DE102019106016A1 - PROCESS AND EQUIPMENT FOR DECLACKING METALLURGICAL MELT - Google Patents

Abstract

The present invention provides a method and a device (10) for purification, with which both the purification and the metal recovery from the slag (60 ') can take place quickly and easily, the risk of slag fires also being reduced.

Description

The present invention relates to a method for deslagging metallurgical melts according to the preamble of claim 1 and a device for deslagging metallurgical melts according to the preamble of claim 6.

Metallurgical melts are created in order to obtain metals or alloys with the highest possible purity. Both raw materials and recycling materials can be used. Such metallurgical melts are produced, for example, in melting or casting furnaces, but also in ladles.

When metals are melted from their ores, as well as when metals or their alloys are melted under atmospheric or technological influence, slag is formed, which, depending on the melting technique and starting material, dross, dross, ash or larger Oxygen-induced oxidation are called burn-up. In addition to oxidic products, these slags can also contain impurities primarily adhering to the melt or process-related reaction products.

Melts must therefore be freed from such slags before they can be used further, ie "purged" or "scraped off". The problem here is that these slags are of lower density and therefore float on the melt, but have a higher melting point than the melt itself, which is why the slag lying on the melt is usually highly viscous, which means that melt components are included in the Slag favors. As a result, the formation of slag is always accompanied by a loss of melt.

There are several methods of removing the slag from the melt.

The DE 39 28 671 C2 describes a method in which a melting furnace has a barrier for slag and the slag is regularly drawn off by means of a slag pusher and tilting the entire furnace, whereby the melt separates from the slag. As an alternative to the slag pusher and tilting, a floating lifting device can also be used in conjunction with a slag pallet to automatically transfer the slag into a slag container (also known as a "bucket") when the furnace door is opened. To collect the slag behind the barrier, an electromagnetic stirrer is used to generate a flow. However, only small melting furnaces can be operated with this.

The DE 197 29 702 A1 describes a method for large melting furnaces, in which the slag floating on the melt is drawn off from the melt by means of a device for removing the slag in the form of a pull-off plate, which is arranged on a long movable arm, and is pulled over the bridge on the charging side of the melting furnace of the melting furnace is transferred to a slag container. An attempt is then made to recover at least part of the melt bound in the slag.

• Aluminium ist einer der wichtigsten Rohstoffe für innovative Industriezweige wie die Luft- und Raumfahrt sowie den Fahrzeugbau. Am grundsätzlichen Herstellungsprinzip aus dem Aluminiumerz Bauxit hat sich seit Ende des 19. Jahrhunderts nichts geändert. Mittels Elektrolyse wird es nach dem sogenannten „Hall Heroult Prozess“ bei 960 °C gewonnen. Die Gewinnung von Aluminium aus Erz hat große Nachteile, da problematische Reststoffe wie Rotschlamm anfallen. Weiterhin ist die Herstellung von Aluminium sehr energieintensiv.
• Recyceltes Aluminium hingegen braucht bei der Herstellung lediglich 5 % der Energie gegenüber der Gewinnung aus Erz. Außerdem fallen hierbei kaum noch giftige Rückstände an.

In the case of the production of aluminum melts, the situation is as follows:

• Aluminum is one of the most important raw materials for innovative industries such as aerospace and vehicle construction. The basic production principle from the aluminum ore bauxite has not changed since the end of the 19th century. It is obtained by electrolysis using the so-called “Hall Heroult process” at 960 ° C. The extraction of aluminum from ore has major disadvantages, as problematic residues such as red mud arise. Furthermore, the production of aluminum is very energy-intensive.
• Recycled aluminum, on the other hand, only needs 5% of the energy to manufacture it compared to extraction from ore. In addition, there are hardly any toxic residues.

The aluminum to be recycled is melted in melting furnaces and poured into various semi-finished products. When aluminum is melted down, impurities, overheating at certain points and the oxide layer on the starting material result in metal losses - aluminum dross. In Germany alone, around 40,000 tons of metal are lost every year. The aluminum dross consists essentially of aluminum oxide and aluminum. The metal content of the aluminum dross is 50 - 70%. The aluminum is bound in the Al2O3 framework like in a sponge.

