sealable iron outlet, and at least one gas conduit suitable for gas discharge and / or introduction. Naturally, the container may comprise a plurality of gas conduits, for example separate conduits for gas discharge and introduction, or a plurality of conduits for the introduction of various gases. The iron discharge container is suitably constructed so as to withstand both such pressures, i.e., pressures below atmospheric pressure (about 100 mbar or less, preferably about 10 mbar or less) that are dominant in the discharge process, and pressures above atmospheric pressure (often, such as about 2 bar to about 10 bar, higher than 2 bar) that result from the refill of process gas. A plurality of iron discharge containers may be arranged in parallel to receive iron from a single direct reduction shaft. For example, two, three, four, five, six, seven, eight, nine, or ten ore discharge containers may be arranged to discharge iron from a single direct reduction shaft.

[0080] Before discharging iron into the discharge vessel, the iron inlet and outlet are set in a sealed state. A vacuum source arranged in fluid communication with 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 the pump are preferably configured such that the discharge vessel can reach 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 of the air is evacuated from the discharge vessel. If the achievable vacuum level during the evacuation stage is low enough, the discharge vessel can then be refilled with process gas from the direct reduction shaft to the prevailing pressure within the direct reduction shaft. If the achievable vacuum level during the evacuation stage is not low enough, an undesired amount of air may remain in the discharge vessel. In such a case, the discharge vessel may first be refilled with an inert gas and then a further evacuation step may be carried out. In this way, the remaining amount of air can be reduced to a safe level. The evacuation and refilling steps with inert gas can be carried out as many times as necessary to ensure safety. In the final refilling step, the discharge vessel is filled with process gas that is introduced into the direct reduction shaft during the discharge of the sponge iron. Once an appropriate atmosphere has been established inside the discharge vessel, the iron inlet can be opened to allow the sponge iron to be received into the vessel from the direct reduction shaft. Once the sponge iron has been 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 are removed once again by flushing with an inert gas, venting the vessel, and / or applying a vacuum before opening the outlet of the discharge vessel to discharge the contained sponge iron and replaced with an inert gas at an appropriate pressure. The process gas discharged in this step may be reused in the direct reduction shaft.

[0081] Sponge iron In this specification, the term "crude iron" is used to denote all iron produced for further processing into steel, whether obtained from a blast furnace (i.e., pig iron) or directly from a direct reduction shaft as in the processes of the present disclosure (i.e., sponge iron). Sponge iron obtained at the DR shaft outlet is typically mainly in the form of pellets due to the structural integrity of the direct reduction pellets and the prevailing conditions in the DR shaft. Such sponge iron is typically referred to as direct reduced iron (DRI). Depending on the process parameters, DRI may be provided as hot DRI (HDRI) or cold DRI (CDRI). Cold DRI may also be known as type (B) DRI. DRI can be prone to reoxidation and in some cases is pyrophoric. However, several means of passivating DRI are known. One such means commonly used to facilitate overseas transport of the product is to press hot DRI into briquettes. Such briquettes are generally referred to as hot briquetted iron (HBI) and may also be known as type (A) DRI.

[0082] The sponge iron product obtained by the process of this specification can be essentially fully metallized sponge iron, i.e., sponge iron having a degree of reduction (DoR) 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. Kinetically, it is often not commercially favorable to obtain sponge iron with a DoR greater than about 96%, but such sponge iron can be produced if desired.

[0083] As described above, the process described herein is suitable for producing carbon-free sponge iron or carburized sponge iron as desired. Carburized sponge iron means sponge iron containing carbon. The carbon present in the sponge iron product may typically be in the form of cementite (Fe3C) and / or graphite. Graphite is prone to becoming dust and is easily lost from the sponge iron before reaching the melt in the EAF. Therefore, if the carbon is present as cementite in the sponge iron, it may be preferred.

