Device and method for charging iron ore into direct reduction shaft furnace and / or discharging sponge iron from direct reduction shaft furnace

Abstract

The present disclosure relates to an apparatus and method for charging iron ore (207) into a direct reduction shaft furnace (211), and an apparatus and method for discharging sponge iron (208) from a direct reduction shaft furnace. The methods each include the steps of evacuating gas from the vessel by applying a vacuum, followed by refilling the vessel with process gas from the direct reduction shaft furnace. Furthermore, the present disclosure relates to a system for producing sponge iron comprising such a device for charging iron ore and / or discharging sponge iron. Further, the present disclosure relates to a process for direct reduction of iron ore wherein the process comprises introducing process gas from direct reduction to a direct reduction shaft furnace with charging of iron ore and / or discharging of sponge iron.

Description

Technical Field

[0001] The present invention relates to an apparatus for charging iron ore into a direct reduction shaft furnace, and a method for charging iron ore into a direct reduction shaft furnace using such an apparatus. The present invention also relates to an apparatus for discharging sponge iron from a direct reduction shaft furnace, and a method for discharging sponge iron from a direct reduction shaft furnace using such an apparatus. Furthermore, the present invention relates to a system for producing sponge iron comprising such an apparatus, and a method for directly reducing iron ore. Background Art

[0002] Steel is the world’s most important engineering and construction material. In the modern world, it is difficult to find any object that does not contain steel or does not rely on steel for its manufacture and / or transportation. In this way, steel is intricately involved in almost every aspect of our modern lives.

[0003] In 2018, global production of crude steel totaled 1810 million tonnes, far exceeding any other metal, and is expected to reach 2800 million tonnes by 2050, with 50% of this expected to come from primary iron sources. Steel is also the most recycled material in the world, with a very high recycling rating, as the metal can be used over and over again after being remelted using electricity as the primary energy source.

[0004] Steel is therefore a cornerstone of modern society and will play an even more important role in the future.

[0005] Steel is produced in three main ways:

[0006] i) Integrated production using raw iron ore in a blast furnace (BF), where the iron oxides in the ore are reduced by carbon to produce iron. The iron is further processed in a steel mill by blowing oxygen in a basic oxygen furnace (BOF) and subsequently refined to produce steel. This process is also commonly referred to as "oxygen steelmaking".

[0007] ii) Scrap-based production using recycled steel which is melted in an electric arc furnace (EAF) using electricity as the main energy source. This process is also often referred to as "electric steelmaking".

[0008] iii) Production based on direct reduction of raw iron ore which is reduced with a carbon-containing reducing gas in a direct reduction (DR) process to produce sponge iron. The sponge iron is subsequently melted in an EAF along with scrap steel to produce steel.

[0009] The term crude iron is used herein to denote all iron produced for further processing into steel, whether it is obtained from a blast furnace (ie pig iron) or a direct reduction shaft furnace (ie sponge iron).

[0010] Although the above process has been improved for decades and is approaching the theoretical minimum energy consumption, there is still a fundamental problem that has not been solved. The reduction of iron ore using carbon-containing reducing agents results in the production of CO2 as a by-product. For every ton of steel produced in 2018, an average of 1.83 tons of CO2 was produced. The steel industry is one of the industries with the highest CO2 emissions, accounting for about 7% of global CO2 emissions. As long as carbon-containing reducing agents are used, it is impossible to avoid the excessive production of CO2 during the steel production process.

[0011] The HYBRIT initiative has been set up 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 decarbonise the steel industry.

[0012] The core of the HYBRIT concept is the production of sponge iron from raw ore based on direct reduction. However, instead of using a carbonaceous reducing agent gas such as natural gas as in current commercial direct reduction processes, HYBRIT proposes the use of hydrogen as a reducing agent, known as hydrogen direct reduction (H-DR). Hydrogen can be produced by electrolysis of water using primarily fossil-free and / or renewable primary energy sources, as is the case for example with Swedish electricity production. Thus, the key step of reducing iron ore can be achieved without the need for fossil fuels as input, and with water as a by-product instead of CO2.

[0013] In prior art fossil-based direct reduction systems, as well as in the proposed hydrogen-based direct reduction system, it is essential that the iron ore can be safely charged into the direct reduction shaft furnace. Since the process gas passing through the shaft furnace is highly flammable (in fossil-based processes typically containing hydrogen, carbon monoxide and hydrocarbons), the formation of an explosive air / process gas mixture must be avoided when the ore is introduced into the shaft furnace. This is usually achieved by ensuring that only inert (i.e. flammable non-oxidant) sealing gas, rather than air, is introduced into the shaft furnace when the ore is charged, and that no process gas escapes the shaft furnace uncontrolled through the charging device. Exactly how this is achieved depends on the design of the direct reduction system.

[0014] Typically, in DR shaft furnaces operating at low pressure (e.g. ≤ 2 bar) (e.g. Midrex process), a dynamic gas seal is arranged at the sealing pipe connecting the ore charge container to the direct reduction shaft furnace. At one or more points in the sealing pipe, an inert sealing gas is introduced at a pressure exceeding the operating pressure of the DR shaft furnace. This higher pressure sealing gas prevents air from being introduced into the DR shaft furnace with the iron ore charge, and prevents process gases from escaping the DR shaft furnace through the sealing pipe.

[0015] Typically, in DR shaft furnaces operating at relatively high pressures (e.g. >2 bar) (e.g. the Hyl ZR process), a charging vessel is arranged at the inlet of the direct reduction shaft furnace. The ore is charged into a pressurizable charging vessel which is first flushed with an inert sealing gas to exclude air and then pressurized with the sealing gas to a pressure greater than the operating pressure of the DR shaft furnace. After pressurization, the valve separating the charging vessel and the DR shaft furnace is opened to allow the iron ore charge to be introduced into the shaft furnace together with the sealing gas. Typically, a plurality of charging vessels are arranged in parallel to supply the DR shaft furnace with ore.

[0016] Similar devices are also commonly located at the discharge end of a direct reduction shaft furnace to allow safe discharge of the sponge iron produced.

[0017] There remains a need for improved methods of charging iron ore into a direct reduction shaft furnace and / or discharging sponge iron from a direct reduction shaft furnace. Summary of the invention

[0018] The inventors of the present invention have identified a number of disadvantages of the prior art methods of charging iron ore into a direct reduction shaft furnace.

[0019] Prior art methods of charging the ore typically require the use of large quantities of seal gas. The seal gas is typically produced on-site, using, for example, an air separator unit when the seal gas is nitrogen. The large quantities of seal gas required result in increased capital and operating costs for the direct reduction system.

