Process and metallurgical vessel for the direct reduction of ores

Abstract

The invention relates to a method for the direct reduction of ores, in particular iron, non-ferrous, or fine ores, in a metallurgical vessel (1) having a receiving container (2) provided with a refractory lining (3). In order to enable the direct reduction in an improved ecological manner, the invention provides that the metallurgical vessel (1) has at least one integrated electrical heating element (4) in the form of an electrical resistance heater, wherein the refractory lining (3) is temporarily heated by the at least one electrical heating element (4). Furthermore, the invention relates to a metallurgical vessel for the direct reduction of ores.

Description

[0001] The invention relates to a process for the direct reduction of ores, in particular ferrous, non-ferrous, or fine ores, in a metallurgical vessel comprising a receiving container provided with a refractory lining. Furthermore, the invention relates to a metallurgical vessel for the direct reduction of ores.

[0002] The direct reduction of ores represents an alternative to the traditional blast furnace process for producing crude steel from ore. This alternative is particularly interesting from the perspective of protecting the atmosphere from carbon dioxide. In direct reduction, a metallurgical vessel (furnace) is filled with ores, using carbon monoxide and hydrogen to extract oxygen from the ore, thus producing sponge iron.

[0003] It is common practice to use gas burners in direct reduction, which typically use natural gas as the fuel. This is particularly true for drying or preheating the refractory lining or wear lining of metallurgical vessels (i.e., vessels used in metallurgical processes). Drying takes place in the lining area or workshop, but also directly at the metallurgical plant.

[0004] The disadvantage of this approach is that drying or preheating results in an undesirably high level of CO2 emissions, which pollutes the environment.

[0005] Furthermore, unwanted water emissions are generated by the combustion of natural gas. The water is absorbed by the refractory mass and can later diffuse into the semi-finished products. This has a negative impact on the quality of the material being produced.

[0006] Furthermore, there is a risk of localized heating (so-called “hot spot”), which can lead to cracks in the refractory mass and consequently to increased wear.

[0007] Gas burners cannot be used because they cause undesirable side effects, particularly a reduction in the purity of the semi-finished product. This is particularly true for the direct reduction of ores.

[0008] WO 2022 / 029298 A1 discloses a pouring nozzle or pouring manifold that can be heated with an electric heating element. EP 3 473 733 B1 discloses a melting pot in which two areas are separated from each other by a weir. It is mentioned that, in the production of sponge iron, heating can be achieved using electrical energy, in particular by an electric arc; electric heaters are also mentioned in this context.

[0009] The invention is based on the object of developing a process of the type mentioned above in such a way that direct reduction becomes possible in an improved, environmentally friendly manner. In particular, the drying and preheating of the metallurgical vessel used should be carried out without the generation of greenhouse gases.

[0010] The solution to this problem by the invention is characterized in that the metallurgical vessel has at least one integrated electrical heating element in the form of an electrical resistance heater, wherein the refractory lining is temporarily heated by the at least one electrical heating element.

[0011] The metallurgical vessel may have a wear lining on the refractory lining, which is also heated by the at least one electrical heating element.

[0012] According to one embodiment of the method, the metallurgical vessel is heated with at least one electric heating element before the ore is introduced. Thus, the focus here is on heating the vessel.

[0013] Heating can take place before the ore is introduced until a predetermined dryness level is reached in the metallurgical vessel, particularly in the refractory lining or wear lining. In this case, achieving the desired dryness level is particularly relevant.

[0014] It can also be provided that the metallurgical vessel is heated with at least one electrical heating element during the direct reduction, i.e. in the actual production process.

[0015] The heating is preferably carried out in a controlled or regulated manner to a predetermined temperature of a point in the metallurgical vessel or of the material contained in the metallurgical vessel.

[0016] The proposed metallurgical vessel for the direct reduction of ores comprises a receiving container which is provided with a refractory lining, wherein according to the invention at least one electrical heating element in the form of an electrical resistance heater is integrated in the metallurgical vessel, which is designed to heat the refractory lining.

