Ammonia NH3-based reduction of metal oxide-containing materials

Abstract

A method for reducing a metal oxide-containing material (2) is used, in which a reducing gas obtained with ammonia NH3 is used, which is fed to a reduction reactor (2) containing the metal oxide-containing material, from which a top gas is discharged. At least a portion of the top gas is used as a component in the preparation of a reducing gas, if necessary after top gas treatment. The device (1) for reducing a metal oxide-containing material (3) comprises a reduction reactor (2), a top gas discharge pipe (4) for discharging the top gas from the reduction reactor (2), at least one feed pipe (7) for ammonia input, a preparation unit (6) for preparing a reducing gas, into which the at least one feed pipe (7) for ammonia input opens, and a feed pipe (8) for feeding a reducing gas and / or a precursor of the reducing gas to the reduction reactor (2). The top gas discharge pipe (5) opens into the preparation unit (6).

Description

[Technical field]

[0001] The present application relates to a method and apparatus for reducing metal oxide-containing materials, using a reducing gas obtained using ammonia NH3. [Background technology]

[0002] It is known to reduce materials containing metal oxides, for example iron oxide, such as ores, with a reducing gas. For example, by direct reduction with a reducing gas in a reduction unit, such as a reduction shaft, but also in the blast furnace process, for example carbon monoxide CO acts as a reducing gas in a blast furnace reduction unit. In conventional processes currently used in large-scale industry, the reducing gas is mainly based on natural gas. In this case, therefore, large amounts of carbon dioxide CO2 are produced, which is undesirable, especially for environmental reasons.

[0003] In order to reduce CO2 emissions during the reduction of metal oxide-containing materials, it is known to use hydrogen H2 as a reducing gas. In this case, hydrogen can be used as the only reducing gas or in combination with other gases, for example natural gas-based reducing gases. The greater the proportion of CO2-neutral hydrogen H2 in the reducing gas, the less CO2 is emitted. However, storing and transporting hydrogen H2 from production to consumers is problematic and costly due to its physical properties.

[0004] It is also known to use ammonia NH3 as a reducing agent to reduce the emission of CO2 during the reduction of metal oxide-containing materials. Ammonia has clear advantages over hydrogen H2 in terms of storage and transportation.

[0005] Ammonia can be broken down into nitrogen and hydrogen: 2NH3→N2+3H2

[0006] Hydrogen H2, as a reducing agent, can react with metal oxides, such as iron oxide: 3Fe2O3+H2→2Fe3O4+H2O Fe3O4+H2→3FeO+H2O FeO+H2→Fe+H2O

[0007] But also ammonia itself can act as a reducing agent: 9Fe2O3+2NH3→6Fe3O4+N2+3H2O 3Fe3O4+2NH3→9FeO+N2+3H2O 3FeO+2NH3→3Fe+N2+3H2O

[0008] That is, in principle, the reducing gas obtained using ammonia NH3 can be used for the reduction of the metal oxide-containing material. The reducing gas can be, for example, ammonia NH3 or a mixture of ammonia NH3 with one or more other gases, preferably one or more of which can have a reducing effect on the metal oxide-containing material, which is the case, for example, with a mixture of ammonia and its decomposition products hydrogen H2 and nitrogen N2, although it is understood that other gases can also be included in the mixture. However, the reducing gas obtained using ammonia NH3 can also be a reducing gas that does not contain ammonia NH3, but a reducing gas that contains the decomposition product hydrogen H2 obtained from the decomposition, either alone or together with the decomposition product nitrogen N2, possibly in a mixture with one or more other gases that can have a reducing effect on the metal oxide-containing material, preferably.

[0009] The reduction reaction of metallic iron Fe with hydrogen H2 and ammonia NH3, and the reaction of decomposing ammonia into nitrogen N2 and hydrogen H2 are endothermic reactions. Therefore, in industrial implementation, the problem is how to supply a sufficient amount of energy to carry out such reactions while conserving resources.

[0010] During the decomposition of ammonia and its action as a reducing agent, in addition to hydrogen H2, a significant amount of nitrogen N2 is produced. Therefore, in industrial implementation, the question arises as to how the produced nitrogen can be usefully used for the process. Summary of the Invention [Problem to be solved by the invention]

[0011] An object of the present invention is to contribute to solving at least some of the problems mentioned above. [Means for solving the problem]

[0012] The present invention relates to a method for reducing a metal oxide-containing material, the method comprising the steps of: A reducing gas obtained using ammonia NH3 is used, The reducing gas is supplied to a reduction reactor containing a metal oxide-containing material; A method in which top gas is discharged from a reduction reactor, The problem is solved by a method, characterized in that at least a portion of the furnace gas, if necessary after treatment of the furnace gas, is used as a component in the preparation of a reducing gas.

[0013] The metal oxide containing material is preferably an iron oxide containing material.