The aluminum dross floats on the weld pool. At this point, the aluminum dross has an insulating effect and prevents further heat input into the weld pool. Furthermore, aluminum dross tends to burn if sufficient oxygen is available. For the reasons mentioned, it is therefore necessary to pull off the aluminum dross and remove it from the weld pool. Descaling machines are usually used for descaling. The descaling machine is positioned in front of the open melting furnace and a movable arm with a shield moves into the melting furnace. The shield is gently dipped into the weld pool and the aluminum dross will successively pulled in the direction of the furnace opening and initially placed on the furnace sleeper ("bridge"). The aim of depositing is that some of the liquid aluminum flows back into the melting furnace. The aluminum dross is then drawn into buckets in front of the melting furnace.

There are different methods for further processing aluminum dross. The aim of all processes is to prevent dross fires through rapid cooling and thus to preserve the metal content in the aluminum dross.

The most common method is dross pressing using a separate press. When pressing dross, the aluminum dross in the bucket is compressed with a hydraulic ram. In addition to the cooling effect, the solidifying aluminum collects into smaller plates. In further operations, the aluminum is mechanically separated from the aluminum oxide and can be melted down again, so that up to 60% of the dross can be returned to the production cycle as aluminum.

Based on the dross pressing, matching cast lids are placed on dross pans. The aim of this is to use the heat capacity of the lid to cool the aluminum dross and to prevent possible fires by cutting off the oxygen supply. The further processing of the cold aluminum dross is carried out in the same way as for dross pressing.

Another method for treating aluminum dross is inert gas cooling. To do this, the dross pan is placed in a lockable chamber and cooled by adding inert gas and dross fires are suffocated. Further processing takes place in the same way as for dross presses.

All these processes prevent dross fires and contribute to the recovery of aluminum from the aluminum dross, but they require complex special systems and are very time-consuming.

It is therefore the object of the present invention to provide a method for recovering metals from the slag when producing metallurgical melts, which method is less complex and less time-consuming. In particular, aluminum dross should be able to be treated faster and more cost-effectively.

This object is achieved with a method for purifying according to claim 1 and a device for purifying according to claim 6. Advantageous further developments are given in the dependent subclaims and the description. Even if there are different terms, the terms “slag” or “purification” and “melting furnace” should be used in the context of the present invention.

On the part of the invention, it was recognized that the problem posed can be achieved particularly easily in a surprising manner if the slag is pressed before being transferred into a slag container, because then the slag has not yet cooled down and can be pressed better. This makes the pressing process less expensive. In addition, metal pressed out of the slag can flow back directly into the melt of the melting furnace, which can significantly reduce working hours. In addition, the slag cools down during the pressing process, so that slag fires can be effectively prevented.

The method according to the invention for deslagging metallurgical melts, wherein the slag is drawn off from the melt, is thus characterized in that the slag is pressed before being transferred into a slag container.

In an advantageous further development it is provided that the slag is pressed in the furnace with a pulling device used to pull off the slag. The method is then particularly easy to carry out because no separate pressing device located outside the furnace is required. The phrase “in the oven” also includes outer areas of the oven, such as an oven bridge.

In an advantageous development it is provided that the slag is pressed between the pulling device and a counter bearing. The pressing process is then particularly easy to implement in terms of design.

In an advantageous development, it is provided that molten material emerging from the slag during pressing is fed to the melt. This significantly reduces working hours, as there is no need to charge the recovered metal again.

In an advantageous development, it is provided that the slag rests on a bridge of a melting furnace when it is pressed out, the pressing process preferably being started immediately after the slag has been drawn off onto the bridge. This allows the recovered metal to be fed into the melt and at the same time the bridge prevents the re-entry of the withdrawn slag into the melt.

