Iron melt from sintered body

Abstract

The present invention relates to a process for producing an iron melt (80) from an iron oxide-containing material (30), in which a reducing gas (90) containing at least hydrogen is supplied to 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 body, and the reducing gas (90) comprises at least 60% by volume of hydrogen H2. A solid pre-reduced product obtained in the pre-reduction step is supplied from the reduction reactor (20) to a melting device (40), where the solid pre-reduced product is subjected to a treatment including introducing energy to produce at least a melt, the energy being introduced substantially in the form of electricity, and reducing at least a portion of the iron oxide contained in the solid pre-reduced product. The treatment may also include setting a carbon content in the melt. The reduction reactor (20) for the pre-reduction is embodied as a reduction shaft having a feed zone (A) for feeding the iron oxide-containing material (30), a withdrawal zone (B) for withdrawing the solid pre-reduced product obtained in the pre-reduction step, and an introduction zone (C) for introducing the reducing gas (90), the reduction shaft being conical below the introduction zone (C) with a wall angle of less than 20° to the vertical and tapering from the introduction zone towards the withdrawal zone (B). A system for carrying out the process according to the invention comprises: a reduction reactor (20) for the direct reduction of the iron oxide-containing material; a melting device (60); and a feed device (50) for feeding the melting device (60) with the solid product obtained by the direct reduction process.

Description

[Technical Field]

[0001] The present application relates to a process and apparatus for producing an iron melt from an iron oxide material, including a sintered body, in which a reducing gas comprising at least hydrogen is used to pre-reduce the iron oxide material and the pre-reduction product is melted. [Background technology]

[0002] It is known that metal oxide materials, such as iron oxide materials (e.g., lump ores, oxide briquettes, or pellets), can be reduced using a reducing gas. For example, by direct reduction with a reducing gas in a reduction unit, e.g., in a reduction shaft. In conventional pre-reduction and direct reduction processes currently used on an industrial scale, the reducing gas, other than hydrogen, is mainly based on carbon (e.g., carbon monoxide CO and / or methane CH4) from natural gas. This therefore generates large amounts of carbon dioxide CO2, which is undesirable, particularly for environmental policy reasons.

[0003] It is also known that the blast furnace route is used to reduce iron oxide material (such as sinter) to liquid pig iron. This involves reduction with carbonaceous gases, mainly based on coal or coke, and this production route results in significant CO2 emissions. Sinter is produced from iron ore-based sinter feedstock in sinter plants, which are generally located near the blast furnace. In the steel industry, sinter plants supply the blast furnace with material known as blast furnace sinter or steelmaking sinter. The processes for producing sintered products in sintering plants in the steel industry are well known, see, for example, "Agglomeration of Iron Ores", D.F. Ball, J. Dartnell, J. Davison, A. Grieve, R. Wild, 1973 edition, 388 pages, page 34, or "Handbuch fur Agglomerationstechnik" [Handbook of Agglomeration Technology], Gerald Heinze, 2000 edition, 261 pages, page 102, Wiley-VCH Verlag GmbH, Weinheim, or "Ullmann's Encyclopedia of Industrial Chemistry", 28029 pages, "Iron" chapter, page 15 ff., 2006 Wiley-VCH Verlag GmbH, Weinheim. It is based on the establishment of bonds between particles in a mixture of feedstocks containing at least fine iron ore, aggregates (e.g., lime chips, dolomite, quicklime), and fuel such as coke breeze, and by oxidative roasting combined with surface melting of the particles, obtains solid agglomerates as a product.

[0004] A known way to reduce CO2 emissions in the reduction of metal oxide-containing materials is to use hydrogen (H2) as the reducing gas. Here, hydrogen can be used as the only reducing gas or in combination with other gases, such as carbon from natural gas or based on coal or coke. The greater the proportion of CO2-neutral hydrogen (H2) in the reducing gas, the lower the CO2 emissions. Depending on the availability of natural gas or other gases and hydrogen, their contribution to the reducing gas can be varied by mixing different amounts.

[0005] The more hydrogen available, the greater the extent to which climate-related carbon-based contributions from natural gas or other gases can be avoided.

[0006] It would be desirable to operate existing plants and procedures where the reducing gas is based partially on hydrogen and mostly on carbon from natural gas or other gases, with an increased proportion of hydrogen in the reducing gas, which would allow for flexibility in responding to the availability of natural gas or other gases and hydrogen, and would allow for the utilization of investments already made in the plant.

[0007] At least until sufficient hydrogen is available to use a reducing gas based entirely on hydrogen, the reducing gas will need to be based on carbon and hydrogen from natural gas or other gases.