[0014] The method for reduction is, for example, a direct reduction method.

[0015] The reducing gas is obtained using ammonia NH3. The reducing gas may be, for example, ammonia NH3 or a mixture of ammonia NH3 with one or more other gases, preferably those capable of having a reducing effect on the metal oxide-containing material, as is the case, for example, with ammonia and its decomposition products hydrogen H2 and nitrogen N2, although obviously other gases may also be included in the mixture. However, the reducing gas obtained with ammonia NH3 may also be a reducing gas that does not contain ammonia NH3, but that comprises the decomposition product hydrogen H2 obtained from the decomposition, either alone or together with the decomposition product nitrogen N2, possibly in a mixture with one or more other gases that may preferably have a reducing effect on the metal oxide-containing material.

[0016] That is, the reducing gas may contain ammonia, and may be composed partially or completely of ammonia. If it is only partially composed of ammonia, it contains further components. One aspect of the use of ammonia is mixing with further components. For example, ammonia can be added to the further components so that it constitutes 0.5 vol% or more of the gas stream obtained after mixing. The further components can be both components that are inert with respect to reaction with the metal oxide-containing material under the conditions prevailing in the reduction reactor, such as nitrogen N2, and components that react with the metal oxide-containing material under the conditions prevailing in the reduction reactor. In this respect, components that have a reducing effect on the metal oxide-containing material are preferred. For example, they can be a hydrocarbon-containing gas, a carbon-containing gas, a hydrogen-containing gas or hydrogen. The reducing gas can also be obtained using ammonia by decomposing the ammonia and mixing the resulting mixture of nitrogen and hydrogen with further components of the reducing gas, after enrichment or depletion of nitrogen or hydrogen as required. The reducing gas can also be obtained using ammonia by decomposing the ammonia and separating the hydrogen obtained in this process from the nitrogen before mixing it with further components of the reducing gas, or by feeding the entire reducing gas together with, if necessary, the remaining small amounts of nitrogen formed during the decomposition.

[0017] Basically, ammonia can be of any "color". By "color" it is understood that the coloring is related to the basic production method. The color of ammonia is often related to the color of the hydrogen used in its production. For example, ammonia produced using green hydrogen will be green, while ammonia produced using hydrogen obtained by sequestering the carbon dioxide CO2 produced will be blue. Ammonia can also be produced using turquoise hydrogen, for example if the hydrogen is produced by separating the carbon C produced, or pink hydrogen, for example if the hydrogen is produced using electricity from nuclear power plants. Similarly, mixtures of one or more of these "colors" of ammonia or the color of the hydrogen on which the ammonia is based are also possible.

[0018] The reducing gas is a gas introduced into the reduction reactor or into the internal space containing the metal oxide-containing material in which the reduction reaction is carried out, and has a composition and a temperature at the time of introduction. Before this composition and temperature are provided, a precursor of the reducing gas is present, and the reducing gas is prepared based on the precursor. The preparation can be carried out, for example, by adding further components or by heating. The preparation can also be carried out by a chemical reaction that proceeds in the precursor without external assistance, for example, changing the chemical composition or temperature.

[0019] The reduction reactor is, for example, a reduction shaft, for example when a direct reduction process is carried out using a reduction shaft comprising a fixed bed of metal oxide-containing material. The reduction reactor is, for example, a fluidized bed reactor, for example when a direct reduction process is carried out using a reduction reactor comprising a fluidized bed of metal oxide-containing material. In this case, the fluidized bed reactor can comprise a plurality of individual partial reactors, which are, for example, connected in parallel or in series and together form a fluidized bed reactor. The reduction reactor is, for example, a fluidized bed reactor, for example when a direct reduction process is carried out using a reduction reactor comprising a fluidized bed of metal oxide-containing material, which can then comprise a number of individual partial reactors, which are, for example, connected in parallel or in series and together form a fluidized bed reactor. The reduction reactor may be a blast furnace comprising a fixed bed comprising metal oxide-containing material, and ammonia may replace, for example, PCI coal or fossil reduction gases in the operation of the blast furnace.

[0020] The top gas is discharged from the reduction reactor. The top gas is generated from the reduction gas when it flows through the reduction reactor, based on the reaction between its components and the metal oxide-containing material that takes place in the reduction reactor, or from the products that are generated during these reactions, such as the metallic iron that is generated. The top gas has a smaller reducing power than the reduction gas as a result of the reduction reaction that takes place in the reduction reactor.

[0021] At least a partial amount of the top gas, after processing if necessary, is utilized as a component in the preparation of the reducing gas, both when the composition of the top gas is not changed and only a partial amount of the resulting top gas is utilized, and also when not all components of the resulting top gas are utilized, for example when enrichment of components, such as hydrogen enrichment, is performed and the corresponding enriched gas stream is utilized in whole or in part. That is, one step in the preparation of the reducing gas is the mixing of the furnace gas with other components of the reducing gas, if no treatment is carried out, whereupon the resulting mixed gas forms the reducing gas or a reducing gas is prepared on the basis of this mixed gas and further steps are carried out, such as the addition of additional components, or heating to a desired temperature when introduced into the reduction reactor, or chemical reactions resulting in a change in composition.

