EP0063711B1 - Electrode for arc furnaces and its use - Google Patents
Electrode for arc furnaces and its use Download PDFInfo
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- EP0063711B1 EP0063711B1 EP82102771A EP82102771A EP0063711B1 EP 0063711 B1 EP0063711 B1 EP 0063711B1 EP 82102771 A EP82102771 A EP 82102771A EP 82102771 A EP82102771 A EP 82102771A EP 0063711 B1 EP0063711 B1 EP 0063711B1
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- electrode according
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- electrode
- bottom portion
- carbon material
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- 239000003575 carbonaceous material Substances 0.000 claims abstract description 25
- 238000001816 cooling Methods 0.000 claims abstract description 12
- 238000004519 manufacturing process Methods 0.000 claims abstract description 9
- 239000007788 liquid Substances 0.000 claims abstract description 5
- 239000000463 material Substances 0.000 claims description 9
- 238000000576 coating method Methods 0.000 claims description 5
- 239000011248 coating agent Substances 0.000 claims description 4
- 238000005452 bending Methods 0.000 claims description 3
- 239000000571 coke Substances 0.000 claims description 2
- 239000002245 particle Substances 0.000 claims 1
- 239000002184 metal Substances 0.000 abstract description 18
- 229910052751 metal Inorganic materials 0.000 abstract description 18
- 210000002445 nipple Anatomy 0.000 abstract description 15
- 230000008901 benefit Effects 0.000 abstract description 5
- 239000007770 graphite material Substances 0.000 abstract 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 13
- 229910002804 graphite Inorganic materials 0.000 description 6
- 239000010439 graphite Substances 0.000 description 6
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 5
- 229910052802 copper Inorganic materials 0.000 description 5
- 239000010949 copper Substances 0.000 description 5
- 238000010276 construction Methods 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- 229910000976 Electrical steel Inorganic materials 0.000 description 3
- 239000002826 coolant Substances 0.000 description 3
- 229910001018 Cast iron Inorganic materials 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 229910017052 cobalt Inorganic materials 0.000 description 2
- 239000010941 cobalt Substances 0.000 description 2
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 229910052593 corundum Inorganic materials 0.000 description 2
- 239000010431 corundum Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- -1 ferrous metals Chemical class 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 239000010410 layer Substances 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000005524 ceramic coating Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000010891 electric arc Methods 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 238000005087 graphitization Methods 0.000 description 1
- 238000005470 impregnation Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 230000007257 malfunction Effects 0.000 description 1
- 238000010309 melting process Methods 0.000 description 1
- 239000011241 protective layer Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B7/00—Heating by electric discharge
- H05B7/02—Details
- H05B7/06—Electrodes
- H05B7/08—Electrodes non-consumable
- H05B7/085—Electrodes non-consumable mainly consisting of carbon
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B7/00—Heating by electric discharge
- H05B7/02—Details
- H05B7/10—Mountings, supports, terminals or arrangements for feeding or guiding electrodes
- H05B7/101—Mountings, supports or terminals at head of electrode, i.e. at the end remote from the arc
Definitions
- the invention relates to an electrode for arc furnaces made of an upper section made of metal and an edible lower section made of carbon material, which have a substantially cylindrical shape and are connected to one another by a screw nipple or the like or else directly, the upper section having a liquid cooling device has a flow channel and a return channel and the upper section can preferably be protected in its lower area by a high-temperature-resistant coating, and their use.
- Arc furnaces for the production of electrical steel, copper, corundum, cobalt, silicon etc. have so far been operated with graphite electrodes as current-carrying elements.
- An electrode string is usually composed of a plurality of graphite units which are connected to one another by screw connections or the like. Three electrode strands are often used as current-carrying elements per furnace for these electrothermal high-temperature melting processes.
- electrodes for electric arc furnaces have been described in DE-A-1 565 751, which consist of an upper metallic head piece, a lower metallic head piece, both electrical conductors connecting to one another, a ceramic mass including these conductors and the lower head piece, and one lower head piece consist of replaceable attached electrode tip.
- a liquid-cooled electrode is also known from DE-A-2 845 367, which has a cylindrical clamping part fastened to the electrode support arm, a metallic cooling system fastened to it and guiding the electrode current and carrying a threaded part at the free end for screwing on the electrode tip, and a tubular heat shield , which contains the cooling system in the area exposed to the furnace atmosphere at a distance and in a fixed spatial association therewith.
- EP-A-12 573 discloses a combination electrode in which the laterally external metallic contact of the metal shaft is mounted in an insulating manner with respect to the internal metallic cooling system.
- a ceramic coating secured with hooks is provided, which extends to approximately the height of the screw nipple connection with which a carbon part is attached.
- the invention is therefore based on the object of providing an electrode for arc furnaces of the type mentioned at the outset, in which the metal shaft and carbon material are matched to one another in such a way that the electrode can be operated in a manner which is less susceptible to faults.
- this is intended to reduce electrode downtime and simplify the manufacturing process for the carbon parts that form the lower section of the electrode.
- This object is achieved by creating an electrode of the type mentioned at the outset, which is characterized in that the lower section is formed from fine-grained, high-strength, highly graphitic carbon material with a bulk density of at least 1.70 g / cm 3 .
- the lower section is connected to the upper section of metal generally by a nipple made of metal such as cast iron or copper, but preferably graphite.
- a nipple made of metal such as cast iron or copper, but preferably graphite.
- another type of fastening with the upper section made of metal can also be selected, if necessary.