[0017] Again, a wear lining can be arranged on the refractory lining.

[0018] Preferably, control or regulating means are arranged to control or regulate the at least one electrical heating element such that a predetermined temperature is maintained at a location in the metallurgical vessel or in the material contained in the metallurgical vessel. In this case, at least one temperature sensor is preferably arranged on or in the metallurgical vessel, which is connected to the control or regulating means.

[0019] The invention thus provides electrical drying, preheating and / or heating of the metallurgical container and in particular its refractory material in direct reduction plants or furnaces.

[0020] The electric resistance heating can be integrated into the refractory lining itself or into the area between the metal casing (receiving vessel) and the refractory lining.

[0021] This allows for different operating modes in the direct reduction plant or in the direct reduction furnace: First, the permanent refractory lining can be dried after relining the refractory lining. The moisture in the lining must be removed before its subsequent use in direct reduction. For this purpose, the electrical resistance heating is operated via appropriate control units, power circuits, and converters. The lining is dried according to a predefined program (predefined temperature profile over time). Temperature control can be implemented so that the temperature in the vessel, measured by a sensor (particularly a thermocouple), follows the required temperature profile.

[0022] To dry a wear lining, which is applied over the permanent lining and from which moisture must also be removed, the electric resistance heater can be used in a similar way. Here, too, it is recommended to specify a profile for the temperature progression and its control. The wear lining is then heated by heat transfer from the refractory lining, which in turn is heated by the electric resistance heater. Temperature sensors (particularly thermocouples) located in the refractory lining then also provide information about the temperature of the wear lining.

[0023] In preparation for reduction operations, the metallurgical vessel can also be preheated using the electric resistance heater, ensuring that the refractory lining or wear lining reaches the desired temperature before production begins. Here, too, a desired temperature profile or target temperature can be precisely achieved using control.

[0024] Finally, electrical resistance heating can also be used in the production process of the direct reduction vessel or furnace. Again, a predetermined temperature is preferably controlled, which is measured by a sensor in the metallurgical vessel. Electrical heating enables precise maintenance of the desired or required temperature of the ore grain to be processed. The aim is to set a desired melting temperature in the metallurgical vessel. The determination of the actual temperature can also be supported by model calculations or linked to them. In particular, various temperature measurements can be taken into account using a model calculation and integrated into the control concept.

[0025] The integrated electrical resistance heating in the system or furnace in question allows the aforementioned measures to be carried out alternatively or additionally.

[0026] The drying of the permanent lining or the wear lining, i.e. the refractory lining or lining, can already be carried out during delivery or in the preparation workshop.

[0027] The preheating of the metallurgical vessel or the refractory lining or lining can take place immediately before the start of the process (which then takes place directly at the plant).

[0028] Temperature control can be carried out in the metallurgical vessel or furnace, which is then carried out on the plant during the reduction process.

[0029] The proposed approach offers several advantages compared to previously known solutions: The use of electric resistance heating during the drying of refractory linings and wear linings, as well as during the preheating of the metallurgical vessel in direct reduction vessels or furnaces, and then also during the production process, allows for precise maintenance of the reduction temperature within a defined range. The temperature can be kept precisely constant. For this purpose, a control system is advantageously used to maintain the temperature in the vessel or furnace at a setpoint.

[0030] This results in an improved quality of the reduction products compared to previously known solutions.

[0031] Sticking or caking of the ore grains to be processed in the container can be prevented in an improved manner.

[0032] The drawing illustrates an embodiment of the invention. The sole figure schematically shows a metallurgical vessel (furnace) in which direct reduction of ores takes place.

[0033] The figure shows the metallurgical vessel 1, which has a receiving container 2 (made of steel) which is provided with a refractory lining 3 inside the vessel 1.