[0022] If necessary, top gas treatment is performed.

[0023] The process may include one or more steps. Possible steps may be, for example, the following: - Dust removal, which can be carried out dry or wet; -cooling, - Adjusting the water vapor content to the desired level, if necessary by cooling; -compression, -heating, - Desulfurization: for example when reducing sulfur-containing materials, especially when reformers are used to prepare the reducing gas.

[0024] The dedusting is preferably carried out dry, since the heat content of the gas can be more effectively utilized in the process than in wet dedusting. For example, the heat can be utilized for vaporization of ammonia. The heat can also be utilized elsewhere in the process, if necessary via a heat transfer medium, for example to generate hot water and / or steam.

[0025] Adjusting the steam content to the desired level is advantageous, for example, when natural gas is reformed in a reformer together with steam during the preparation of the reducing gas. Adjusting the steam content to the desired level is also advantageous because it affects the quality of the reducing gas, expressed as the ratio of the volume percentage contents of carbon monoxide CO, hydrogen H2, carbon dioxide CO2, water H2O (CO+H2) / (CO2+H2O) or hydrogen H2 and water H2O H2 / H2O.

[0026] Within the scope of this application, the gas obtained after one or more processing steps is referred to as processed gas.

[0027] If the furnace gas is treated, the treatment gas is used as a component in the preparation of the reducing gas, i.e. the furnace gas is used indirectly in the preparation of the reducing gas through the treatment gas obtained on the basis of the furnace gas. A step in the preparation of the reducing gas is then the mixing of the treatment gas with other components of the reducing gas. Either the resulting mixed gas forms the reducing gas or a reducing gas is prepared on the basis of this mixed gas, which undergoes further steps such as the addition of additional components, or heating to the desired temperature when introduced into the reduction reactor, or chemical reactions resulting in a change in composition.

[0028] The top gas has a lower reducing power than the reducing gas as a result of the reduction reactions carried out in the reduction reactor, but it still contains components with reducing properties, such as hydrogen H2, whose reducing power has not been exhausted, and also has an energy content based on its temperature.

[0029] It is advantageous to utilize the reducing power still present in the top gas for the reduction process. It is also advantageous to utilize the amount of energy for the reduction process. A higher utilization rate reduces the additional energy required for the heating step to set the required temperature of the reducing gas. In particular for endothermic reactions taking place in the reduction reactor, it is important to supply energy to the reduction reactor in order to maintain the reaction. The energy can be supplied via a reducing gas, which can be varied, for example, by the amount and temperature of the reducing gas supplied. In the direct reduction of iron oxide, the reducing gas preferably has a temperature of 750° C. or more, particularly preferably 800° C. or more. When using a reducing gas which reduces based only on hydrogen H2 and / or ammonia NH3, in the direct reduction of iron oxide, for example, a specific amount of reducing gas introduced into the reduction reactor is 2000 Nm3 per ton of direct reduced iron DRI. 3 More than 2200Nm, preferably 2200Nm 3 / tDRI or more. When using a reducing gas that also contains a reducing component based on natural gas, a lower value, for example 1500 to 1600 Nm 3 / tDRI is preferred.

[0030] By utilizing the top gas for preparing a reducing gas, either directly as the top gas and / or indirectly via a process gas obtained on the basis of the top gas, it is possible to utilize the reduction potential remaining in the top gas and to utilize the heat content of the top gas. The nitrogen contained in the top gas can be used as a heat transfer medium in the process. Even though nitrogen is inert to the reduction reaction, it contributes to carrying out the process in a resource-saving manner. The energy that nitrogen carries to the reduction reactor by its heat does not have to be introduced into the reduction reactor by other substances, for example by components with the reduction potential of the reducing gas. These components, for example ammonia NH3, hydrogen H2, and hydrocarbons, are more expensive and more complicated to supply than the nitrogen N2 (1 volume percent of nitrogen N2 compared to 3 volume percent of hydrogen H2) that is generated during the decomposition of ammonia NH3, and therefore do not necessarily have to be used in stoichiometric excess. These components should be used mainly for the purpose of reduction. The use of these components, which only input heat and do not contribute significantly to the reaction conversion, is not resource-saving and is more expensive than the use of nitrogen.

[0031] According to one embodiment, the treatment of the top gas withdrawn from the reduction reactor includes method steps for reducing the nitrogen content.