[0084] Carburized sponge iron may contain 0.1 - 5 wt% carbon, such as 0.5 - 3 wt% carbon, such as about 1 - 2 wt% carbon. It is typically desirable for the sponge iron to have a carbon content of 0.5 - 5 wt%, preferably 1 - 4 wt%, such as about 3 wt%, for further processing, although this may depend on the ratio of sponge iron to scrap used in the subsequent EAF processing step. Optionally, the carburized sponge iron product of the present process may then be further carburized by other means before further processing.

[0085] Gas Hydrogen gas is preferably obtained at least in part by electrolysis of water. When the electrolysis of water is carried out using renewable energy, it enables the supply of reducing gas from a renewable source. Electrolytic hydrogen may be conveyed directly from the electrolyzer to the DR shaft by a conduit, or the hydrogen may be stored during production and conveyed to the DR shaft as needed.

[0086] When carbon dioxide is used as makeup gas or inert gas in the processes described herein, the carbon dioxide source is preferably substantially pure carbon dioxide, such as at least 95% by volume carbon dioxide, preferably at least 98% by volume carbon dioxide. The carbon dioxide source may preferably be a high-concentration source, preferably of high-concentration biological origin. For example, enriched “green” CO2 can be obtained as a byproduct of biogas production by anaerobic digestion or as a byproduct of bioethanol production. When the carbon dioxide used in the process is from a renewable source, the process can be net negative with respect to CO2 emissions. However, even the use of a carbon dioxide source from a fossil source that would otherwise be directly emitted means that the process cannot emit CO2 in excess. An alternative means of supplying carbon dioxide is to use 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 and the biomass is burned using substantially 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, yielding a substantially pure carbon dioxide source. Conventionally, supplying substantially pure oxygen has been an economic obstacle to the use of oxy-fuel combustion. However, in this case, oxygen can be rapidly supplied at low additional cost from the electrolysis of water, making oxy-fuel preheating of the reducing gas economically feasible.

[0087] The carburizing gas can be introduced as makeup gas into the reduction zone of the direct reduction shaft or into the lower part of the reactor (such as the isobaric zone or the cooling / carburizing cone, etc.). The carburizing gas can be any gas known or anticipated in the art for performing carburization. The gas in this regard refers to a substance that may be liquid or solid at room temperature but is gaseous at the high temperatures prevailing in the carburizing reactor. Suitable carburizing gases include hydrocarbons such as methane, natural gas, LPG, or petroleum, or other carbonaceous substances such as synthesis gas, lower (C1 - C6) alcohols, esters, and ethers. The carburizing gas may be of fossil origin, but in order to reduce the net emissions of CO2, it is preferably obtained in part or in whole from renewable sources. Renewable means resources that are naturally replenished on a human time scale. The high utilization rate of carbon present in the carburizing gas enables the use of renewable carburizing gases even if they are relatively scarce and costly compared to fossil equivalents. Suitable renewable carburizing gases include biomethane, biogas, gases obtained from the pyrolysis or partial combustion of biomass (such as bio - synthesis gas), lower alcohols or ethers such as methanol, DME, or ethanol obtained from renewable raw materials, or combinations thereof. Carburizing gases containing sulfur may be used since sulfur is known to prevent the nucleation of graphite and passivate the sponge iron product.

[0088] The composition of the carburizing gas can be selected to match the finally obtained carburized sponge iron. The carburization reaction with hydrocarbons is relatively endothermic and results in a relatively low - temperature final product, while the reaction with a CO - containing carburizing gas is more exothermic and results in a higher - temperature final product. This effect can be utilized to adjust the temperature of the resulting final product. For example, if a high - temperature product is desired for briquetting (HBI), a gas containing partially oxidized carbon (e.g., in the form of CO, ketones, aldehydes) can be used, and if low - temperature sponge iron (CDRI) is desired, biomethane can be used.

[0089] In some operations, an inert gas such as nitrogen or purified flue gas may be used. Nitrogen can be obtained, for example, by cryogenic distillation of air using an air separator unit (ASU). Purified flue gas means flue gas that has been treated to be reliably suitable for use as a sufficiently inert gas. Such treatment may include afterburning to remove excess oxygen and / or drying of the flue gas.