[0020] In addition, using the ore charging method of the prior art, the sealing gas is inevitably introduced into the process gas. As mentioned above, the sealing gas commonly used, such as nitrogen, must be inert (i.e., not forming an explosive mixture with the process gas) and therefore remain in the process gas. However, other components of the process gas are usually consumed (e.g., H2, CO, CH4) or removed from the cycle (e.g., H2O, CO2) due to the reaction. This means that if no action is taken, the sealing gas gradually accumulates in the process gas and will constitute an ever-increasing proportion. In order to avoid such a situation, a certain proportion of the process gas is usually discharged from the process gas loop and burned to maintain a suitable concentration of inert components in the process gas. This is economically harmful, especially for the proposed direct reduction method based on hydrogen, because the reducing gas in such a case is expected to be more expensive than the fossil-based reducing gas at least initially. If the reducing gas is fossil-based, the discharge process gas also has negative environmental consequences because it causes an increase in CO2 emissions.

[0021] The outlet of the direct reduction shaft furnace from which the produced sponge iron is discharged also needs to be sealed, and the prior art method of discharging the sponge iron has the same disadvantages as the prior art method of charging ore.

[0022] It would be advantageous to have a method for charging iron ore into a direct reduction shaft furnace and / or discharging sponge iron from a direct reduction shaft furnace which overcomes or at least mitigates at least some of the above disadvantages. In particular, it would be desirable to be able to achieve a method for charging iron ore into a direct reduction shaft furnace and / or discharging sponge iron from a direct reduction shaft furnace which reduces the need for seal gas and potentially avoids the need to vent process gas, thereby potentially reducing the operating costs of a direct reduction plant.

[0023] In order to better solve one or more of these problems, a method for charging iron ore into a direct reduction shaft furnace is provided having the features defined in the independent claims.

[0024] The method comprises the following steps:

[0025] a) setting the ore outlet of the ore charging container to a sealed state;

[0026] b) setting the ore inlet of the ore charging container to an open state;

[0027] c) filling the ore charging container with iron ore through the ore inlet;

[0028] d) setting the ore inlet to a sealed state;

[0029] e) evacuating gas from the ore charge container by applying a vacuum;

[0030] f) refilling the ore charging container with process gas from the direct reduction shaft furnace; and

[0031] g) The ore outlet is set to an open state to charge the iron ore into the direct reduction shaft furnace.

[0032] According to the disclosed method, a charging container filled with ore is evacuated by applying a vacuum and then refilled with process gas from the direct reduction shaft furnace via a gas transfer conduit connecting the direct reduction shaft furnace or its process gas loop to the ore charging container. Since the application of the vacuum removes substantially all of the air from the charging container, this allows the container to be directly filled with process gas from the direct reduction shaft furnace and does not require flushing the charging container with large amounts of sealing gas to ensure oxygen removal. This can be compared to the volume of sealing gas used to flush the charging container in prior art methods, which is typically about 5 times the volume of the charging container for each charge. In addition, since the container is refilled with process gas from the direct reduction shaft furnace, no inert gas is introduced into the process gas when the ore is charged into the shaft furnace, and therefore there is less inert gas accumulation and less combustion need in the direct reduction process gas.

[0033] Process gas from a direct reduction shaft furnace means process gas taken from a direct reduction shaft furnace or process gas taken from a process gas circuit of a direct reduction shaft furnace. If taken from a process gas circuit, the process gas is preferably taken from a point in the process gas circuit before the spent process gas is mixed with make-up gas.

[0034] According to another aspect of the present invention, the object of the present invention is achieved by a method for tapping sponge iron from a direct reduction shaft furnace according to the attached independent claim.

[0035] The method for discharging sponge iron comprises the following steps:

[0036] i) setting the iron outlet and iron inlet of the iron tapping container to a sealed state;

[0037] ii) evacuating gas from the tapping vessel by applying a vacuum;

[0038] iii) refilling the iron charging container with process gas from the direct reduction shaft furnace;

[0039] iv) setting the iron inlet of the iron tapping container to an open state;

[0040] v) filling the iron outlet container with sponge iron through the iron inlet; and

[0041] vi) Set the iron inlet to a sealed state.

[0042] In a similar manner to the process used to charge iron ore, a vacuum is used to remove substantially all of the air from the discharge vessel, which means that it can be refilled with process gas from the direct reduction shaft furnace without the risk of forming an explosive mixture. Thus, when the vessel is opened to the direct reduction shaft furnace to discharge the sponge iron, no dilution of the process gas occurs.

[0043] Unless expressly stated otherwise, the following matters apply independently to both the method for charging iron ore and the method for discharging sponge iron.

[0044] At normal temperature (20° C.), a vacuum may be applied to bring the ore charging container (and alternatively, or additionally, the tapping container) to a pressure of about 100 mbar or less, preferably about 10 mbar or less, even more preferably about 1 mbar or less. The use of a relatively strong vacuum results in sufficient evacuation of air (oxidant) from the container and avoids the formation of an explosive mixture when refilling with process gas (reductant) from the direct reduction shaft furnace.

[0045] The method may further comprise the steps of: removing gas from the ore charging container (and alternatively, or additionally, from the iron tapping container) by applying a vacuum; and refilling the container with an inert gas. These steps may be performed after step d) of setting the ore inlet to a sealed state, but before step e) of evacuating gas from the ore charging container by applying a vacuum (or after step i in the method for tapping sponge iron, but before step ii). That is, additional vacuum evacuation / refilling cycles may be performed. This means that even with a relatively poor vacuum, e.g. greater than about 100 mbar, the process may be performed in stages by first performing an initial vacuum evacuation / refilling cycle to provide a gas mixture in the container that mainly comprises inert gas but has some residual air. For the purposes of the present invention (i.e., to avoid the formation of a potentially explosive gas / air mixture), subsequent vacuum evacuation / refilling cycles should be sufficient to provide a gas mixture in the container that essentially comprises process gas from the direct reduction shaft furnace.

[0046] Of course, it is possible to carry out as many vacuum evacuation / refilling cycles as desired, for example three or four vacuum evacuation / refilling cycles in total, 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 carried out, so it is preferred to use as few vacuum evacuation / refilling cycles as possible. In the case of more than one vacuum evacuation / refilling cycle, the refilling in the initial cycle is carried out with inert gas, and refilling is carried out only in the final refilling step with process gas from the direct reduction shaft furnace.

[0047] The inert gas may be selected from the list consisting of: carbon dioxide, nitrogen, clean flue gas and combinations thereof.The carbon dioxide may originate from a biogenic source, ie non-fossil CO2.

[0048] In particular, the method for charging the direct reduction shaft furnace with iron ore may comprise the further steps of: setting the ore outlet to a sealed state; removing process gases from the ore charging container by exhausting and / or applying a vacuum; refilling the ore charging container with a gas selected from air, an inert gas and a combination thereof; and setting the ore inlet to an open state. The inert gas may be selected from carbon dioxide, nitrogen, clean flue gas and a combination thereof. In this way, the charging container may be prepared for the introduction of further iron ore charges while ensuring efficient use of the gas.