[0032] In this case, the furnace gas is subjected to a treatment including at least a reduction in the nitrogen content of the furnace gas. In this case, the nitrogen is not completely separated. The reduction in the nitrogen content is performed in order to suppress the enrichment of nitrogen in the reducing gas due to the use of the furnace gas and the associated decrease in the reducing power of the reducing gas. For the reduction of the nitrogen content, for example, methods using different permeabilities, different adsorption powers, different boiling points for the stepwise liquefaction of the individual fractions can be considered. It is also possible to combine several of these methods. For example, membrane separation using hollow fiber membranes, or porous graphene-based separation membranes, or single- or multi-stage inorganic membranes, pressure swing adsorption (PSA), cryogenic distillation, etc. The resulting gas stream with an increased nitrogen content can be thermally utilized, for example in a reducing gas furnace or reformer. The gas stream with an increased content of reducing components due to the separation of inert nitrogen, for example a gas stream with an increased hydrogen content, is utilized for the preparation of reducing gas. The reduction of the nitrogen content is advantageously carried out with closed-loop control so that the reducing gas contains less than 40 Vol. %, preferably less than 30 Vol. %, particularly preferably less than 20 Vol. % nitrogen.

[0033] During the treatment of the top gas, the amount of nitrogen contained in the top gas is reduced, but the treated gas still contains residual nitrogen, which in this way is utilized in the process, and which, even though inert to the reduction reaction, contributes to carrying out the process in a resource-saving manner.

[0034] The nitrogen content in the reducing gas can also be open-loop and / or closed-loop controlled to a setpoint value by correspondingly open-loop and / or closed-loop controlling a portion of the top gas which is not used as a component in the preparation of the reducing gas, if necessary after processing the top gas. This portion is discharged from the preparation cycle of the reducing gas. The discharge gas can be thermally utilized, for example in a gas furnace, a reducing gas furnace, a reformer. The discharge gas is preferably discharged after the top gas has been cooled.

[0035] According to one embodiment, the top gas and / or the process gas is doped with at least one component of a first group consisting of the following during the preparation of the reducing gas: ammonia; available in liquid or gaseous form; Hydrogen obtained from ammonia, for example as pure hydrogen or in a mixture of nitrogen N2 and hydrogen H2.

[0036] That is, the top gas and / or the process gas may be doped with one or more members of the first group. The ammonia is preferably added in gaseous form. Ammonia can be heated, for example electrically, before being added. Heating can be performed, for example, by using a gas furnace, which is heated, for example, by electrical energy or by burning fuel. In the first group, hydrogen is hydrogen obtained from ammonia, i.e. ammonia-based hydrogen. This includes that this hydrogen is added as a component of a mixed gas, for example as a component of a mixed gas of nitrogen and hydrogen that is generated during the decomposition of ammonia.

[0037] According to one embodiment, the top gas and / or the process gas is doped with at least one component of a second group consisting of the following during the preparation of the reducing gas: -Natural gas, -Hydrocarbons, e.g. ethane C2H6, propane C3H8, butane C4H 10 , -hydrogen, - Carbon monoxide, - Coke oven gas, -Synthetic gas containing multiple components from the group consisting of CO, H2, CH4, C2-C6 hydrocarbons, N2, and CO2.

[0038] In this case, the hydrogen is hydrogen obtained from a source other than ammonia, i.e. hydrogen that is not obtained from ammonia and is not ammonia-based. In this case, the hydrogen is, for example, green hydrogen, blue hydrogen, grey hydrogen, turquoise hydrogen, pink hydrogen. These "colors" are understood to be colorings related to the basic production method. For example, green hydrogen is produced by electrolysis of water using electricity from renewable energies, or by gasification or fermentation of biomass, or by steam reforming of biogas, but what these green hydrogen production methods have in common is that the production is CO2-free. In the case of blue hydrogen, the CO2 produced during production is stored and is not released into the atmosphere. This is the case, for example, when the carbon dioxide CO2 produced is sequestered. In the case of turquoise hydrogen, the carbon C produced is separated. In the case of pink hydrogen, the hydrogen is produced using electricity from nuclear power plants. It is also possible to mix one or more of these "colors" of hydrogen. Grey hydrogen is produced from fossil fuels, for example from natural gas, by steam reforming, and the resulting CO2 is largely released into the atmosphere. Other colored hydrogens are possible, and it is also possible to mix one or more of these "colors" of hydrogen.

[0039] By synthesis gas is understood an industrially produced gas mixture, which mainly contains carbon monoxide and hydrogen, and also contains variable amounts of other gases, such as carbon dioxide. In principle, synthesis gas can be produced from solid, liquid and gaseous starting materials. As liquid starting materials for synthesis gas, for example, various crude oil fractions can be used, including both low-boiling and high-boiling fractions. The most important gaseous reactant for synthesis gas production is natural gas. Production methods include, for example, steam reforming of natural gas or liquid hydrocarbons, or gasification of coal, biomass, or other residual materials. The composition of synthesis gas may be, for example, carbon monoxide CO = 41 Vol%, carbon dioxide CO2 = 14 Vol%, hydrogen H2 = 34 Vol%, methane CH4 = 5 Vol%, hydrocarbons C2-C6 = 2 Vol%, and nitrogen N2 = 4 Vol%.

