EP0843020A1 - Four à arc électrique à double sole pour la fusion en continu - Google Patents

Four à arc électrique à double sole pour la fusion en continu Download PDF

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Publication number
EP0843020A1
EP0843020A1 EP97119472A EP97119472A EP0843020A1 EP 0843020 A1 EP0843020 A1 EP 0843020A1 EP 97119472 A EP97119472 A EP 97119472A EP 97119472 A EP97119472 A EP 97119472A EP 0843020 A1 EP0843020 A1 EP 0843020A1
Authority
EP
European Patent Office
Prior art keywords
furnace
raw material
zone
molten metal
metal
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.)
Granted
Application number
EP97119472A
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German (de)
English (en)
Other versions
EP0843020B1 (fr
Inventor
Milorad Pavlicevic
Angelico Della Negra
Alfredo Poloni
Gianni Gensini
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.)
Danieli and C Officine Meccaniche SpA
Original Assignee
Danieli and C Officine Meccaniche SpA
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 Danieli and C Officine Meccaniche SpA filed Critical Danieli and C Officine Meccaniche SpA
Publication of EP0843020A1 publication Critical patent/EP0843020A1/fr
Application granted granted Critical
Publication of EP0843020B1 publication Critical patent/EP0843020B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/56—Manufacture of steel by other methods
    • C21C5/562—Manufacture of steel by other methods starting from scrap
    • C21C5/565—Preheating of scrap
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/52—Manufacture of steel in electric furnaces
    • C21C5/5252—Manufacture of steel in electric furnaces in an electrically heated multi-chamber furnace, a combination of electric furnaces or an electric furnace arranged for associated working with a non electric furnace
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D13/00—Apparatus for preheating charges; Arrangements for preheating charges
    • F27D13/002—Preheating scrap

Definitions

  • This invention concerns an electric arc furnace for the continuous melting of steel and its alloys as set forth in the main claim.
  • the invention is applied to the field of steel production and to be more exact, to electric arc furnaces for the continuous melting of raw material of various types, such as for example, scrap, iron rejects from mechanical processing, iron briquettes, solid or liquid cast iron, sponge iron or any other type.
  • the invention is applied particularly to furnaces fed with alternating current.
  • the state of the art covers electric arc furnaces fed with direct or alternating current which use alternative energy sources such as burners, supersonic lances, tuyIER situated under the bath of molten metal, and other sources.
  • furnaces are used to produce steels starting from scrap materials of various kinds such as waste metal, chips and off-cuts from mechanical processing, steel returns, iron salvage materials etc.
  • scrap materials of various kinds such as waste metal, chips and off-cuts from mechanical processing, steel returns, iron salvage materials etc.
  • salvage materials and iron alloys other raw materials are used, such as sponge iron, solid or liquid cast iron or other materials, because the pollution they cause is limited.
  • Both the salvage materials and the other above-mentioned materials can be loaded into the furnace in a single lot, or also in a semi-continuous manner by using loading baskets, or in a continuous manner by using transporter belts and loading and distribution means.
  • the transfer of the molten metal from the first to the second body takes place when the melting process is complete, and this increases the times of the operating cycle.
  • furnaces of the type known to the art because of their particular conformation, have a particularly high energy consumption.
  • a further shortcoming derives from the difficulties met in the tapping step, because of the solidification of the molten steel inside the tapping conduit.
  • the state of the art includes FR-A-1.482.929 which proposes a system of continuous loading, by means of briquettes, between the electrodes, transferring the molten steel to a second furnace where the temperature of the melted metal is raised and where the composition of the melted metal is corrected before being tapped.
  • DE-A-2.504.911 proposes a continuous loading tower at the base of which a plurality of burners melt the metal which is transferred by means of the source method into a second furnace where electrodes provide to raise the temperature before the metal is tapped.
  • AT-B-344.215 proposes a system similar to the previous one, but the transfer of the liquid metal is controlled by a system of magnetic fields.
