Method for melting and then keeping warm a light metal alloy, in particular an aluminium alloy, in an electric arc furnace and electric arc furnace

Abstract

The invention relates to a method for melting and subsequently holding at temperature a light metal alloy (6-6b), in particular an aluminum alloy, in an electric arc furnace (1-1b). Advantageously, a gas atmosphere (8-8b) comprising a reactive gas and / or an inert gas is generated in a melting chamber (2-2b) of the electric arc furnace (1-1b). In one embodiment of the invention, the gas atmosphere (8-8b) is generated by introducing a silane with the molecular formula SinH₂n+2 or mixtures of silanes from the group of silanes with the molecular formula SinH₂n+2 into the melting chamber (2-2b), wherein n < 6. The invention further relates to an electric arc furnace (1-1b).

Description

[0001] The invention relates to a method for melting and subsequently keeping warm a light metal alloy, in particular an aluminum alloy, in an electric arc furnace and to an electric arc furnace.

[0002] Electric arc furnaces for melting and subsequently holding iron alloys at high temperatures are known. Gas-fired melting furnaces for melting and subsequently holding aluminum alloys or other light metal alloys are also known.

[0003] The invention is based on the objective of creating a method of the type mentioned above by which a light metal alloy can be melted in an electric arc furnace, i.e., in an electric arc melting furnace, and the molten metal can subsequently be kept at temperature. For example, when using so-called green electricity to operate the electric arc furnace, melting and keeping at temperature of an aluminum alloy is possible in a CO₂-neutral manner.

[0004] Until now, electric arc furnaces have not been used for melting light metal alloys, especially aluminum alloys, because light metal alloys are particularly susceptible to the absorption of gases such as hydrogen or the inclusion of solid reaction products during melting, which are formed by the reaction of elements such as hydrogen or oxygen that degrade alloy properties.

[0005] Furthermore, the invention is based on the objective of creating a method of the aforementioned type with which a high-quality light metal alloy melt can be produced and the light metal alloy melt can subsequently be kept warm.

[0006] It is conceivable that, by means of a method according to the invention, existing impurities, for example oxygen, are removed from an alloy and carried away via the furnace atmosphere.

[0007] According to the invention, the problem is solved by generating a gas atmosphere in a melting chamber of the electric arc furnace which contains a reactive gas and / or an inert gas.

[0008] A melting chamber is a section of an electric arc furnace where a light metal alloy can be melted by the application of heat energy. A gas atmosphere may be present, serving as a protective atmosphere.

[0009] Hydrogen and oxygen are typically elements in light metal alloys that reduce the quality of a casting made from the molten light metal alloy.

[0010] For example, hydrogen dissolved in a molten aluminum alloy causes so-called hydrogen porosity upon solidification, which is a significant quality defect.

[0011] Hydrogen can enter a melt, for example, due to high humidity when loading a melting furnace.

[0012] Oxygen introduced into a liquid aluminum alloy reacts with the aluminum to form aluminum oxide, resulting in a microstructural defect known as an inclusion in a casting produced from the molten light metal alloy. This significantly reduces the mechanical strength of the casting locally in the area of ​​the inclusion.

[0013] Because the gas atmosphere contains a reactive gas and / or an inert gas, it is prevented, for example, from oxygen or hydrogen entering a melt produced using the inventive method.

[0014] An inert gas is a gas that displaces an unwanted gaseous component in the melting chamber without reacting chemically itself, while a reactive gas is a gas that reacts chemically with an unwanted gaseous component in the melting chamber and renders it harmless by forming a new component.

[0015] An inert gas can be, for example, a noble gas such as argon (Ar) or nitrogen (N₂). Advantageously, a particularly clean, i.e., contamination-free, melt can be produced using a process according to the invention.

[0016] Advantageously, the gas atmosphere is created by introducing a silane with the molecular formula Si n H 2n+2 or mixtures of silanes from the group of silanes with the molecular formula Si n H 2n+2 into the melting chamber, where n < 6.

