Iron melts from sinter

Abstract

The invention relates to a method for producing an iron melt (80) from an iron oxide-containing material (30), in which a reducing gas (90) containing at least hydrogen is fed into a reduction reactor (20) containing the iron oxide-containing material (30) for pre-reduction. The iron oxide-containing material (30) comprises at least 35% by mass of sintered ore and the reducing gas (90) comprises at least 60% by volume of hydrogen H2. According to the invention, the solid pre-reduction product obtained in the pre-reduction is fed from the reduction reactor (20) to a melting device (40) and there is carried out a treatment comprising at least the following steps:-an energy supply is carried out in order to produce a melt, where the energy supply is achieved essentially by electrical power,-at least a part of the amount of iron oxides contained in the solid pre-reduction product is reduced. The treatment may also include adjusting the carbon content in the melt. The reduction reactor (20) for pre-reduction is designed as a reduction shaft, which has: a feed region (A) for feeding the iron oxide-containing material (30); -a removal region (B) for removing the solid pre-reduction product obtained in the pre-reduction,-an introduction region (C) for introducing a reduction gas (90), the reduction shaft being designed in a conical shape below the introduction region (C), the wall angle of the reduction shaft to the vertical being less than 20 DEG, and the reduction shaft narrowing from the introduction region towards the removal region (B). A plant for carrying out the method according to the invention comprises a reduction reactor (20) for the direct reduction of iron oxide-containing material, a melting device (60), and an addition device (50) for feeding the solid product of the direct reduction method into the melting device (60).

Description

Technical Field

[0001] The present application relates to a method and an apparatus for producing an iron melt from an iron oxide-containing material, the iron oxide-containing material comprising sintered ore, wherein the iron oxide-containing material is pre-reduced using a reducing gas containing at least hydrogen, and the pre-reduced product is melted. Prior art

[0002] It is known to reduce materials containing metal oxides (e.g. iron oxide), such as lumps, oxide agglomerates or pellets, by means of reducing gases. For example, by direct reduction with reducing gases in a reduction device (e.g. a reduction shaft). In conventional pre-reduction or direct reduction processes currently used on a large scale in industry, the reducing gas is based, in addition to hydrogen, on carbon, for example carbon monoxide CO and / or methane CH4 from natural gas. This produces large amounts of carbon dioxide CO2, which is undesirable, in particular for environmental policy reasons.

[0003] It is well known that iron oxide-containing materials, such as sintered ore, can be reduced to liquid pig iron via the blast furnace route. The reduction is mainly carried out by carbon-containing gases based on coal or coke, which leads to large carbon dioxide CO2 emissions in this production route. Sintered ore is produced from sintered raw materials based on iron ore in a sintering plant, which is usually located in the vicinity of the blast furnace. The sintering plant of the ironmaking industry supplies the blast furnace with a material known as blast furnace sintered ore or sintered ore or ironmaking sintered ore. The processes for producing sintered ore products in sintering plants of the iron industry are well known, see for example specialist books such as “Agglomeration of Iron Ores”, DFBall, J.Dartnell, J.Davison, A.Grieve, R.Wild, 1973 edition, pages 388, 34, or “Handbuch für Agglomerationstechnik”, Gerald Heinze, 2000 edition, pages 261, 102, Wiley-VCH Verlag GmbH, Weinheim, or “Ullmann's Enyclopedia of Industrial Chemistry”, pages 280-29, chapter “Iron”, pages 15 et seq., 2006 Wiley-VCH Verlag GmbH, Weinheim. The method is based on the production of solid agglomerates as a product by oxidative roasting of a raw material mixture containing at least fine iron ore, additives (such as limestone chips, dolomite, quicklime) and fuel (such as coke powder) to bond particles to each other by melting the particle surfaces.

[0004] In order to reduce CO2 emissions in the reduction of metal oxide-containing materials, it is known to use hydrogen H2 as a reducing gas. Here, hydrogen can be used as the only reducing gas, or in combination with other gases (which are based on carbon in natural gas, or coal or coke, for example). The greater the content of CO2-neutral hydrogen H2 in the reducing gas with respect to the reduction reaction, the less CO2 is emitted. Depending on the availability of natural gas or other gases and hydrogen, their contribution to the reducing gas can be changed by mixing different amounts. The more hydrogen is available, the more the share of climate problems caused by carbon from natural gas or other gases can be avoided.

[0005] Advantageously, existing plants and processes in which the reducing gas is mainly based on carbon and partly on hydrogen from natural gas or other gases are also operated with an increased content of hydrogen in the reducing gas. This enables a flexible response to the availability of natural gas or other gas and hydrogen and allows the utilization of plant investments already made. At least until sufficient amounts of hydrogen are available for use as a reducing gas based entirely on hydrogen, the reducing gas must still rely on carbon and hydrogen from natural gas or other gases.