[0040] That is, the process gas may be doped with one or more members of the second group.

[0041] The first or second group components may be added to the top gas or process gas before the start or completion of the process, but if a process is present, it is preferred that they are added after the process is completed, i.e., to the process gas.

[0042] The simultaneous use of green ammonia NH3 and green hydrogen H2 is advantageous, since it is particularly advantageous economically and allows a particularly large reduction in the CO2 load of the process product. If the amount of green hydrogen H2 used needs or has to be reduced (for example, for reasons of availability or cost), it is particularly advantageous to increase the amount of green ammonia NH3 used. If the amount of green ammonia NH3 used needs or has to be reduced (for example, for reasons of availability or cost), it is also possible to increase the amount of green hydrogen H2 used.

[0043] According to one embodiment, after combining the furnace gas or process gas with at least one component of the first group, at least one component of the second group is added to the resulting mixed gas. The mixed gas present after combining the furnace gas or process gas with at least one component of the first group is a precursor of a reducing gas to which at least one component of the second group is added. In this case, the resulting mixed gas may be a reducing gas or a precursor of a reducing gas. If it is a precursor, further steps such as mixing additional components, or heating to a desired temperature when introduced into the reduction reactor, or a chemical reaction that results in a change in composition, are performed. The gas mixture resulting from combining the furnace gas or process gas with at least one component of the first group may be further modified, such as by mixing additional components, or by heating, or by chemical reaction resulting in a change in composition, before at least one component of the second group is added to the gas mixture. Heating can be achieved, for example, by means of an electrically operated heating device. Heating can be carried out indirectly, for example by means of a gas burner, and in one variant the precursor is also heated by the resulting off-gas via a heat exchanger. Natural gas or furnace gas can be used, for example, as the fuel basis for the gas burner. The use of furnace gas is preferred, since its chemical energy is used in the reduction process. The chemical reaction leading to the change in composition can be initiated, for example, by reforming the precursor (especially when natural gas is added). The heating in the reformer used here can be effected indirectly, for example by gas burners, and in one variant the precursor is also heated by the resulting off-gases via a heat exchanger. Natural gas or top gas can be used, for example, as the fuel basis for the gas burners. The use of top gas is preferred, since its chemical energy is used in the reduction process.

[0044] According to one embodiment, after combining the furnace gas or process gas with at least one component of the second group, at least one component of the first group is added to the resulting mixed gas. The mixed gas present after combining the furnace gas or process gas with at least one component of the second group is a precursor of a reducing gas to which at least one component of the first group is added. The resulting mixed gas may be a reducing gas or a precursor of a reducing gas. If it is a precursor, further steps such as mixing additional components, or heating to a desired temperature when introduced into the reduction reactor, or a chemical reaction that results in a change in composition, are performed. The gas mixture resulting after combining the top gas or process gas with at least one component of the second group may be further modified before the addition of at least one component of the first group, such as by mixing additional components, or by heating to a desired temperature when introduced into the reduction reactor, or by a chemical reaction resulting in a change in composition. Heating may be performed, for example, by using an electrically operated heating device. Heating can be carried out indirectly, for example, by gas burners, and in one variant, the precursor is also heated by the resulting off-gas through a heat exchanger. Natural gas or furnace gas can be used, for example, as the fuel basis for the gas burners. The use of furnace gas is preferred, since its chemical energy is used in the reduction process. The chemical reaction leading to the change in composition can be initiated, for example, by reforming the precursor (especially when natural gas is added). Heating in the reformer used here can be achieved indirectly, for example by gas burners, and in one variant the precursor is also heated by the resulting off-gases via a heat exchanger. Natural gas or top gas can be used, for example, as the fuel basis for the gas burners.

[0045] Ammonia may be added to the top gas, the process gas, the precursor of the reducing gas, etc. When using a reduction reactor having a bustle to introduce the reducing gas into the interior space containing the metal-oxide-containing material in which the reduction reaction takes place, ammonia may be added, for example, to the gas leading to the bustle.

[0046] According to one embodiment, the method for reducing metal oxide-containing material is carried out in a reduction reactor having a cooling zone and / or a product cooler, the method being characterized in that ammonia is introduced into the cooling zone and / or the product cooler of the reduction reactor.

[0047] Ammonia is preferably introduced in gaseous form. Ammonia is decomposed in the reduction reactor, the reaction taking place being mainly endothermic. The decomposition takes place already in the cooling zone, i.e. the ammonia introduced in the cooling zone is on the one hand used for cooling, since it is decomposed endothermically, and on the other hand used for the reduction reaction in the reduction reactor.