[0017] The inventors have discovered that for n < 6 a particularly clean melt can be produced, that is, a melt that is almost free of unwanted reaction products.

[0018] For example, a silane reacts with oxygen in the melting chamber to form SiO2, which is insoluble in a light metal alloy melt such as an aluminum alloy and can be removed from the melt by so-called skimmering.

[0019] The inventors have surprisingly discovered that the reactivity of the gas atmosphere can be adjusted by mixing different silanes. For example, for a gas atmosphere in an electric arc furnace used to melt an aluminum alloy, silanes from the aforementioned group with 0 < n < 3 are advantageous, while for a magnesium alloy, mixtures of silanes with 2 < n < 4 are advantageous.

[0020] Those silanes from the aforementioned group that are liquid at room temperature can be introduced into the melting chamber through a nozzle, for example when heating the electric arc furnace, and evaporate there to form the gas atmosphere.

[0021] In one embodiment of the invention, the gas atmosphere is generated by introducing a silane with the molecular formula SiₙH₂n+2 or mixtures of silanes from the group of silanes with the molecular formula SiₙH₂n+2 and an inert gas into the melting chamber, wherein n < 6, and the proportion of silanes from the group of silanes with the molecular formula SiₙH₂n+2 in the gas atmosphere is between 0.01 vol% and 30.00 vol%, wherein the sum of all gases forming the gas atmosphere is 100 vol%. The proportion of silanes from the aforementioned group must be higher the more moist the material to be melted is or the more contaminated it is.

[0022] An inert gas can be a noble gas such as argon (Ar) or nitrogen (N 2 ).

[0023] The inventors have recognized that by mixing an inert gas with a reactive substance such as a silane from the aforementioned group or mixtures thereof in the aforementioned volume fraction, a gas atmosphere is created which enables the pollution-free melting of a light metal alloy to be melted in the melting chamber in the electric arc furnace.

[0024] A proportion of 3 vol.% to 15 vol.% of silanes from the group of silanes with the molecular formula Si n H 2n+2 in the gas atmosphere has proven to be particularly advantageous for an aluminium alloy.

[0025] In one embodiment of the invention, a gas atmosphere is generated by introducing monosilane (SiH₄) into the melting chamber. The use of monosilane has proven particularly advantageous for industrial processes, especially when melting an aluminum alloy, due to its good availability and particularly high chemical affinity for oxygen.

[0026] In a further embodiment of the invention, the gas atmosphere is generated by introducing an inert gas and monosilane (SiH 4 ) into the melting chamber, wherein the proportion of monosilane (SiH 4 ) in the gas atmosphere is between 0.01 vol.-% and 30.00 vol.-%, wherein the sum of all gases forming the gas atmosphere is 100 vol.-%.

[0027] The inventors have recognized that by using a mixture of an inert gas such as nitrogen (N₂) or argon (Ar) with monosilane as a reactive gas, a gas atmosphere can be created that allows for sufficient removal of critical components such as oxygen and hydrogen. Advantageously, the inventive method creates a particularly economical electric arc furnace for melting a light metal alloy.

[0028] Advantageously, the gas atmosphere is generated by introducing an inert gas into the melting chamber and, in the area of ​​an electric arc of the electric arc melting furnace, additionally introducing a silane from the group of silanes with the molecular formula Si n H 2n+2 , preferably monosilane (SiH 4 ), or mixtures of silanes from the group of silanes with the molecular formula Si n H 2n+2 , where n < 6 .

[0029] The highest temperature occurs in the area of ​​an electric arc. Since the solubility of gaseous elements in a light metal alloy increases with rising temperature, it is advantageous to introduce a silane from the aforementioned group, or mixtures of silanes from the aforementioned group, directly in the area of ​​an electric arc, i.e., in the area of ​​highest temperature. This also benefits by trapping the unwanted components before they penetrate the melt.