  • DE-U-8.412.739.2 and EP-A-170.809 show continuous loading systems associated with an electric furnace to control the temperature of the liquid metal.
  • EP-A-240.485 and EP-A-548.041 show continuous loading towers with axially movable burners at their base; the burners melt the metal which is transferred to an electric furnace, which serves to control the temperature of the molten metal and to refine it before tapping.
  • WO-A-96/19592 provides for two twin electric melting furnaces, of which the main one is associated with a tower to continuously load the scrap.
  • WO-96/32505 provides for a furnace associated with a central well device to continuously feed and pre-heat cast iron produced by the blast furnace; around the furnace there are four electrodes arranged obliquely with respect to the vertical axis of the furnace.
  • This device with the feeder well is associated with a loading and pre-heating well inside which the material to be melted is unloaded; the melted metal is then transferred into another container equipped with auxiliary heating means, from which spilling takes place.
  • the passage of the liquid metal between the two containers is not regulated, so that it is not possible to ensure an adequate and constant control of the flow or of the slag which is present above the liquid metal; nor is it possible to ensure that a part of the load is maintained in a solid state in the loading and pre-melting well.
  • the purpose of the invention is to obtain an electric arc furnace able to ensure a continuous production of high quality or any quality steel, with reduced operating times.
  • a further purpose is to achieve a furnace and a method able to provide a considerable saving of energy.
  • the invention includes the use of an electric arc furnace, fed with direct current, equipped with two inter-communicating main bodies and constituting a single, integrated structure: a first body, used to continuously load the raw material, to carry out a first melting thereof and to perform a first refining of the liquid metal, and a second body for the definitive refining, the decantation and the tapping of the molten steel.
  • the furnace is fed with direct current so as to exploit the greater stability of the electric arc compared with the electric arc obtained in furnaces fed with alternating current; this gives a more efficient melting of the raw material and also a reduction in the disturbances on the outside electric line.
  • a cathode positioned at the central part of the first body of the furnace and also another one positioned at the central part of the second field, both of which cooperate with one or more anodes arranged on the hearth or with other equivalent and suitable means to ensure the passage of the electric current.
  • the central position of the cathode makes it possible to obtain a peripheral distribution of the load, ensuring uniformity and homogeneity in the distribution of the material inside the furnace and preventing material from accumulating in particular zones of the furnace.
  • the first body of the furnace has two or more cathodes arranged symmetrically with respect to the furnace.
  • the method according to the invention includes a substantially continuous loading of the materials which comprise the load, advantageously in such a way that there is always a part of the load in a solid state in the first body.
  • loading means cooperating with means to distribute the raw material evenly within the first body of the furnace.
  • the raw material consists of scrap which can be integrated with cast iron ingots, sponge iron and iron carbide.
  • these means cooperate with a distribution zone located in the upper part of the furnace and associated with the appropriate thrust means able to load the raw material into the furnace as soon as a condition of even distribution is achieved in that zone.
  • the two bodies of the furnace have a substantially circular section and a high ratio of height to diameter.
  • At least the first body of the furnace that is, the one for loading and melting, has a column-shaped body which exploits the re-use of energy to pre-heat the scrap and the other raw material loaded.
  • the panels located on the roof of the furnace are arranged so as to induce a discharge of the fumes generated during the cycle with a cyclonic development in order to increase the time they remain inside the furnace; in this way, the efficiency of the pre-heating of the raw material loaded is increased and at the same time, the fumes are cooled as heat is transferred to the load material.
  • the roof of the second body of the furnace is inclined in the direction of the first body so as to assist the flow of the discharge fumes into the first body, thus increasing the efficiency of the pre-heating of the scrap metal and raw material to be loaded.
  • the method according to the invention includes the use of burners which make the temperature of the first body of the furnace homogeneous and thus improve the melting of the raw material; they also cooperate with the aforesaid means to load and distribute the raw material so as to guarantee a better and more regular descent of the raw material into the furnace, thus assisting the continuous loading.