[0048] In this case, the cooling using ammonia can be closed-loop controlled, for example, so that the temperature of the reduced material removed from the reduction reactor has a target temperature for further processing. For example, if the hot DRI (HDRI) removed from the reduction reactor is subsequently compressed, it may be aimed for a different temperature than when it is fed to the EAF, if desired.

[0049] A further object of the present invention is an apparatus for reducing a metal oxide-containing material, the apparatus comprising: a reduction reactor, a top gas discharge pipe for discharging the top gas from the reduction reactor; at least one feed pipe for the ammonia input; a preparation unit for preparing a reducing gas, into which at least one supply pipe for the input of ammonia opens; a supply pipe for supplying a reducing gas and / or a precursor of a reducing gas to the reduction reactor; Including, It is characterised in that the top gas discharge pipe opens into the preparation unit.

[0050] An apparatus for reducing metal-oxide-containing material can include one or more reduction reactors. The apparatus for reducing metal-oxide containing material may include one or more top gas exhausts. The device for reducing metal-oxide-containing material may comprise one or more feed tubes for the input of ammonia, which are suitable for the addition of liquid ammonia, or for the addition of gaseous ammonia, or for the addition of both liquid and gaseous ammonia, or for the addition of hydrogen H2 obtained by decomposition of ammonia, either alone or in a mixture with nitrogen N2. The apparatus for reducing metal-oxide-containing material may include one or more feed tubes.

[0051] In such an apparatus, ammonia NH3 may be used to obtain the reducing gas. The reducing gas is prepared in a preparation unit using ammonia NH3. For this purpose, the preparation unit may include one or more decomposition units for decomposing ammonia. For this purpose, the preparation unit may also include one or more mixing devices, which may mix liquid or gaseous ammonia and / or at least one of its decomposition products hydrogen H2 and nitrogen N2 with other components and may also mix the mixture of decomposition products with other components. The preparation unit may also include one or more component supply pipes for supplying components used in the preparation of the reducing gas. The preparation unit may also include one or more separation devices for separating the mixture of hydrogen H2 and nitrogen N2 obtained in the decomposition of ammonia. In this case, separation is understood to mean not only complete separation but also enrichment or depletion of hydrogen H2 or nitrogen N2. For example, in the preparation unit, the supply pipe for ammonia input may open into a furnace gas conduit, which opening is understood as a mixing device. It is therefore possible to prepare the reducing gas using ammonia and furnace gas as components. For example, in the preparation unit, the feed pipe for the ammonia input can open into a process gas conduit, which opening is understood as a mixing device, so that a reducing gas can be prepared using ammonia and process gas as components. For example, in the preparation unit, the supply pipe for the ammonia input can open into a precursor conduit for the reducing gas, this opening being understood as a mixing device, so that the reducing gas can be prepared with ammonia. For example, if a reduction reactor with a bustle is used, the reduction reactor or its bustle is supplied with reducing gas via a feed line, which is generated by adding ammonia to the top gas line via a feed line for ammonia input, the feed line also serving as a preparation unit and mixer, since the top gas and ammonia are mixed during the flow-through and the reducing gas is prepared. The supply line may otherwise be part of the preparation unit, for example if supply lines for supplying additional components to the precursor gas open into it or if a heating device is present in the supply line.

[0052] Optionally, the preparation unit comprises a device for heating the ammonia, whereby the ammonia can be heated before being added to the top gas and / or the process gas.

[0053] If necessary, the top gas discharge pipe includes one or more treatment units. The preparation unit is supplied with treatment gas through the top gas discharge pipe. The treatment unit is, for example, a dry or wet dust remover, or a cooling device, or a compression device, or a heating device, or a cooling device, or a water vapor content adjuster, or a desulfurization device, etc. It is also possible for one treatment unit to perform multiple treatment functions. For example, the cooling device can also function as a device for adjusting the water vapor content.

[0054] According to a preferred embodiment, the top gas discharge pipe comprises at least one treatment unit which is a device for reducing the nitrogen content, thus making it possible to reduce the nitrogen content of the top gas and to provide a treatment gas having a reduced nitrogen content compared to the top gas.

[0055] This may be, for example, a device that reduces the nitrogen content based on different permeabilities, a device that utilizes different adsorption strengths such as pressure swing adsorption, a device that utilizes different boiling points to reduce the nitrogen content.

[0056] According to a preferred embodiment, the preparation unit comprises at least one supply pipe for supplying one or more components of the group consisting of: -Natural gas, -Hydrocarbons, e.g. ethane C2H6, propane C3H8, butane C4H 10 , -hydrogen, - Carbon monoxide, - Coke oven gas, -Synthetic gas.

[0057] That is, for example, natural gas supply pipes, hydrogen supply pipes, carbon monoxide supply pipes, coke oven gas supply pipes, synthesis gas supply pipes, hydrocarbon supply pipes. One or more or all of the feeders may be suitable for supplying multiple group members, for example natural gas / syngas / coke oven gas feeder lines.

