DE102023206511A1 - Cascade vessel arrangement, method for degassing and/or refining a molten metallic composition and metallurgical plant for producing a molten metallic composition - Google Patents

Abstract

The present application relates to a 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 an outlet opening in its bottom (11). (12) for a melt pool (13) of the accumulating degassed and/or refined molten metallic composition.

Description

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.

Electric steel production, particularly using direct reduction technology, is becoming increasingly important due to its lower CO2 footprint. In direct reduction technology, iron ore is not melted, but is reduced directly in the solid state to metallic iron, which is then used in the form of a so-called DRI (“Direct Reduced Iron”) or in the form of HBI (“Hot Briquetted Iron”) in electric steel production. Such processes and systems are basically known from the state of the art. For example, the WO 2017/207472 A1 a process and a plant for producing liquid pig iron from such a directly reduced iron product (DRI), which is subsequently melted in an electric arc furnace (EAF).

The liquid pig iron produced using this route is usually subjected to secondary metallurgical treatment before casting and then to vacuum treatment. The primary aim 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 in the art for this purpose.

However, such processes require very high investment costs. In addition, these processes require their own processing time in the ongoing production process, which increases the overall production time accordingly and leads to high operating costs.

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

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

Description of the Invention

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.

The cascade container arrangement according to the invention is intended for degassing and/or refining a molten metallic composition, wherein the composition can then be provided to a continuous casting plant. The cascade intermediate container arrangement, which is preferably intended for use in a metallurgical plant, comprises a degassing container for degassing and/or refining a pouring stream comprising the molten metallic composition, as well as a separately formed intermediate container arranged downstream of the degassing container, via which the degassed and/or refined molten metallic composition can be provided to the continuous casting plant, wherein the degassing container 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 melt bath of the accumulating degassed and/or refined molten metallic composition.

In an inventive manner, a solution in the form of a cascade container arrangement and a solution in the form of a plant for degassing and/or refining a molten metallic composition is proposed, which combines the process of vacuum treatment and the subsequent direct provision of the degassed and/or refined molten metallic composition to the continuous casting plant. Because the cascade container arrangement is integrated into a continuous casting plant, the technically complex transport of the ladle from the conventional degassing This has a particularly beneficial effect on the process times, which can be reduced by up to one hour per ladle. In addition to the associated significant reduction in operating costs, the investment costs can also be significantly reduced. Furthermore, the risk of contamination of the melt through the introduction of hydrogen and possibly nitrogen and/or oxygen is greatly reduced. In addition, sequential casting of several ladles is made possible.

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 meaningful manner and can define further embodiments of the invention. In addition, the features specified in the claims are specified and explained in more detail in the description, with further preferred embodiments of the invention being presented.

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).

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).

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

The term "metallic raw material" in the sense of the present invention is understood to mean a directly reduced iron product (DRI product) which has an iron content of at least 75.0% by weight. In a preferred embodiment, the directly reduced iron product (DRI product) can have an iron content of at least 80.0% by weight, more preferably an iron content of at least 85.0% by weight. This can basically be fed to the melting unit in hot form as an HDRI 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 melting unit, for example via a conveyor device under a protective atmosphere.

The term "metallic material" in the context of the present invention is understood to mean a material which is formed from a non-ferrous metallic material. The non-ferrous metallic material can preferably be selected from the series 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% by weight.

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.

In an advantageous further development, the degassing container has a shadow tube at its outlet opening, which extends into the intermediate container arranged underneath. This is typically provided with a slide, via which the outlet opening of the degassing container can be opened and/or closed.

In order to enable the degassed and/or refined molten metallic composition to be metered 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 bath of the accumulating degassed and/or refined molten metallic composition. The intermediate container can preferably be designed in such a way that the at least one outlet opening can be closed or opened in a regulated and/or controllable manner using a stopper and/or slide valve.