[0030] In one embodiment of the invention, an electric arc is formed between a first electrode and a second electrode, wherein one of the electrodes is at least partially formed by a light metal alloy arranged in the melting chamber. Advantageously, an electric arc furnace with a simple design is created, for the operation of which only a single external electrode is required.

[0031] Advantageously, an electric arc is formed between a first electrode and a second electrode, with both electrodes being arranged above a light metal alloy located in the melting chamber.

[0032] If both electrodes are positioned above the light metal alloy to be melted, they are advantageously completely surrounded by the gas atmosphere. An electric arc generated between the electrodes indirectly heats the light metal alloy to be melted, thus enabling particularly low local superheating of the alloy during melting.

[0033] In indirect heating, the electric arc has no direct contact with a light metal alloy to be melted in the melting chamber of the electric arc furnace.

[0034] Furthermore, it is advantageous that the electric arc can be completely surrounded by the gas atmosphere.

[0035] In a further embodiment of the invention, an electric arc is formed between a first electrode and a second hollow electrode into which the first electrode is at least partially immersed. Such an electrode arrangement acts in the manner of a heating rod.

[0036] The electric arc is generated between an inner wall of the second, hollow electrode and the first electrode, which is immersed in a cavity of the second, hollow electrode. The electric arc heats the hollow electrode. This allows for the advantageous indirect heating of a light metal alloy to be melted, and overheating of the molten metal, even in certain areas, is advantageously prevented. Furthermore, the hollow electrode advantageously shields the electric arc.

[0037] A process is being created that makes it possible to produce a particularly high-quality melt.

[0038] In those processes where the light metal alloy is indirectly heated to melt it, that is, in those processes where the electric arc does not directly hit the light metal alloy to be melted, a melt can be created that is particularly clean, i.e., free from impurities, by means of lower local overheating in combination with the gas atmosphere.

[0039] An electric arc furnace according to the invention is characterized in that it is set up to carry out a process according to the invention and has a melting chamber.

[0040] An electric arc furnace according to the invention can be a single-chamber furnace having only a single melting chamber. Such a single-chamber electric arc furnace is suitable for batch operation, i.e., for discontinuous operation.

[0041] The electric arc furnace can have an arc furnace vessel for holding a light metal alloy to be melted and a partially spherical segment-shaped lid, which is placed on the arc furnace vessel during operation and in which at least one of the electrodes is arranged. The gas atmosphere is introduced into the partially spherical segment-shaped lid.

[0042] In one embodiment of the invention, the electric arc furnace has a charging chamber that is fluidically connected to a melting chamber. In such a two-chamber furnace, a particularly large quantity of a light metal alloy can advantageously be melted. It is understood that a barrier in the form of a weir can be provided between adjacent furnace chambers of a multi-chamber furnace. This would interrupt the fluidic connection, and the multi-chamber furnace could then be operated in batch mode.

[0043] Advantageously, the electric arc furnace comprises a charging chamber with a heating device, the heating device being configured for preheating a light metal alloy to be melted. Such an electric arc furnace can be designed as a two-chamber furnace, comprising a charging chamber and a melting chamber, or as a three-chamber furnace, comprising a charging chamber, a melting chamber, and a melt discharge chamber. A two-chamber furnace of the aforementioned configuration is particularly economical to operate, while a three-chamber furnace of the aforementioned configuration is particularly economical and can be operated continuously.

[0044] Preheating can be used, for example, to additionally dry a light metal alloy that is to be melted.

[0045] It is conceivable that preheating thermally removes impurities such as lubricants from the light metal alloy to be melted, and these are then discharged via a chimney. This is particularly relevant when the light metal alloy is in the form of scrap metal, which is recycled by melting and further processing to produce high-quality castings.

