Cascade container arrangement, method for degassing and / or refining a molten metal composition and metallurgical installation for producing a molten metal composition

Abstract

The present application relates to a cascade container arrangement (1) for degassing and / or refining a molten metal composition and providing same to a continuous casting plant (7), wherein the cascade intermediate container arrangement (1) is preferably intended for use in a metallurgical installation (2), comprising: a degassing container (8) for degassing and / or refining a casting stream comprising the molten metal composition; and a separate intermediate container (15), arranged downstream of the degassing container (8), via which the degassed and / or refined molten metal composition can be provided to the continuous casting plant (7), wherein the degassing container (8) has: an entry opening (10) which is arranged in the degassing container cover (9) and has a vacuum connection (23) for vacuum-tight connection to a ladle (6); an inlet (16) for an inert gas; an outlet (17) for generating a vacuum; and, in the degassing container base (11), an exit opening (12) for a molten bath (13) of the collected degassed and / or refined molten metal composition.

Description

[0001] Cascade vessel arrangement, method for degassing and / or refining a molten metallic composition and metallurgical plant for producing a molten metallic composition

[0002] The present invention relates to a cascade container arrangement for degassing and / or refining a molten metallic composition, which can be provided after a degassing and / or refining step of a continuous casting plant, a method for degassing and / or refining a molten metallic composition, preferably by means of the cascade container arrangement according to the invention, and a metallurgical plant for producing a molten metallic composition, which can be provided after a degassing and / or refining step of a continuous casting plant.

[0003] Electric steel production, particularly using direct reduction technology, is gaining increasing importance due to its lower carbon footprint. In direct reduction technology, iron ore is not melted but directly reduced in its solid state to metallic iron, which is then used in electric steel production in the form of so-called DRI ("Direct Reduced Iron") or HBI ("Hot Briquetted Iron"). Such processes and systems are generally known from the prior art. For example, WO 2017 / 207472 A1 discloses a process and system for producing liquid pig iron from such a directly reduced iron product (DRI), which is subsequently melted in an electric arc furnace (EAF).

[0004] The molten pig iron produced using this route is typically subjected to secondary metallurgical treatment before casting, followed by a vacuum treatment. The primary goal of such vacuum treatment is to reduce the hydrogen, nitrogen, and oxygen content in the melt. The so-called Ruhrstahl-Heraeus process ("RH process") and vacuum degassing have long been known for this purpose.

[0005] Page 1 However, such processes require very high investment costs. Furthermore, these processes require their own processing time during ongoing production, which increases the overall production time accordingly and leads to high operating costs.

[0006] Against this background, the present invention is based on the object of providing an apparatus for degassing and / or refining a molten metallic composition which is improved compared to the prior art, in particular to provide an apparatus with which the treatment time for degassing and / or refining a molten metallic composition in the production process can be reduced.

[0007] In a further aspect, the object of the present invention is to provide a process for degassing and / or refining a molten metallic composition which is improved compared to the prior art, in particular to provide a process with which the treatment time for degassing and / or refining a molten metallic composition in the production process can be reduced.

[0008] Description of the invention

[0009] According to the invention, the object is achieved according to a first aspect by a cascade container arrangement having the features of patent claim 1 and by a metallurgical plant having the features of patent claim 13.

[0010] The cascade container arrangement according to the invention is intended for degassing and / or refining a molten metallic composition, which composition can then be provided to a continuous casting plant.The cascade intermediate vessel arrangement, which is preferably intended for use in a metallurgical plant, comprises a degassing vessel for degassing and / or refining a pouring stream comprising the molten metallic composition, and a separately formed intermediate vessel arranged downstream of the degassing vessel, via which the degassed and / or refined molten metallic composition can be made available to the continuous casting plant, wherein the degassing vessel has an inlet opening arranged in its roof with a vacuum connection for vacuum-tight connection to a ladle, an inlet for an inert gas, an outlet for generating a vacuum and in its bottom an outlet opening for a molten bath of the accumulating degassed and / or refined molten metallic composition.