[0008] It is also desirable when blast furnace operation is discontinued and replaced with another direct reduction or smelting reduction process in an integrated metallurgical plant, so that existing plant can still be utilized in the reduction process after the switchover, allowing investments already made in the plant to continue to be utilized after the switchover. [Prior art documents] [Non-patent literature]

[0009] [Non-Patent Document 1] “Agglomeration of Iron Ores”, DFBall, J. Dartnell, J. Davison, A. Grieve, R. Wild, 1973 edition, 388 pages, page 34 [Non-patent document 2] “Handbuch fur Agglomerationstechnik” [Handbook of Agglomeration Technology], Gerald Heinze, 2000 edition, 261 pages, page 102, Wiley-VCH Verlag GmbH, Weinheim [Non-patent document 3] “Ullmann's Encyclopedia of Industrial Chemistry”, 28029 pages, “Iron” chapter, page 15 ff., 2006 Wiley-VCH Verlag GmbH, Weinheim Summary of the Invention [Problem to be solved by the invention]

[0010] The object of the present invention is to provide a process and an apparatus that allows carrying out a pre-reduction with a hydrogen-rich reducing gas proceeding from an iron oxide material containing sinter apart from the blast furnace route and providing a pig iron-like material. [Means for solving the problem]

[0011] The purpose of this is to A process for producing an iron melt having a carbon content of preferably 1 to 5% by mass from an iron oxide material, 1. A process in which a reducing gas containing at least hydrogen and optionally a carbon support is passed to a reduction reactor containing an iron oxide material for pre-reduction, the iron oxide material comprises at least 35% by weight of the sintered body; the reducing gas comprises at least 60% by volume of hydrogen H2; The solid pre-reduced product obtained by pre-reduction from the reduction reactor is fed to a melting device, optionally via a bunker device; The solid pre-reduced product is subjected in the melter (40) to at least the following steps: - supplying energy to generate a melt, the supplied energy being electrical in nature; - reducing at least a portion of the iron oxide present in the solid pre-reduced product; and subjected to a treatment comprising This process optionally also includes adjusting the carbon content in the melt. A process characterized by This is achieved by:

[0012] This process is carried out without a blast furnace, i.e., without the central component of the conventional blast furnace route, meaning that a blast furnace is not involved in the reduction of the iron oxide material. This process is carried out without a blast furnace. Therefore, this process avoids the conventional blast furnace route. The reduction reactor for pre-reduction is not a blast furnace. Pre-reduction refers to reduction in which iron oxide is still present in the final solid product. The reduction reactor for pre-reduction is a reduction shaft, and the reduction with reducing gas is carried out in a reduction shaft containing a fixed bed of iron oxide material. The iron oxide material is introduced into the reduction shaft at the top and passes therethrough by gravity, during which the reduction reaction occurs.

[0013] The reducing gas contains at least 60% by volume of hydrogen as a reducing component, or may consist of hydrogen. The reducing gas also optionally contains one or more gaseous carbon carriers as additional reducing components. The carbon carriers are, for example, carbon monoxide (CO) or methane (CH4) provided by, introduced with, or produced from natural gas.

[0014] Hydrogen can be, for example, green, blue, gray, turquoise, or pink. These "colors" refer here to colors related to the underlying production method. Green hydrogen is produced, for example, by electrolysis of water using electricity from renewable energy sources, by gasification or fermentation of biomass, or by steam reforming of biogas. A common factor in green hydrogen production modes is that the production is CO2-free. In the case of blue hydrogen, the CO2 formed during production is stored to prevent it from entering the atmosphere, for example, when CO2 is sequestrated. Turquoise hydrogen is produced by removing the carbon dioxide produced. Pink hydrogen is hydrogen produced using nuclear power. Gray hydrogen is produced from fossil fuels, such as natural gas, by steam reforming, and the CO2 produced is primarily released into the atmosphere.

[0015] Other hydrogen colors are possible.

[0016] Mixtures of hydrogen having one or more of these "colors" are also possible.

[0017] When a carbon support is present as an additional reducing component, the ratio of the proportions of hydrogen and carbon support in the reducing gas can be varied, for example, by combining different amounts in the preparation of the reducing gas, e.g., by increasing the proportion of hydrogen in the reducing gas.

[0018] The reducing gas is the gas introduced into the reduction reactor, and its composition and temperature are those at the time of introduction. Before the reducing gas has this composition and temperature, it is in the form of a precursor that is used as the basis for preparing the reducing gas. The preparation may include, for example, the addition of further components, heating, or modification. The preparation may also be carried out by a chemical reaction that occurs in the precursor without external intervention, for example, a chemical reaction that changes the chemical composition or temperature. The change in the preparation may change the proportion of hydrogen in the reducing gas.

[0019] The iron melt produced according to the present invention preferably has a carbon content of 1.0% to 5% by mass. Because it primarily consists of iron (it is a liquid pig-iron-like product), the term "liquid pig-iron-like product" in this application is used synonymously with the term "iron melt" to refer to the iron melt produced according to the present invention. From the perspective of the steel production process (e.g., LD / BOF), the liquid pig-iron-like product, preferably having a carbon content of 1.0% to 5% by mass, is "similar" to pig iron from a blast furnace, meaning that it can be processed in much the same way as pig iron from a blast furnace, via the blast furnace route of steel production, excluding the blast furnace. The higher the carbon content, the more cooled scrap can be used for further processing into steel, and the greater the amount of cooled scrap reduces the CO2 emissions per unit amount of steel produced from the liquid pig-iron-like product produced according to the present invention.