[0046] In one embodiment of the invention, the electric arc furnace has a device for generating an electric arc, comprising two electrodes between which an electric arc can be formed, wherein one of the two electrodes is formed from a light metal alloy arranged in the electric arc furnace, or both electrodes are arranged above a light metal alloy arranged in the electric arc furnace.

[0047] Advantageously, only one external electrode is required. Such an arc furnace, in which one of the two electrodes is formed by the light metal alloy to be melted, is particularly cost-effective and requires little maintenance.

[0048] In a further embodiment of the invention, the electric arc furnace has a device for generating an electric arc, comprising two electrodes between which an electric arc can be formed, wherein a first of the two electrodes is hollow and a second of the two electrodes is at least partially immersed in the first hollow electrode, wherein the electric arc is formed in a cavity of the first hollow electrode when the electric arc furnace is in operation.

[0049] An indirect heating of the light metal alloy to be melted is advantageous. Local overheating caused by the direct impact of an electric arc on the light metal alloy is prevented.

[0050] It is conceivable that the two electrodes are arranged above a light metal alloy located in the arc furnace, or that the hollow electrode is immersed in a light metal alloy that is already at least partially molten.

[0051] Advantageously, the electric arc furnace has a device for generating an electric arc comprising two electrodes, one of which is placed in a cover, and the cover can be placed on an area of ​​a light metal alloy arranged in the electric arc furnace.

[0052] The cover is preferably shaped in a spherical segment shape in certain areas.

[0053] The cover, preferably shaped in a spherical segment shape, sits floating on a section of a light metal alloy arranged in the electric arc furnace and can be melted in the gas atmosphere created inside the cover, which is bounded by a surface of the light metal alloy in the electric arc furnace and by the inside of the cover. Advantageously, heat can be introduced only locally into the light metal alloy to be melted.

[0054] In this case, a second of the two electrodes can be formed from the light metal alloy.

[0055] In one embodiment of the invention, the electric arc, which is designed as a multi-chamber furnace, is configured in such a way that a melt exchange between the melting chamber and at least one further chamber is possible.

[0056] For this purpose, a stirring device, such as an electromagnetic stirrer, can be used. Advantageously, this creates a melt in which the alloying elements are distributed particularly homogeneously. This is beneficial, for example, in industrial melting processes. Furthermore, a homogeneous heat distribution within the molten material is achieved advantageously during the melting of a light metal alloy. Locally severe overheating is prevented by the removal of already molten alloy.

[0057] It is conceivable that multiple or continuous passages through several chambers of such a multi-chamber furnace occur.

[0058] The invention is explained in more detail below with reference to exemplary embodiments and the accompanying drawings relating to these embodiments. The drawings show: Fig. 1 several embodiments of an electric arc furnace according to the invention, Fig. 2 several further embodiments of an electric arc furnace according to the invention, Fig. 3 a special embodiment of an electric arc furnace according to the invention.

[0059] A in Fig. 1a The arc furnace 1, shown schematically in a cutaway side view, is designed as a single-chamber furnace comprising a melting chamber 2.

[0060] The electric arc furnace 1 also has an electric arc furnace vessel 3 and an electric arc furnace lid 4, wherein three vertically arranged electrodes 5 are passed through the electric arc furnace lid 4.

[0061] In this embodiment, the melting chamber 2 is bounded by the arc furnace lid 4 and an aluminum alloy 6 of type AlSi8Cu3 to be melted. An electric arc 7 is formed between the aluminum alloy 6 and each of the vertical electrodes 5, with the aluminum alloy 6 forming a counter electrode to the electrodes 5. The electric arc 7 heats the aluminum alloy 6 to be melted directly, that is, directly by forming a counter electrode to the vertical electrode 5.

[0062] A gas atmosphere 8 in the melting chamber 2 consists of monosilane (SiH 4 ) with a proportion of 5.00 vol% monosilane and a proportion of 95.00 vol% nitrogen (N 2 ).