[0049] According to another aspect of the invention, the object of the invention is achieved by a method for direct reduction of iron ore to sponge iron according to the attached independent claims. The method comprises introducing process gas from direct reduction into the direct reduction shaft furnace concomitantly with charging of iron ore into the direct reduction shaft furnace and / or concomitantly with discharging sponge iron from the direct reduction shaft furnace. "Concomitantly with charging of iron ore into the direct reduction shaft furnace" means that process gas from direct reduction is introduced together with the iron ore charged into the shaft furnace. "Concomitantly with discharging sponge iron from the direct reduction shaft furnace" means that process gas from direct reduction is introduced from the discharge container when the discharge container is opened to allow the sponge iron to be discharged from the shaft furnace. "Introducing […] concomitantly" means that the gas can be introduced into the direct reduction shaft furnace, for example, using the method for charging of iron ore into the direct reduction shaft furnace and / or discharging sponge iron from the direct reduction shaft furnace as described herein and in the attached independent claims.

[0050] Since gases are inevitably introduced into the direct reduction shaft furnace accompanying the charging and / or discharge of solids into the direct reduction shaft furnace, by introducing such gases for reducing the iron ore and / or optionally for carburizing the iron ore, the method introduces only gases for the purpose of direct reduction and avoids the introduction of gases that may have a deleterious effect on the process. Gases that may have a deleterious effect on the process are, for example, inert gases, such as nitrogen, which may accumulate in the process gas and, if accumulated to too high a concentration, reduce the reducing power of the process gas. Usually, the discharge of the process gas is necessary to ameliorate the effects of such accumulation. Therefore, the disclosed method allows a more efficient use of the process gas and thus the operating costs of the method can be reduced.

[0051] The method may include introducing supplementary gas into the direct reduction shaft furnace in a countercurrent manner to the iron ore. The supplementary gas is selected from hydrogen, methane (e.g. natural gas or biomethane) and synthesis gas (e.g. biosynthesis gas). The supplementary gas can ensure that sufficient reducing gas is introduced into the process to fully reduce the iron ore to sponge iron.

[0052] According to another aspect of the present invention, the object of the present invention is achieved by a device for charging iron ore into a direct reduction shaft furnace according to the attached independent claim. The device for charging iron ore comprises:

[0053] - Ore charging container;

[0054] - a direct reduction shaft furnace; and

[0055] - Vacuum source.

[0056] A vacuum source is arranged in controllable fluid communication with the ore charge container.

[0057] The ore charging container is arranged to be controllably fluidly connected to the direct reduction shaft furnace via a gas transfer conduit, which is arranged to extend between the direct reduction shaft furnace or its process gas circuit and the ore charging container. The gas transfer conduit may, for example, extend from an upper part of the direct reduction shaft furnace, for example near a top gas outlet of the direct reduction shaft furnace.

[0058] Such an arrangement facilitates carrying out a method for charging iron ore into a direct reduction shaft furnace as described herein and in the appended independent claim.The ore charging vessel, or more particularly the ore outlet of the ore charging vessel, is typically arranged to communicate with the inlet of the direct reduction shaft furnace, thereby allowing ore to be transferred from the ore charging vessel to the direct reduction shaft furnace.

[0059] According to a further aspect of the invention, the object of the invention is achieved by an apparatus for tapping sponge iron from a direct reduction shaft furnace according to the attached independent claim.

[0060] The equipment used to discharge sponge iron includes:

[0061] -Sponge iron tapping container;

[0062] - a direct reduction shaft furnace; and

[0063] - Vacuum source.

[0064] A vacuum source is disposed in controllable fluid communication with the tapping container.

[0065] The sponge iron tapping vessel is arranged to be in controllable fluid communication with the direct reduction shaft furnace via a gas transfer conduit arranged to extend between the direct reduction shaft furnace or its process gas loop and the sponge iron tapping vessel.

[0066] Such an arrangement facilitates carrying out a method for tapping sponge iron from a direct reduction shaft furnace as described herein and in the appended independent claims.The tap container, or more specifically the iron inlet of the tap container, is typically arranged to communicate with the outlet of the direct reduction shaft furnace, thereby allowing sponge iron to be transferred from the direct reduction shaft furnace to the tap container.

[0067] Unless expressly stated otherwise, the following matters apply independently to both the apparatus for charging iron ore and the apparatus for discharging sponge iron.

[0068] The ore charging container may include a sealable ore inlet and a sealable ore outlet. The gas transfer conduit may include a controllable valve. The iron tapping container may include a sealable iron inlet and a sealable iron outlet. The gas transfer conduit may include a controllable valve. A vacuum source and / or a source of sealing gas may be arranged to be in fluid communication with the gas transfer conduit.

[0069] The apparatus may further comprise a source of inert gas.The source of inert gas may be arranged in controllable fluid communication with the ore charging vessel and / or the tapping vessel.

[0070] If the device further comprises a source of inert gas, the inert gas may be selected from the list consisting of: carbon dioxide, nitrogen, clean flue gas and combinations thereof.The carbon dioxide may originate from a biogenic source, ie non-fossil CO2.

[0071] The apparatus may be configured to obtain a pressure of about 100 mbar or less, preferably about 10 mbar or less, even more preferably about 1 mbar or less, at ambient temperature (20°C) in the ore charging vessel (and alternatively, or additionally in the tapping vessel). This may require:

[0072] The vacuum source is strong enough to bring the container to the desired pressure, and / or

[0073] The container is configured to withstand such low pressure (ie, the container may be a vacuum container), and / or

[0074] Any openings in the container, such as the sealable inlet, the sealable outlet and / or the gas conduit may be sealable to the extent that they may allow the vacuum source to maintain such pressure in the container.

[0075] According to yet another aspect of the invention, the object of the invention is achieved by a system for producing sponge iron according to the attached independent claims. The system comprises a device for charging iron ore as described herein, and / or a device for discharging sponge iron as described herein. That is, the system comprises a device for charging iron ore as described herein; or a device for discharging sponge iron as described herein; or a device for charging iron ore and a device for discharging sponge iron as described herein. The system may also comprise a charging device and / or a discharging device as generally known in the art. The system also comprises a source of supplementary gas arranged in fluid communication with the direct reduction shaft furnace. If the system comprises a device for charging iron ore, the ore charging container may be arranged in communication with the inlet of the direct reduction shaft furnace. If the system comprises a device for discharging sponge iron, the iron tapping container may be arranged in communication with the outlet of the direct reduction shaft furnace. If the system comprises both a device for charging iron ore and a device for discharging sponge iron, the system may require only a single vacuum source and optionally a single source of inert gas. That is, the charging and discharging devices do not necessarily require separate gas and / or vacuum sources, and one or more of these sources may be combined.

[0076] The source of the supplementary gas may be an electrolyser. The electrolyser may produce hydrogen by electrolysis of water, or may produce synthesis gas (a mixture of carbon monoxide and hydrogen) by electrolysis of water and carbon dioxide. Thus, the supplementary gas may be hydrogen or synthesis gas, such as biosynthesis gas. In this way, sponge iron may be produced without the use of fossil fuels as a source of reducing gas.