[0006] It is also advantageous that when the blast furnace is not in operation and another direct or smelting reduction method is used instead, the existing equipment in the integrated smelter can also be used after the changeover in the reduction method, so that the equipment investment already made can continue to be used after the changeover. Summary of the invention

[0007] Technical Purpose

[0008] The object of the present invention is to provide a method and an apparatus which allow to pre-reducing an iron oxide-containing material containing sintered ore with a hydrogen-rich reducing gas without going through a blast furnace route and to provide a pig iron-like material.

[0009] Technical Solution

[0010] This purpose is achieved by:

[0011] A method for producing an iron melt, preferably an iron melt having a carbon content of 1 to 5 mass %, from an iron oxide-containing material,

[0012] wherein a reducing gas containing at least hydrogen and optionally a carbon carrier is fed into a reduction reactor containing an iron oxide-containing material for pre-reduction,

[0013] Features

[0014] The iron oxide-containing material comprises at least 35 mass % of sintered ore,

[0015] and the reducing gas contains at least 60% by volume of hydrogen H2,

[0016] and adding the solid pre-reduction product obtained in the pre-reduction from the reduction reactor to the melting device, optionally through the silo device,

[0017] and there a processing is carried out which comprises at least the following steps:

[0018] - energy supply for producing the melt, wherein the energy supply is substantially carried out by electricity,

[0019] - reducing at least a portion of the amount of iron oxides contained in the solid pre-reduction product,

[0020] The treatment optionally also includes adjusting the carbon content in the melt.

[0021] The method can be carried out without a blast furnace, i.e. without the core component of the conventional blast furnace route - i.e. no blast furnace is involved in the reduction of the iron oxide-containing material. The method can be operated without a blast furnace. Therefore, the method is not carried out via the conventional blast furnace route. The reduction reactor used for the prereduction is not a blast furnace. Prereduction is understood to mean a reduction in which iron oxide is still present in the solid product obtained at the end. The reduction reactor used for the prereduction is a reduction shaft, and the reduction with reducing gas is carried out in the reduction shaft containing a fixed bed of the iron oxide-containing material. The iron oxide-containing material is fed into the reduction shaft from above and migrates through the reduction shaft under the effect of gravity, wherein the reduction reaction takes place.

[0022] The reducing gas contains at least 60% by volume of hydrogen as a reducing component. It can also consist of hydrogen. Optionally, the reducing gas also contains one or more gaseous carbon carriers as an additional reducing component or components. The carbon carriers are provided, for example, by natural gas; these are, for example, carbon monoxide CO or methane CH4 introduced by natural gas or produced by natural gas.

[0023] For example, this can be green, blue, grey, turquoise, pink hydrogen. These “colors” are understood to refer to the coloring associated with the underlying production method. For example, green hydrogen is produced by electrolysis of water using electricity generated from renewable sources, or by gasification or fermentation of biomass, or by steam reforming of biogas - the common feature of the types of production of green hydrogen is that the production is carried out without CO2. In the case of blue hydrogen, the CO2 produced during the production process is stored so that it does not enter the atmosphere; for example, if it is produced by sequestering the carbon dioxide CO2 produced. In the case of turquoise hydrogen, it is produced by separating the carbon C produced. In the case of pink hydrogen, the hydrogen is produced using nuclear power. In the case of grey hydrogen, it is produced from fossil fuels - for example from natural gas by steam reforming - in which the CO2 produced is mainly released into the atmosphere. Other colors of hydrogen are also conceivable. Mixtures of one or more of these “colors” of hydrogen are also conceivable.

[0024] If carbon carriers are present as additional reducing components, the ratio of the hydrogen and carbon carrier contents in the reducing gas can be varied, for example, by combining different amounts when preparing the reducing gas. For example, the ratio can also be varied so that the hydrogen content in the reducing gas is increased.

[0025] The reducing gas is a gas introduced into the reduction reactor, which has a composition and temperature present when introduced. Before the given composition and temperature, there is a precursor of the reducing gas, based on which the reducing gas is prepared. For example, the preparation may include adding other components, heating, reforming. The preparation may also include a chemical reaction that occurs in the precursor without external intervention, which chemical reaction, for example, changes the chemical composition or temperature. If changes are made in the preparation, the hydrogen content in the reducing gas may change.

[0026] The iron melt produced according to the invention preferably has a carbon content of 1.0 mass% to 5 mass%. It consists mainly of iron - it is a liquid pig iron-like product; in the present application, the term "liquid pig iron-like product" is used synonymously with the term "iron melt" for the iron melt produced according to the invention. The liquid pig iron-like product having a carbon content of preferably 1.0 mass% to 5 mass% is "similar" to pig iron from a blast furnace from the point of view of the steelmaking process (e.g. LD / BOF), i.e. it can be processed in essentially the same way as pig iron from a blast furnace, i.e., followed by steelmaking except for the blast furnace of the blast furnace route. The higher the carbon content, the more cooling waste can be used for subsequent processing into steel; a greater amount of cooling waste reduces the CO2 emissions per unit amount of steel produced by the liquid pig iron-like product produced according to the invention.

[0027] Particularly preferably, the liquid pig iron-like product has a carbon content of at least 2.0% by mass, very particularly preferably at least 2.5% by mass. Particularly preferably, the liquid pig iron-like product has a carbon content of up to 4.7% by mass, very particularly preferably up to 4.5% by mass.