[0063] The gas atmosphere 8, which is a mixture of a reactive gas and an inert gas, was created after the aluminum alloy 6 was introduced into the electric arc furnace vessel 3 and the electric arc furnace lid 3 was attached to the electric arc furnace vessel 2 by introducing nitrogen and monosilane into the melting chamber.

[0064] For the sake of clarity, the following are included in the Fig. 1a-1d No device for introducing gases to form the gas atmosphere 8 or contacting the electrodes is shown.

[0065] A in Fig. 1b The arc furnace 1, shown schematically in a cutaway side view, differs from the one in Fig. 1a This is demonstrated by the fact that it has a vertical electrode 5 extending through an electric arc furnace vessel 3 and a vertical counter electrode 9, and by the fact that a gas atmosphere 8 consists exclusively of monosilane (SiH₄). The counter electrode 9 is embedded in an aluminum alloy 6 to be melted and projects from it towards the electrode 5.

[0066] An arc 7 is formed between the two electrodes 5, 9, through which the aluminum alloy 6 to be melted is indirectly heated, whereby indirectly means that the arc has no direct contact with the aluminum alloy 6.

[0067] A in Fig. 1c The arc furnace 1, shown schematically in a cutaway side view, differs from the one in Fig. 1b shown by providing two horizontal electrodes 10, 11, between which an arc is formed, thereby indirectly heating an aluminum alloy 6.

[0068] A in Fig. 1d The arc furnace 1, shown schematically in a cutaway side view, differs from those in Fig. 1a-c shown by the fact that a vertical electrode 12 is partially hollow, wherein a counter electrode 9 is partially immersed in a cavity 12, and a substantially annular arc 7 is formed between an inner side of the cavity 12 and the counter electrode 9, through which an indirect heating of an aluminum alloy 6 takes place.

[0069] A in Fig. 1a bis 1d The electric arc furnace 1 shown can be operated in so-called batch operation.

[0070] A detail of an in Fig. 1a-d The electric arc furnace 1 shown shows Fig. 1e exemplified by an electric arc furnace 1 according to Fig. 1a .

[0071] A groove 13 is formed around the perimeter of an electric arc furnace vessel 3. This groove connects the melting chamber 2 to the surrounding environment containing the electric arc furnace 1 via an inner gap (not marked with a reference numeral) on the side of the groove 13 facing the melting chamber 2 and an outer gap (not marked with a reference numeral) on the side of the groove 13 facing away from the melting chamber 2. Suspended particles 14 can collect in the groove 13, which acts as a collection area. These suspended particles 14 are formed by the reaction of the monosilane (SiH₄) in the gas atmosphere with oxygen, for example, which is to be removed from the light metal alloy. In this embodiment, the monosilane (SiH₄) can react with oxygen to form SiO₂.

[0072] Because the electric arc furnace 1 in this embodiment is operated under overpressure, similar to a low-pressure furnace, gas from the atmosphere flows through the inner gap into the groove 13, carrying with it the SiO₂ formed by the aforementioned reaction in the melting chamber 2 into the groove 13. The suspended particles 14 can escape from the groove 13 through the outer gap and be collected for disposal.

[0073] It is also conceivable to remove the suspended particles 14 from the groove 13 by removing the electric arc furnace lid 4.

[0074] It will now be on Fig. 2 Reference is made where identical or equivalent parts are used with the same reference number as in Fig. 1 are designated and the letter a is appended to the relevant reference number.

[0075] A in Fig. 2a The arc furnace 1a, shown schematically in a cutaway side view, differs from those in Fig. 1a-d The electric arc furnace shown is distinguished by the fact that it is designed as a two-chamber furnace, i.e., in addition to a melting chamber 2a, it has a charging chamber 15.

[0076] Between the charging chamber 15 and the melting chamber 2a a weir 16 is arranged, the upper side of which forms an inclined plane 17 on which charged, solid material can slide.