- This is provided with a liquid cooling device, which is usually formed from at least one flow and one return channel. With its inlet channel, the cooling device preferably also reaches the upper outer region of the nipple, which is particularly preferred. Alternatively, it is also possible to flow through the nipple with the cooling system itself, if necessary.
- the upper section extends over 40 to 80%, preferably 60 to 80%, of the total length of the electrode.
- the advantages of the invention are achieved when the lower section is formed from fine-grained, high-strength, highly graphitic carbon material with a bulk density of at least 1.70 g / cm 3 , particularly advantageous results are obtained with bulk densities in the range from 1.75 to 1 , 92 g / cm 3 reached. The use of the latter carbon materials is therefore particularly favorable.
- the carbon material which forms the lower section of the electrode according to the invention can have a specific electrical resistance of less than 6 ⁇ mm 2 / m.
- the carbon material has a thermal conductivity of more than 200 W / mK.
- the fine-grained, high-strength, highly graphitic carbon material forming the lower section can advantageously be chosen such that the bending strength is more than 15 N / mm 2 .
- An electrode of the type mentioned at the outset is therefore particularly advantageous in which the lower section made of fine-grained, highly graphitic carbon material has a bulk density of 1.75 to 1.92 g / cm 3 , a specific electrical resistance of: 5 6 Q mm 2 / m, has a thermal conductivity of> 200 W / mK and a flexural strength of more than 15 N / mm 2 .
- carbon material with a maximum grain size of 1 to 3 mm is used with particular advantage.
- the carbon material used in the lower section of the electrode according to the invention can be produced particularly cheaply from high-quality premium coke using binding and impregnating agents.
- particularly good lower sections are obtained at a graphitization temperature above 2900 ° C.
- the diameter of the lower section is smaller than that of the upper section made of metal and also smaller than that of full graphite electrodes for a given load.
- the diameter of the lower section is advantageously in the range from 150 to 500 mm.
- the lower section has a threaded box on one end face and a threaded pin on the other end face. It is hereby possible to connect the lower section directly to the upper section made of metal without an intermediate nipple and also to screw the remainder of the previously used lower section onto the underside of the new lower section.
- the lower section has a central bore of 20 to 50 mm in diameter, which is similar to hollow electrodes but better, but not continuous, through.
- the lateral surface of the lower section can also advantageously be unprocessed.
- the electrodes can have a smaller dimension than conventional electrodes.
- the electrodes have considerable shock resistance and greater resistance to side erosion.
- the carbon electrode parts can be pressed, annealed, impregnated and graphitized more easily than is the case with larger dimensioned electrodes.
- the electrode according to the invention can advantageously be used for the production of non-ferrous metals, such as copper and cobalt, but also for the production of corundum, silicon, etc.
- the electrode is preferred for the production of electrical steel.
- the electrode according to the invention is particularly suitable for the production of electrical steel in the so-called “high power” or “ultra high power” range at current intensities of 40 to 80 KA, the diameter of the lower section then being in the range of approximately 400 to 600 mm Find.
- a particularly preferred current load for the electrodes according to the invention is in the range from 50 to 75 KA for the aforementioned diameters of the carbon part.
- An embodiment of an electrode according to the invention is shown in longitudinal section in the figure, but the invention is not limited to this.
- the cooling medium usually water
- the cooling medium also enters a chamber within the screw nipple 1, the z. B. is made of cast iron.
- the upper section 5 made of metal here consists of an upper area of larger diameter and a lower-lying area of smaller diameter, which is drawn into the screw nipple 1, which is the connection to the lower section 6 made of carbon material, which is made of fine-grained, high-strength, highly graphitic carbon material with a bulk density of at least 1.70 g / cm 3 is formed.
- the high-temperature-resistant coating 4 is formed from a number of individual molded parts, which can be carried on a bearing 7.
- the high-temperature-resistant insulation 4 is adjoined here by an electrically conductive intermediate layer 11, which is delimited inwards by the inner metal shaft or its section of smaller diameter 12 which is drawn inwards.
- bores can also be provided through which inserted pins ensure a good fit of the high-temperature-resistant molded parts via a spring.
- Current can be supplied to the electrode via the jaws 18.
- the object of the invention is not limited to the construction shown in the figure. So z. B. particularly advantageous in the context of the invention constructions that have deviations from the electrode type shown in the figure.
- the metal shaft has an essentially constant diameter. Rings made of high temperature resistant material - preferably graphite - can be screwed onto these.
- the cooling system can preferably be designed in such a way that the cooling medium flows around the nipple in its upper outer region, but this does not enter the nipple itself.
- An electrically conductive intermediate layer is not always provided in such constructions.
- the carbon material of the edible lower section is formed from fine-grained, high-strength, highly graphitic carbon material with a bulk density of at least 1.7 g / cm 3 .
- An electrode was used, the upper section of which was made of copper and which was cooled with water via a system of flow and return channels.
- the copper shaft which was inside the furnace atmosphere, was protected by a high temperature resistant coating.
- the lower section was screwed to the metal shaft via a graphite nipple.
- the lower section had a smaller diameter than the upper section, which was approximately 350 mm.
- the specific electrical resistance was 5.1 ⁇ mm 2 / m.
- the electrode had a central bore of 30 mm in diameter.
- Three electrodes were inserted into an oven with a capacity of 50 t, in which piece of scrap was used as the input material.
- the furnace was operated with three phases with a maximum phase current of 50 KA at a voltage of 490 V.