[0077] Additional objects, advantages and novel features of the present invention will become apparent to those skilled in the art from the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] For a more complete understanding of the present invention, as well as additional objects and advantages thereof, the detailed description set forth below should be read in conjunction with the accompanying drawings, in which like reference numerals represent like items in different figures, and in which:

[0079] Figure 1 Schematically illustrates the ore-based steelmaking value chain according to the Hybrit concept;

[0080] Figure 2 An exemplary embodiment of a system suitable for performing the methods disclosed herein is schematically illustrated;

[0081] Figure 3 a flow chart schematically illustrating an exemplary embodiment of a method for charging iron ore as disclosed herein; and

[0082] Figure 4 is a flow chart schematically illustrating an exemplary embodiment of a method for discharging sponge iron as disclosed herein. DETAILED DESCRIPTION

[0083] The present invention is based on the inventors' recognition that the use of a vacuum to remove air from a charging vessel when charging iron ore into a direct reduction shaft furnace, followed by refilling with process gas from the direct reduction shaft furnace (e.g. top gas) or its process gas circuit, offers a wide range of potential advantages. The use of an inert sealing gas is avoided, since the presently disclosed method first removes the air atmosphere and replaces it with process gas from the direct reduction shaft furnace, in contrast to prior art methods which are based on diluting the atmosphere in the charging vessel (corresponding to a number of "container volumes" of sealing gas that need to be flushed) until the atmosphere is sufficiently inert. Since no inert sealing gas is introduced into the direct reduction shaft furnace, accumulation of inert gas in the process gas can be avoided, and the need to vent the process gas can be reduced or completely avoided.

[0084] The same concepts can be applied when tapping sponge iron from a direct reduction shaft furnace, and the same or similar advantages are obtained.

[0085] The term process gas is used herein to refer to the gas mixture in the direct reduction process, regardless of the stage in the process. That is, process gas refers to the gas introduced into, passed through, left and recycled back to the direct reduction shaft furnace. The process gas loop of the direct reduction shaft furnace means a series of gas pipelines that transport the spent process gas from the direct reduction shaft furnace through a series of treatments (such as dust removal, heat exchange, compression, and mixing with make-up gas) back to the point where it re-enters the direct reduction shaft furnace. More specific terms are used to refer to the process gas at different points in the process, or to refer to the component gases that are added to the process gas to form part of the process gas.

[0086] The reducing gas is a gas which is introduced at a point below the inlet of the shaft furnace and which flows upwardly against the moving bed of ore to reduce the ore and optionally carburize the sponge iron.

[0087] Top gas is a partially wasted process gas which is removed from the upper end of the shaft furnace close to the ore inlet. After treatment, the top gas can be recycled back to the direct reduction shaft furnace as a component of the reducing gas.

[0088] Make-up gas is fresh gas added to the process gas to maintain reducing power. Usually, make-up gas is added to the recycled top gas before reintroduction into the direct reduction shaft furnace. Therefore, the reducing gas usually contains make-up gas and recycled top gas. Make-up gas and recycled top gas can be mixed together before introduction into the direct reduction shaft furnace, or can be introduced into the shaft furnace separately and mixed in the shaft furnace.

[0089] The sealing gas is a gas which enters the direct reduction shaft furnace from the ore charging device at the inlet of the direct reduction shaft furnace. The outlet end of the direct reduction shaft furnace can also be sealed using a sealing gas, and thus the sealing gas can enter the DR shaft furnace from the discharge device at the outlet of the direct reduction shaft furnace. Therefore, the variations of the present invention are also applicable to the use of sealing gas introduced during the discharge of sponge iron from the direct reduction shaft furnace. The sealing gas as used in the prior art methods is usually an inert gas. The present disclosure is based on the concept of using a process gas from the direct reduction shaft furnace as a sealing gas (i.e., instead of an inert sealing gas).

[0090] An inert gas is a gas that does not form a potentially flammable or explosive mixture with air or process gas, ie a gas that may not act as an oxidant or fuel in a combustion reaction under the conditions existing in the process.

[0091] “Process gas from a direct reduction shaft furnace or its process gas circuit” means process gas which originates internally from a direct reduction shaft furnace or from a process gas circuit of a direct reduction shaft furnace, for example a reducing gas circuit or a cooling gas (carburising) circuit. Process gas which originates internally from a direct reduction shaft furnace may, for example, be top gas removed from an upper part of a direct reduction shaft furnace or cooling gas removed from a lower cone part of a direct reduction shaft furnace. If process gas from a process gas circuit is used, this is preferably process gas taken from a point in the process gas circuit before mixing with make-up gas. That is to say, the process gas originating from the process gas circuit is preferably purely “recycled” process gas. Hereinafter, in the present application, the term “process gas from a direct reduction shaft furnace” in relation to gas for filling charging and / or discharge containers is intended to include process gas from a direct reduction shaft furnace or from a process gas circuit of a direct reduction shaft furnace, unless expressly stated otherwise.

[0092] Loading of iron ore

[0093] The iron ore charge is usually composed mainly of iron ore pellets, but some lump iron ore may also be introduced. Iron ore pellets usually contain mainly hematite, as well as additional additives or impurities such as gangue, flux and binder. However, the pellets may contain some other metals and other ores such as magnetite. Iron ore pellets designated for direct reduction processes are commercially available, and such pellets can be used in the present method.

[0094] The ore charging container is typically a container comprising a sealable ore inlet, a sealable ore outlet and at least one gas conduit suitable for evacuating and / or introducing gas. Of course, the container may include multiple gas conduits, such as separate conduits for evacuating and introducing gas, or multiple conduits for introducing various gases. The ore charging container is appropriately constructed to withstand the pressures to which it is subjected: both the sub-atmospheric pressure (c:a 100 mbar or less, preferably c:a 10 mbar or less) present during the evacuation step and the super-atmospheric pressure (typically greater than 2 bar, such as about 2 bar to about 10 bar) caused by refilling the sealing gas. A plurality of ore charging containers may be arranged in parallel to supply ore to a single direct reduction shaft furnace. For example, two, three, four, five, six, seven, eight, nine or ten ore charging containers may be arranged to supply ore to a single direct reduction shaft furnace.

[0095] Before the ore is loaded into the charging container, the ore outlet is set to a sealed state so as to be able to accommodate the ore to be introduced. "Set to a state" means that if the component is not already in such a state, it is placed in the relevant state, or if it is already in such a state, it is maintained in that state. Therefore, the term "set to a state" does not necessarily involve a change of state. The ore is loaded into the container through the inlet, and the inlet is then sealed. A vacuum source arranged to be fluidly connected to the gas conduit is then used to evacuate the atmosphere from the charging container. The vacuum source can be, for example, a vacuum pump. Such pumps are known in the art. Preferably, the charging container and the pump are configured so that the charging 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 normal temperature (20°C). Therefore, substantially all the air is evacuated from the charging container. If the vacuum achievable in the evacuation stage is low enough, the charging container can then be directly refilled with process gas from the direct reduction shaft furnace.