[0090] Embodiments Next, the present invention will be described in more detail with reference to specific exemplary embodiments and the drawings. However, the present invention is not limited to the exemplary embodiments discussed herein and / or shown in the drawings, and can be modified within the scope of the appended claims. Furthermore, the drawings should not be considered to be drawn to scale as some features may be exaggerated to more clearly illustrate certain features.

[0091] Figure 1 schematically shows a prior art embodiment of an ore-based steelmaking value chain according to the Hybrit concept. The ore-based ironmaking value chain starts from the iron ore mine 101. After mining, the iron ore 103 is beneficiated and processed in the pelletizing plant 105 to produce iron ore pellets 107. These pellets, together with the lumpy ore used in the process, are converted into sponge iron 109 by reduction in the direct reduction shaft 111 using hydrogen gas 115 as the main reducing agent and producing water 117 as the main by-product. The hydrogen gas 115 is preferably produced by electrolyzing water 117 in the electrolyzer 119 using mainly electricity 121 obtained from a fossil fuel-free or renewable source 122. The hydrogen gas 115 may be stored in the hydrogen storage tank 120 before being introduced into the direct reduction shaft 111. The sponge iron 109 is optionally melted using the electric arc furnace 123 together with a certain proportion of scrap iron 125 or other iron sources to produce the melt 127. The melt 127 is further subjected to a downstream secondary metallurgy process 129 to produce steel 131. The entire value chain from ore to steel is intended to be fossil fuel-free and emit little or no carbon.

[0092] Figure 2 schematically shows an exemplary embodiment of a system suitable for implementing the process disclosed herein.

[0093] The direct reduction shaft 211 is arranged with an inlet 211a for the iron ore 207, an outlet 211b for discharging the sponge iron 208, an inlet 211c for the reducing gas, and an outlet 211d for the top gas. The charging container 213 is arranged in communication with the inlet 211a to the direct reduction shaft 211. The discharge container 231 is arranged in communication with the outlet 211b of the direct reduction shaft 211.

[0094] The charging container 213 is provided with 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 container 213 is arranged to communicate with the ore bin 227. The gas inlet 213c of the charging container 213 is arranged to communicate directly with the top gas outlet 211d of the direct reduction shaft 211 via the gas transfer conduit 221. The gas outlet 213d is arranged to communicate with the vacuum pump 229 and further communicate with the vent line 228.

[0095] The discharge container 231 is provided with an inlet 231a for sponge iron 208, an outlet 231b for sponge iron 208, a gas inlet 231c, and a gas outlet 231d. The inlet 231a of the discharge container 231 is arranged to communicate with the outlet 211b of the direct reduction shaft 211. The gas inlet 231c of the charging container 231 is arranged to communicate directly with the top gas outlet 211d of the direct reduction shaft 211 via the gas transfer conduit 251. The gas outlet 231d is arranged to communicate with the vacuum pump 249 and further communicate with the vent line 248.

[0096] First, the ore inlet 213a and the vent line 228 of the charging container 213 are open, and the ore outlet 213b and the gas inlet 213c are closed. The iron ore 207 from the ore bin 227 is introduced into the charging container 213. When the ore is loaded, the ore inlet 213a and the vent line 228 are sealed, the valve to the vacuum pump 229 is opened, the air in the charging container 213 is discharged, and the pressure in the charging container 213 is reduced to about 100 mbar or less. When the target pressure is reached, the valve to the vacuum pump 229 is closed, the gas transfer line from the top gas outlet 211d to the gas inlet 213c is opened, and the charging container 213 is pressurized with the top gas 216 to a pressure close to the operating pressure of the direct reduction shaft 211. When pressurized, the ore outlet 213b of the charging container 213 is opened, and the iron ore 207 can be charged into the inlet 211a of the direct reduction shaft 211. 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 flow of the reducing gas 217, and as a result, sponge iron 208 is obtained at the outlet 211b of the reactor 211.