[0020] The carbon content of the liquid pig-iron-like product is more preferably at least 2.0% by mass, most preferably at least 2.5% by mass. The carbon content of the liquid pig-iron-like product is more preferably at most 4.7% by mass, most preferably at most 4.5% by mass.

[0021] In a preferred embodiment, the solid pre-reduced product obtained in the pre-reduction is applied to the melter via a bunker device, which facilitates the dosing of the solid pre-reduced product into the melter.

[0022] The energy supply is essentially, preferably entirely, electrically, i.e., electrical energy. By "essentially" in this context is meant at least 75%, preferably at least 80%. Such an electrical energy supply does not produce CO2, which has a beneficial effect on the CO2 balance of the process.

[0023] In an advantageous embodiment, the carbon content in the melt is adjusted using a supplied carbon support.

[0024] These may be solid and / or liquid and / or gaseous carbon carriers. Carbon carriers may include, for example, coal powder, coke powder, graphite powder, or natural gas. Carbon carriers may also be partially or wholly derived from carbon-neutral sources, such as biomass, such as charcoal, which improves the CO balance of the process. Carbon carriers may be introduced, for example, via a probe or submerged nozzle.

[0025] However, it is possible that the solid pre-reduced product already contains sufficient carbon that no adjustment of the carbon content is made during processing.

[0026] In an advantageous embodiment, the carbon content in the melt is adjusted using supplied oxygen: if the carbon content exceeds the desired value of the iron melt, the oxygen supply can be used to oxidize or reduce the carbon content, for example, the carbon in the melt can react to give off CO, which can be released from the melt in gaseous form.

[0027] In an advantageous embodiment, reduction of at least a portion of the iron oxide present in the solid pre-reduced product is carried out by means of the provided carbon support.

[0028] These may be solid and / or liquid and / or gaseous carbon carriers. Carbon carriers may include, for example, coal powder, coke powder, graphite powder, or natural gas. Carbon carriers may also be partially or wholly derived from carbon-neutral sources, such as biomass, such as charcoal, which improves the CO balance of the process. [Effects of the Invention]

[0029] The use of hydrogen as the reduction gas allows pre-reduction or direct reduction to reduce or avoid carbon dioxide (CO2) emissions. Compared to carbon supports, which generate carbon dioxide (CO2) during pre-reduction or direct reduction, the higher the hydrogen content in the reduction gas, the more carbon dioxide (CO2) emissions can be avoided, which is desirable for environmental reasons.

[0030] The use of sintered bodies also makes it possible to utilize existing investments in sinter plants made for conventional blast furnace route operations for processes that do not involve a blast furnace, which is desirable from both an economic and environmental standpoint.

[0031] The iron oxide material comprises at least 35% by mass of sinter. For a definition of sinter, also known as blast furnace sinter or iron-making sinter, and a description of its production in the steel industry, reference is made to the above explanation in the introduction to this application. In the context of this application, the term "sinter" is primarily used, although it is also possible to use the terms "blast furnace sinter" or "iron-making sinter".

[0032] The feedstocks used to produce the sintered body are, for example, fine iron ore or a mixture of fine iron ores with a particle size of 0.001 to 10 mm, such as aggregates in the form of lime chips, dolomite, or quicklime, and, if necessary, feed-back materials from the steel production process, such as blast furnace fines, rolling scale, sintered powder, or BOF powder. The fuels used are, for example, coke fines, anthracite, graphite, or biochar with a particle size of 0.01 to 10 mm, preferably 0.1 to 5 mm, and more preferably 1 to 3 mm. The resulting sintered body is a solid, porous, easily reducible mass with a particle size of, for example, 0.1 to 75 mm, preferably 3 to 50 mm, and particularly preferably 5 to 35 mm.

[0033] The use of sinter as a component of the fixed-bed burden in reduction shafts is known in principle, see, for example, Shi Ben-jing et al., "Reducing process of sinter in COREX shaft furnace and influence of sinter proportion on reduction properties in composite burden," J. Cent. South Univ. (2021) 28:690-698, DOI 10.1007 / s11771-021-4638-5. However, due to fragmentation reasons, it is not recommended to increase the sinter content of the burden beyond 25%-30% by mass.

[0034] In contrast, the process of the present invention is carried out with a proportion of sinter in the iron oxide material of the charge of at least 35% by weight, preferably at least 50% by weight, particularly preferably more than 50% by weight, most preferably at least 60% by weight. As the inventors of the present application have found, the proposed process with a high hydrogen content in the reducing gas allows stable process control even in previously undesirable ranges and allows for a significantly improved utilization of existing sinter plant infrastructure.