[0058] The presence of a feed pipe and possibly a mixing device allows the addition of a second group of components to the top gas and / or the process gas.

[0059] According to a preferred embodiment, the reduction reactor comprises a cooling zone and / or a product cooler, and the ammonia feed pipe opens into the cooling zone and / or into the product cooler.

[0060] A further subject of the present application is a signal processing device having a machine-readable program code, characterized in that the program code comprises closed-loop control instructions for carrying out the method according to the invention. A further subject is a signal processing device for carrying out the method according to any one of claims 1 to 7. The signal processing device is part of an open-loop and / or closed-loop control of an apparatus for the reduction of metal-oxide-containing material.

[0061] A further subject of the present application is a machine-readable program code for a signal processing device which is part of an open-loop and / or closed-loop control of an apparatus for reducing metal-oxide-comprising material, characterized in that the program code comprises closed-loop control instructions causing the signal processing device to perform the method according to the invention.A further subject is a computer program product comprising instructions for a signal processing device which is part of an open-loop and / or closed-loop control of an apparatus for reducing metal-oxide-comprising material, characterized in that the instructions cause the signal processing device to perform the method according to any one of claims 1 to 7 when the program for the signal processing device is executed.

[0062] A further subject of the present application is a storage medium having stored thereon a machine-readable program code according to the invention. A further subject of the present application is a storage medium having stored thereon a computer program for performing the method according to any one of claims 1 to 7.

[0063] A further subject of the present application is the open-loop and / or closed-loop control of an apparatus for reducing metal-oxide-containing material using a computer comprising a computer program product comprising instructions which cause a computer to carry out the steps of the method according to any one of claims 1 to 7 when the computer program is executed by the computer.

[0064] A further subject of the present application is a computer program product comprising instructions which, when said computer program is executed by a computer, cause said computer to carry out the steps of the method according to any one of claims 1 to 7. A further subject of the present application is a computer-readable data carrier on which such a computer program product is stored.

[0065] In the following, the invention will be explained by way of example with reference to a number of schematic drawings. [Brief description of the drawings]

[0066] [Figure 1] FIG. 2 shows a schematic representation of the implementation of a variant of the method according to the invention in a variant of the device according to the invention for reducing metal oxide-containing material. [Diagram 2] FIG. 13 shows a schematic diagram of a further variant. [Diagram 3] FIG. 13 shows a further variation. [Figure 4] FIG. 13 shows a schematic diagram of a further variant. [Diagram 5] FIG. 13 shows a schematic diagram of a further variant. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0067] FIG. 1 shows a schematic representation of the implementation of the method according to the invention in an apparatus 1 according to the invention for reducing metal oxide-containing material. A metal oxide-containing material 3, in this case an iron oxide-containing material, is introduced into a reduction reactor 2, in this case a reduction shaft, and a fixed bed 4 is formed. For the reduction of the metal oxide-containing material 3 in the reduction reactor 2, a reducing gas is used. From the reduction reactor 2, a top gas is discharged by means of a top gas outlet 5. The top gas outlet 5 opens into a preparation unit 6 for preparing the reducing gas. A feed pipe 7 for the introduction of ammonia opens into the preparation unit 6. In the preparation unit 6, the preparation of the reducing gas is carried out by means of ammonia NH3 and by means of the top gas as a component. The reducing gas obtained by means of ammonia and the top gas is fed through a feed pipe 8 to the reduction reactor 2, which contains the metal oxide-containing material 3. In the preparation unit 6, the top gas is mixed with ammonia, and the mixed gas obtained in this case is the reducing gas. That is to say, the top gas is directly used in the preparation of the reducing gas.

[0068] FIG. 2 shows diagrammatically, similarly to FIG. 1, a variant in which the top gas is indirectly used for the preparation of the reducing gas. A preparation unit 6 is fed with a process gas via a top gas outlet 5. The process gas is obtained by processing the top gas. A device 9 for reducing the nitrogen content is present in the top gas outlet 5, and a stream of process gas depleted in nitrogen is fed via the top gas outlet 5 to the preparation unit 6. In the preparation unit 6, the process gas is mixed with ammonia, and the resulting mixed gas is the reducing gas. In FIG. 2, as a result of the reduction in the nitrogen content, a partial amount of the top gas is used as a component in the preparation of the reducing gas.

[0069] 3 shows, roughly analogously to FIG. 2, a schematic variant in which the preparation unit 6 includes a natural gas supply 10. This makes it possible to add natural gas to the gas mixture resulting after combining the process gas with ammonia, or to add ammonia to the gas mixture resulting after combining the process gas with natural gas. The gas mixture obtained in this case can be used as a precursor of a reducing gas, which can be converted into a reducing gas in a reformer, not shown separately.