- the flectrode according to the invention could be used in continuous operation, with a graphite consumption of 3.1 kg / t liquid steel.
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- Discharge Heating (AREA)
- Vertical, Hearth, Or Arc Furnaces (AREA)
- Furnace Details (AREA)
- Acyclic And Carbocyclic Compounds In Medicinal Compositions (AREA)
- Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
- Fats And Perfumes (AREA)
- Electrochromic Elements, Electrophoresis, Or Variable Reflection Or Absorption Elements (AREA)
- Resistance Heating (AREA)
- Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
- Ceramic Products (AREA)
- Devices For Indicating Variable Information By Combining Individual Elements (AREA)
- Conductive Materials (AREA)
Abstract
Description
Die Erfindung betrifft eine Elektrode für Lichtbogenöfen aus einem oberen Abschnitt aus Metall und einem verzehrbaren unteren Abschnitt aus Kohlenstoffmaterial, die eine im wesentlichen zylindrische Form aufweisen und durch einen Schraubnippel oder dergleichen oder auch direkt miteinander verbunden sind, wobei der obere Abschnitt eine Flüssigkeits-Kühleinrichtung mit einem Vorlaufkanal und einem Rücklaufkanal aufweist und der obere Abschnitt vorzugsweise in dessen unterem Bereich durch eine hochtemperaturfeste Beschichtung geschützt sein kann, sowie deren Verwendung.The invention relates to an electrode for arc furnaces made of an upper section made of metal and an edible lower section made of carbon material, which have a substantially cylindrical shape and are connected to one another by a screw nipple or the like or else directly, the upper section having a liquid cooling device has a flow channel and a return channel and the upper section can preferably be protected in its lower area by a high-temperature-resistant coating, and their use.
Lichtbogenöfen zur Erzeugung von Elektrostahl, Kupfer, Korund, Kobalt, Silizium etc., werden bisher mit Graphitelektroden als stromzuführenden Elementen betrieben. Üblicherweise setzt sich ein Elektrodenstrang aus mehreren, miteinander durch Schraubverbindungen oder dergleichen verbundenen Graphiteinheiten zusammen. Häufig werden drei Elektrodenstränge als stromführende Elemente pro Ofen für diese elektrothermischen Hochtemperaturschmelzprozesse eingesetzt.Arc furnaces for the production of electrical steel, copper, corundum, cobalt, silicon etc. have so far been operated with graphite electrodes as current-carrying elements. An electrode string is usually composed of a plurality of graphite units which are connected to one another by screw connections or the like. Three electrode strands are often used as current-carrying elements per furnace for these electrothermal high-temperature melting processes.
Es sind auch bereits Kombinationselektroden aus einem Metallschaft, an denen durch eine Schraubverbindung, wie Nippel, etc., eine Spitze aus Kohlenstoffmaterial angefügt ist, für den Lichtbogenofenbetrieb beschrieben worden.Combination electrodes made of a metal shaft, to which a tip made of carbon material is attached by means of a screw connection, such as nipples, etc., have also been described for arc furnace operation.
So sind in DE-A-1 565 751 Elektroden für elektrische Lichtbogenöfen beschrieben worden, die aus einem oberen metallischen Kopfstück, einem unteren metallischen Kopfstück, aus beide miteinander verbindenden elektrischen Leitern, aus einer diese Leiter und das untere Kopfstück einschließenden keramischen Masse und aus einem unteren Kopfstück auswechselbar befestigten Elektrodenspitze bestehen.For example, electrodes for electric arc furnaces have been described in DE-A-1 565 751, which consist of an upper metallic head piece, a lower metallic head piece, both electrical conductors connecting to one another, a ceramic mass including these conductors and the lower head piece, and one lower head piece consist of replaceable attached electrode tip.
Eine flüssigkeitsgekühlte Elektrode ist auch aus DE-A-2 845 367 bekannt, die einen am Elektrodentragarm befestigten zylindrischen Einspannteil, ein an dieser befestigtes, den Elektrodenstrom führendes metallisches Kühlsystem, das am freien Ende einen Gewindeteil zum Aufschrauben der Elektrodenspitze trägt, und einen rohrförmigen Hitzeschirm, der das Kühlsystem in dem der Ofenatmosphäre ausgesetzten Bereich mit Abstand und in fester räumlicher Zuordnung zu diesem enthält, aufweist.A liquid-cooled electrode is also known from DE-A-2 845 367, which has a cylindrical clamping part fastened to the electrode support arm, a metallic cooling system fastened to it and guiding the electrode current and carrying a threaded part at the free end for screwing on the electrode tip, and a tubular heat shield , which contains the cooling system in the area exposed to the furnace atmosphere at a distance and in a fixed spatial association therewith.
Aus EP-A-12 573 geht eine Kombinationselektrode hervor, bei der der seitlich außenliegende metallische Kontakt des Metallschaftes gegenüber dem innenliegenden metallischen Kühlungssystem isolierend gelagert ist. Im unteren Teil des metallischen Kühlungsschaftes ist eine mit Haken gesicherte keramische Beschichtung vorgesehen, die sich bis etwa auf die Höhe der Schraubnippelverbindung erstreckt, mit der ein Kohlenstoffteil angefügt ist.EP-A-12 573 discloses a combination electrode in which the laterally external metallic contact of the metal shaft is mounted in an insulating manner with respect to the internal metallic cooling system. In the lower part of the metallic cooling shaft, a ceramic coating secured with hooks is provided, which extends to approximately the height of the screw nipple connection with which a carbon part is attached.