[0035] The remainder of the charge is e.g. -lump ore, -oxide briquettes, -pellet The iron oxide material may be from the group

[0036] The use of an essentially electric melting unit allows for the production of steel products comparable to existing downstream processes, which is not possible with EAF.

[0037] Pre-reduction is preferably carried out to a metallization of at least 70%, preferably at least 80%, and most preferably at least 85%. The higher the metallization, the less post-reduction is required in the subsequent processing steps of the solid pre-reduced product obtained in the pre-reduction. The term "post-reduction" refers to the reduction of at least a portion of the iron oxide still present in the solid pre-reduced product. In post-reduction using carbon from fossil resources, for example, it is particularly preferred to reduce the need for post-reduction if the post-reduction results in carbon dioxide CO emissions.

[0038] Alternatively, if the carbon for post-reduction is derived from biomass, it is possible to reduce CO2 emissions by using carbon for post-reduction.

[0039] The metallization (also known as metallization degree MG) expressed in % is found from the ratio of metallic iron Fe met to the total iron Fe tot in the sample as follows: MG[%]=Fe met / Fe tot*100 Fe met: Metallic iron in the sample (mass percentage m%) Fe tot: Total amount of iron present in the sample (mass percentage m%)

[0040] Since the solid product of the pre-reduction (ie the solid pre-reduction product) still contains iron oxide, its metallization or degree of metallization MG is less than 100%.

[0041] When the temperature of the iron oxide material introduced into the reduction reactor falls below the temperature of the reducing gas, it is heated in the reduction reactor by the reducing gas.

[0042] It is preferred to carry out the process in the reduction reactor at a heating rate of at least 5°C / min, preferably at least 10°C / min, more preferably at least 12°C / min, to minimize problems arising from remaining within the critical temperature range for the transformation of hematite to magnetite and subsequently to wüstite, and therefore for reasons of compressive strength and bulk material pressure.

[0043] The maximum achievable heating rate depends on the physical boundary conditions during heating. The upper limit of the heating rate is 50°C / min, preferably less than 30°C / min.

[0044] The temperature of the reducing gas is preferably above 750° C., more preferably above 800° C., most preferably above 850° C. The temperature of the reducing gas is preferably below 1050° C., more preferably below 1020° C., and particularly preferably below 1000° C.

[0045] For example, if an iron oxide material having a temperature of 20° C. is introduced into the reduction reactor, the reduction gas should heat it to a temperature 600° C. higher within 60 minutes.

[0046] The particle size of the sintered body according to ISO 4701 3rd Edition 2008 10 01 is preferably in the range of 5 mm to 40 mm, more preferably in the range of 8 mm to 32 mm, and most preferably in the range of 10 mm to 25 mm, inclusive, with a maximum sieving efficiency of 5%. Sieving efficiency is also referred to as sieving quality.

[0047] Preferably, the particle stability of the sintered body is such that the RDI test performed on a sample of the sintered body in accordance with ISO 4696-1, 3rd Edition, 2015-09-01, shows that the percentage of particles with a particle size of less than 3.15 mm is 30% or less. Particle stability is determined by the RDI test in accordance with ISO 4696-1, 3rd Edition, 2015-09-01, where RDI stands for Reduction Degradation Index. Such particle stability makes it possible to avoid unstable process control due to poor gas passage and particle collapse during pre-reduction.

[0048] It is preferred if the sintered body has a basicity B2 of greater than 1. The basicity B2 is preferably at most 2.5, more preferably at most 2.2.

[0049] The basicity B2 is given by the ratio of the weight percentages of calcium oxide CaO and silicon dioxide SiO2 in the sample.

[0050] Basicity B2 = CaO / SiO2 (weight percentages in the sample).

[0051] This means that the solid pre-reduced product obtained in the pre-reduction can be efficiently used in subsequent processing steps having corresponding basicity requirements, and no measures need to be taken to adjust the basicity during the subsequent processing steps or during the transfer of the solid pre-reduced product from the reduction reactor to the melter.

[0052] The slag obtained in the melter preferably has a basicity B2 within the range of values ​​from 0.9 to 1.2, inclusive of the two limits.

[0053] Slag is produced in the melter, and the slag obtained in the melter preferably has a basicity B4 in the range of values ​​from 0.8 to 1.2, inclusive of the two limits.

[0054] Basicity B4 is given as the ratio of the sum of the weight percentages of calcium oxide CaO and magnesium oxide MgO to the sum of the weight percentages of silicon dioxide SiO2 and aluminum oxide Al2O3 in the sample.

[0055] Basicity B4 = (CaO + MgO) / (SiO2 + Al2O3) (weight percentage of each in the sample).

[0056] The iron oxide material is preferably introduced into the reduction reactor within the input region substantially uniformly across the cross-sectional area of ​​the input region.

[0057] Although the goal is a uniform distribution, operational variations will still occur during the course of the operation, and this is encompassed by the expression "substantially uniform."

