EP0063710A1 - Elektrode für Lichtbogenöfen und Verfahren zu deren Verwendung - Google Patents

Elektrode für Lichtbogenöfen und Verfahren zu deren Verwendung Download PDF

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Publication number
EP0063710A1
EP0063710A1 EP82102770A EP82102770A EP0063710A1 EP 0063710 A1 EP0063710 A1 EP 0063710A1 EP 82102770 A EP82102770 A EP 82102770A EP 82102770 A EP82102770 A EP 82102770A EP 0063710 A1 EP0063710 A1 EP 0063710A1
Authority
EP
European Patent Office
Prior art keywords
electrode according
electrode
lower section
carbon material
range
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP82102770A
Other languages
German (de)
English (en)
French (fr)
Inventor
Hannsgeorg Dr. Dipl.-Ing. Bauer
Dieter H. Dr. Dipl.-Chem. Zöllner
Inge Dr. Dipl.-Chem. Lauterbach-Dammler
Franz Chem. Ing. Grad. Schieber
Friedrich Rittmann
Wolfgang Dipl.-Chem. Lippert
Josef Dr. Dipl.-Ing. Otto
Josef Mühlenbeck
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Arc Technologies Systems Ltd
Original Assignee
Arc Technologies Systems Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Arc Technologies Systems Ltd filed Critical Arc Technologies Systems Ltd
Publication of EP0063710A1 publication Critical patent/EP0063710A1/de
Withdrawn legal-status Critical Current