[0034] Electrical heating elements 4 are integrated in the vessel 1, which can be arranged, for example, between the outer shell of the receiving container 2 and the refractory lining 3.

[0035] What is not shown is that a wear lining may be applied to the refractory lining 3 inside the vessel.

[0036] The electrical heating elements 4 are connected to a control or regulating means 5. A temperature sensor 6 is located inside the vessel 1, which can measure the temperature T of the material located in the vessel 1. The measured temperature T is transmitted to the control or regulating means 5. The control or regulating means 5 then control or regulate the electrical heating elements 4 such that a desired temperature or a desired temperature profile over time is achieved in the vessel 1, in the refractory lining 3, or in the material located in the vessel 1.

[0037] Vessel 1 is filled with ore E and the known direct reduction process is carried out.

[0038] The proposed approach enables climate-neutral production, as gas combustion can be avoided, thus reducing CO2 emissions. Likewise, unwanted water emissions during gas combustion can be avoided. This results in relatively uniform heating of the metallurgical vessel and thus of the ores being processed. This prevents cracks in the refractory material caused by hot spots and reduces wear.

[0039] The electric resistance heating allows for precise temperature control and thus the maintenance of constant temperature conditions, which leads to improved reduction conditions. This improves the quality of the semi-finished products produced.

[0040] The advantage is that the proposed concept can be used for drying, preheating and heating the container. List of reference symbols: 1 metallurgical vessel (furnace) 2 receiving containers 3 refractory lining 4 electric heating element 5 Tax or regulatory means 6 Temperature sensor T Temperature E Ore QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 2022 / 029298 A1

[0008] EP 3 473 733 B1

[0008]

Claims

[1] Method for the direct reduction of ores, in particular of iron, non-ferrous or fine ores, in a metallurgical vessel (1) which has a receiving vessel (2) which is provided with a refractory lining (3), characterized by , that the metallurgical vessel (1) has at least one integrated electric heating element (4) in the form of an electric resistance heater, wherein the refractory lining (3) is heated temporarily by the at least one electric heating element (4). [2] Method according to claim 1, characterized by , that the metallurgical vessel (1) has a wear lining on the refractory lining (3), which is heated by the at least one electric heating element (4). [3] Method according to claim 1 or 2, characterized by , that the metallurgical vessel (1) is heated with the at least one electric heating element (4) before the ore is introduced. [4] Method according to claim 3, characterized by , that the heating takes place before the ore is introduced, until a predetermined drying state is reached in the metallurgical vessel (1), in particular in the refractory lining (3) or in the wear lining. [5] Method according to any one of claims 1 to 4, characterized by , that the metallurgical vessel (1) is heated by the at least one electric heating element (4) during the direct reduction process. [6] Method according to any one of claims 1 to 5, characterized by , that the heating is controlled or regulated to a predetermined temperature (T) of a point of the metallurgical vessel (1) or of the material located in the metallurgical vessel (1). [7] Metallurgical vessel (1) for the direct reduction of ores, in particular of iron, non-ferrous or fine ores, which has a receiving vessel (2) which is provided with a refractory lining (3), in particular for carrying out the process according to any one of claims 1 to 6, characterized by , that at least one electrical heating element (4) in the form of an electrical resistance heater is integrated in the metallurgical vessel (1), which is designed to heat the refractory lining (3). [8] Metallurgical vessel according to claim 7, characterized by , that a wear lining is arranged on the refractory lining (3). [9] Metallurgical vessel according to claim 7 or 8, characterized by, that control or regulating means (5) are arranged to control or regulate the at least one electrical heating element (4) so ​​that a predetermined temperature (T) is present at a point in the metallurgical vessel (1) or in the material located in the metallurgical vessel. [10] Metallurgical vessel according to claim 9, characterized by , that at least one temperature sensor (6) is arranged on or in the metallurgical vessel (1) which is connected to the control or regulating means (5).

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