[0058] What is meant by "uniformly across the cross-sectional area" is the opposite of uniformly at one precise location or limited sub-region of the cross-sectional area; thus, the loading should not be at one precise location or limited sub-region of the cross-sectional area so as to result in an accumulation of material at that location or limited sub-region; instead, the loading should be approximately uniform across the cross-sectional area such that the level of material across the cross-sectional area is approximately constant across the entire region.

[0059] The relevant cross-sectional area is the cross-sectional area perpendicular to the direction of movement of the iron oxide material as it passes through the reduction reactor, from the input region for the inlet of the iron oxide material to the discharge region for the discharge of the solid pre-reduced product obtained in the pre-reduction.

[0060] Nearly uniform loading results in near-uniform passage of gas through the fixed bed, and therefore near-uniform reduction of the fixed bed. This contributes to avoiding local differences in the degree of metallization and stability of the fixed bed particles. This contributes to near-uniform transfer of iron oxide material through the reduction reactor. While the goal is uniform transfer, operational variations still occur during the course of operation, and this is encompassed by the term "nearly uniform." Thus, localized material blockages are nearly avoided, and while the goal is to completely avoid localized material blockages, localized material blockages may still occur during operation for operational reasons, and this is encompassed by the term "nearly avoided."

[0061] The dosing is preferably carried out in such a way that segregation of the iron oxide material due to its particle size and density is substantially avoided and a uniform gas distribution is ensured over the entire cross section. Although the aim is to avoid this completely, segregation will nevertheless occur in the course of operation for operational reasons, and this is encompassed by the expression "substantially uniform".

[0062] This can be achieved by a gimbal mounted dispensing chute, for example as shown in WO2006056350, or as shown in WO2017055419.

[0063] The solid pre-reduced product obtained in the pre-reduction is removed from the reduction reactor in a removal zone. Preferably, removal is performed two-dimensionally across the entire cross-sectional area of ​​the removal zone, for example, via two or more delivery screws that substantially cover the cross-sectional area of ​​the removal zone. What is meant by "two-dimensionally across the entire cross-sectional area" is the opposite of two-dimensionally at one precise location or a limited subregion of the cross-sectional area; therefore, removal should not be at one precise location or a limited subregion in the cross-sectional area to result in an enhanced reduction in the amount of material at that location or that limited subregion; instead, removal should be approximately uniform across the entire cross-sectional area, such that the material level across the entire cross-sectional area is approximately constant across the entire region.

[0064] The two-dimensional removal across the entire cross-sectional area of ​​the removal zone contributes to a substantially uniform transition of the iron oxide material through the reduction reactor. Localized material blockages are therefore substantially avoided. The substantially uniform transition results in a substantially uniform passage of gas through the fixed bed and therefore a substantially uniform reduction in the fixed bed. This contributes to the reduction or avoidance of localized differences in the degree of metallization and stability of the fixed bed particles. The cross-sectional area in question is perpendicular to the direction of movement of the iron oxide material from the input zone for inputting the iron oxide material to the output zone for removing the solid pre-reduced material obtained during pre-reduction.

[0065] The reducing gas is introduced into the reduction reactor at the introduction region. The reducing gas is preferably introduced into the reduction reactor substantially uniformly across the entire cross-sectional area of ​​the introduction region. By "uniformly across the entire cross-sectional area" is meant the opposite of uniformly at one precise location or limited subregion of the cross-sectional area. In this context, "substantially uniform" means that the reducing gas is introduced not only at one point or limited subregion, such as the edge of the reduction reactor, but also beyond the edge toward or at the center of the reduction reactor. This can be achieved, for example, by a gas distribution pipe that extends into the interior of the reduction reactor or traverses the interior, for example, diametrically or, in the case of a circular cross-sectional area of ​​the interior, as a secant.

[0066] The cross-sectional area is perpendicular to the direction of movement of the iron oxide material from an input region for inputting the iron oxide material to an output region for removing the solid products of the direct reduction process.

[0067] The substantially uniform introduction across the entire cross-sectional area results in a substantially uniform passage of gas through the fixed bed, and therefore a substantially uniform reduction of the fixed bed. This contributes to avoiding local differences in the degree of metallization and stability of the fixed bed particles. This contributes to a substantially uniform transfer of the iron oxide material through the reduction reactor. Therefore, localized material blockages are substantially avoided.

[0068] For example, introduction can be achieved as shown in WO2013156548.

[0069] In a preferred embodiment, the solid pre-reduced product obtained in the pre-reduction is fed from the reduction reactor to the melter via a bunker device, which acts as a pressure lock.

[0070] This means that the pressure of the atmosphere surrounding the solid product is changed, which is done in a bunker device that can act as a pressure lock, preventing the escape of reducing gas from the reduction reactor to the melter and vice versa.

[0071] The present application further provides a process for producing steel, the steel being produced based on the iron melt produced according to the present invention.

[0072] In an advantageous embodiment, the LD / BOF process is used to produce steel.