[0096] The process gas may be provided via a gas transfer conduit connecting the direct reduction shaft furnace to the charging vessel. Since the gas transfer line provides direct fluid communication between the charging vessel and the direct reduction shaft furnace, the pressure obtained in the charging vessel is equal to the pressure existing in the direct reduction shaft furnace, as long as the gas transfer conduit remains open for a sufficient period of time. Alternatively, the process gas may be provided from a point in the process gas circuit at a pressure equal to or higher than the pressure existing in the direct reduction shaft furnace. For example, the gas transfer line extends from a point at which the outlet of a compressor arranged in the process gas circuit is arranged. In such a case, the pressure obtained in the charging circuit will exceed the pressure in the direct reduction shaft furnace.

[0097] If the vacuum achievable in the evacuation phase is not low enough, an undesirable amount of air may remain in the charging container. In such a case, the charging container can be initially refilled with an inert gas and then subjected to a further evacuation step. In this way, the amount of remaining air can be reduced to a safe level. To ensure safety, the steps of evacuating and refilling with inert gas can be performed as many times as necessary. In the final refilling step, the charging container is filled with process gas from the direct reduction shaft furnace, which process gas will be reintroduced into the direct reduction shaft furnace after charging. After filling with ore and process gas, the ore outlet of the charging container is set to an open state to allow the mixture of ore and process gas to be charged into the direct reduction shaft furnace.

[0098] After the ore is charged into the direct reduction shaft furnace, the ore charging container should be reset to safely remove any process gases contained in the container and prepare the container for a new charge of ore. This can be done by sealing the ore outlet, evacuating the charging container to remove process gases by exhausting, flushing with inert gas and / or using a vacuum, and then subsequently refilling the charging container with a suitable gas such as air, nitrogen, purified flue gas or carbon dioxide. The process gases exhausted in this step can be recycled to the direct reduction shaft furnace. The container is refilled to a pressure of about atmospheric pressure. When the potentially flammable contents in the container are evacuated and the container is again at or near atmospheric pressure, the inlet of the container can be opened to allow receipt of a new charge of iron.

[0099] Direct reduction

[0100] The direct reduction shaft furnace may be of any type generally known in the art. A shaft furnace means a solid-gas countercurrent moving bed reactor in which iron ore charge is charged at an inlet at the top of the reactor and falls due to gravity toward an outlet arranged at the bottom of the reactor. Reducing gas is introduced at a lower point of the shaft furnace than the ore inlet, and the reducing gas flows upward to reduce the iron ore and optionally to carburize the iron ore.

[0101] The reduction is typically carried out at a temperature of about 900° C. to about 1100° C. The desired temperature is typically maintained by preheating the process gas introduced into the reactor, for example 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 introduction into the reactor. The reduction can be carried out in a DR shaft furnace at a pressure of about 1 bar to about 10 bar, preferably about 3 bar to about 8 bar.

[0102] In conventional direct reduction processes, the make-up gas used to make up the process gas is fossil-based and typically contains synthesis gas and natural gas in varying proportions. The present disclosure is applicable to processes utilizing such fossil-based make-up gas. However, preferably, the make-up gas is not derived from fossil fuels to provide a fossil-free process for obtaining sponge iron.

[0103] The supplementary gas may be mainly composed of hydrogen. For example, the supplementary gas may contain at least 80% by volume, preferably greater than 90% by volume, and even more preferably greater than 95% by volume of hydrogen (volume % determined under standard conditions of 1 atmosphere and 0°C); substantially composed of at least 80% by volume, preferably greater than 90% by volume, and even more preferably greater than 95% by volume of hydrogen; or composed of at least 80% by volume, preferably greater than 90% by volume, and even more preferably greater than 95% by volume of hydrogen. The disclosed method allows the production of substantially carbon-free sponge iron by using hydrogen as a supplementary gas and not introducing a carbon-containing gas into the process gas. However, in some cases, it may be desirable to obtain carbon-enhanced sponge iron. Therefore, in order to achieve a suitable carbon-enhancing level of sponge iron, a certain amount of carbon-enhancing gas and / or carbon dioxide may be added as a supplementary gas. The carbon-enhancing gas is a carbon-containing gas that can directly carbonize sponge iron, such as all incompletely oxidized carbon compounds, such as hydrocarbons or carbon monoxide. Such gases include, but are not limited to, methane, biogas, synthesis gas, and mixtures thereof. However, the carbon-enhancing effect in the present method may be achieved alternatively or additionally by introducing carbon dioxide. Under the carbon-poor conditions present in a direct reduction shaft furnace, the carbon dioxide may be converted to carbon monoxide, which subsequently carburizes the sponge iron. The methane may be biomethane and / or the synthesis gas may be biosynthesis gas. The carbon dioxide may be derived from a biogenic source, ie non-fossil CO2.

[0104] In addition to hydrogen, the balance of the make-up gas may therefore also comprise, consist essentially of or consist of carbon dioxide and / or recarburizing gas. If carbon dioxide and / or recarburizing gas constitute part of the make-up gas, these may be introduced into the direct reduction shaft furnace together with the hydrogen make-up gas. Alternatively, a proportion or all of the carbon dioxide and / or recarburizing gas constituting part of the make-up gas may be added to the direct reduction shaft furnace separately from the main volume of make-up gas. For example, the recarburizing gas may be added to the recarburizing zone or the cooling zone of the direct reduction shaft furnace.

[0105] The process gas may be at least partially recirculated, whereby top (exhaust) gas from the DR shaft furnace may be cleaned and treated to remove by-products such as water and / or dust prior to reintroduction into the DR shaft furnace. This recycled top gas may be mixed with fresh make-up gas prior to reintroduction into the reactor, or may be introduced separately from any fresh make-up gas supply.

[0106] Since no inert gas is added to the process gas in the disclosed process, venting / flaring of the process gas can be reduced or avoided compared to prior art processes. The need to produce an inert gas as a seal gas is also reduced, and capital equipment such as an air separation unit can be downsized or avoided altogether.

[0107] Sponge iron is obtained as a reduction product of iron ore and is discharged from an outlet at the bottom end of the direct reduction shaft furnace. The shaft furnace may have a cooling and discharge hopper arranged at the bottom to cool the sponge iron before being discharged from the outlet.

[0108] Discharge of sponge iron

[0109] The discharge of sponge iron from a direct reduction shaft furnace has similar requirements as the charging of iron ore into a shaft furnace. It is critical that no flammable / explosive gas mixture is formed during discharge, and it is preferred to avoid the introduction of inert gas into the process gas as much as possible. Therefore, the principles of the present invention can also be applied to sponge iron tapping equipment and methods.