[0097] Before discharging the sponge iron 208, the discharge container 231 is first sealed at its inlet 231a and outlet 231b, evacuated using the vacuum pump 249, and refilled with the top gas 216 using the gas transfer line 251. The container 231 is then in a state where it can receive the sponge iron 208. The inlet 231a of the container is opened so that the sponge iron 208 can fall into the container. Next, the inlet 231a of the discharge container and the gas transfer line 251 to the discharge container are closed, the discharge container 231 is evacuated using the vacuum pump 229, and refilled to atmospheric pressure using the vent line 248. Then, the outlet 231b of the discharge container 231 is opened to release the sponge iron 208.

[0098] The makeup gas 215 is supplied from a makeup gas source 220 such as a hydrogen gas storage tank or a water electrolysis cell. The makeup gas 215 is mixed with the treated top gas 218 to form the reducing gas 217. The reducing gas 217 is passed through a preheater 241 before being introduced into the direct reduction shaft 211. The top gas 216 exiting the outlet 211d is passed through a plurality of treatment devices 243 to prepare the gas for reintroduction into the DR shaft 211. The plurality of treatment devices can include cleaning steps such as passing through an electrostatic precipitator to remove solids from the gas, heat exchange with other process gases such as the reducing gas 217, and water separation. The treated top gas 218 is mixed with the makeup gas 215 and passed through the preheater 241 before being reintroduced into the direct reduction shaft 211 through the inlet 211c. The temperature of the gas entering the inlet 211c can be further increased by partial oxidation. In such a case, a supply of oxygen (not shown) may be arranged between the preheater 241 and the inlet 211c.

[0099] When the ore is discharged from the charging vessel 213, the vessel can be prepared for a new charge of ore. First, the ore outlet 213b is closed. Then, the process gas is discharged from the charging vessel 213 using the vacuum pump 229. Next, the charging vessel is refilled with gas to atmospheric pressure. In the illustrated example, the vessel 213 is refilled with air via the ventilation line 228. Finally, the ore inlet 213a is opened to receive a further charge of iron ore.

[0100] Although one or both of the gas transfer conduits 221, 251 are shown as extending from the top gas outlet 211d, alternatively they may extend from another location in the process gas circuit, such as a line for conveying the top gas 216 or a line for conveying the treated top gas 218. The gas transfer conduits 221, 251 are shown as being partially integrated, but may be completely separate lines.

[0101] Figure 3 is a flowchart schematically showing an exemplary embodiment of a process for charging iron ore into a direct reduction shaft as disclosed herein. Step s301 indicates 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 if the ore outlet 213b and the ore inlet 213a are already in the closed and open states respectively, these steps do not involve any change in the state of the charging device. In step s307, the ore charging vessel 213 is charged with iron ore 207 via the ore inlet 213a. In step s309, the ore inlet 213a is set to a sealed state. In step s312, the gas is discharged from the ore charging vessel 213 by the application of a vacuum. In step s313, the ore charging vessel is refilled with process gas from the direct reduction shaft, such as the top gas 216. 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 indicates the end of the process.

[0102] The listed steps are executed continuously, but there may be intervening steps. For example, for some reason, if 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 a low pressure, one or more additional evacuation / refilling cycles may be executed between step s309 and step s312. One such evacuation / refilling cycle is shown in FIG. 3. This includes a step s310 of discharging gas from the ore charging vessel 213 by application of a vacuum and a step s311 of refilling the ore charging vessel with an inert gas.

[0103] FIG. 4 is a flowchart schematically showing 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 the iron inlet 231b of the iron discharge vessel 231 are set to a sealed state. Note that if the outlet 231b and the inlet 231a are already in a closed state, these steps do not involve any change in the state of the discharge device. In step s405, gas is discharged from the iron discharge vessel 231 by application of a vacuum. In step s407, the iron charging vessel 231 is refilled with process gas from the direct reduction shaft such as the top gas 216. 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 through the iron inlet 231a. In step s411, the iron inlet is set to a sealed state. In this way, the sponge iron 208 is discharged from the direct reduction shaft 211. Through some 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 indicates the end of the process. The listed steps are executed continuously, but there may be intervening steps. For example, for some reason, if 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 a low pressure, one or more additional exhaust / refilling cycles may be executed between step s403 and step s405 (not shown).