[0073] This is preferably done using scrap to the extent of at least 10% by weight, preferably at least 15% by weight, more preferably at least 20% by weight.

[0074] The present application relates to a reduction reactor for pre-reduction of iron oxide materials, designed as a reduction shaft, comprising: The reduction shaft, - a dosing area for dosing iron oxide material; an unloading zone for unloading the solid pre-reduction product obtained in the pre-reduction; an introduction region for introducing a reducing gas; and The reduction shaft is of conical design below the inlet zone with a wall angle to the vertical of less than 20°, preferably less than 10°, narrowing from the inlet zone towards the outlet zone. The present invention further provides a reduction reactor characterized by:

[0075] If the longitudinal axis of the reduction shaft is arranged vertically, the input area is in the upper area of ​​the reduction shaft and the discharge area is in the lower area of ​​the reduction shaft. The introduction area is between the input area and the discharge area. Below the introduction area, the reduction shaft is conical and narrows towards the discharge area, so that the diameter decreases towards the discharge area.

[0076] The conical design with a small wall angle prevents the formation of bridges and therefore uneven transition through the reduction shaft. A nearly uniform transition, also referred to as bulk flow in reference to the bulk product, is desirable. Localized material blockages are therefore largely avoided. A nearly uniform transition results in a nearly uniform passage of gas through the fixed bed, and thus a nearly uniform reduction in the fixed bed. This contributes to avoiding localized differences in the degree of metallization and the stability of the fixed bed particles. It has been found that the conical design with a small wall angle of the reduction shaft below the introduction zone eliminates the occurrence of problems with uniform removal of the solid product. Therefore, stable process control can be achieved even with the sintered content of iron oxide material and the hydrogen content of the reduction gas according to the process of the present invention.

[0077] The process of the present invention can be carried out using such a reduction reactor.

[0078] The reduction shaft above the introduction zone preferably has a generally conical design with a wall angle of at least 3° to the vertical, preferably at least 1° to the vertical, widening toward the introduction zone. In this context, "generally conical" means that there may be conical as well as cylindrical sections. This design prevents the formation of bridges and material over the voids, thus preventing uneven transition through the reduction shaft. When the longitudinal axis of the reduction shaft is positioned vertically, the introduction zone is located in the upper region of the reduction shaft, and the removal zone is located in the lower region of the reduction shaft. The introduction zone is located between the introduction zone and the removal zone.

[0079] The reduction reactor preferably comprises a dosing device for dosing the iron oxide material, which is suitable for approximately uniform dosing over the entire cross-sectional area of ​​the reduction shaft in the dosing region.

[0080] For example, the dosing device may comprise a gimbal type dispenser as shown in WO2006056350.

[0081] The cross-sectional area is perpendicular to the direction of movement of the iron oxide material as it moves through the reduction shaft from an input area for input of the iron oxide material directly to an output area for output of the solid products of the reduction process, which is also perpendicular to the longitudinal axis of the reduction shaft.

[0082] The dosing device is preferably suitable for dosing while substantially avoiding segregation of the iron oxide material due to particle size and / or particle density of the iron oxide material.

[0083] The dosing device preferably comprises an open-loop and / or closed-loop control device designed for flexible closed-loop and / or open-loop control of the dosing.

[0084] The closed-loop control device can, for example, automatically utilize measurement data from a thermocouple suitable for ascertaining the gas temperature above the bed in the reduction shaft and measurement data from a thermocouple suitable for ascertaining the gas temperature in the bed in the reduction shaft for purposes of closed-loop control.

[0085] For example, an operator can define a distribution profile, which is then implemented under open-loop and / or closed-loop control.

[0086] The removal zone preferably has a delivery device suitable for two-dimensional removal over the entire cross-sectional area of ​​the reduction shaft in the removal zone, for example, the delivery device comprises a number of delivery screws that substantially cover the cross-sectional area of ​​the removal zone.

[0087] The cross-sectional area is perpendicular to the direction of movement of the iron oxide material from an input region for inputting the iron oxide material to an output region for outputting the solid product of the direct reduction process, which is also perpendicular to the longitudinal axis of the reduction shaft.

[0088] The introduction region preferably has an introduction device suitable for substantially uniform introduction over the entire cross-sectional area of ​​the reduction shaft in the introduction region.

[0089] For example, the introduction device may include a plurality of introduction tubes that substantially cover the cross-sectional area of ​​the withdrawal region.

[0090] The cross-sectional area is perpendicular to the direction of movement of the iron oxide material from an input region for inputting the iron oxide material to an output region for outputting the solid product of the direct reduction process, which is also perpendicular to the longitudinal axis of the reduction shaft.

[0091] The present application relates to a plant for carrying out the process of the present invention for producing iron melt, comprising: - a reduction reactor for the direct reduction of iron oxide materials according to claim 12 or 13; a melting device; - an application device for introducing the solid process product from the direct reduction into the melting device; To be prepared Further provided is a plant characterized by:

[0092] The melting apparatus comprises a device for supplying electrical energy.