[0110] The iron-tapping container is typically a container comprising a sealable iron inlet, a sealable iron outlet and at least one gas conduit suitable for evacuating and / or introducing gas. Of course, the container may include multiple gas conduits, such as a separate conduit for evacuating and introducing gas, or multiple conduits for introducing various gases. The iron-tapping container is appropriately constructed to withstand the pressures to which it is subjected: both the subatmospheric pressure (c:a 100 mbar or less, preferably c:a 10 mbar or less) present during the evacuation step and the superatmospheric pressure (usually greater than 2 bar, such as about 2 bar to about 10 bar) generated by refilling the process gas. A plurality of iron-tapping containers may be arranged in parallel to receive iron from a single direct reduction shaft furnace. 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 furnace.

[0111] Before the iron is discharged into the discharge container, the iron inlet and outlet are set to a sealed state. A vacuum source arranged to be in fluid communication with the gas conduit is used to evacuate the atmosphere from the discharge container. The vacuum source can be, for example, a vacuum pump. Such a pump is known in the art. Preferably, the discharge container and the pump are configured so that the discharge 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). Therefore, substantially all of the air is evacuated from the discharge container. If the vacuum achievable in the evacuation stage is low enough, the discharge container can then be refilled with process gas from the direct reduction shaft furnace to the pressure present in the direct reduction shaft furnace. If the vacuum achievable in the evacuation stage is not low enough, an undesirable amount of air may remain in the discharge container. In such a case, the discharge container can be initially refilled with an inert gas, and then a further evacuation step is performed. In this way, the remaining amount of air can be reduced to a safe level. In order to ensure safety, the steps of evacuating and refilling the inert gas can be performed multiple times as needed. In the final refilling step, the discharge container is filled with process gas, which will be introduced into the direct reduction shaft furnace after the sponge iron is discharged. After a suitable atmosphere is established inside the discharge container, the iron inlet can be opened to allow the sponge iron to be received into the container from the direct reduction shaft furnace. After the sponge iron is loaded, the inlet of the discharge container can be closed. The closed container then contains a mixture of hot sponge iron and process gas. Preferably, before opening the outlet of the discharge container to release the contained sponge iron, the gaseous contents in the container should be removed again by purging with inert gas, emptying the container and / or applying a vacuum, and replaced with an inert gas at a suitable pressure. The process gas evacuated in this step can be recycled to the direct reduction shaft furnace.

[0112] Sponge Iron

[0113] The term crude iron is used herein to refer to all iron produced for further processing into steel, whether they are obtained from a blast furnace (i.e., pig iron) or obtained from a direct reduction shaft furnace as in the disclosed method (i.e., sponge iron). Due to the structural integrity of the direct reduction pellets and the conditions existing in the DR shaft furnace, the sponge iron obtained at the outlet of the DR shaft furnace is usually mainly in the form of pellets. Such sponge iron is generally referred to as direct reduced iron (DRI). Depending on the process parameters, it can be provided as hot (HDRI) or cold (CDRI). Cold DRI may also be referred to as type (B) DRI. DRI may be prone to reoxidation and, in some cases, is self-igniting. However, there are many known methods for passivating DRI. One such passivation method, which is generally used to facilitate overseas transportation of the product, is to press the hot DRI into briquettes. Such briquettes are generally referred to as hot briquetted iron (HBI), and may also be referred to as type (A) DRI.

[0114] The sponge iron product obtained by the process herein may be a substantially fully metallized sponge iron, i.e. a sponge iron having a degree of reduction (DoR) greater than about 90%, e.g., 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, expressed as a percentage of the initial amount of oxygen present in the iron oxide. Due to the reaction kinetics, it is generally not commercially advantageous to obtain sponge iron having a DoR greater than about 96%, but such sponge iron may be produced if desired.

[0115] As mentioned above, the method described herein is applicable to the production of carbon-free sponge iron or carbon-enhanced sponge iron, as required. Carbon-enhanced sponge iron means sponge iron containing carbon. The carbon present in the sponge iron product can generally be in the form of carburant (Fe3C) and / or graphite. Graphite tends to become dust and tends to be lost from sponge iron before reaching the melt of the EAF. For this reason, if carbon is present in the sponge iron as a carburant, it may be preferred.

[0116] The carbon-reinforced sponge iron may contain 0.1 to 5 percent carbon by weight, such as 0.5 to 3 percent carbon by weight, such as about 1 to 2 percent carbon by weight. For further processing, it is generally desirable that the sponge iron has a carbon content of 0.5 to 5 percent by weight, preferably 1 to 4 percent by weight, such as about 3 percent by weight, but this may depend on the ratio of sponge iron to scrap steel used in the subsequent EAF processing step. If desired, the carbon-reinforced sponge iron product of the process of the present invention may then be further carbon-reinforced by other methods before further processing.

[0117] gas

[0118] The hydrogen can preferably be obtained at least in part by electrolysis of water. If the water electrolysis is carried out using renewable energy, this allows the reducing gas to be provided by a renewable source. The electrolyzed hydrogen can be conveyed directly from the electrolysis device to the DR shaft furnace via a conduit, or the hydrogen can be stored after production and conveyed to the DR shaft furnace as needed.

[0119] If carbon dioxide is used as a supplementary gas or inert gas in the methods described herein, it is preferred that the carbon dioxide source is substantially pure carbon dioxide, such as 95% by volume or more, preferably 98% by volume or more carbon dioxide. The carbon dioxide source may preferably be from a high concentration source, preferably a high concentration biological source. For example, concentrated "green" CO2 can be obtained as a by-product of biogas production by anaerobic digestion or as a by-product of bioethanol production. If the carbon dioxide used in the process comes from a renewable source, the process may be net negative in terms of CO2 emissions. However, even if a carbon dioxide source from a fossil source that would otherwise be directly discharged is used, it means that the process may not result in any excess CO2 emissions. An alternative method for providing carbon dioxide is to preheat the reducing gas using oxy-fuel combustion of biomass before introducing it into a direct reduction shaft furnace. The principle of oxy-fuel combustion is simple: biomass is burned using substantially pure oxygen as an oxidant. The resulting flue gas stream is substantially composed of carbon dioxide and steam. Steam can be removed by simple condensation, thereby providing a substantially pure source of carbon dioxide. Conventionally, the provision of substantially pure oxygen is an economic barrier to utilizing oxy-combustion. However, in the present case, a supply of available oxygen can be readily provided by water electrolysis at low additional cost, thereby making oxygen-enriched preheating of the reducing gas economically feasible.