[0011] In an inventive manner, a solution for degassing and / or refining a molten metallic composition is proposed in the form of a cascade container arrangement and a system in the form of a plant, which combines the vacuum treatment process with the subsequent direct provision of the degassed and / or refined molten metallic composition to the continuous casting plant. By integrating the cascade container arrangement into a continuous casting plant, the technically complex transport of the ladle from the conventional degassing device to the continuous casting plant can be eliminated. This has a particularly advantageous effect on process times, which can be reduced by up to one hour per ladle. In addition to the associated significant reduction in operating costs, investment costs can also be significantly lowered.Furthermore, this significantly reduces the risk of contamination of the melt due to the introduction of hydrogen, and possibly nitrogen and / or oxygen. Furthermore, it enables sequential casting of multiple ladles.

[0012] Further advantageous embodiments of the invention are specified in the dependent claims. The features listed individually in the dependent claims can be combined with one another in a technologically expedient manner and can define further embodiments of the invention. Furthermore, the features specified in the claims are further specified and explained in the description, where further preferred embodiments of the invention are presented.

[0013] The electrically operated melting unit can be in the form of an electric arc furnace (EAF), a submerged arc furnace (SAF) or an induction furnace (IF).

[0014] The electrically operated secondary metallurgical unit, on the other hand, can be designed in the form of a ladle furnace (LF) or an induction furnace (IF).

[0015] The pan may consist of a steel housing and / or be made of a composite material, in particular a glass fiber reinforced plastic (GRP).

[0016] The term "metallic raw material" in the context of the present invention refers to a directly reduced iron product (DRI product) which has an iron content of at least 75.0 wt.%. In a preferred embodiment, the directly reduced iron product (DRI product) can have an iron content of at least 80.0 wt.%, more preferably an iron content of at least 85.0 wt.%. This can generally be fed to the smelting unit in hot form as a DRI product, in cold form as a CDRI product, in hot briquette form as an HBI product and / or in particulate form, preferably with an average particle diameter of a maximum of 20.0 mm. Such a DRI product is typically produced in a direct reduction plant, as already described in the prior art, and can be fed directly to the smelting unit, for example via a conveyor system under a protective atmosphere.

[0017] For the purposes of the present invention, the term "metallic material" refers to a material formed from a non-ferrous metallic material. The non-ferrous metallic material can preferably be selected from the group comprising a nickel-based material, a cobalt-based material, a copper-based material, an aluminum-based material, and / or combinations thereof. Such materials are produced, for example, via galvanic manufacturing processes and have a purity of at least 98 wt.%.

[0018] Preferably, the degassing vessel and the intermediate vessel are at least partially lined with refractory material. Refractory materials known to those skilled in the art, such as Al2O3 (so-called sausages), can be used for this purpose.

[0019] In an advantageous development, the degassing vessel has a shroud at its outlet opening, which extends into the intermediate vessel located below it. This shroud is typically provided with a slide valve, via which the outlet opening of the degassing vessel can be opened and / or closed.

[0020] In order to enable dosing of the degassed and / or refined molten metallic composition into the continuous casting plant, it is preferably provided that the intermediate container has at least one closable outlet opening arranged in its base for a melt pool of the accumulating degassed and / or refined molten metallic composition. The intermediate container can preferably be designed such that the at least one outlet opening can be closed or opened in a regulated and / or controllable manner using a plug and / or slide valve. In order to enable variable distance and height adjustment between the degassing container and the ladle during operation, it is advantageously provided that the vacuum connection has an elastically designed sealing unit, via which the ladle can then be connected to it in a vacuum-tight manner.The sealing unit can preferably be prestressed by means such that, by docking the ladle to the sealing unit, a temporary vacuum-tight connection is created, i.e., a vacuum-tight connection that is essentially valid for the duration of the discharge of the degassed and / or refined molten metallic composition. The sealing unit can be configured such that it spatially encompasses the outlet nozzle of the ladle, the entire ladle slide, or at least part or all of the ladle base, or a connecting flange of the ladle. In this respect, it can advantageously be provided for the ladle to have a connecting flange, for example, on the outer cylinder surface.

[0021] Furthermore, the sealing unit can have a connecting flange, which optionally includes a sealing means, such as a high-temperature-resistant gasket. The connecting flange can also be water-cooled to cool any sealing means present. In addition, the ladle can also preferably include a connecting flange, optionally water-cooled, via which the ladle can be connected in a vacuum-tight manner to the inlet opening of the degassing vessel.

[0022] In a particularly advantageous embodiment, the elastically designed sealing unit is designed in the form of a metallic bellows.