[0093] In a preferred embodiment, the applicator device comprises a bunker device.

[0094] In a preferred embodiment, the application device comprises a bunker device that functions as a pressure lock.

[0095] In a preferred embodiment, the plant for carrying out the process of the present invention also includes a device for adjusting the carbon content, such as a device for adding carbonaceous material to the melter or a device for adding oxygen to the melter. Thus, the effect of the device for adjusting the carbon content is, for example, to add carbonaceous material to the melter and / or to reduce the carbonaceous material present in the melter, for example, in the solid product introduced into the melter and / or the iron melt. The reduction can be carried out, for example, by reaction with oxygen, and the resulting gas can be extracted from the iron melt or the melter.

[0096] There may be an application device for applying admixtures to the melter, for example to set the desired basicity of the slag obtained in the melter.

[0097] The present application further provides a signal processing device having a machine-readable program code, characterized in that it comprises open-loop and / or closed-loop control commands for carrying out the process of the present invention. It also provides a signal processing device for carrying out the process according to any one of claims 1 to 11.

[0098] The present application further provides machine-readable program code for a signal processing device, the program code comprising open-loop and / or closed-loop control commands for causing the signal processing device to perform the process of the present invention. There is further provided a computer program product comprising commands for the signal processing device, which, when executed by the program for the signal processing device, causes the signal processing device to perform the process of any one of claims 1 to 11.

[0099] The present application further provides a storage medium having stored thereon a machine-readable program code of the present invention, as well as a storage medium having stored thereon a computer program for performing the process according to any one of claims 1 to 11.

[0100] The invention will now be described by way of example with reference to some schematic drawings. [Brief explanation of the drawings]

[0101] [Figure 1] 1 is a schematic diagram showing a plant of the present invention; [Figure 2] FIG. 1 is a schematic diagram showing a reduction reactor of the present invention for pre-reduction. DETAILED DESCRIPTION OF THE INVENTION [Example]

[0102] 1 is a schematic diagram showing a plant 10 having a reduction reactor 20 for the direct reduction of iron oxide material 30, a melter 40, and an application device 50 for introducing the solid product produced in the reduction reactor 20 into the melter 40. A bunker device 60, which functions as a pressure lock and is included in the application device 50, is optional (and therefore shown in dashed lines). A device 70 for adjusting the carbon content is likewise optional (and therefore shown in schematic form in dashed lines), e.g., a device for adding carbonaceous material to the melter 40, or a device for adding oxygen to the melter 40.

[0103] For example, to produce iron melt 80 from iron oxide material 30 containing more than 50% by mass of sintered body, reducing gas 90 containing more than 60% by volume of hydrogen H2 is supplied to reduction reactor 20 containing iron oxide material 30 for pre-reduction. For example, the particle size of the sintered body is in the range of 8 mm to 32 mm. Its basicity B2 is preferably greater than 1.

[0104] When the temperature of the iron oxide material 30 introduced into the reduction reactor 20 falls below the temperature of the reducing gas 90, it is heated by the reducing gas 90 in the reduction reactor 20, where a preferred heating rate is, for example, 10°C / min.

[0105] The solid pre-reduced product obtained in the pre-reduction reactor 20 still contains iron oxide, which is preferably metallized to a degree of at least 70%. If necessary, it is transferred from the reduction reactor 20 to the melting device 40 via an optional bunker device 60. An iron melt having a carbon content of preferably 1 to 5% by mass is produced therefrom in the melting device 40. The process for producing the iron melt 80 includes at least the supply of energy for producing the melt and the reduction of at least a portion of the iron oxide present in the solid pre-reduced product. If necessary, the carbon content of the melt can also be adjusted using an optional carbon content adjustment device 70.

[0106] The energy is essentially supplied by electricity.

[0107] Processing in melter 40 forms slag 100, the basicity B2 of which is preferably between 0.9 and 1.2. For clarity, optional application devices for applying admixture to melter 40 are not shown.

[0108] 2 is an enlarged schematic view of a reduction reactor 20 for the pre-reduction of iron oxide material 30. It is designed as a reduction shaft having an input area A for inputting the iron oxide material 30, an output area B for outputting the solid pre-reduction product obtained in the pre-reduction, and an input area C for introducing a reducing gas 90.

[0109] The reduction shaft 20 is of conical design below the introduction area C, with a wall angle of less than 20° to the vertical, narrowing from the introduction area C towards the withdrawal area B.

[0110] In the illustrated embodiment, the reduction shaft above the introduction area is conical with a wall angle of 1° to 3° to the vertical, and is shown here exaggerated and not to scale.