Derartige Kombinationselektroden sind im Prinzip bereits seit längerer Zeit bekannt, so z. B. aus der im Jahre 1912 ausgegebenen DE-C-268 660.Such combination electrodes have been known in principle for a long time, such. B. from DE-C-268 660 issued in 1912.
Bei den heute üblichen Elektrodensträngen treten erhebliche Verluste an Kohlenstoffmaterial, unter anderem durch Seitenoxidation auf. Bei den Vollstrangelektroden aus Kohlenstoffmaterial sind daher Versuche unternommen worden, durch Imprägnierung oder durch Aufbringung von Schutzschichten, wie keramischen und/oder metallischen Coatings, diesem unerwünschten Effekt entgegenzuwirken. Diese Maßnahmen haben einerseits aber nur begrenzte Wirkung, führen andererseits aber auch zu einer Verteuerung der Elektroden.Considerable losses of carbon material occur, among other things due to side oxidation, in the electrode strands common today. In the case of full-strand electrodes made of carbon material, attempts have therefore been made to counteract this undesirable effect by impregnation or by applying protective layers, such as ceramic and / or metallic coatings. On the one hand, these measures have only a limited effect, but on the other hand they also make the electrodes more expensive.
Bei den vorstehend angeführten Kombinationselektroden aus Metallschaft und angeschraubtem Kohlenstoffteil kann sich, je nach Konstruktion und Länge des in den Ofen eingeführten Metallschaftes, eine Verminderung der Seitenoxidation ergeben. Aber auch diese Elektroden bedürfen einer weiteren Verbesserung im Hinblick auf eine Verminderung der Seiten- und Spitzenoxidationsverluste. Auch bedürfen Metallschaft und hiermit verbundenes Kohlenstoffmaterial zum Erhalt optimaler Betriebsbedingungen und eines wenig störungsanfälligen Betriebes unter Minimierung der Bruchverluste der Elektroden einer ständigen Verbesserung.Depending on the construction and length of the metal shaft inserted into the furnace, a reduction in side oxidation can result in the combination electrodes made of metal shaft and screwed-on carbon part. However, these electrodes also require further improvement with a view to reducing side and peak oxidation losses. In addition, the metal shaft and the carbon material connected to it require constant improvement in order to maintain optimal operating conditions and operation that is less prone to malfunctions while minimizing the breakage losses of the electrodes.
Der Erfindung liegt daher die Aufgabe zugrunde, eine Elektrode für Lichtbogenöfen der eingangs genannten Art zu schaffen, bei der Metallschaft und Kohlenstoffmaterial aufeinander derart abgestimmt sind, daß ein wenig störungsanfälliger Betrieb der Elektrode möglich ist. Insbesondere soll es möglich sein, den Verbrauch der Kohlenstoffmaterialien durch Seitenoxidation und hohe Bruchraten, insbesondere bei extremer Strombelastung der Elektroden zu senken. Gleichzeitig soll hierdurch eine Verminderung der Elektrodenausfallzeiten und eine Vereinfachung des Herstellungsverfahrens der Kohlenstoffteile, die den unteren Abschnitt der Elektrode ausbilden, erreicht werden.The invention is therefore based on the object of providing an electrode for arc furnaces of the type mentioned at the outset, in which the metal shaft and carbon material are matched to one another in such a way that the electrode can be operated in a manner which is less susceptible to faults. In particular, it should be possible to reduce the consumption of carbon materials by side oxidation and high breakage rates, especially when the electrodes are subjected to extreme current. At the same time, this is intended to reduce electrode downtime and simplify the manufacturing process for the carbon parts that form the lower section of the electrode.
Diese Aufgabe wird durch die Schaffung einer Elektrode der eingangs genannten Art gelöst, die dadurch gekennzeichnet ist, daß der untere Abschnitt aus feinkörnigem, hochfesten, hochgraphitischen Kohlenstoffmaterial mit einer Rohdichte von mindestens 1,70 g/cm3 gebildet ist.This object is achieved by creating an electrode of the type mentioned at the outset, which is characterized in that the lower section is formed from fine-grained, high-strength, highly graphitic carbon material with a bulk density of at least 1.70 g / cm 3 .
Der untere Abschnitt ist mit dem oberen Abschnitt aus Metall im allgemeinen durch einen Nippel verbunden, der aus Metall, wie Gußeisen oder Kupfer, vorzugsweise aber Graphit besteht. Anstelle des Nippels kann aber gegebenenfalls auch eine andere Befestigungsart mit dem oberen Abschnitt aus Metall gewählt werden. Dieser ist mit einer Flüssigkeits-Kühleinrichtung versehen, die üblicherweise aus mindestens einem Vorlauf- und einem Rücklaufkanal gebildet ist. Die Kühleinrichtung erreicht mit ihrem Zulaufkanal vorzugsweise auch den oberen äußeren Bereich des Nippels, was besonders bevorzugt ist. In alternativer Weise ist es aber auch möglich, den Nippel gegebenenfalls mit dem Kühlsystem selbst zu durchströmen.The lower section is connected to the upper section of metal generally by a nipple made of metal such as cast iron or copper, but preferably graphite. Instead of the nipple, another type of fastening with the upper section made of metal can also be selected, if necessary. This is provided with a liquid cooling device, which is usually formed from at least one flow and one return channel. With its inlet channel, the cooling device preferably also reaches the upper outer region of the nipple, which is particularly preferred. Alternatively, it is also possible to flow through the nipple with the cooling system itself, if necessary.