[0028] According to a preferred embodiment, the solid pre-reduction product obtained in the pre-reduction is added to the melting device via a silo device. This facilitates metering of the solid pre-reduction product into the melting device.

[0029] The energy supply is basically, preferably completely, realized by electricity, i.e., by electrical energy. In this context, basically means at least 75%, preferably at least 80%. In the case of such energy supply realized by electricity, no CO2 is produced, which is conducive to the CO2 balance of the method.

[0030] According to an advantageous embodiment, the carbon content in the melt is adjusted by the supplied carbon carrier. These may be solid carbon carriers and / or liquid carbon carriers and / or gaseous carbon carriers. The carbon carrier may comprise, for example, coal dust, coke, graphite powder or natural gas. The carbon carrier may also come partly or completely from a carbon-neutral source, for example from biomass such as charcoal; this improves the CO2 balance of the process. For example, the carbon carrier may be introduced via a lance or an under-bath nozzle. However, it is also possible not to adjust the carbon content during the process, since the solid pre-reduction product already contains enough carbon.

[0031] According to an advantageous embodiment, the carbon content in the melt is adjusted by the supplied oxygen. If the carbon content is higher than the desired value for the iron melt, the carbon content can be oxidatively reduced by the supply of oxygen, for example, the carbon in the melt can react to form CO and escape from the melt in gaseous form.

[0032] According to an advantageous embodiment, the reduction of at least a portion of the amount of iron oxides contained in the solid pre-reduction product is carried out by means of supplied carbon supports. These may be solid carbon supports and / or liquid carbon supports and / or gaseous carbon supports. The carbon supports may comprise, for example, coal dust, coke, graphite powder or natural gas. The carbon supports may also partly or completely come from a carbon-neutral source, for example from biomass such as charcoal; this improves the CO2 balance of the process.

[0033] Advantageous Effects of the Invention

[0034] The use of hydrogen in the reduction gas makes it possible to carry out pre-reduction or direct reduction with reduced or avoided CO2 emissions. The higher the hydrogen content in the reduction gas, the more CO2 emissions can be avoided compared to carbon carriers that produce CO2 during pre-reduction or direct reduction. This makes ecological sense. The use of sintered ore makes it possible to use existing investments in sintering plants for the operation of the conventional blast furnace route for processes that do not require a blast furnace. This makes economic and ecological sense.

[0035] The iron oxide-containing material comprises at least 35% by mass of sinter. For the definition of sinter (also called blast furnace sinter or ironmaking sinter) and an explanation of its production in the ironmaking industry, please refer to the above explanation in the introduction of this application. In the present application, the term "sinter" is mainly used, but the terms "blast furnace sinter" or "ironmaking sinter" can also be used. Input materials for the production of sinter are, for example, fine iron ore or fine iron ore mixtures with a particle size of, for example, 0.001-10 mm, additives in the form of, for example, limestone chips, dolomite, quicklime, optional return materials from the steelmaking process, such as blast furnace dust, iron oxide scale, sintering dust, BOF dust, and as fuel, for example, coke powder, anthracite, graphite, biochar with a particle size of, for example, 0.01-10 mm, preferably 0.1-5 mm, particularly preferably 1-3 mm. The product sintered ore is a solid, porous and easily reducible agglomerate with a particle size of, for example, 0.1-75 mm, preferably 3-50 mm, particularly preferably 5-35 mm.

[0036] The use of sinter as a component of the fixed bed feed in the reduction shaft is well known - see, for example, "Reducing process of sinter in COREX shaft furnace and influence of sinter proportion on reduction properties in composite burden", Shi Ben-jing et al., J. Cent. South Univ. (2021) 28: 690–698, DOI 10.1007 / s11771-021-4638-5. However, due to decomposition reasons, it is not recommended to increase the sinter content of the feed to more than 25% by mass to 30% by mass. On the contrary, the method of the present invention is carried out by a sinter content of at least 35% by mass, preferably at least 50% by mass, particularly preferably more than 50% by mass, and very particularly preferably at least 60% by mass in the iron oxide-containing material of the feed. As the inventors of the present application have found, the proposed method using a high hydrogen content in the reducing gas makes it possible to achieve stable process control even in a range that has not been recommended so far and can significantly better utilize the existing sintering plant infrastructure.

[0037] The remainder of the feed may be, for example, an iron oxide-containing material selected from the following materials:

[0038] - Lump ore,

[0039] - oxide agglomerates,

[0040] -Pellets.

[0041] The use of a basic electric melting unit makes it possible to produce an equivalent steel product using existing downstream processes, which is not possible in an EAF.

[0042] Preferably, the pre-reduction is carried out to a metallization degree of at least 70%, preferably at least 80%, very particularly preferably at least 85%. The higher the metallization degree, the less the need for post-reduction of the solid pre-reduction product obtained during the pre-reduction in a subsequent treatment step. The term "post-reduction" is to be understood as meaning the reduction of at least a portion of the iron oxides still contained in the solid pre-reduction product. If the post-reduction leads to carbon dioxide CO2 emissions - for example in the case of post-reduction using carbon from fossil sources, it is particularly advantageous to reduce the need for post-reduction. However, when carbon is used for post-reduction, CO2 emissions can also be reduced if the carbon used for post-reduction comes from biomass.