In order to enable variable distance and height adjustment between the degassing vessel 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 docking the ladle to the sealing unit creates a temporary vacuum-tight connection, i.e. essentially for the duration of the emptying of the degassed and/or refined molten metallic composition. The sealing unit can be designed such that it seals the outlet nozzle of the ladle, the entire ladle slide, or at least part or the entire ladle bottom, or a connection flange of the Spatially encompasses the pan. In this respect, it can advantageously be provided that the pan has a connecting flange, for example on the outer cylinder surface.

Furthermore, the sealing unit can have a connection flange, which optionally includes a sealing agent, such as a high-temperature-resistant seal. The connection flange can also be water-cooled in order to cool the sealing agent that may be present. In addition to this, the pan can also preferably include a connection flange, possibly water-cooled, via which the pan can be connected in a vacuum-tight manner to the inlet opening of the degassing container.

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

According to a further advantageous embodiment variant, the degassing container 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.

• i) Bereitstellen einer Pfanne, die mit einer schmelzflüssigen metallischen Zusammensetzung befüllt ist;
• ii) Fluten eines Entgasungsbehälters der erfindungsgemäßen Kaskaden-Behälteranordnung mit einem Inertgas, wie beispielsweise Argon;
• iii) Andocken der Pfanne an den Entgasungsbehälter;
• iii) Evakuieren des Entgasungsbehälters auf ein Druckniveau von mindestens kleiner 100 mbar, vorzugsweise auf ein Druckniveau von mindestens kleiner 10 mbar;
• iv) Entleeren der Pfanne unter Vakuum, derart, dass ein schmelzflüssiger Gießstrahl innerhalb der Entgasungsvorrichtung ausgebildet wird;
• v) Entgasen und/oder Raffinieren des schmelzflüssigen Gießstrahls innerhalb des Entgasungsbehälters mittels Vakuums; und
• vi) Einleiten der entgasten und/oder raffinierten schmelzflüssigen metallischen Zusammensetzung in den Zwischenbehälter unter atmosphärischen Bedingungen, sobald ein vordefinierter Füllstand innerhalb des Entgasungsbehälters erreicht wurde.

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 container 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 pan 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 jet is formed within the degassing device;
• v) degassing and/or refining the molten casting stream within the degassing vessel by means of vacuum; and
• (vi) introducing the degassed and/or refined molten metallic composition into the intermediate vessel under atmospheric conditions once a predefined filling level within the degassing vessel has been reached.

Advantageously, the degassed and/or refined molten metallic composition is introduced into the intermediate container via a shadow pipe. Since the intermediate container is not shielded from the environment, the melt can be easily drained into the intermediate container as soon as a defined fill level is reached in the degassing container.

In an advantageous embodiment variant, 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 has been reached within the intermediate container, and after the predefined fill level in the intermediate container has been reached, the pouring stream is then 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.

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 the height difference between the two filling levels in the containers is at least 1.4 m.

fiqure designation

• 1 eine Ausführungsvariante der erfindungsgemäßen Kaskaden-Behälteranordnung in einer schematischen Darstellung.

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 to 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 size relationships shown 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:

• 1 a variant of the cascade container arrangement according to the invention in a schematic representation.

In 1 a variant embodiment of the cascade container arrangement 1 according to the invention is shown, 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.

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

The molten metallic composition is then subjected to secondary metallurgical treatment in the subsequent electrically operated secondary metallurgical unit 4, which can be designed, for example, in the form of a ladle furnace. The transport between the respective stations usually takes place via a ladle 6.

The molten metallic composition then treated by secondary metallurgy, hereinafter referred to as melt, is then fed to the cascade container arrangement 1, in which it can be degassed and/or refined under vacuum and then fed directly to a continuous casting plant 7.

This includes the 1 The cascade container arrangement 1 shown comprises a degassing container 8 which can be moved in the horizontal plane (shown by the horizontal arrow) and which is partially lined with refractory material, in particular at the points which can come into contact with the hot melt. The degassing container 8 has an inlet opening 10 arranged in its degassing container roof 9, through which the melt is fed to the cascade container arrangement 1. The degassing container 8 also comprises an outlet opening 12 arranged in its vacuum container bottom 11, through which the melt present as a melt bath 13 is then fed from the degassing container 8 to an intermediate container 15 via a shadow pipe 14 after the degassing and/or refining process. As can be further seen from the illustration, the degassing container 8 also comprises an inlet 16 through which an inert gas can be supplied to the degassing container, as well as an outlet 17 for generating a vacuum.