Es ist günstig, wenn der obere Abschnitt sich über 40 bis 80%, vorzugsweise 60 bis 80%, der Gesamtlänge der Elektrode erstreckt.It is advantageous if the upper section extends over 40 to 80%, preferably 60 to 80%, of the total length of the electrode.
Wenngleich die Vorteile der Erfindung bereits dann erreicht werden, wenn der untere Abschnitt aus feinkörnigem, hochfesten, hochgraphitischen Kohlenstoffmaterial mit einer Rohdichte von mindestens 1,70 g/cm3 gebildet ist, werden besonders vorteilhafte Ergebnisse bei Rohdichten im Bereich von 1,75 bis 1,92 g/cm3 erreicht. Daher ist die Verwendung der zuletzt genannten Kohlenstoffmaterialien besonders günstig.Although the advantages of the invention are achieved when the lower section is formed from fine-grained, high-strength, highly graphitic carbon material with a bulk density of at least 1.70 g / cm 3 , particularly advantageous results are obtained with bulk densities in the range from 1.75 to 1 , 92 g / cm 3 reached. The use of the latter carbon materials is therefore particularly favorable.
Das Kohlenstoffmaterial, das den unteren Abschnitt der erfindungsgemäßen Elektrode ausbildet, kann in einer bevorzugten Ausführungsform der Erfindung einen spezifischen elektrischen Widerstand von weniger als 6 Ω mm2/m aufweisen.In a preferred embodiment of the invention, the carbon material which forms the lower section of the electrode according to the invention can have a specific electrical resistance of less than 6 Ω mm 2 / m.
Es ist auch günstig, wenn das Kohlenstoffmaterial eine Wärmeleitfähigkeit von mehr als 200 W/mK aufweist. Schließlich kann das den unteren Abschnitt bildende feinkörnige, hochfeste, hochgraphitische Kohlenstoffmaterial mit Vorteil derart gewählt werden, daß die Biegefestigkeit mehr als 15 N/mm2 beträgt.It is also favorable if the carbon material has a thermal conductivity of more than 200 W / mK. Finally, the fine-grained, high-strength, highly graphitic carbon material forming the lower section can advantageously be chosen such that the bending strength is more than 15 N / mm 2 .
Somit ist eine Elektrode der eingangs genannten Art besonders vorteilhaft, bei der der untere Abschnitt aus feinkörnigem, hochgraphitischen Kohlenstoffmaterial eine Rohdichte von 1,75 bis 1,92 g/cm3, einen spezifischen elektrischen Widerstand von :5 6 Q mm2/m, eine Wärmeleitfähigkeit von > 200 W/mK und eine Biegefestigkeit von mehr als 15 N/mm2 aufweist.An electrode of the type mentioned at the outset is therefore particularly advantageous in which the lower section made of fine-grained, highly graphitic carbon material has a bulk density of 1.75 to 1.92 g / cm 3 , a specific electrical resistance of: 5 6 Q mm 2 / m, has a thermal conductivity of> 200 W / mK and a flexural strength of more than 15 N / mm 2 .
Bei der Herstellung des unteren Abschnittes wird mit besonderem Vorteil von Kohlenstoffmaterial ausgegangen, das eine maximale Korngröße von 1 bis 3 mm aufweist. Das in dem unteren Abschnitt der erfindungsgemäßen Elektrode zum Einsatz gelangende Kohlenstoffmaterial kann besonders günstig aus hochwertigem Premiumkoks unter Verwendung von Binde- und Imprägnierungsmitteln hergestellt werden. Bei der Verwendung der genannten oder gegebenenfalls auch anderer Ausgangsstoffe werden bei einer Graphitierungstemperatur über 2900°C besonders gute untere Abschnitte erhalten.In the manufacture of the lower section, carbon material with a maximum grain size of 1 to 3 mm is used with particular advantage. The carbon material used in the lower section of the electrode according to the invention can be produced particularly cheaply from high-quality premium coke using binding and impregnating agents. When using the named or possibly other starting materials, particularly good lower sections are obtained at a graphitization temperature above 2900 ° C.
Nach einer bevorzugten Ausführungsform der erfindungsgemäßen Elektrode ist der Durchmesser des unteren Abschnittes geringer als der des oberen Abschnittes aus Metall und auch geringer als derjenige von Vollgraphitelektroden bei vorgegebener Belastung. Der Durchmesser des unteren Abschnittes liegt vorteilhaft im Bereich von 150 bis 500 mm.According to a preferred embodiment of the electrode according to the invention, the diameter of the lower section is smaller than that of the upper section made of metal and also smaller than that of full graphite electrodes for a given load. The diameter of the lower section is advantageously in the range from 150 to 500 mm.
Nach einer Ausführungsform der Erfindung besitzt der untere Abschnitt an der einen Stirnseite eines Gewindeschachtel und an der anderen Stirnseite einen Gewindezapfen. Es ist hierdurch möglich, den unteren Abschnitt direkt ohne zwischengeschalteten Nippel mit dem oberen Abschnitt aus Metall zu verbinden und außerdem das Reststück des vorher verwendeten unteren Abschnittes an die Unterseite des neuen unteren Abschnittes anzuschrauben.According to one embodiment of the invention, the lower section has a threaded box on one end face and a threaded pin on the other end face. It is hereby possible to connect the lower section directly to the upper section made of metal without an intermediate nipple and also to screw the remainder of the previously used lower section onto the underside of the new lower section.