Independent protection is claimed for the device according to the invention for purifying metallurgical melts, the device being adapted to withdraw slag from the melt, the device having means for withdrawing the slag from the melt and being characterized in that the device has means for pressing, which are adapted to press the slag before transferring it into a slag container.

In an advantageous development it is provided that the device is adapted to carry out the method according to the invention.

In an advantageous development it is provided that the means for pulling off are part of the means for pressing. As a result, the device is particularly simple.

In an advantageous development, it is provided that the means for pulling off have a pull-off shield, to which a counter-shield is assigned, so that the slag can be squeezed out between the pull-off shield and counter-shield. In this way, the pressing out process can be carried out particularly quickly and easily.

In an advantageous development it is provided that the peel-off shield and the counter-shield each have lower edges, the lower edge of the peel-off shield being arranged at the same height or above the lower edge of the counter-shield during pressing so that molten material emerging from the slag is diverted under the peel-off shield. This allows the molten material to be returned to the melt in a particularly simple manner. Since the furnace bridge usually has a slight gradient (2 ° -3 °), the arrangement at the same height allows the molten material to flow off.

In an advantageous development it is provided that the means for pressing at least on one of the surfaces that press the slag between them has one or more guides for diverting the molten material emerging from the slag, the guides preferably being designed as openings in the surface are, wherein the guides are arranged in particular in the peelable shield. This also allows the molten material to be returned to the melt particularly easily.

In an advantageous development it is provided that the pull-off shield and / or the counter-shield are designed so that they can be cooled. As a result, these shields can be cooled during the pressing and ejection of the slag, as a result of which the adhesion of the slag to the shields is reduced and thus the detachability of the slag is improved. Corresponding means for cooling can be designed to be electrically activatable, for example with the aid of a Peltier element, or with a refrigerant circuit of the usual type and with a corresponding refrigerant fluid.

In an advantageous development it is provided that the means for pressing have ejectors for detaching the slag from the means for pressing, the ejectors preferably being designed as plungers, which are arranged in particular on the peeler plate and / or the counter plate. As a result, the squeezed-out slag is very easily released again from the means for pressing, so that it can be quickly transferred to the slag container and is not conveyed back into the melt.

In an advantageous development, it is provided that the device is designed to be movable relative to a substrate of the device. As a result, several melting furnaces can be operated one after the other and the charging opening of a melting furnace can also be opened quickly.

In an advantageous further development it is provided that the means for pressing out are designed to be vertically liftable and / or horizontally displaceable. This allows easy maneuvering in relation to a melting furnace.

• 1 eine perspektivische Ansicht der erfindungsgemäßen Einrichtung im Zusammenspiel mit einem Schmelzofen,
• 2 die erfindungsgemäße Einrichtung nach 1 im Zusammenspiel mit dem Schmelzofen in einer Schnittansicht in einem ersten Betriebszustand (vor dem Ofen, Ofen geschlossen),
• 3 die erfindungsgemäße Einrichtung nach 1 im Zusammenspiel mit dem Schmelzofen in einer Schnittansicht in einem zweiten Betriebszustand (Ofen offen und Abziehschild maximal nach innen),
• 4 die erfindungsgemäße Einrichtung nach 1 im Zusammenspiel mit dem Schmelzofen in einer Schnittansicht in einem dritten Betriebszustand (Ofen offen und Abziehschild und Gegenschild pressen Schlacke auf Brücke) und 5 die erfindungsgemäße Einrichtung nach 1 im Zusammenspiel mit dem Schmelzofen in einer Schnittansicht in einem vierten Betriebszustand (Ofen offen und Abziehschild und Gegenschild außerhalb, Schlacke fällt in Kübel).