[0120] The recarburizing gas can be introduced into the reduction zone of the direct reduction shaft furnace as a supplementary gas, or into the lower part of the reactor (e.g., in the isobaric zone or cooling / recarburizing zone). The recarburizing gas can be any gas known or desired in the art for providing recarburization. Gas in this regard refers to a substance that is gaseous at the high temperatures present in the recarburizing reactor, but it can be liquid or solid at room temperature. Suitable recarburizing gases include hydrocarbons, such as methane, natural gas, LPG or petroleum; or other carbon-containing substances, such as synthesis gas, low-level (C1-C6) alcohols, esters and ethers. The recarburizing gas can be of fossil origin, but preferably, it is obtained in part or in whole from renewable sources to reduce net CO2 emissions. Renewable refers to resources that are naturally replenished on a human time scale. The high utilization rate of the carbon present in the recarburizing gas allows the use of renewable recarburizing gases, although they are relatively scarce and costly compared to fossil equivalents. Suitable renewable recarburizing gases include biomethane; biogas; gases obtained from the pyrolysis or partial combustion of biomass (e.g., biosyngas); lower alcohols or ethers derived from renewable raw materials such as methanol, DME, or ethanol; or combinations thereof. Sulfur-containing recarburizing gases may be used, as sulfur is known to prevent graphite nucleation and passivate sponge iron products.

[0121] The composition of the carburizing gas can be selected to suit the final carburized sponge iron to be obtained. The carburizing reaction with hydrocarbons is relatively endothermic, resulting in a relatively cold final product, while the reaction with a carburizing gas containing CO is more exothermic, resulting in a hotter final product. This effect can be used to adjust the temperature of the final product obtained. For example, if a hot product is desired for briquetting (HBI), a gas containing some partially oxidized carbon (e.g. in the form of CO, ketones, aldehydes) can be used, while if cold sponge iron (CDRI) is desired, biomethane can be used.

[0122] In some operations, an inert gas such as nitrogen or purified flue gas may be used. Nitrogen can be obtained, for example, by cryogenically distilling air using an air separator unit (ASU). Purified flue gas means flue gas that has been treated to ensure that it is suitable for use as a sufficiently inert gas. Such treatment may include post-combustion to remove excess oxygen, and / or drying the flue gas.

[0123] Implementation

[0124] The invention will now be described in more detail with reference to certain exemplary embodiments and the accompanying drawings. However, the invention is not limited to the exemplary embodiments discussed herein and / or shown in the accompanying drawings, but may be varied 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 in order to more clearly illustrate certain features.

[0125] Figure 1A prior art embodiment of an ore-based steelmaking value chain according to the Hybrit concept is schematically shown. The ore-based steelmaking value chain begins with an iron ore mine 101. After mining, the iron ore 103 is concentrated and processed in a pelletizing plant 105, and iron ore pellets 107 are produced. These pellets, together with any lump ore used in the process, are converted into sponge iron 109 by reduction in a direct reduction shaft furnace 111 using hydrogen 115 as the main reducing agent, and water 117 is produced as the main by-product. The hydrogen 115 is produced by electrolyzing water 117 in an electrolysis device 119 using electricity 121, preferably mainly derived from a fossil-free or renewable source 122. The hydrogen 115 can be stored in a hydrogen storage 120 before being introduced into the direct reduction shaft furnace 111. The sponge iron 109 is melted using an electric arc furnace 123 together with optionally a certain proportion of scrap iron 125 or other iron sources to provide a melt 127. The melt 127 is subjected to further downstream secondary metallurgical processes 129, and steel is produced 131. It is intended that the entire value chain from ore to steel may be fossil-free and produce only low or zero carbon emissions.

[0126] Figure 2 An exemplary embodiment of a system suitable for performing the methods as disclosed herein is schematically shown.

[0127] The direct reduction shaft furnace 211 is arranged with an inlet 211a for iron ore 207, an outlet 211b for discharging sponge iron 208, an inlet 211c for reducing gas, and an outlet 211d for top gas. A charging container 213 is arranged to communicate with the inlet 211a of the direct reduction shaft furnace 211. A discharge container 231 is arranged to communicate with the outlet 211b of the direct reduction shaft furnace 211.

[0128] The charging container 213 includes an inlet 213a for the iron ore 207, an outlet 213b for the 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 with the top gas outlet 211d of the direct reduction shaft furnace 211 via the gas transfer conduit 221. The gas outlet 213d is arranged to communicate with the vacuum pump 229, and is further arranged to communicate with the exhaust line 228.

[0129] The discharge container 231 includes an inlet 231a for the sponge iron 208, an outlet 231b for the 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 furnace 211. The gas inlet 231c of the charging container 231 is arranged to communicate with the top gas outlet 211d of the direct reduction shaft furnace 211 via a gas transfer conduit 251. The gas outlet 231d is arranged to communicate with a vacuum pump 249, and is further arranged to communicate with an exhaust line 248.

[0130] Initially, the ore inlet 213a and the exhaust line 228 of the charging vessel 213 are open, and the ore outlet 213b and the gas inlet 213c are closed. Iron ore 207 from the ore bin 227 is introduced into the charging vessel 213. After being loaded with ore, the ore inlet 213a and the exhaust line 228 are sealed, the valve to the vacuum pump 229 is opened, and air is evacuated from the charging vessel 213, thereby reducing the pressure in the charging vessel 213 to about 100 mbar or less. After reaching the target pressure, 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 vessel 213 is pressurized with the top gas 216 to a pressure close to the operating pressure of the direct reduction shaft furnace 211. After pressurization, the ore outlet 213b of the charging container 213 is opened to allow the iron ore 207 to be charged into the inlet 211a of the direct reduction shaft furnace 211. The iron ore 207 charged into the direct reduction shaft furnace 211 gradually passes through the shaft furnace and is discharged at the outlet 211b. During its passage through the shaft furnace 211, the ore 207 is reduced by the reducing gas 217 flowing in countercurrent, so that sponge iron 208 is obtained at the discharge outlet 211b of the reactor 211.

[0131] 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 ready to receive the sponge iron 208. The inlet 231a of the container is opened, allowing the sponge iron 208 to fall into the container. The inlet 231a of the discharge container and the gas transfer line 251 leading to the discharge container are then closed, the discharge container 231 is evacuated using the vacuum pump 229, and refilled to atmospheric pressure using the exhaust line 248. The outlet 231b of the discharge container 231 can then be opened to release the sponge iron 208.

[0132] The supplementary gas 215 is supplied by a supplementary gas source 220, such as a hydrogen storage or a water electrolysis device. The supplementary gas 215 is mixed with the treated blast furnace gas 218 to form a reducing gas 217. The reducing gas 217 passes through a preheater 241 before being introduced into the direct reduction shaft furnace 211. The blast furnace gas 216 leaving the outlet 211d passes through a plurality of treatment devices 243 to prepare a gas for reintroduction into the DR shaft furnace 211. The plurality of treatment devices may include a cleaning step, such as an electrostatic precipitator to remove solids from the gas, heat exchange with other process gases such as the reducing gas 217, and separation of water. The treated blast furnace gas 218 is mixed with the supplementary gas 215 and passes through a preheater 241 before being reintroduced into the direct reduction shaft furnace 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 supplier (not shown) of oxygen may be arranged between the preheater 241 and the inlet 211c.