[0043] The metallization rate (also called metallization degree MG) expressed in % is obtained from the ratio of metallic iron Fe met to the total iron Fe tot in the sample according to the following formula:

[0044] MG[%]=Fe met / Fe tot*100

[0045] Fe met: metallic iron in the sample (mass percentage m%)

[0046] Fe tot: Total iron contained in the sample (mass percentage m%)

[0047] Since the pre-reduced solid product, ie, the solid pre-reduction product, still contains iron oxide, its metallization ratio or its metallization degree MG is less than 100%.

[0048] If the temperature of the iron oxide-containing material fed into the reduction reactor is lower than the temperature of the reducing gas, it is heated by the reducing gas in the reduction reactor.

[0049] Preferably, the process is carried out in the reduction reactor at a heating rate of at least 5° C. / min, preferably at least 10° C. / min, particularly preferably at least 12° C. / min. This minimizes problems caused by staying in the critical temperature range associated with the transformation from hematite to magnetite and subsequently to wüstite and associated therewith due to compressive strength and bulk pressure.

[0050] The maximum achievable heating rate depends on the physical boundary conditions during the heating process. The upper limit of the heating rate is 50°C / min, preferably below 30°C / min.

[0051] The temperature of the reducing gas is preferably above 750° C., particularly preferably above 800° C., very particularly preferably above 850° C. The temperature of the reducing gas is preferably below 1050° C., particularly preferably below 1020° C., very particularly preferably below 1000° C.

[0052] For example, if an iron oxide-containing material having a temperature of 20° C. is fed into the reduction reactor, it should be heated to a temperature of up to 600° C. by the reducing gas within 60 minutes.

[0053] According to ISO4701 3rd edition 20081001, the particle size of the sintered ore is preferably 5 mm-40 mm, particularly preferably 8 mm-32 mm, very particularly preferably 10 mm-25 mm, including the limits of the range data, wherein the screening efficiency is up to 5%. Screening efficiency is also called screening efficiency and screening quality.

[0054] Preferably, for the particle stability of the sintered ore, the result of the RDI test performed on the sintered ore sample according to ISO 4696-1 third edition 2015-09-01 shows that the content of particles with a particle size of less than 3.15 mm is less than or equal to 30%. The particle stability is determined using the RDI test according to ISO 4696-1 third edition 2015-09-01; RDI stands for reduction pulverization rate. With this particle stability, poor ventilation and unstable process control caused by particle decomposition during the pre-reduction process can be avoided.

[0055] Preferably, the basicity B2 of the sintered ore is greater than 1. The basicity B2 is preferably at most 2.5, particularly preferably at most 2.2. The basicity B2 is derived from the ratio of the weight percentage contents of calcium oxide CaO and silicon dioxide SiO2 in the sample.

[0056] Basicity B2 = CaO / SiO2 (weight percentage content of each in the sample).

[0057] Therefore, the solid pre-reduction product obtained in the pre-reduction process can be easily used in downstream processing steps with corresponding basicity requirements; no measures for adjusting the basicity are required in subsequent processing steps or during the transfer of the solid pre-reduction product from the reduction reactor to the melting device.

[0058] The slag produced in the melting device preferably has a basicity B2 whose value lies in the range from 0.9 to 1.2, both limits included.

[0059] The slag is produced in the melting device. Preferably, the slag produced in the melting device has a basicity B4, whose value ranges from 0.8 to 1.2, including both limits. The basicity B4 is derived from the ratio of the sum of the weight percentage contents of calcium oxide CaO and magnesium oxide MgO to the sum of the weight percentage contents of silicon dioxide SiO2 and aluminum oxide Al2O3 in the sample.

[0060] Basicity B4 = (CaO + MgO) / (SiO2 + Al2O3) (weight percentage content in each sample).

[0061] Preferably, the iron oxide-containing material is fed into the reduction reactor in the feed zone substantially uniformly across the cross-sectional area of ​​the feed zone.

[0062] The goal is a uniform distribution, but deviations may occur during operation due to handling, which are included by the wording "substantially uniform".

[0063] Uniformly through the cross-sectional area is to be understood as the opposite of point-wise at one location or in a limited sub-area of ​​the cross-sectional area; thus, the input should not be carried out point-wise at one location or in a limited sub-area of ​​the cross-sectional area so that material accumulation occurs at that location or in this limited sub-area, but rather the input should be carried out essentially uniformly through the entire cross-sectional area so that the material level through the cross-sectional area is essentially constant everywhere.

[0064] The relevant cross-sectional area is the cross-sectional area perpendicular to the direction of movement of the iron oxide-containing material when migrating through the reduction reactor from an input zone for inputting the iron oxide-containing material to a removal zone for removing the solid pre-reduction product obtained during the pre-reduction process.