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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, the upper section being a liquid cooling device with a flow channel and has a return channel and the upper section can preferably be protected in its lower region by a high-temperature-resistant coating, and methods of using it.
  • An electrode string is usually composed of a plurality of graphite units which are connected to one another by screw connections or the like. Often! three electrode strings are used as current-carrying elements per furnace for these electrothermal high-temperature melting processes.
  • electrodes for electric arc furnaces have been described in DE-OS 15 65 751, which consist of an upper metallic head piece, a lower metallic head piece, both electrical conductors connecting one another, and a ceramic mass enclosing these conductors and the lower head piece and consist of a lower head piece interchangeably attached electrode tip.
  • a liquid-cooled electrode is also known from DE-OS 28 45 367, which has a cylindrical clamping part fastened to the electrode support arm, a metallic cooling system fastened to it, carrying the electrode current, which carries a threaded part at the free end for screwing on the electrode tip, and a tubular heat shield which the cooling system in the area exposed to the furnace atmosphere at a distance and in contains fixed spatial assignment to it.
  • a combination electrode emerges from the European patent laid-open specification 12 573, 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.
  • Such combination electrodes have in principle been known for a long time, e.g. from DE-PS 268 660 issued in 1912.
  • the electrodes have been exposed to increasing electrical (and thus thermal) stress to reduce melting times. Due to the constantly increasing stresses on the electrodes, there have also been extreme demands on the quality of the carbon strands, be they 'those which consist exclusively of carbon material, or be those which are nippled on a cooled metal shaft.
  • the requirements for graphite parts with regard to their density, specific electrical resistance, thermal expansion, thermal conductivity, strength and elasticity as well as thermal shock resistance were continuously increased. This has not only led to an intensification of the graphitization processes that have been carried out over longer periods of time at higher temperatures, but also to additional densification processes, etc.
  • the invention has for its object to provide electrodes for arc furnace operation that can withstand the considerable mechanical, thermal and electrical stresses prevailing there in a particularly suitable manner.
  • an electrode that is particularly suitable for practical operation is to be made available, the production or operation of which can be carried out in a more economical manner than previously.
  • This object is achieved by creating an electrode for arc furnaces of the type mentioned at the outset, which is characterized in that the carbon material is formed only partially from graphitic structural elements or is free thereof.
  • the invention is based on the surprising finding that, when using carbon materials of inferior quality than was previously considered essential for the operation of the electric arc furnace, there is nevertheless good practical behavior with combination electrodes.
  • carbon material which is only partially formed from graphitic structural elements or is completely or almost completely free thereof, the feared formation of cracks or flaking does not occur.
  • the carbon material is connected to the metal shaft via a screw nipple known per se, which consists, for example, of graphite or metal and can also be cooled.
  • the metal shaft which can also be viewed as a power supply to the carbon part, generally consists of a highly conductive metal, for example copper.
  • a liquid cooling system is provided in the metal shaft, which can have a flow and return channel, which can optionally also cool at least part of the screw nipple externally or internally can Such constructions of the metal shaft, which can be at least partially externally protected by a high-temperature-resistant coating, are known.
  • the length and the diameter of the lower section made of carbon material are selected such that, compared to electrode strands of the same or corresponding overall dimensions, which consist exclusively of graphitic carbon material, there is at least the same electrical load capacity.
  • the dimensioning of the upper section made of metal and the lower section made of carbon material is coordinated with one another in such a way that at least some of the metal shaft is regularly inserted into the arc furnace itself.
  • the carbon part advantageously has an output length of approximately 2 to 3 m with total electrode output lengths of approximately 5.5 to 8 m, preferably 6 to 7 m.
  • the proportion of graphitic structural elements within the lower section made of carbon material can be in the range from 0 to 90% by weight. It has been found to be particularly advantageous if the proportion of graphitic structural elements is in the range from 50 to 85% by weight, but particularly preferably 60 to 80% by weight, based on the weight of the carbon material.
  • graphitic structural elements should essentially be understood to mean natural graphite or electrographite or a mixture thereof. Waste graphite, e.g. from synthetic graphite production.
  • non-graphitic structural components of the carbon material consist of anthracite, coal coke and / or normal petroleum coke, and in the context of the invention the lower section can also consist entirely of these materials or mixtures thereof.
  • the carbon material in the lower section is in the range from 0 to 90% by weight, preferably 50 to 85% by weight, but particularly preferably 60 to 80% by weight
  • Electrographite or natural graphite or a mixture thereof and the rest is formed from anthracite, coal coke and / or normal petroleum coke.
  • the lower section of the electrode according to the invention can be produced in a manner known per se. ⁇ Among these, the production by vibration or by extrusion should be emphasized. Such methods are known.
  • the carbon material used as the lower section in the electrode according to the invention particularly advantageously has a specific electrical resistance in the range from 10 to 30 ⁇ mm 2 / m.
  • the electrodes have a particularly favorable operating behavior, the carbon material of which has a specific electrical resistance in the range from 10 to 20 ⁇ mm 2 / m and in particular 13 to 20 ⁇ mm 2 / m.
  • the diameter of the lower section is generally in the range of about 200 to 600 mm. Particularly favorable results were achieved with diameters of the lower section in the range from approximately 300 to 400 mm.
  • the diameter of the upper section made of metal can be chosen to be larger, but also smaller, than the diameter of the lower section.
  • the bulk density of the carbon material of the lower section is particularly preferably in the range between 1.50 and 1.65 g / cm 3 .
  • a particularly advantageous electrode in the context of the invention in which the upper section made of metal accounts for approximately half the total length of the electrode or more, has a carbon part with approx. 50 to 85% of graphitic structural elements made of natural graphite and / or electrographite, the non-graphitic structural components consisting of anthracite, coal coke and / or normal petroleum coke, the specific electrical resistance of the lower section being in the range from 10 to 20 ⁇ mm 2 / m at a bulk density in the range between 1.50 and 1.65 g / cm 3 .
  • the electrodes according to the invention are characterized by favorable operating behavior with trouble-free operation.
  • the carbon materials in the lower section can be produced from cheaper raw materials by means of simpler production processes than the conventionally used full graphite electrodes. Therefore, the electrode operation can be made cheaper with the same electrical load capacity.
  • the electrode according to the invention has its preferred application for the production of steel in the arc furnace operation. But it can also be used for the production of non-ferrous metals such as copper or cobalt, but also for the production of corundum, silicon, etc., can be used.
  • the combination electrodes according to the invention are used with particular advantage with diameters of the lower section made of carbon material in the range from 300 to 400 mm, preferably with maximum phase currents in the range from 10 to 30 KA.
  • 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 inside the screw nipple 1, which e.g. 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 only partially formed from graphitic structural elements is or is free of it.
  • 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 on the inside by the drawn-in, inner metal shaft or its section of smaller diameter 12.
  • additional bores can be provided through which inserted pins ensure a good fit of the high-temperature-resistant molded parts via a spring.
  • the object of the invention is not limited to the construction 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.
  • Such and different types of embodiments of the electrode according to the invention are included in the scope of the invention insofar as the carbon material of the consumable lower section is only partially formed from graphitic structural elements or is free thereof.
  • a combination electrode made of a water-cooled copper shaft was used, which was cooled with water by a cooling system consisting of the supply and return lines.
  • the copper shaft was protected in the area of the furnace by a high temperature resistant coating.
  • the copper shaft was screwed to the carbon material via a graphite nipple, which essentially consisted of waste graphite from the synthetic graphite production.
  • the carbon material had a bulk density of 1.62 g / cm 3 and a specific electrical resistance of 18.5 ⁇ mm 2 / m.
  • Three such electrodes were in an oven at 50 ton capacity and three phases with a maximum "phase current of 50,000 A at an operating voltage of 490 V applied.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Discharge Heating (AREA)
  • Vertical, Hearth, Or Arc Furnaces (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
  • Furnace Details (AREA)
  • Electric Stoves And Ranges (AREA)
  • Resistance Heating (AREA)
EP82102770A 1981-04-23 1982-04-01 Elektrode für Lichtbogenöfen und Verfahren zu deren Verwendung Withdrawn EP0063710A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3116258A DE3116258A1 (de) 1981-04-23 1981-04-23 Elektrode fuer lichtbogenoefen und verfahren zur deren verwendung
DE3116258 1981-04-23