Bei den Ausführungsformen der erfindungsgemäßen Elektrode, bei denen auf die Zwischenschaltung eines Nippels verzichtet worden ist, ergeben sich auch hierdurch Vorteile, zumal der Übergangsbereich vom unteren zum oberen Abschnitt aufgrund der dort gegebenen Temperaturdifferenz und unterschiedlichen Temperaturausdehnungskoeffizienten der jeweiligen Materialien bei den vorbekannten Kombinationselektroden besonders störungsanfällig ist.In the embodiments of the electrode according to the invention, in which the interposition of a nipple has been dispensed with, advantages also result from this, especially since the transition area from the lower to the upper section is particularly susceptible to faults in the known combination electrodes due to the temperature difference and different coefficients of thermal expansion of the respective materials .
Im übrigen kann es auch vorgesehen sein, daß der untere Abschnitt eine ähnlich zu Hohlelektroden durchgehende, besser jedoch nicht durchgehende, zentrische Bohrung von 20 bis 50 mm Durchmesser aufweist. Auch kann mit Vorteil die Mantelfläche des unteren Abschnittes unbearbeitet sein.In addition, it can also be provided that the lower section has a central bore of 20 to 50 mm in diameter, which is similar to hollow electrodes but better, but not continuous, through. The lateral surface of the lower section can also advantageously be unprocessed.
Durch die Bereitstellung der erfindungsgemäßen Elektrode werden eine Reihe von Vorteilen erzielt. Die Elektroden können bei vorgegebener Belastung eine geringere Dimensionierung als herkömmliche Elektroden aufweisen. Im übrigen hat sich gezeigt, daß die Elektroden eine erhebliche Schockfestigkeit und eine größere Beständigkeit gegen Seitenabbrand aufweisen. Durch die Ausbildung geringerer Dimensionierungen des Kohlenstoffteils lassen sich die Kohlenstoffelektrodenteile einfacher pressen, glühen, imprägnieren und graphitieren, als dies bei größer dimensionierten Elektroden der Fall ist.A number of advantages are achieved by providing the electrode according to the invention. For a given load, the electrodes can have a smaller dimension than conventional electrodes. In addition, it has been shown that the electrodes have considerable shock resistance and greater resistance to side erosion. By forming smaller dimensions of the carbon part, the carbon electrode parts can be pressed, annealed, impregnated and graphitized more easily than is the case with larger dimensioned electrodes.
Die erfindungsgemäße Elektrode kann mit Vorteil zur Herstellung von Buntmetallen, wie Kupfer und Kobalt, aber auch zur Herstellung von Korund, von Silizium, etc., eingesetzt werden.The electrode according to the invention can advantageously be used for the production of non-ferrous metals, such as copper and cobalt, but also for the production of corundum, silicon, etc.
Ihre bevorzugte Verwendung findet die Elektrode jedoch zur Herstellung von Elektrostahl. Die erfindungsgemäße Elektrode eignet sich besonders für die Herstellung von Elektrostahl im sogenannten »High Power«- oder »Ultra High Power«-Bereich bei Stromstärken von 40 bis 80 KA, wobei dann Durchmesser des unteren Abschnittes im Bereich von ca. 400 bis 600 mm Anwendung finden. Eine speziell bevorzugte Strombelastung für die erfindungsgemäßen Elektroden liegt im Bereich von 50 bis 75 KA bei den vorgenannten Durchmessern des Kohlenstoffteils.However, the electrode is preferred for the production of electrical steel. The electrode according to the invention is particularly suitable for the production of electrical steel in the so-called "high power" or "ultra high power" range at current intensities of 40 to 80 KA, the diameter of the lower section then being in the range of approximately 400 to 600 mm Find. A particularly preferred current load for the electrodes according to the invention is in the range from 50 to 75 KA for the aforementioned diameters of the carbon part.
Nachstehend wird eine Ausführungsform einer erfindungsgemäßen Elektrode im Längsschnitt in der Figur gezeigt, wobei die Erfindung nicht hierauf beschränkt ist.An embodiment of an electrode according to the invention is shown in longitudinal section in the figure, but the invention is not limited to this.