[0065] The substantially uniform input results in substantially uniform aeration of the fixed bed and thus substantially uniform reduction in the fixed bed. This helps to avoid local differences in the degree of metallization and particle stability of the fixed bed. This helps to ensure a substantially uniform migration of the iron oxide-containing material through the reduction reactor. The goal is to achieve a uniform migration, but deviations may occur during operation due to operation, which are included by the wording "substantially uniform". Localized material blockages are thereby substantially avoided; the goal is to completely avoid localized material blockages; but localized material blockages may occur during operation due to operation, which are included by the wording "substantially avoided".

[0066] Preferably, the input is carried out in such a way that precipitation of the iron oxide-containing material according to the size and density of its particles is substantially avoided and a uniform gas distribution through the cross-sectional area is ensured. The goal is to avoid it completely; however, precipitation may still occur during operation due to the operation, which is included by the wording "substantially uniform".

[0067] This can be achieved, for example as shown in WO2006056350A1, by a gimbal mounting distribution slot, for example as shown in WO2017055419A1.

[0068] The solid pre-reduction product obtained during the pre-reduction process is removed from the reduction reactor in a removal zone. Preferably, the removal is in the form of a surface. The removal is carried out through the cross-sectional area of ​​the removal area, for example by means of a plurality of discharge screws which substantially cover the cross-sectional area of ​​the removal area. The removal through the cross-sectional area in the form of a surface should be understood as the opposite of the removal at one point or in a limited sub-area of ​​the cross-sectional area; thus, the removal should not be carried out at one point or in a limited sub-area of ​​the cross-sectional area, so that a serious reduction in the amount of material occurs at this point or in this limited sub-area, but the removal should be carried out substantially uniformly over the entire cross-sectional area, so that the material level through the cross-sectional area is substantially constant everywhere.

[0069] The removal in the form of a surface through the cross-sectional area of ​​the removal zone helps to ensure that the iron oxide-containing material migrates substantially uniformly through the reduction reactor. Localized material blockages are thus substantially avoided. The substantially uniform migration leads to substantially uniform aeration of the solidified bed and thus substantially uniform reduction in the fixed bed. This helps to reduce or avoid local differences in the degree of metallization and particle stability of the fixed bed. The relevant cross-sectional area is the cross-sectional area perpendicular to the direction of movement of the iron oxide-containing material from the input zone for inputting the iron oxide-containing material to the removal zone for removing the solid pre-reduction product obtained in the pre-reduction process.

[0070] The reducing gas is introduced into the reduction reactor in an introduction zone. Preferably, the introduction of the reducing gas into the reduction reactor is carried out substantially uniformly through the cross-sectional area of ​​the introduction zone. Uniformly through the cross-sectional area should be understood as being the opposite of being introduced at one location in a point-like manner or in a limited sub-area of ​​the cross-sectional area. In this context, substantially uniformly means that the reducing gas is introduced not only in a point-like manner or in a limited sub-area, such as at the edge of the reduction reactor, but also away from the edge towards the center of the reduction reactor or in the center of the reduction reactor. This can be achieved, for example, by a gas distribution pipe extending into the interior of the reduction reactor or - in the case of a circular cross-sectional area of ​​the interior, for example in a diametrical direction or as a secant - across the interior.

[0071] The relevant cross-sectional area is the cross-sectional area perpendicular to the direction of movement of the iron oxide containing material from an input zone for inputting the iron oxide containing material to a removal zone for removing the solid product of the direct reduction process.

[0072] Substantially uniform introduction through the cross-sectional area results in substantially uniform aeration of the fixed bed and thus substantially uniform reduction in the fixed bed. This helps to avoid local differences in the degree of metallization and particle stability of the fixed bed. This helps to ensure substantially uniform migration of the iron oxide-containing material through the reduction reactor. Localized material blockages are thereby substantially avoided.

[0073] This introduction can be achieved, for example, as shown in WO2013156548A1.

[0074] According to a preferred embodiment, the solid pre-reduction product obtained in the pre-reduction is fed from the reduction reactor to the melting device via a silo device, wherein the silo device is used as a gas pressure valve. The pressure of the atmosphere around the solid product changes. This is done in the silo device that can be operated as a gas pressure valve. This can prevent the reducing gas from the reduction reactor from flowing into the melting device or the gas from the melting device from flowing into the reduction reactor.

[0075] A further subject matter of the present application is a method for producing steel, wherein the steel is produced on the basis of an iron melt produced according to the invention.

[0076] According to an advantageous embodiment, the LD / BOF process is used in the steel production. Preferably, this is done with a scrap content of at least 10% by mass, preferably at least 15% by mass, particularly preferably at least 20% by mass.

[0077] Another subject of the present application is a reduction reactor for prereduction of iron oxide-containing materials, which is designed as a reduction shaft and is characterized in that:

[0078] The reduction shaft has

[0079] - an input area for inputting iron oxide containing material;

[0080] a removal zone for removing the solid pre-reduction product obtained in the pre-reduction,

[0081] - an introduction zone for introducing reducing gas,

[0082] The reduction shaft is designed as a cone below the introduction region, with a wall angle of less than 20°, preferably less than 10° to the vertical, wherein it narrows from the introduction region toward the removal region.