Publications (1)

Publication Number Publication Date
EP0063710A1 true EP0063710A1 (de) 1982-11-03

Family

ID=6130714

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82102770A Withdrawn EP0063710A1 (de) 1981-04-23 1982-04-01 Elektrode für Lichtbogenöfen und Verfahren zu deren Verwendung

Country Status (16)

Country Link
EP (1) EP0063710A1 (fi)
JP (1) JPS5894793A (fi)
AU (1) AU8185782A (fi)
BR (1) BR8202308A (fi)
DD (1) DD202363A5 (fi)
DE (1) DE3116258A1 (fi)
DK (1) DK181882A (fi)
ES (1) ES8400645A1 (fi)
FI (1) FI820868L (fi)
GB (1) GB2098839A (fi)
HU (1) HU186609B (fi)
NO (1) NO820800L (fi)
PL (1) PL236042A1 (fi)
PT (1) PT74763B (fi)
TR (1) TR21298A (fi)
ZA (1) ZA822012B (fi)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0109839A2 (en) * 1982-11-19 1984-05-30 Union Carbide Corporation Method of making graphite electrodes

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE268660C (fi) *
DE1565751A1 (de) * 1965-07-13 1970-02-12 Oestberg Jan Erik Elektrode fuer elektrische Lichtbogenoefen
FR2176546A1 (en) * 1972-03-23 1973-11-02 Siderurgie Fse Inst Rech Composite furnace electrode - esp for steel prodn
DE2918757A1 (de) * 1978-05-09 1979-11-22 Canada Steel Co Elektrode fuer lichtbogenoefen
EP0012573A1 (en) * 1978-12-19 1980-06-25 British Steel Corporation Electric arc furnace electrodes
US4256918A (en) * 1977-06-06 1981-03-17 Korf-Stahl Ag Electrode for arc furnaces

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE268660C (fi) *
DE1565751A1 (de) * 1965-07-13 1970-02-12 Oestberg Jan Erik Elektrode fuer elektrische Lichtbogenoefen
FR2176546A1 (en) * 1972-03-23 1973-11-02 Siderurgie Fse Inst Rech Composite furnace electrode - esp for steel prodn
US4256918A (en) * 1977-06-06 1981-03-17 Korf-Stahl Ag Electrode for arc furnaces
DE2918757A1 (de) * 1978-05-09 1979-11-22 Canada Steel Co Elektrode fuer lichtbogenoefen
EP0012573A1 (en) * 1978-12-19 1980-06-25 British Steel Corporation Electric arc furnace electrodes

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0109839A2 (en) * 1982-11-19 1984-05-30 Union Carbide Corporation Method of making graphite electrodes
EP0109839A3 (en) * 1982-11-19 1985-06-19 Union Carbide Corporation Graphite electrodes and method for their production

Also Published As

Publication number Publication date
FI820868L (fi) 1982-10-24
ZA822012B (en) 1983-02-23
JPS5894793A (ja) 1983-06-06
TR21298A (tr) 1984-03-22
HU186609B (en) 1985-08-28
ES511724A0 (es) 1983-11-01
ES8400645A1 (es) 1983-11-01
PT74763B (de) 1983-10-28
NO820800L (no) 1982-10-25
DK181882A (da) 1982-10-24
AU8185782A (en) 1982-10-28
GB2098839A (en) 1982-11-24
DE3116258A1 (de) 1982-11-11
DD202363A5 (de) 1983-09-07
BR8202308A (pt) 1983-04-05
PL236042A1 (en) 1983-02-28
PT74763A (de) 1982-05-01

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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Effective date: 19830416

STAA Information on the status of an ep patent application or granted ep patent

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Effective date: 19841228

RIN1 Information on inventor provided before grant (corrected)

Inventor name: LAUTERBACH-DAMMLER, INGE, DR. DIPL.-CHEM.

Inventor name: SCHIEBER, FRANZ, CHEM. ING. GRAD.

Inventor name: ZOELLNER, DIETER H., DR. DIPL.-CHEM.

Inventor name: MUEHLENBECK, JOSEF

Inventor name: LIPPERT, WOLFGANG, DIPL.-CHEM.

Inventor name: OTTO, JOSEF, DR. DIPL.-ING.

Inventor name: RITTMANN, FRIEDRICH

Inventor name: BAUER, HANNSGEORG, DR. DIPL.-ING.