[0070] 4 shows, roughly analogously to FIG. 2, a schematic variant in which the ammonia feed pipe 11 opens into the cooling zone 12 of the reduction reactor 2. This allows ammonia to be introduced into the cooling zone during direct reduction in the reduction reactor 2.

[0071] Figure 5 shows a schematic diagram of a variant of the reduction reactor, similar to Figure 1, but with the bustle 13 of the reduction reactor. Reducing gas is fed to the bustle 13 through a feed pipe 8. To prepare the reducing gas, ammonia is fed to the top gas conduit 14 through ammonia input feed pipe 7. In this case, the feed pipe 8 is regarded as both a preparation unit and a mixer, since ammonia and top gas are mixed therein. [Explanation of symbols]

[0072] 1 Apparatus for reducing metal oxide-containing materials 2. Reduction reactor 3 Materials containing metal oxides 4 Fixed floor 5. Top gas exhaust pipe 6 Preparation Unit 7. Supply pipe for ammonia injection 8 Supply pipe 9. Equipment for reducing nitrogen content 10 Natural gas supply pipe 11 Ammonia supply pipe 12 Cooling Zone 13 Bustle 14 Top gas pipe

Claims

1. A method for reducing a metal oxide-containing material (2), comprising the steps of: Ammonia NH ３ A reducing gas obtained using The reducing gas is supplied to a reduction reactor (2) containing a metal oxide-containing material; In the method, a furnace gas is discharged from the reduction reactor, 4. A process according to claim 3, wherein at least a portion of said furnace gas is used as a component in the preparation of said reducing gas, optionally after treatment of said furnace gas.

2. 2. The method according to claim 1, characterized in that the treatment of the top gas withdrawn from the reduction reactor (2) comprises a method step of reducing the nitrogen content.

3. The furnace gas and / or the treatment gas may include, during the preparation of the reducing gas, -ammonia, - hydrogen from ammonia, 3. The method according to claim 1 or 2, characterized in that at least one member of a first group consisting of:

4. The furnace gas and / or the treatment gas may include, during the preparation of the reducing gas, - Natural gas, - hydrocarbons, -hydrogen, - Carbon monoxide, - Coke oven gas, -CO, H ２ , C.H. ４ , C2-C6 hydrocarbons, N ２ , CO ２ A synthesis gas containing a plurality of components from a group of components consisting of:

4. The method according to claim 1, further comprising the step of adding at least one member of a second group consisting of:

5. 5. The method according to claim 4, characterized in that after combining the furnace gas or process gas with at least one component of a first group, at least one component of a second group is added to the resulting mixed gas.

6. 5. The method according to claim 4, characterized in that after combining the furnace gas or process gas with at least one component of the second group, at least one component of the first group is added to the resulting mixed gas.

7. A process carried out in a reduction reactor (2) equipped with a cooling zone (12) and / or a product cooling device, 7. The method according to any one of claims 1 to 6, characterized in that ammonia is introduced into the cooling zone (12) of the reduction reactor (2) and / or into the product cooler.

8. An apparatus (1) for reducing a metal oxide-containing material (3), a reduction reactor (2), a top gas discharge pipe (4) for discharging the top gas from the reduction reactor (2); at least one feed pipe (7) for the ammonia input, a preparation unit (6) for preparing a reducing gas, into which at least one feed pipe (7) for the input of ammonia opens, a supply pipe (8) for supplying a reducing gas and / or a precursor of a reducing gas to said reduction reactor (2); In an apparatus comprising: Apparatus (1), characterized in that the furnace gas discharge pipe (5) opens into the preparation unit (6).

9. 9. Apparatus according to claim 8, characterized in that the top gas discharge (5) comprises at least one treatment unit which is a device (9) for reducing the nitrogen content.

10. A preparation unit (6), - Natural gas, - hydrocarbons, -hydrogen, - Carbon monoxide, - Coke oven gas, - Syngas, 10. Apparatus according to claim 8 or 9, characterized in that it comprises at least one supply pipe (10) for supplying one or more components of the group consisting of:

11. In an apparatus in which the reduction reactor (2) has a cooling zone (12) and / or a product cooling device, 11. Apparatus according to any one of claims 8 to 10, characterised in that an ammonia feed pipe (11) opens into the cooling zone (12) and / or into the product cooler.

12. 1. A signal processing apparatus having machine readable program code, comprising: A signal processing device, characterized in that said program code comprises closed-loop control instructions for carrying out the method according to any one of claims 1 to 7.

13. 8. Machine-readable program code for a signal processing device, the program code comprising closed-loop control instructions for causing the signal processing device to carry out a method according to any one of claims 1 to 7.

14. A storage medium having the machine-readable program code according to claim 13 stored thereon.

15. 8. Open-loop and / or closed-loop control of an apparatus for reducing metal-oxide-containing material using a computer comprising a computer program product comprising instructions that cause a computer to perform the steps of the method according to any one of claims 1 to 7 when the computer program is executed by the computer.

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