[0083] When the longitudinal axis of the reduction shaft is arranged vertically, the input area is located in the upper area of ​​the reduction shaft, while the removal area is located in the lower area of ​​the reduction shaft. The introduction area is located between the input area and the removal area. Below the introduction area, the reduction shaft is designed as a cone, which narrows toward the removal area; therefore, the diameter becomes smaller toward the removal area.

[0084] The conical design with small wall angles counteracts bridging situations and thus counteracts uneven migration in the reduction shaft. What is desired is a substantially uniform migration, which is also called mass flow in connection with bulk material. As a result, local material blockages are substantially avoided. The substantially uniform migration leads to a substantially uniform fixed bed ventilation and thus to a substantially uniform reduction in the fixed bed. This helps to avoid local differences in the degree of metallization and the particle stability of the fixed bed. It has been shown that the occurrence of problems in the uniform removal of the solid product is counteracted by the conical design of the reduction shaft below the introduction zone with small wall angles. As a result, even in the case of a sinter content of the iron oxide-containing material and a hydrogen content of the reducing gas according to the method of the invention, a stable process control can be achieved.

[0085] The method of the present invention can be carried out by using such a reduction reactor.

[0086] Preferably, the reduction shaft above the introduction area is designed as a basic cone, with a wall angle of less than 3° to the vertical, preferably a wall angle of at least 1° to the vertical; it widens towards the introduction area. In this context, basic cone means that in addition to conical subsections, there can also be cylindrical subsections. This design counteracts bridging situations and shaft walling, and thus counteracts uneven migration in the reduction shaft. When the longitudinal axis of the reduction shaft is arranged vertically, the input area is located in the upper area of ​​the reduction shaft, and the removal area is located in the lower area of ​​the reduction shaft. The introduction area is located between the input area and the removal area.

[0087] Preferably, the reduction reactor comprises an input device for inputting the iron oxide-containing material, the input device being adapted to provide substantially uniform input across the cross-sectional area of ​​the reduction shaft in the input region. For example, the input device comprises a gimbal mounted distribution trough as shown in WO2006056350A1.

[0088] The relevant cross-sectional area is the cross-sectional area perpendicular to the direction of movement of the iron oxide-containing material when migrating through the reduction shaft from an input area for inputting the iron oxide-containing material to a removal area for removing the solid product of the direct reduction process. This is also perpendicular to the longitudinal axis of the reduction shaft.

[0089] Preferably, the input means is adapted to input while substantially avoiding precipitation of the iron oxide containing material depending on the size and / or density of its particles.

[0090] Preferably, the input device comprises a control and / or regulation device which is designed to flexibly regulate and / or control the input. For example, the regulation device can automatically use measurement data from a thermocouple suitable for determining the temperature of the gas above the bulk material in the reduction shaft and measurement data from a thermocouple suitable for determining the temperature of the gas within the bulk material in the reduction shaft for regulation. For example, an operator can preset a profile which is then implemented in a controlled and / or regulated manner.

[0091] Preferably, there is a discharge device in the removal area, which is suitable for removing in the removal area in the form of a surface through the cross-sectional area of ​​the reduction shaft. For example, the discharge device comprises a plurality of discharge screws that substantially cover the cross-sectional area of ​​the removal area. The relevant cross-sectional area is the cross-sectional area perpendicular to the direction of movement of the iron oxide-containing material from the input area for inputting the iron oxide-containing material to the removal area for removing the solid product of the direct reduction process. This is also perpendicular to the longitudinal axis of the reduction shaft.

[0092] Preferably, in the introduction region there is an introduction device which is adapted to introduce substantially uniformly through the cross-sectional area of ​​the reduction shaft in the introduction region. For example, the introduction device comprises a plurality of introduction pipes which substantially cover the cross-sectional area of ​​the removal region. The relevant cross-sectional area is the cross-sectional area perpendicular to the direction of movement of the iron oxide-containing material from the input region for inputting the iron oxide-containing material to the removal region for removing the solid product of the direct reduction process. This is also perpendicular to the longitudinal axis of the reduction shaft.

[0093] Another subject of the present application is a plant for carrying out the method according to the invention for producing an iron melt, characterized in that

[0094] It includes

[0095] - A reduction reactor for direct reduction of iron oxide-containing materials according to any one of claims 12 to 13,

[0096] - melting device,

[0097] - an addition device for feeding the solid products of the direct reduction process into the melting device.

[0098] The melting device comprises means for supplying electrical energy.

[0099] According to a preferred embodiment, the adding device comprises a silo device.

[0100] According to a preferred embodiment, the adding device comprises a silo device acting as a gas pressure valve.