The characteristics and further advantages of the present invention will become clear in the following on the basis of the description of a preferred exemplary embodiment in connection with the figures. It shows purely schematically:

• 1 a perspective view of the device according to the invention in conjunction with a melting furnace,
• 2 the device according to the invention 1 in interaction with the melting furnace in a sectional view in a first operating state (in front of the furnace, furnace closed),
• 3 the device according to the invention 1 in interaction with the melting furnace in a sectional view in a second operating state (furnace open and pull-off shield maximally inwards),
• 4th the device according to the invention 1 in interaction with the melting furnace in a sectional view in a third operating state (furnace open and peeler plate and counter plate press slag onto the bridge) and 5 the device according to the invention 1 in interaction with the melting furnace in a sectional view in a fourth operating state (furnace open and peel-off shield and counter-shield outside, slag falls into the bucket).

It's in the 1 to 5 to recognize that the device according to the invention 10 to detoxify melts 12 with a melting furnace 14th cooperates, which is designed as a hearth melting furnace and one of a vertically movable furnace door 16 closable melting range 18th with a charging opening 20th , an oven ramp 22nd and a furnace bridge 24 having.

The purification device 10 shows one on rails 26th on the side of the furnace 14th movable base 28 on, on the control systems 30th and a control stand 32 with a heat shield 34 are arranged.

Still are on the base 28 medium 36 arranged for pulling off, which has a telescopic mast or boom 38 have and a peel-off label attached 40 . The peel-off shield 40 has openings (not shown) that the peel-off label 40 so penetrate completely from the counter shield 48 facing side to the melting range 18th pass through.

For driving the extension and retraction movement of the telescopic mast or boom 38 are the first controllable means 42 certainly. For vertical displacement of the mast or boom 38 are second controllable means 44 certainly. This means 42 , 44 can for example be designed as hydraulic means. However, a purely electrical training is also possible. It is only important that both the penetration depth of the peelable shield 40 in the oven 14th as well as the vertical height of the peelable label 40 above the melt 12 are adjustable.

Furthermore, there is the peel-off label 40 Part of the means 46 for pressing, which also has a counter shield 48 have on a further telescopic arm 50 are arranged. That arm 50 is also hydraulically operated by way of example, with the vertical height via a parallelogram guide 52 and hydraulic means 54 and the extension and retraction movement of the telescopic arm 50 controllable hydraulic means 56 are provided. Here too the hydraulic means could 54 , 56 also be designed purely electrically. It is important that both the penetration depth of the counter shield 48 in the oven 14th , as well as the vertical height of the counter shield 48 over the furnace bridge 24 are adjustable.

Control of peeling shield 40 and counter shield 48 is done by an operator (not shown) on the operator's platform 32 in connection with the control systems 30th that receive their energy via an energy supply line (not shown) attached to the base 28 to a tree 58 attached so they don't get into the rails 26th may advise.

For draining the slag 60 into the slag container that can be provided 62 (Buckets) are discharge means 64 on the side of the furnace bridge 24 arranged.

In addition, in the peelable shield 40 and / or in the opposite shield 48 Means (not shown) for removing adhering slag 60 ' be provided, which are designed, for example, as activatable mandrels, plungers or the like. Ejector, which, if necessary, from the inside of the pull-off shield 40 or the counter shield 48 over the pressing surfaces 66 or. 68 (see. 3 ) can step out and so the slag 60 ' could repel.

Means (not shown) for cooling the peelable shield can also be used 40 and / or counter shield 48 be provided, making these shields 40 , 48 are each designed to be coolable.

The method according to the invention is now carried out as follows.

With a charging device, not shown, the melting furnace 14th loaded with raw material and the oven door 16 closed. After the melt has formed completely 12 becomes the establishment 10 by means of the rails 26th in front of the oven door 16 placed and it becomes the oven door 16 open (cf. 2 ).

Then the peel-off shield 40 with the telescopic mast 38 in the melting range 18th introduced (cf. 3 ) and shares 60 ' the slag 60 over the furnace ramp 22nd on the furnace bridge 24 pulled and against the counter shield 48 pressed. Before that, the counter shield 48 with its lower edge on the furnace bridge 24 filed (cf. 4th ).

Alternatively, a large part or the entire melting range can also be used first 18th of the furnace 14th of slag 60 be freed, taking the slag 60 ' on the furnace bridge 24 is deposited, and only then is it pressed out.