Bei der gezeigten Elektrode wird das Kühlmedium, im Regelfall Wasser, durch den Vorlaufkanal 2 ein- und durch den Rücklaufkanal 3 zurückgeführt. Dabei tritt das Kühlmedium auch in eine Kammer innerhalb des Schraubnippels 1, der z. B. aus Gußeisen gebildet ist, ein. Der obere Abschnitt 5 aus Metall besteht hier aus einem oberen Bereich größeren Durchmessers und einem tieferliegenden Bereich geringeren Durchmessers, der bis in den Schraubnippel 1 eingezogen ist, der die Verbindung zu dem unteren Abschnitt 6 aus Kohlenstoffmaterial darstellt, das aus feinkörnigem, hochfesten, hochgraphitischen Kohlenstoffmaterial mit einer Rohdichte von mindestens 1,70 g/cm3 gebildet ist. Die hochtemperaturfeste Beschichtung 4 ist aus einer Anzahl einzelner Formteile gebildet, die auf einem Lager 7 getragen sein können. An die hochtemperaturfeste Isolierung 4 schließt sich hier eine elektrisch leitende Zwischenschicht 11 an, die nach innen durch den vorgezogenen, innenliegenden Metallschaft bzw. dessen Abschnitt geringeren Durchmessers 12 begrenzt ist.In the electrode shown, the cooling medium, usually water, is introduced through the feed channel 2 and returned through the return channel 3. The cooling medium also enters a chamber within the screw nipple 1, the z. B. is made of cast iron. The upper section 5 made of metal here consists of an upper area of larger diameter and a lower-lying area of smaller diameter, which is drawn into the screw nipple 1, which is the connection to the
Neben den Kühlbohrungen 15 können zusätzlich Bohrungen vorgesehen sein, durch die eingeführte Stifte über eine Feder für einen guten Sitz der hochtemperaturfesten Formteile sorgen. Über die Backen 18 kann der Elektrode Strom zugeführt werden.In addition to the
Der Gegenstand der Erfindung ist jedoch nicht auf die in der Figur gezeigte Konstruktion beschränkt. So sind z. B. im Rahmen der Erfindung Konstruktionen besonders vorteilhaft, die Abweichungen zu dem in der Figur gezeigten Elektrodentyp aufweisen. Bei solchen Elektroden, die im Rahmen der Erfindung bevorzugt sind, weist der Metallschaft einen im wesentlichen konstanten Durchmesser auf. Auf diesen können Ringe aus hochtemperaturfestem Material - mit Vorzug solche aus Graphit - aufgeschraubt werden. Das Kühlungssystem kann hierbei mit Vorzug derart ausgebildet sein, daß der Nippel in seinem oberen äußeren Bereich durch das Kühlmedium umströmt wird, dieses aber in den Nippel selbst nicht eintritt. Eine elektrisch leitende Zwischenschicht ist bei solchen Konstruktionen nicht immer vorgesehen. Solche und andersartige Ausführungsformen der erfindungsgemäßen Elektrode sind im Rahmen der Erfindung mit eingeschlossen, soweit das Kohlenstoffmaterial des verzehrbaren unteren Abschnittes aus feinkörnigem, hochfesten, hochgraphitischen Kohlenstoffmaterial mit einer Rohdichte von mindestens 1,7 g/cm3 gebildet ist.However, the object of the invention is not limited to the construction shown in the figure. So z. B. particularly advantageous in the context of the invention constructions that have deviations from the electrode type shown in the figure. In such electrodes, which are preferred in the context of the invention, the metal shaft has an essentially constant diameter. Rings made of high temperature resistant material - preferably graphite - can be screwed onto these. The cooling system can preferably be designed in such a way that the cooling medium flows around the nipple in its upper outer region, but this does not enter the nipple itself. An electrically conductive intermediate layer is not always provided in such constructions. Such and different embodiments of the electrode according to the invention are included in the scope of the invention insofar as the carbon material of the edible lower section is formed from fine-grained, high-strength, highly graphitic carbon material with a bulk density of at least 1.7 g / cm 3 .
Der Einsatz der erfindungsgemäßen Elektrode wird im nachstehenden Beispiel veranschaulicht:The use of the electrode according to the invention is illustrated in the example below:
Es wurde eine Elektrode verwendet, deren oberer Abschnitt aus Kupfer bestand, das über ein System aus Vor- und Rücklaufkanal mit Wasser gekühlt wurde. Der Kupferschaft, der innerhalb der Ofenatmosphäre befindlich war, war durch eine hochtemperaturfeste Beschichtung geschützt. An dem Metallschaft war der untere Abschnitt über einen Graphitnippel angeschraubt. Der untere Abschnitt besaß gegenüber dem oberen Abschnitt einen geringeren Durchmesser, der bei etwa 350 mm lag. Der spezifische elektrische Widerstand lag bei 5,1 Ω mm2/m. Die Elektrode wies eine zentrische Bohrung von 30 mm Durchmesser auf.An electrode was used, the upper section of which was made of copper and which was cooled with water via a system of flow and return channels. The copper shaft, which was inside the furnace atmosphere, was protected by a high temperature resistant coating. The lower section was screwed to the metal shaft via a graphite nipple. The lower section had a smaller diameter than the upper section, which was approximately 350 mm. The specific electrical resistance was 5.1 Ω mm 2 / m. The electrode had a central bore of 30 mm in diameter.
Drei Elektroden wurden in einen Ofen mit 50 t Fassungsvermögen eingeführt, in dem als Einsatzgut stückiger Schrott befindlich war. Der Ofen wurde mit drei Phasen mit einem maximalen Phasenstrom von 50 KA bei einer Spannung von 490 V betrieben.Three electrodes were inserted into an oven with a capacity of 50 t, in which piece of scrap was used as the input material. The furnace was operated with three phases with a maximum phase current of 50 KA at a voltage of 490 V.
Die erfindungsgemäße Flektrode konnte im Dauerbetrieb eingesetzt werden, wobei sich ein Graphitverbrauch von 3,1 kg/t flüssiger Stahl er gab.The flectrode according to the invention could be used in continuous operation, with a graphite consumption of 3.1 kg / t liquid steel.