Claims

1. An apparatus for charging iron ore (207) into a direct reduction shaft (211), comprising: - an ore charging vessel (213); - a direct reduction shaft (211); - a vacuum source (229), wherein the vacuum source is disposed in controllable fluid communication with the ore charging vessel, and the ore charging vessel is disposed in controllable fluid communication with the direct reduction shaft or its process gas circuit via a gas transfer conduit (221) disposed to extend between the direct reduction shaft or its process gas circuit and the ore charging vessel.

2. The apparatus according to claim 1, wherein the ore charging vessel comprises a sealable ore inlet (213a) and a sealable ore outlet (213b), and the gas transfer conduit comprises a controllable valve (221a).

3. The apparatus according to any one of claims 1 or 2, further comprising a ventilation line disposed in controllable fluid communication with the ore charging vessel.

4. The apparatus according to any one of claims 1 to 3, further comprising an inert gas source, wherein the inert gas source is disposed in controllable fluid communication with the ore charging vessel.

5. The apparatus according to claim 4, wherein the inert gas is selected from the list consisting of carbon dioxide, nitrogen, purified flue gas, and combinations thereof.

6. The apparatus according to any one of claims 1 to 5, configured to achieve a pressure within the ore charging vessel at room temperature of about 100 mbar or less, preferably about 10 mbar or less, and even more preferably about 1 mbar or less.

7. An apparatus for discharging sponge iron from a direct reduction shaft, comprising: - a sponge iron discharge vessel (231); - a direct reduction shaft (211); - a vacuum source (249), wherein the vacuum source is disposed in controllable fluid communication with the iron discharge vessel, and the sponge iron discharge vessel is disposed in controllable fluid communication with the direct reduction shaft or its process gas circuit via a gas transfer conduit (251) disposed to extend between the direct reduction shaft or its process gas circuit and the sponge iron discharge vessel.

8. - an apparatus for charging iron ore according to any one of claims 1 to 6 and / or an apparatus for discharging sponge iron according to claim 7; and - a makeup gas source (220) disposed in fluid communication with the direct reduction shaft for a system for the production of sponge iron.

9. The system according to claim 8, wherein the makeup gas source is an electrolytic cell and the makeup gas is hydrogen.

10. A process for charging iron ore into a direct reduction shaft, comprising: a) setting the ore outlet of the ore charging container to a closed state (s303); b) setting the ore inlet of the ore charging container to an open state (s305); c) charging iron ore into the ore charging container through the ore inlet (s307); d) setting the ore inlet to a closed state (s309); e) discharging gas from the ore charging container by applying a vacuum (s312); f) refilling the ore charging container with process gas from the direct reduction shaft (s313); g) setting the ore outlet to an open state and charging iron ore into the direct reduction shaft (s315). A process including the above steps.

11. h) setting the ore outlet to a closed state; i) removing process gas from the ore charging container by applying ventilation and / or vacuum; j) refilling the ore charging container with a gas selected from air, inert gas, and combinations thereof; k) setting the ore inlet to an open state. The process according to claim 10, further including the above steps.

12. A process for discharging sponge iron from a direct reduction shaft, comprising: i) setting the iron outlet and the iron inlet of the iron discharging container to a closed state (s403); ii) discharging gas from the iron discharging container by applying a vacuum (s405); iii) refilling the iron charging container with process gas from the direct reduction shaft (s407); iv) setting the iron inlet of the iron discharging container to an open state (s409); v) charging sponge iron into the iron discharging container through the iron inlet (s411); vi) setting the iron inlet to a closed state (s411). A process including the above steps.

13. A process for direct reduction of iron ore, including introducing process gas from direct reduction into the direct reduction shaft in conjunction with the step of charging the iron ore into the direct reduction shaft and / or in conjunction with the step of discharging sponge iron from the direct reduction shaft.

14. The process according to claim 13, wherein the process gas from direct reduction is introduced by a process for charging the iron ore according to any one of claims 10 or 11 and / or by a process for discharging the sponge iron according to claim 12.

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