Due to the pressure when squeezing out between the peel-off plate 40 and counter shield 48 occurs in the slag 60 ' contained molten material and passes through the peel shield 40 through the perforations so that it goes into the melt 12 is returned.

The counter shield is effective 48 as a barrier so that neither molten material nor slag 60 ' across the bridge 24 from the furnace 14th can get out. The peel-off shield 40 in turn, prevents the slag from coming back 60 ' in the melting range 18th .

In addition, the lower edge of the peel-off label 40 opposite the furnace bridge 24 be raised to the extent that liquid metal is between the peel plate 40 and furnace bridge 24 into the melt 12 can flow back without causing slag 60 ' into the melt 12 is conveyed during pressing. The lower edge of the counter shield is located here 48 on the furnace bridge 24 to create a seal against the molten material. Due to the slope of the furnace bridge 24 it is enough that the lower edge of the peel-off label is 40 is at the same height as the lower edge of the counter shield 48 .

It is in 4th to see that the peelable label 40 and the counter shield 48 are arranged plane-parallel to one another with an incline downward in the direction of the melting range 18th , thereby eliminating the drainage of the liquid metal that comes out of the slag 60 ' is pressed into the melt 12 is promoted into it.

Instead of a plane-parallel arrangement, however, an arrangement could also be selected, for example, in which the distance between the peel-off plate 40 and counter shield 48 tapers upwards, so that the pressure acts downwards and thereby the slag 60 ' or the molten material does not emerge upwards.

Then the counter shield 48 from the furnace 14th pulled away and the squeezed out slag 60 ' by means of the peel-off plate 40 about the discharge means 64 into the slag container 62 promoted (cf. 5 ). Thereby the means for ejecting the slag 60 ' in peelable shield 40 and counter shield 48 activated to the slag 60 ' better off the shields 40 , 48 to solve. This detachment can also be promoted by the cooling means from the peel-off shield 40 and / or counter shield 48 at least when ejecting, but preferably already activated by pressing.

This process is repeated until the melting furnace 14th is completely purged, this process in conventional melting furnaces 14th with a capacity of 35 to 60 t takes 15 to 20 minutes. The workload can be reduced by using wider peel-off shields 40 and counter shields 48 be reduced with the counter shield 48 is preferably wider than the peelable label 40 so that with the peelable label 40 free against that firmly on the furnace bridge 24 applied counter shield 40 can be worked without the slag 60 ' or molten material from the furnace 14th can get out.

It can be seen that deslagging and pressing can be carried out in one operation, which considerably shortens the working time and the facility 10 for purification does not have to be designed in a much more complex way than previously existing facilities such as those exemplified by the DE 197 29 702 A1 shows.

While the previously known methods only reduce the metal losses after the slag has already left the melting process, according to the invention the slag is used 60 before cooling in the furnace 14th pressed out, which already reduces the initial occurrence of metal losses. A substantial amount of metal in the slag flows 60 in the furnace 14th back so that this portion does not have to be processed and melted down again. The slag also cools 60 already during the pressing process and thus further metal losses due to slag fires are reduced.

These measures can reduce the metal content of the slag 60 ' by pressing in the melting furnace 14th can be reduced by about 50%. This metal remains in the process.

The means for pressing are advantageously designed for a pressing force of 20 kN, possibly even more, with larger surfaces and counter surfaces of the pull-off shield 40 and counter shield 48 larger pressing forces can also be used.

Even if the invention was explained essentially in connection with the production of aluminum from recycled material, the invention is not restricted to this, but other metals and alloys can also be processed and ores can also be used for their production.

From the above illustration it has become clear that with the present invention a method and a device 10 be provided for purification, with which both the purification and the metal recovery from the slag 60 can be done quickly and easily and the risk of slag fires is reduced.