Claims (16)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AT82102771T ATE15120T1 (en) | 1981-04-23 | 1982-04-01 | ELECTRODE FOR ARC FURNACES AND THEIR USE. |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19813116221 DE3116221A1 (en) | 1981-04-23 | 1981-04-23 | ELECTRODE FOR ARC FURNACES AND THEIR USE |
| DE3116221 | 1981-04-23 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0063711A1 EP0063711A1 (en) | 1982-11-03 |
| EP0063711B1 true EP0063711B1 (en) | 1985-08-21 |
Family
ID=6130709
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP82102771A Expired EP0063711B1 (en) | 1981-04-23 | 1982-04-01 | Electrode for arc furnaces and its use |
Country Status (18)
| Country | Link |
|---|---|
| EP (1) | EP0063711B1 (en) |
| JP (1) | JPS5894794A (en) |
| AT (1) | ATE15120T1 (en) |
| AU (1) | AU8219982A (en) |
| BR (1) | BR8202309A (en) |
| DD (1) | DD202362A5 (en) |
| DE (2) | DE3116221A1 (en) |
| DK (1) | DK181782A (en) |
| ES (1) | ES8400644A1 (en) |
| FI (1) | FI821029L (en) |
| GB (1) | GB2097638A (en) |
| GR (1) | GR75550B (en) |
| HU (1) | HU186006B (en) |
| NO (1) | NO820908L (en) |
| PL (1) | PL236124A1 (en) |
| PT (1) | PT74764B (en) |
| TR (1) | TR21231A (en) |
| ZA (1) | ZA822054B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH655128A5 (en) * | 1983-01-28 | 1986-03-27 | Von Roll Ag | ELECTRODE FOR METALLURGICAL FURNACES. |
| DE3316366C2 (en) * | 1983-05-05 | 1985-10-17 | Mannesmann AG, 4000 Düsseldorf | Furnace vessel for a direct current arc furnace |
| IT1288858B1 (en) * | 1996-02-29 | 1998-09-25 | Danieli Off Mecc | ADAPTER DEVICE FOR ELECTRODES, WITH AUXILIARY REACTANCE FUNCTION, IN AN ELECTRIC ARC OVEN. |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE268660C (en) * | ||||
| SE337435B (en) * | 1965-07-13 | 1971-08-09 | J Oestberg | |
| FR2176546A1 (en) * | 1972-03-23 | 1973-11-02 | Siderurgie Fse Inst Rech | Composite furnace electrode - esp for steel prodn |
| CA1074381A (en) * | 1978-05-09 | 1980-03-25 | Otto E. Prenn | Composite electrode with non-consumable upper section |
| DE2725537A1 (en) * | 1977-06-06 | 1978-12-14 | Korf Stahl | ELECTRODE FOR ARC FURNACE |
| DE2845367C2 (en) * | 1978-10-18 | 1981-01-22 | Korf & Fuchs Syst Tech | Liquid-cooled holder for the tip of an electrode of an arc furnace |
| US4287381A (en) * | 1978-12-19 | 1981-09-01 | British Steel Corporation | Electric arc furnace electrodes |
-
1981
- 1981-04-23 DE DE19813116221 patent/DE3116221A1/en not_active Withdrawn
-
1982
- 1982-03-19 NO NO820908A patent/NO820908L/en unknown
- 1982-03-24 FI FI821029A patent/FI821029L/en not_active Application Discontinuation
- 1982-03-25 GB GB8208739A patent/GB2097638A/en not_active Withdrawn
- 1982-03-25 ZA ZA822054A patent/ZA822054B/en unknown
- 1982-03-31 AU AU82199/82A patent/AU8219982A/en not_active Abandoned
- 1982-04-01 EP EP82102771A patent/EP0063711B1/en not_active Expired
- 1982-04-01 DE DE8282102771T patent/DE3265539D1/en not_active Expired
- 1982-04-01 AT AT82102771T patent/ATE15120T1/en not_active IP Right Cessation
- 1982-04-05 GR GR67817A patent/GR75550B/el unknown
- 1982-04-14 ES ES511792A patent/ES8400644A1/en not_active Expired
- 1982-04-15 PT PT74764A patent/PT74764B/en unknown
- 1982-04-22 JP JP57068534A patent/JPS5894794A/en active Pending
- 1982-04-22 BR BR8202309A patent/BR8202309A/en unknown
- 1982-04-22 DD DD82239231A patent/DD202362A5/en unknown
- 1982-04-23 PL PL23612482A patent/PL236124A1/xx unknown
- 1982-04-23 TR TR21231A patent/TR21231A/en unknown
- 1982-04-23 DK DK181782A patent/DK181782A/en not_active Application Discontinuation
- 1982-04-23 HU HU821298A patent/HU186006B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| DE3265539D1 (en) | 1985-09-26 |
| ZA822054B (en) | 1983-03-30 |
| PL236124A1 (en) | 1982-12-06 |
| HU186006B (en) | 1985-05-28 |
| ES511792A0 (en) | 1983-11-01 |
| PT74764B (en) | 1983-11-15 |
| TR21231A (en) | 1984-02-06 |
| FI821029A0 (en) | 1982-03-24 |
| AU8219982A (en) | 1982-11-25 |
| DK181782A (en) | 1982-10-24 |
| EP0063711A1 (en) | 1982-11-03 |
| DE3116221A1 (en) | 1982-11-11 |
| BR8202309A (en) | 1983-04-05 |
| FI821029L (en) | 1982-10-24 |
| PT74764A (en) | 1982-05-01 |
| NO820908L (en) | 1982-10-25 |
| ATE15120T1 (en) | 1985-09-15 |
| ES8400644A1 (en) | 1983-11-01 |
| JPS5894794A (en) | 1983-06-06 |
| DD202362A5 (en) | 1983-09-07 |
| GR75550B (en) | 1984-07-27 |
| GB2097638A (en) | 1982-11-03 |
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