[0023] According to a further advantageous embodiment, the degassing vessel can be designed to be movable at least in the horizontal plane, whereby the metallurgical plant can be used both conventionally without degassing and with continuous degassing in an inline process of pouring jet degassing.

[0024] In a further aspect, the present invention also relates to a method for degassing and / or refining a molten metallic composition, preferably by means of the cascade vessel arrangement according to the invention, wherein the molten metallic composition is provided after a degassing and / or refining step of a continuous casting plant. The method according to the invention comprises the steps: i) providing a ladle filled with a molten metallic composition; ii) flooding a degassing vessel of the cascade vessel arrangement according to the invention with an inert gas, such as argon; iii) docking the ladle to the degassing vessel; iii) evacuating the degassing vessel to a pressure level of at least less than 100 mbar, preferably to a pressure level of at least less than 10 mbar;iv) emptying the ladle under vacuum such that a molten pouring stream is formed within the degassing device; v) degassing and / or refining the molten pouring stream within the degassing vessel by means of vacuum; and vi) introducing the degassed and / or refined molten metallic composition into the tundish under atmospheric conditions once a predefined fill level within the degassing vessel has been reached.

[0025] Advantageously, the degassed and / or refined molten metallic composition is introduced into the tundish via a shroud. Since the tundish is not shielded from the environment, the melt can be easily drained into the tundish once a defined fill level is reached in the degassing vessel.

[0026] In an advantageous embodiment, the introduction of the degassed and / or refined molten metallic composition into the intermediate container according to step vi) is carried out in two process stages, such that the degassing process is suspended during a first process stage at least until a predefined fill level within the intermediate container has been reached, and after reaching the predefined fill level in the intermediate container, the pouring stream is subsequently degassed and / or refined again by means of a vacuum in a second process stage. In this context, it is preferably provided that inert gas is again supplied to the degassing container during the first process stage.

[0027] In a further advantageous embodiment, the degassed and / or refined molten metallic composition is only introduced into the continuous casting plant after a predefined filling level has been reached in the two containers, particularly preferably when a height difference between the two filling levels in the containers is at least 1.4 m.

[0028] Figure designation

[0029] The invention and the technical environment are explained in more detail below with reference to the figures. It should be noted that the invention is not intended to be limited by the exemplary embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and combine them with other components and findings from the present description and / or figures. In particular, it should be noted that the figures and in particular the illustrated proportions are only schematic. The same reference numerals denote the same objects, so that explanations from other figures can be used as a supplement if necessary. They show:

[0030] Fig. 1 shows a variant of the cascade container arrangement according to the invention in a schematic representation.

[0031] Figure 1 shows an embodiment variant of the cascade container arrangement 1 according to the invention, which in the present case forms part of a metallurgical plant 2, which comprises an electrically operated melting unit 3 and an electrically operated secondary metallurgical unit 4 arranged downstream of the melting unit 3.

[0032] In the electrically operated melting unit 3, which may be configured, for example, in the form of an electric arc furnace, a metallic raw material and / or material 5 is melted. This metallic raw material and / or material 5, for example, a DRI product, can also be melted as a mixture with other metal-containing and / or carbon-containing components, depending on the desired material quality to be cast.

[0033] In the subsequent electrically operated secondary metallurgical unit 4, which may be configured, for example, in the form of a ladle furnace, the molten metallic composition is then subjected to secondary metallurgical treatment. Transport between the respective stations typically takes place via a ladle 6. The molten metallic composition, subsequently treated by secondary metallurgy, hereinafter referred to as the melt, is then fed to the cascade vessel arrangement 1, where it can be degassed and / or refined under vacuum and then fed directly to a continuous casting plant 7.

[0034] For this purpose, the cascade container arrangement 1 shown in Figure 1 comprises a degassing container 8 which is movable in the horizontal plane (represented by the horizontal arrow) and which is partially lined with refractory material, particularly at the points that may come into contact with the hot melt. The degassing container 8 has an inlet opening 10 arranged in its degassing container ceiling 9, through which the melt is fed to the cascade container arrangement 1. Furthermore, the degassing container 8 comprises an outlet opening 12 arranged in its vacuum container base 11, through which the melt present as a molten bath 13 is then fed from the degassing container 8 via a shroud 14 to an intermediate container 15 after the degassing and / or refining process.As can be further seen from the illustration, the degassing vessel 8 also comprises an inlet 16 through which an inert gas can be supplied to the degassing vessel, as well as an outlet 17 for generating a vacuum.