Unless otherwise stated, all features of the present invention can be freely combined with one another. Unless otherwise stated, the features described in the description of the figures can also be freely combined with the other features as features of the invention. A restriction of individual features of the exemplary embodiment to the combination with other features of the exemplary embodiment is expressly not provided; these individual features can be used independently Combination with other features, in particular features specified in the set of claims, can be used. In addition, objective features, reformulated, can also be used as process features and process features, reformulated, as objective features. Such a reformulation is therefore automatically disclosed.

List of reference symbols

10

Device according to the invention for purification

12

melt

14th

Melting furnace

16

Oven door

18th

Melting range

20th

Charging opening

22nd

Furnace ramp

24

Furnace bridge

26th

rails

28

movable base of the device 10

30th

Control systems

32

Control station

34

Heat shield

36

Means for peeling off

38

telescopic mast or boom

40

Peel-off shield

42

first controllable funds

44

second controllable means

46

Means of pressing

48

Counter shield

50

telescopic arm

52

Parallelogram guide for arm 50

54

controllable funds

56

controllable funds

58

tree

60

slag

60 '

Proportions of slag 60

62

Slag containers, buckets

64

Discharge means

66

Pressing surface of the peeling shield 40

68

Pressing surface of the counter plate 48

QUOTES INCLUDED IN THE DESCRIPTION

This list of the 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 assumes no liability for any errors or omissions.

Patent literature cited

• DE 3928671 C2 [0006]
• DE 19729702 A1 [0007, 0055]

Claims (12)

Method for deslagging metallurgical melts (12), wherein the slag (60, 60 ') is drawn off from the melt (12), characterized in that the slag (60, 60') is pressed before being transferred into a slag container (62) . Procedure according to Claim 1 , characterized in that the slag (60, 60 ') is pressed with a pulling device (36) used to pull off the slag (60, 60'). Procedure according to Claim 1 or 2 , characterized in that the slag (60, 60 ') is pressed between the pulling device (36) and a counter bearing (48). Method according to one of the preceding claims, characterized in that molten material emerging from the slag (60 ') during pressing is fed to the melt (12). Method according to one of the preceding claims, characterized in that the slag (60 ') rests on a bridge (24) of a melting furnace (14) when it is pressed out, the pressing process preferably immediately after the slag (60') has been drawn off onto the bridge (24) ) is started. A device (10) for deslagging metallurgical melts (12), the device (10) being adapted to withdraw slag (60, 60 ') from the melt (12), the device (10) having means (36) for withdrawing the slag (60, 60 ') from the melt (12), characterized in that the device (10) has means (46) for pressing which are adapted to remove the slag (60') before transferring it into a slag container (62 ) to press. Device (10) according to Claim 6 , characterized in that the device (10) is adapted to the method according to one of Claims 1 to 5 and / or that the means (36) for pulling off are part of the means (46) for pressing. Device (10) according to one of the Claims 6 or 7th , characterized in that the means (36) for pulling off have a pull-off shield (40) to which a counter-shield (48) is assigned so that the slag (60 ') can be squeezed out between the pull-off shield (40) and counter-shield (48). Device (10) according to Claim 8 , characterized in that the peeling shield (40) and the counter shield (48) each have lower edges, the lower edge of the peeling shield (40) being arranged during pressing at the same height or above the lower edge of the counter shield (48), so that from the slag (60 ') escaping molten material is drained under the peel-off shield (40). Device (10) according to one of the Claims 6 to 9 , characterized in that the means (46) for pressing comprises, on at least one of the surfaces which press the slag (60 ') between them, one or more guides for discharging the molten material emerging from the slag (60'), the Guides are preferably designed as openings in the surface, the guides in particular in the peel-off plate (40) Claim 8 are arranged. Device (10) according to one of the Claims 6 to 10 , characterized in that the peel-off shield (40) and / or the counter-shield (48) are designed to be coolable. Setup according to one of the Claims 6 to 11 , characterized in that the means (46) for pressing have ejectors for detaching the slag (60 ') from the means (36) for pressing, the ejectors preferably being designed as plungers, which in particular are attached to the peeling plate (40) and / or the counter plate (48) Claim 8 are arranged.

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