The intermediate container 15, also known in technical jargon as a distributor or distribution channel or tundish, comprises a container trough 18 with an opening through which the shadow pipe 14 of the degassing container 8 arranged above extends into it, 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 melt bath 13 in the intermediate container 15, to be metered into the continuous casting plant 7, the intermediate container 15 is provided with an adjustable and/or controllable plug 21 and/or an adjustable and/or controllable slide 22, via which it can then be closed and opened.

Again 1 As can also be seen, the degassing container 8 also has a vacuum connection 23, via which the degassing container 8 can be connected to the pan 6 in a vacuum-tight manner. For this purpose, the vacuum connection 23 in the present case comprises an elastic sealing unit 24 designed in the form of a metallic bellows, via which the pan 6 can then be connected to the degassing container 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 pan 6 and to the degassing container 8 is possible.

The process sequence is explained below using a possible design 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 connected to the cascade vessel arrangement 1, as shown in 1 The supply of 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. The pressure level in the degassing vessel 8 causes the pouring stream to fan out, as can be seen from the 1 so that degassing and/or refining of the molten pouring stream is achieved. During this process phase, the outlet opening 12 is closed until a predefined fill level is reached. Once the predefined fill level in the degassing vessel 8 has been reached, degassing is interrupted. The outlet opening 12 is opened, whereupon the melt is drained by supplying inert gas into the degassing vessel 8 through the shadow pipe 14 into the intermediate vessel 15, which is not shielded from the ambient conditions. In 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 within the intermediate vessel 15 is reached. Once the predefined fill level in the intermediate vessel 15 has been reached, the supply of inert gas is stopped again and the degassing vessel is evacuated again, so that the pouring stream is degassed and/or refined again under vacuum. In this process stage, the melt present as melt bath 13 continues to be drained into the intermediate container 15. 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, the melt present in the degassing container as melt bath 13 is drained into the intermediate container 15 and simultaneously fed from the intermediate container 15, in which it is also present as melt bath 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.

reference sign

1

cascade tank arrangement

2

metallurgical plant

3

melting unit

4

secondary metallurgical unit / ladle furnace

5

metallic raw and/or material / DRI product

6

Pan

7

continuous casting plant

8

degassing tank

9

degassing tank ceiling

10

entrance opening

11

degassing tank bottom

12

outlet opening of the degassing tank

13

melt pool

14

shadow tube

15

intermediate container

16

inlet

17

outlet

18

container tray

19

container tray bottom

20

outlet opening of the intermediate container

21

Plug

22

slider

23

vacuum connection

24

sealing unit / bellows

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• WO 2017/207472 A1 [0002]

Claims (15)

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 outlet opening (12) for a Melt bath (13) of the accumulating degassed and/or refined molten metallic composition. 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 underneath. 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 melt bath (13) of the accumulating degassed and/or refined molten metallic composition. 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). Cascade container arrangement (1) according to claim 4 , wherein the sealing unit (24) has a connecting flange. Cascade container arrangement (1) according to one of the preceding claims, wherein the degassing container (8) is movable at least in the horizontal plane. 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) which is 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 filling level within the degassing vessel (8) has been reached. procedure 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). procedure 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 the predefined fill level in the intermediate container (15) has been reached, the pouring stream is then degassed and/or refined again by means of vacuum in a second process stage. procedure according to claim 9 , wherein inert gas is supplied to the degassing vessel (8) during the first process stage. procedure according to claim 9 or 10 , wherein the degassed and/or refined molten metallic composition is only introduced into the continuous casting plant (7) after a predefined filling level has been reached in the two containers (8, 15). procedure according to claim 11 , whereby the height difference between the two filling levels is at least 1.4 m. 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. Metallurgical plant (2) after 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). Metallurgical plant (2) after 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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