[0101] According to a preferred embodiment, the apparatus for carrying out the method according to the invention further comprises means for regulating the carbon content; for example, means for adding carbon-containing material to the melting device, or means for adding oxygen to the melting device. Thus, the means for regulating the carbon content operate, for example, in such a way that it adds carbon-containing material to the melting device and / or reduces the carbon-containing material present in the melting device, for example in the solid product and / or in the iron melt supplied to the melting device. For example, the reduction can be achieved by reaction with oxygen; the generated gas can be taken from the iron melt or the melting device.

[0102] There may also be a device for adding additives to the melting device, for example, to adjust the slag produced in the melting device to a desired basicity.

[0103] Another subject of the present application is a signal processing device with a machine-readable program code, characterized in that it has control and / or regulation instructions for executing the method according to the invention. Another subject is a signal processing device for carrying out the method according to any one of claims 1 to 11.

[0104] Another subject of the present application is a machine-readable program code for a signal processing device, characterized in that the program code has control and / or regulation instructions, which cause the signal processing device to perform the method according to the invention. Another subject is a computer program product comprising instructions for a signal processing device, which, when the program for the signal processing device is executed, causes the signal processing device to perform the method according to any one of claims 1 to 11.

[0105] Another subject of the present application is a storage medium on which a machine-readable program code according to the invention is stored. Another subject is a storage medium on which a computer program for executing the method according to any one of claims 1 to 11 is stored. BRIEF DESCRIPTION OF THE DRAWINGS

[0107] The present invention is described below in an exemplary manner with reference to a number of schematic diagrams.

[0108] Figure 1 A device according to the invention is schematically shown.

[0109] Figure 2 A reduction reactor for pre-reduction according to the invention is schematically shown.

[0110] Description of the implementation plan Example

[0111] Figure 1 Schematically shown is an apparatus 10 comprising a reduction reactor 20 for direct reduction of an iron oxide-containing material 30, a melting device 40 and an addition device 50 for feeding the solid product produced in the reduction reactor 20 into the melting device 40. Optional and therefore shown in dashed lines is a silo device 60, which is contained in the addition device 50 and acts as a gas pressure valve. Also optional and therefore shown schematically in dashed lines is a device 70 for adjusting the carbon content - which can be, for example, a device for adding carbonaceous material to the melting device 40, or a device for adding oxygen to the melting device 40.

[0112] In order to produce an iron melt 80 from an iron oxide-containing material 30 (which, for example, contains more than 50% by mass of sintered ore), a reducing gas 90 containing more than 60% by volume of hydrogen H2 is fed into a reduction reactor 20 containing the iron oxide-containing material 30 for pre-reduction. For example, the particle size of the sintered ore is 8 mm to 32 mm. Its basicity B2 is preferably greater than 1.

[0113] If the temperature of the iron oxide-containing material 30 fed into the reduction reactor 20 is lower than the temperature of the reducing gas 90 , it is heated by the reducing gas 90 in the reduction reactor 20 ; a heating rate of 10° C. / min is advantageous here, for example.

[0114] The solid pre-reduction product obtained by pre-reduction in the reduction reactor 10 still contains iron oxides. It is preferably metallized to at least 70%. It is added to the melting device 40 from the reduction reactor 20, optionally through the optional silo device 60. There, an iron melt is produced, and its carbon content is preferably 1-5% by mass. The process for producing the iron melt 80 includes at least energy supply to produce the melt and reducing at least a part of the amount of iron oxides contained in the solid pre-reduction product. Optionally, it also includes adjusting the carbon content in the melt using the optional device 70 for adjusting the carbon content.

[0115] The energy supply here is essentially provided by electricity.

[0116] During treatment in the melting device 40, a slag 100 is produced, the basicity B2 of which is preferably between 0.9 and 1.2. For the sake of clarity, the illustration of an optionally present addition device for adding additives to the melting device 40 has been omitted.

[0117] Figure 2 Schematically shown is an enlarged view of a reduction reactor 20 for pre-reduction of an iron oxide-containing material 30. It is designed as a reduction shaft, wherein it has an input area A for inputting the iron oxide-containing material 30, a removal area B for removing the solid pre-reduction product obtained during the pre-reduction process, and an introduction area C for introducing a reducing gas 90.

[0118] The reduction shaft 20 is designed conically below the introduction region C. Its wall angle to the vertical is less than 20°, and it narrows from the introduction region C toward the removal region B.

[0119] In the embodiment shown, the reduction shaft above the introduction region is designed as a cone, with a wall angle of 1° to 3° to the vertical—not shown exaggeratedly to scale here.

[0120] Citation List

[0121] Patent Literature

[0122] W02006056350A1

[0123] WO2017055419A1

[0124] WO2013156548A1

[0125] Non-patent literature

[0126] "Reducing process of sinter in COREX shaft furnace and influence of sinter proportion on reduction properties in composite burden", Shi Ben-jing et al., J.Cent.South Univ. (2021) 28:690-698, DOI 10.1007 / s11771-021-4638-5

[0127] ISO4701 3rd edition 20081001

[0128] ISO 4696-1 3rd edition 2015-09-01

[0129] "Agglomeration of Iron Ores", DFBall, J.Dartnell, J.Davison, A.Grieve, R.Wild, 1973 edition, 388 pages, page 34

[0130] "Handbuch für Agglomerationstechnik", Gerald Heinze, 2000 edition, page 261, page 102, Wiley-VCH Verlag GmbH, Weinheim

[0131] "Ullmann's Enyclopedia of Industrial Chemistry", page 28029, chapter "Iron", page 15 et seq., 2006 Wiley-VCH Verlag GmbH, Weinheim.