[0077] In melting chamber 2a, a light metal alloy is melted. This is achieved through a process in Fig. 2a A stirring device (not shown), which may include an electromagnetic stirrer, can move the already molten light metal alloy in the direction of arrows 18, so that molten light metal alloy can reach a lower region 19 of the charging chamber 15. Advantageously, a particularly large quantity of a light metal alloy can be melted.

[0078] A in Fig. 2b The arc furnace 1a, shown schematically in a cutaway side view, differs from the one in Fig. 2a This is demonstrated by the fact that it has a heating device 19 in a charging chamber 15, by which ingots 20 of a light metal alloy to be melted can be preheated while lying on a holding device 21. After preheating, the ingots 20 are tipped onto an inclined plane 17 of a weir 16 and thereby moved towards a melting chamber 2a.

[0079] A in Fig. 2c The arc furnace 1a, shown schematically in a cutaway side view, differs from those in Fig. 2a, b shown by the fact that it is designed as a three-chamber furnace, which, in addition to a charging chamber 15 and a melting chamber 2a, has a melt extraction chamber 22, which is spatially separated from a melting chamber 2a by a weir 23.

[0080] The bath level in melt extraction chamber 22 can be advantageously adjusted by means of an overpressure existing in that chamber. Advantageously, the quantity of melt to be transferred from melting chamber 2a to melt extraction chamber 22 can also be adjusted.

[0081] A further advantage is that, with adjustable molten metal extraction from the melt extraction chamber, no permanent repositioning of the electrodes 5a is required. This results in a simply constructed electric arc furnace 1a that requires no control, in particular no permanent control of the electrode spacing.

[0082] The melt extraction chamber 22 also creates an electric arc furnace 1a, which can be operated continuously.

[0083] It will now be on Fig. 3 Reference is made where identical or equivalent parts are used with the same reference number as in Fig. 1 and Fig. 2 are designated and the letter b is appended to the relevant reference number.

[0084] An electric arc furnace 1b, shown schematically in a sectioned side view in Fig. 3a, differs from those in Fig. 1 and 2 by a cover 24 in the manner of an electric arc furnace lid being placed gas-tight on a region 25 of a light metal alloy 6b to be melted, wherein a melting chamber 2b is bounded by the cover 24 and the light metal alloy 6b to be melted. In all of the Fig. 1 bis 3 In the electric arc furnaces 1-1b shown, a gas atmosphere 8-8b is created in which a reactive gas and / or inert gas with a defined composition is introduced into the electric arc furnace lid 4-4b or into a cover 24 before the start of a melting process.

[0085] It goes without saying that all combinations of the in Fig. 1 bis 3 The features shown and described are conceivable. For example, a Fig. 2c shown arc furnace 1a electrodes according to Fig. 1c exhibit.

[0086] Furthermore, it is conceivable that an electric arc furnace in Fig. 2a-c The electric arc furnace 1a shown is in Fig. 1a-d has a groove designated with reference numeral 13 for receiving suspended solids 14.

Claims

1. Method for melting and subsequently holding at temperature a light metal alloy (6-6b), in particular an aluminium alloy, in an electric arc furnace (1-1b), characterized by that a gas atmosphere (8-8b) is generated in a melting chamber (2-2b) of the electric arc furnace (1-1b) which contains a reactive gas and / or an inert gas.

2. Method according to claim 1, characterized by , the gas atmosphere (8-8b) is produced by a silane with the molecular formula Si n -H 2n+2 or mixtures of silanes from the group of silanes with the molecular formula Si n H 2n+2 into the melting chamber (2-2b) where n < 6.

3. Method according to claim 1 or 2, characterized by that the gas atmosphere (8-8b) is produced by a silane with the molecular formula Si n H 2n+2 or mixtures of silanes from the group of silanes with the molecular formula Si n H 2n+2and an inert gas is or are introduced into the melting chamber (2-2b), wherein n < 6 , and a proportion of silanes from the group of silanes with the molecular formula Si n H 2n+2 the concentration in the gas atmosphere is between 0.01 vol.% and 30.00 vol.%, where the sum of all gases forming the gas atmosphere is 100 vol.%.