[0035] The intermediate container 15, also known in technical jargon as a tundish, distributor, or tundish, comprises a container trough 18 with an opening through which the shroud 14 of the degassing container 8 arranged above extends, as well as with a closable outlet opening 20 arranged in its container trough base 19, which in turn is directly connected to the continuous casting plant 7. In order to enable the degassed and / or refined melt, which is also present as a molten bath 13 in the intermediate container 15, to be metered into the continuous casting plant 7, the intermediate container 15 is provided with a controllable and / or adjustable plug 21 and / or a controllable and / or adjustable slide valve 22, via which it can then be closed and opened.

[0036] As can also be seen from Figure 1, the degassing vessel 8 further comprises a vacuum connection 23, via which the degassing vessel 8 can be connected to the ladle 6 in a vacuum-tight manner. For this purpose, the vacuum connection 23 in this case comprises an elastic sealing unit 24 in the form of a metallic bellows, via which the ladle 6 can then be connected to the degassing vessel 8 in a vacuum-tight manner. The sealing unit 24 can, for example, be designed in such a way that a variable distance and height adjustment to the ladle 6 and the degassing vessel 8 is possible.

[0037] The process sequence is explained below using a possible embodiment variant. First, the degassing vessel 8 is flooded with an inert gas, for example argon, via the inlet 16 until it is almost free of ambient air. Then, the ladle 6 filled with the molten metallic composition is docked in a vacuum-tight manner to the cascade vessel arrangement 1, as shown in Figure 1. The supply of the inert gas is stopped. The degassing vessel 8 is evacuated via the outlet 17 to a pressure level of at least less than 100 mbar, preferably to a pressure level of at least less than 10 mbar. As soon as the specified pressure level in the degassing vessel 8 is reached, the emptying of the ladle 6 begins. Due to the pressure level present in the degassing vessel 8, the pouring stream is fanned out, as shown in Figure 1, so that degassing and / or refining of the molten pouring stream is achieved.During this process phase, the outlet opening 12 remains closed until a predefined fill level is reached. Once the predefined fill level in the degassing vessel 8 is reached, degassing is interrupted. The outlet opening 12 is opened, whereupon the melt is discharged by supplying inert gas into the degassing vessel 8 through the shadow tube 14 into the intermediate vessel 15, which is not shielded from the ambient conditions. During this process stage, in which the degassed and / or refined molten metallic composition is introduced into the intermediate vessel 15, the degassing process is suspended at least until a predefined fill level is reached within the intermediate vessel 15.Once the predefined fill level in the intermediate container 15 has been reached, the supply of inert gas is stopped again and the degassing container is evacuated again so that the pouring stream is degassed and / or refined again under vacuum. The melt present as molten pool 13 continues to be discharged into the intermediate container 15 during this process stage. At the same time, the melt is fed to the continuous casting plant 7. In this process stage, the pouring stream is thus degassed and / or refined on the one hand; the melt present in the degassing container as molten pool 13 is discharged into the intermediate container 15 and simultaneously fed from the intermediate container 15, where it is also present as molten pool 13, to the continuous casting plant 7, in particular the mold, so that a continuous melt flow is formed from the ladle 6 to the continuous casting plant 7, which is simultaneously degassed and / or refined in the degassing container 8.

[0038]