[0133] After the ore has been discharged from the charging container 213, the container can be prepared for a new charge of ore. First, the ore outlet 213b is closed. Subsequently, the process gas is evacuated from the charging container 213 using a vacuum pump 229. The charging container is then refilled with gas to ambient pressure. In the example shown, the container 213 is refilled with air via an exhaust line 228. Finally, the ore inlet 213a is opened to receive a further charge of iron ore.

[0134] Although shown as extending from the top gas outlet 211 d, one or both of the gas transfer conduits 221, 251 may alternatively extend from another point in the process gas circuit, such as a line carrying the top gas 216 or a line carrying the treated top gas 218. Although shown as partially integrated, the gas transfer conduits 221, 251 may be completely separate lines.

[0135] Figure 3The flowchart schematically shows an exemplary embodiment of a method for charging iron ore into a direct reduction shaft furnace as disclosed herein. Step s301 represents the start of the process. In step s303, the ore outlet 213b of the ore charging container 213 is set to a sealed state. In step s305, the ore inlet 213a of the ore charging container 213 is set to an open state. Note that these steps do not involve any change in the state of the charging device if the ore outlet 213b and the ore inlet 213a are already in the closed and open states, respectively. In step s307, the ore charging container 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, gas is evacuated from the ore charging container 213 by applying a vacuum. In step s313, the ore charging container is refilled with process gas from the direct reduction shaft furnace, such as top gas 216. In step s315, the ore outlet 213b is set to an open state to charge iron ore 207 into the direct reduction shaft furnace 211. Step s317 indicates the end of the process.

[0136] The steps listed are performed in order, but there may be intermediate steps. For example, if for some reason the vacuum applied to the charge container is insufficient to remove substantially all of the air, e.g., if the charge container cannot withstand such low pressures, one or more additional evacuation / refilling cycles may be performed between steps s309 and s312. One such evacuation / refilling cycle is shown in Figure 3 This includes a step s310 of evacuating gas from the ore charge container 213 by applying a vacuum, and a step s311 of refilling the ore charge container with an inert gas.

[0137] Figure 4The flowchart schematically shows an exemplary embodiment of a method for discharging iron ore from a direct reduction shaft furnace as disclosed herein. Step s401 represents the start of the process. In step s403, the iron outlet 231a and the iron inlet 231b of the iron-discharging container 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, the gas is evacuated from the iron-discharging container 231 by applying a vacuum. In step s407, the iron charging container 231 is refilled with process gas (e.g., top gas 216) from the direct reduction shaft furnace. In step s409, the iron inlet 231a of the iron-discharging container 231 is set to an open state. In step s409, the iron-discharging container 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 furnace 211. By a number of optional intermediate steps (not shown), the discharge container is prepared for releasing the sponge iron 208. In the final step s413, the iron outlet 231b is opened and the sponge iron 208 is released. Step s415 represents the end of the process. The steps listed are performed in sequence, but there may be intermediate steps. For example, if for some reason the vacuum applied to the discharge container is insufficient to remove substantially all of the air, for example, if the discharge container cannot withstand such a low pressure, one or more additional evacuation / refilling cycles (not shown) may be performed between steps s403 and s405.

Claims

1. An apparatus for charging iron ore (207) into a direct reduction shaft furnace (211), the apparatus comprising: - ore charging container (213); - a direct reduction shaft furnace (211); and - a vacuum source (229); wherein the vacuum source is arranged in controllable fluid communication with the ore charge container; and The ore charging container is arranged to be controllably fluidly connected to the direct reduction shaft furnace or its process gas circuit via a gas transfer conduit (221), and the gas transfer conduit (221) is arranged to extend between the direct reduction shaft furnace or its process gas circuit and the ore charging container.

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

3. Apparatus according to any one of the preceding claims, further comprising an exhaust line arranged in controllable fluid communication with the ore charging container.

4. Apparatus according to any one of the preceding claims, further comprising a source of inert gas, wherein the source of inert gas is arranged in controllable fluid communication with the ore charge container.

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

6. Apparatus according to any one of the preceding claims, configured to achieve a pressure in the ore charging vessel of about 100 mbar or less, preferably about 10 mbar or less, even more preferably about 1 mbar or less at ambient temperature.

7. An apparatus for discharging sponge iron from a direct reduction shaft furnace, the apparatus comprising: - a sponge iron tapping container (231); - a direct reduction shaft furnace (211); and - a vacuum source (249); wherein the vacuum source is arranged to be controllably in fluid communication with the tapping container; and The sponge iron tapping vessel is arranged to be controllably fluidly connected to the direct reduction shaft furnace or its process gas circuit via a gas transfer conduit (251), and the gas transfer conduit (251) is arranged to extend between the direct reduction shaft furnace or its process gas circuit and the sponge iron tapping vessel.

8. A system for producing sponge iron, the system comprising: - 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 source of make-up gas (220) arranged in fluid communication with said direct reduction shaft furnace.

9. The system of claim 8, wherein the source of the supplemental gas is an electrolyzer and the supplemental gas is hydrogen.

10. A method for charging iron ore into a direct reduction shaft furnace, the method comprising the steps of: a) setting (s303) the ore outlet of the ore charging container to a sealed state; b) setting (s305) the ore inlet of the ore charging container to an open state; c) filling (s307) the ore charging container with iron ore through the ore inlet; d) setting the ore inlet (s309) to a sealed state; e) evacuating (s312) gas from the ore charging container by applying a vacuum; f) refilling (s313) the ore charging container with process gas from the direct reduction shaft furnace; as well as g) setting (s315) the ore outlet to an open state to charge iron ore into the direct reduction shaft furnace.

11. The method according to claim 10, further comprising the steps of: h) setting the ore outlet to a sealed state; i) removing process gases from the ore charging container by evacuating and / or applying a vacuum; j) refilling the ore charge container with a gas selected from the group consisting of air, an inert gas, and combinations thereof; and k) setting the ore inlet to an open state.

12. A method for tapping sponge iron from a direct reduction shaft furnace, the method comprising the steps of: i) setting the iron outlet and the iron inlet of the iron tapping container to a sealed state (s403); ii) evacuating (s405) gas from the tapping container by applying a vacuum; iii) refilling (s407) an iron charging vessel with process gas from said direct reduction shaft furnace; iv) setting (s409) the iron inlet of the iron tapping container to an open state; v) filling (s411) the tapping container with sponge iron via the iron inlet; and vi) setting (s411) the iron inlet to a sealed state.

13. A method for direct reduction of iron ore, wherein the method comprises introducing process gas from direct reduction into a direct reduction shaft furnace concomitantly with charging the iron ore into the direct reduction shaft furnace and / or concomitantly with discharging sponge iron from the direct reduction shaft furnace.

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

Images