4. Method according to any one of claims 1 to 3, characterized by that the gas atmosphere (8-8b) is created by introducing monosilane (SiH4) into the melting chamber.

5. Method according to any one of claims 1 to 4, characterized by that The gas atmosphere (8-8b) is generated by introducing an inert gas and monosilane (SiH4) into the melting chamber (2-2b), wherein the proportion of monosilane (SiH4) in the gas atmosphere is between 0.01 vol% and 30.00 vol%, and wherein the sum of all gases forming the gas atmosphere is 100 vol%.

6. Method according to any one of claims 1 to 5, characterized by that the gas atmosphere (8-8b) is created by introducing an inert gas into the melting chamber (2-2b), and in the area of ​​an electric arc (7-7b) of the electric arc melting furnace (1-1b) additionally a silane from the group of silanes with the molecular formula Si n H 2n+2 , preferably monosilane (SiH4), or mixtures of silanes from the group of silanes with the molecular formula Si n H 2n+2 to be introduced where n < 6.

7. Method according to any one of claims 1 to 6, characterized by that an electric arc (7-7b) is formed between a first electrode (5-5b; 12) and a second electrode (9), one of the electrodes being formed at least partially by a light metal alloy (6-6b) arranged in the melting chamber (2-2b).

8. Method according to any one of claims 1 to 6, characterized by thatan electric arc (7) is formed between a first electrode (10) and a second electrode (11), with both electrodes (10, 11) being arranged above a light metal alloy (6) arranged in the melting chamber (2).

9. Method according to any one of claims 1 to 6, characterized by that an electric arc (7) is formed between a first electrode (9) and a second hollow electrode (12) into which the first electrode (9) is immersed at least partially.

10. Electric arc furnace (1-1b) configured for carrying out a method according to one of claims 1 to 9, and comprising a melting chamber (2-2b).

11. Electric arc furnace according to claim 10, characterized by that the electric arc furnace (1-1b) has a charging chamber (15) which is fluidically connected to a melting chamber (2-2b).

12. Electric arc furnace according to claim 10 or 11, characterized by thatthe electric arc furnace (1-1b) comprises a charging chamber (15) with a heating device (19), wherein the heating device (19) is set up for preheating a light metal alloy (6-6b) to be melted.

13. Electric arc furnace according to one of claims 10 to 12, characterized by that the electric arc furnace (1-1b) has a device for generating an electric arc (7-7b) comprising two electrodes (5-5b; 10, 11; 9, 12) between which an electric arc (7-7b) can be formed, wherein one of the two electrodes is formed of a light metal alloy (6-6b) arranged in the electric arc furnace, or both electrodes (10, 11) are arranged above a light metal alloy (6-6b) arranged in the electric arc furnace (1-1b).

14. Electric arc furnace according to one of claims 10 to 12, characterized by, the electric arc furnace (1-1b) has a device for generating an electric arc (7-7b) comprising two electrodes between which an electric arc can be formed, wherein a first of the two electrodes (12) is hollow and a second of the two electrodes (9) is at least partially immersed in the first hollow electrode (12), wherein the electric arc (7-7b) is formed in a cavity of the first hollow electrode (12) when the electric arc furnace (1-1b) is in operation.

15. Electric arc furnace according to one of claims 10 to 12, characterized by that the electric arc furnace (1-1b) has a device for generating an electric arc 7-7b) comprising two electrodes (5-5b; 10, 11; 9, 12), one of the electrodes (5b) being placed in a cover (24), and the cover (24) being able to be placed on a region (25) of a light metal alloy (6b) arranged in the electric arc furnace (7-7b).

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