[0039] 1 Cascade tank arrangement

[0040] 2 metallurgical plant

[0041] 3 melting unit

[0042] 4 secondary metallurgical unit / ladle furnace

[0043] 5 metallic raw and / or material / DRI product

[0044] 6 pan

[0045] 7 Continuous casting plant

[0046] 8 degassing tanks

[0047] 9 Degassing tank ceiling

[0048] 10 Entrance opening

[0049] 11 Degassing tank bottom

[0050] 12 Outlet opening of the degassing tank

[0051] 13 Melt bath

[0052] 14 Shadow tube

[0053] 15 intermediate containers

[0054] 16 Entrance

[0055] 17 Outlet

[0056] 18 Container tray

[0057] 19 Container tray bottom

[0058] 20 Outlet opening of the intermediate container

[0059] 21 plugs

[0060] 22 sliders

[0061] 23 Vacuum connection

[0062] 24 Sealing unit / bellows

Claims

1. Cascade container arrangement (1) for degassing and / or refining a molten metallic composition and providing it to a continuous casting plant (7), wherein the cascade intermediate container arrangement (1) is preferably intended for use in a metallurgical plant (2), comprising: a degassing container (8) for degassing and / or refining a pouring stream comprising the molten metallic composition, and a separately formed intermediate container (15) arranged downstream of the degassing container (8), via which the degassed and / or refined molten metallic composition can be provided to the continuous casting plant (7), wherein the degassing container (8) has an inlet opening (10) arranged in its roof (9) with a vacuum connection (23) for vacuum-tight connection to a ladle (6), an inlet (16) for an inert gas,an outlet (17) for generating a vacuum and in its bottom (11) an exit opening (12) for a molten bath (13) of the accumulating degassed and / or refined molten metallic composition.

2. Cascade container arrangement (1) according to claim 1, wherein the degassing container (8) has a shadow tube (14) at its outlet opening (12) which extends into the intermediate container (15) arranged thereunder.

3. Cascade container arrangement (1) according to claim 1 or 2, wherein the Intermediate container (15) has at least one closable outlet opening (20) arranged in its bottom (19) for a molten bath (13) of the accumulating degassed and / or refined molten metallic composition.

4. Cascade container arrangement (1) according to one of the preceding claims, wherein the vacuum connection (23) has an elastically designed sealing unit (24) via which the pan (6) can be connected in a vacuum-tight manner to the degassing container (8).

5. Cascade container arrangement (1) according to claim 4, wherein the sealing unit (24) has a connecting flange.

6. Cascade container arrangement (1) according to one of the preceding claims, wherein the degassing container (8) is movable at least in the horizontal plane.

7. A method for degassing and / or refining a molten metallic composition and providing it to a continuous casting plant (7), preferably by means of a cascade container arrangement (1) according to one of the preceding claims, comprising the steps: i) providing a ladle (6) filled with a molten metallic composition; ii) flooding a degassing container (8) of a cascade container arrangement (1) according to one of the preceding claims with an inert gas; iii) docking the ladle (6) to the degassing container (8); iii) evacuating the degassing container (8) to a pressure level of at least less than 100 mbar, preferably to a pressure level of at least less than 10 mbar; iv) emptying the ladle (6) under vacuum such that a molten pouring jet is formed within the degassing device (8);v) degassing and / or refining the molten casting stream within the degassing vessel (8) by means of vacuum; and vi) introducing the degassed and / or refined molten metallic composition into the intermediate vessel (15) under atmospheric conditions as soon as a predefined fill level within the degassing vessel (8) has been reached.

8. The method according to claim 7, wherein the introduction of the degassed and / or refined molten metallic composition into the intermediate container (15) takes place via a shadow tube (14).

9. The method according to claim 7 or 8, wherein the introduction of the degassed and / or refined molten metallic composition into the intermediate container (15) according to step vi) takes place in two process stages, such that the degassing process is suspended during a first process stage at least until a predefined fill level within the intermediate container (15) has been reached, and after reaching the predefined fill level in the intermediate container (15), the pouring stream is then degassed and / or refined again by means of vacuum in a second process stage.

10. The method according to claim 9, wherein inert gas is supplied to the degassing vessel (8) during the first process stage.

11. The method according to claim 9 or 10, wherein the degassed and / or refined molten metallic composition is introduced into the continuous casting plant (7) only after a predefined fill level has been reached in the two containers (8, 15).

12. The method according to claim 11, wherein the height difference between the two filling levels is at least 1.4 m.

13. A metallurgical plant (2) for producing a molten metallic composition, which can be provided after a degassing and / or refining step of a continuous casting plant (7), comprising: i) at least one electrically operated melting unit (3) for melting a metallic raw material and / or work material (5); ii) at least one electrically operated secondary metallurgical unit (4) for secondary metallurgical treatment of the metallic raw material and / or work material (5) melted to form a molten metallic composition; and iii) a cascade container arrangement (1) for degassing and / or refining the molten metallic composition according to one of the preceding claims.

14. Metallurgical plant (2) according to claim 13, wherein the electrically operated melting unit (3) is designed in the form of an electric arc furnace (EAF), a submerged arc furnace (SAF) or an induction furnace (IF).

15. Metallurgical plant (2) according to claim 13 or 14, wherein the electrically operated secondary metallurgical unit (4) is designed in the form of a ladle furnace or an induction furnace (IF).

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