[0132] Reference numerals list

[0133] 10. Equipment

[0134] 20 Reduction Reactor

[0135] 30 Materials containing iron oxide

[0136] 40 Melting device

[0137] 50 Add Device

[0138] 60 Silo device

[0139] 70 Device for adjusting carbon content

[0140] 80 iron melt

[0141] 90 Reducing gas

[0142] 100 Slag

[0143] A Input area

[0144] B Remove Area

[0145] C Introduction area

Claims

1. A method for producing an iron melt (80), preferably an iron melt (80) having a carbon content of 1 to 5% by mass, from an iron oxide-containing material (30), wherein a reducing gas (90) containing at least hydrogen and optionally also containing a carbon carrier is fed into a reduction reactor (20) containing an iron oxide-containing material (30) for pre-reduction, Features The iron oxide-containing material (30) comprises at least 35 mass % of sintered ore, and the reducing gas (90) contains at least 60 volume % of hydrogen H2, and adding the solid pre-reduction product obtained in the pre-reduction from the reduction reactor (20) to the melting device (40) optionally through the silo device (60), and there a processing is carried out which comprises at least the following steps: - energy supply for producing the melt, wherein the energy supply is substantially carried out by electricity, - reducing at least a portion of the amount of iron oxides contained in the solid pre-reduction product, The treatment optionally also includes adjusting the carbon content in the melt.

2. The method according to claim 1, characterized in that: The prereduction is carried out at least up to a metallization degree of 70%, preferably at least 80%, very particularly preferably at least 85%.

3. The method according to claim 1 or 2, characterized in that: This is carried out in the reduction reactor (20) at a heating rate of at least 5°C / min, preferably at least 10°C / min, particularly preferably at least 12°C / min.

4. The method according to any one of the preceding claims, characterized in that The particle size of the sinter is 5 mm to 40 mm, particularly preferably 8 mm to 32 mm, very particularly preferably 10 mm to 25 mm, including the limits of the range, with a screening efficiency in accordance with ISO 4701, 2008, of up to 5%.

5. The method according to any one of the preceding claims, characterized in that As for the particle stability of the sintered ore, the results of the RDI test conducted on the sintered ore sample according to the third edition of ISO 4696-1 on September 1, 2015 show that the content of particles with a particle size of less than 3.15 mm is less than or equal to 30%.

6. A method according to any one of the preceding claims, characterised in that The basicity B2 of the sintered ore is greater than 1.

7. The method according to any of the preceding claims, wherein the iron oxide-containing material (30) is fed into the reduction reactor (20) in an input zone, characterized in that It is input substantially uniformly across the cross-sectional area of ​​the input region.

8. The method according to any of the preceding claims, wherein the solid pre-reduction product obtained in the pre-reduction is removed from the reduction reactor (20) in a removal zone, characterized in that It is removed in the form of a surface by the cross-sectional area of ​​the removed area.

9. The method according to any of the preceding claims, wherein the reducing gas (90) is introduced into the reduction reactor (20) in an introduction zone, characterized in that It is introduced substantially uniformly across the cross-sectional area of ​​the introduction region.

10. The method according to any one of the preceding claims, characterized in that The solid pre-reduction product obtained in the pre-reduction is fed from the reduction reactor (20) to the melting device (40) through the silo device (60), wherein the silo device (60) serves as a gas pressure valve.

11. Method for producing steel, wherein the production of steel is based on an iron melt (80) produced according to any one of claims 1 to 10.

12. A reduction reactor (20) for pre-reduction of an iron oxide-containing material containing at least 35% by mass of sintered ore, designed as a reduction shaft, characterized in that: The reduction shaft has - an input area (A) for inputting iron oxide-containing material (30); a removal zone (B) for removing the solid pre-reduction product obtained in the pre-reduction, - an introduction region (C) for introducing the reducing gas (90), wherein the reduction shaft is designed as a cone below the introduction region (C), with a wall angle of less than 20°, preferably less than 10° to the vertical, wherein it narrows from the introduction region toward the removal region (B).

13. The reduction reactor (20) according to claim 12, characterized in that: The reduction shaft is designed above the introduction region (C) in a substantially conical shape, with a wall angle of less than 3° to the vertical, preferably a wall angle of at least 1° to the vertical, and it widens toward the introduction region (C).

14. An apparatus for carrying out the method according to the invention for producing an iron melt (80), characterized in that: It includes - A reduction reactor (20) for direct reduction of an iron oxide-containing material (30) according to any one of claims 12 to 13, - a melting device (60), - a metering device (50) for feeding solid products of the direct reduction process into the melting device (60).

15. The device according to claim 14, characterized in that The apparatus comprises means (70) for adjusting the carbon content.

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