[0111] References list Patent documents International Publication No. 2006056350 International Publication No. 2017055419 International Publication No. 2013156548 Non-patent literature “Reducing process of sinter in COREX shaft furnace and influence of sinter proportion on reduction properties in composite burden”, Shi Ben-jing et al.in J.Cent.South Univ.(2021)28:690-698, DOI 10.1007 / s11771-021-4638-5 ISO4701 3rd Edition 2008 10 01 ISO4696-1 3rd edition 2015-09-01 “Agglomeration of Iron Ores”, DFBall, J. Dartnell, J. Davison, A. Grieve, R. Wild, edition 1973, 388 pages, page 34 “Handbuch fur Agglomerationstechnik”, Gerald Heinze, 2000 edition, 261 pages, page 102, Wiley-VCH Verlag GmbH, Weinheim “Ullmann's Encyclopedia of Industrial Chemistry”, 28029 pages, “Iron” chapter, page 15ff, 2006 Wiley-VCH Verlag GmbH, Weinheim [Explanation of symbols]

[0112] 10 Plant 20 Reduction reactor 30 Iron oxide materials 40 Melting Device 50 Applicator 60 Bunker equipment 70 Apparatus for adjusting carbon content 80 Iron Melt 90 Reducing Gas 100 slugs A input area B Extraction area C Introduction area

Claims

1. A process for producing an iron melt (80) from an iron oxide material (30) preferably having a carbon content of 1 to 5% by mass, comprising:

1. A process in which a reducing gas (90) containing at least hydrogen and optionally a carbon support is passed to a reduction reactor (20) containing an iron oxide material (30) for pre-reduction, comprising: the iron oxide material (30) comprises at least 35% by weight of a sintered body; The reducing gas (90) is at least 60% by volume of hydrogen H ２ Including, The solid pre-reduced product obtained by pre-reduction from the reduction reactor (20) is fed to a melting device (40), optionally via a bunker device (60); The solid pre-reduced product is subjected in the melter (40) to at least the following steps: - supplying energy to produce a melt, said energy being electrical in nature; - reducing at least a portion of the iron oxide present in said solid pre-reduced product; and subjected to a treatment comprising The treatment optionally also includes adjusting the carbon content in the melt. characterized in that process.

2. 2. The process according to claim 1, characterized in that the pre-reduction is carried out to a metallization of at least 70%, preferably at least 80%, most preferably at least 85%.

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

4. 4. The process according to any one of claims 1 to 3, characterized in that the particle size of the sintered body is in the range of 5 mm to 40 mm, more preferably in the range of 8 mm to 32 mm, most preferably in the range of 10 mm to 25 mm, inclusive, with a sieve efficiency of up to 5% according to ISO 4701 version from 2008.

5. 5. The process according to claim 1, wherein the grain stability of the sintered body is characterized in that the result of an RDI test carried out on a sample of the sintered body according to ISO 4696-1 3rd Edition 2015-09-01 is that the proportion of grains with a grain size of less than 3.15 mm is 30% or less.

6. 6. The process according to claim 1, wherein the sintered body has a basicity B2 greater than 1.

7. 7. The process of claim 1, wherein the iron oxidized material (30) is introduced into the reduction reactor (20) at an input zone, the iron oxidized material (30) being introduced substantially uniformly across the cross-sectional area of ​​the input zone.

8. 8. The process according to claim 1, wherein the solid pre-reduced product obtained in the pre-reduction is removed from the reduction reactor (20) in a removal zone, the solid pre-reduced product being removed over the entire two-dimensional cross-sectional area of ​​the removal zone.

9. 9. The process of claim 1, wherein the reducing gas (90) is introduced into the reduction reactor (20) at an introduction region, the reducing gas (90) being introduced substantially uniformly across the cross-sectional area of ​​the introduction region.

10. 10. The process according to any one of claims 1 to 9, characterized in that the solid pre-reduced product obtained in the pre-reduction is fed from the reduction reactor (20) to the melter (40) via a bunker device (60), the bunker device (60) acting as a pressure lock.

11. 11. A process 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 the pre-reduction of an iron oxide material comprising at least 35% by weight of sintered bodies, designed as a reduction shaft, comprising: The reduction shaft is - a dosing area (A) for dosing said iron oxide material (30); an unloading zone (B) for unloading the solid pre-reduction product obtained in said pre-reduction; an introduction zone (C) for introducing a reducing gas (90); and The reduction shaft is of conical design below the introduction zone (C) with a wall angle of less than 20°, preferably less than 10°, to the vertical, narrowing from the introduction zone towards the removal zone (B). characterized in that A reduction reactor (20).

13. 13. The reduction reactor (20) according to claim 12, characterized in that the reduction shaft above the introduction zone (C) is of a generally conical design with a wall angle of less than 3° to the vertical, preferably at least 1° to the vertical, widening towards the introduction zone (C).

14. A plant for carrying out the process of the invention for producing iron melt (80), comprising: - a reduction reactor (20) according to claim 12 or 13 for the direct reduction of iron oxide material (30); a melting device (60), - an application device (50) for introducing the solid process product from said direct reduction into said melting device (60); Equipped with A plant characterized by:

15. 15. Plant according to claim 14, characterized in that it comprises a device (70) for adjusting the carbon content.

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