  • the burners are of the oxygen-fuel type, with a carbon-based or hydrocarbon-based fuel and at certain stages of the melting cycle they emit only oxygen.
  • both in the first and second body there are supersonic lances and also tuyées to inject oxygen into the lower part of the furnace and/or under the level of the bath.
  • At least the second body includes means to blow carbon into the bath of molten metal.
  • the furnace is made to work with a "swamp" method, that is to say, with a liquid foot always present on the bottom of the furnace.
  • the transfer from the first to the second body takes place through an appropriate channel.
  • the passage takes place when the liquid in the first body overflows as soon as it reaches and surpasses a pre-determined level.
  • the passage of the liquid metal in the refractory channel is regulated by the appropriate means, which may be mechanical, electromagnetic or other means which allow or prevent the passage of the molten metal and possibly regulate the flow thereof; they also regulate the passage of the slag from the first to the second body.
  • This channel moreover permits the passage of the fumes from the second to the first body, thus allowing these fumes to be used in their counter-flow to pre-heat the loaded raw material.
  • the fumes produced in the second body are recovered and sent to the zone where the raw material is distributed, by means of the appropriate conduits.
  • the channel is also equipped with wear-resistant means, of a mechanical, electromagnetic, mixed or other type which, apart from preventing wear on the refractory material, assist and regulate the passage of the liquid metal.
  • the passage of the liquid metal from the first to the second body takes place when the liquid metal is melted and is at the first step of refining, that is, it has attained a first degree of dephosphorization and is partly decarburized.
  • the liquid metal is subjected to complete refining and reaches the desired stage of complete desulphurization and decarburization, whereas in the first body the melting of the raw materials, as they are gradually loaded, continues without interruption.
  • both the first and the second body are equipped, in cooperation with the lower shell, with means to mix and stir the liquid metal, which can be of a mechanical, electromagnetic or other type.
  • the tapping of the liquid steel from the second body is achieved by means of the appropriate means, located on the hearth or on the wall of the second body, and cooperate with a mating tapping conduit.
  • these tapping means cooperate with the appropriate heating means suitable to liquefy any metal which may have solidified in the discharge channel.
  • the cathode is normally composed of an upper metallic portion equipped with a cooling system using water or liquid metal, and by a lower consumable part made of graphite.
  • the anodes too are equipped, in one embodiment of the invention, with a cooling system using water or liquid metal.
  • the attached figure is given as a non-restrictive example and shows a preferred embodiment of an electric arc furnace using the method of continuous melting according to the invention.
  • the electric arc furnace 10 is substantially composed of two bodies, respectively a first body 11 where the raw material is loaded, melted and the molten metal undergoes its first refining, and a second body 12, in this case smaller in diameter than the first, where the molten metal is completely refined and tapped.
  • the first 11 and second 12 bodies are in this case achieved in a single body, define a single structure and are inter-communicating by means of a channel 13.
  • the electric arc furnace 10 is fed with direct current and is equipped respectively with a cathode 14 for the first body 11 and a cathode 114 for the second body 12.
  • cathodes 14 of the first body 11 there are at least two cathodes 14 of the first body 11 and are arranged vertical and symmetrical on the roof of the first body 11.
  • the cathodes 14 and 114 cooperate with four anodes 15 located on the hearth of the furnace and symmetrical with the longitudinal axis of the respective cathodes 14 and 114, in such a way as to distribute the current more evenly in the scrap 17.
  • the cathodes 14 and 114 are located in a housing seating 16 which facilitates the removal of the cathodes 14, 114 for operations of replacement and/or maintenance; furthermore, the seating 16 protects the cathode 14 from falling scrap 17 in cooperation with the appropriate protection means 21.
  • the scrap 17 is loaded continuously in the upper zone 35 of the first body 11 by means of the appropriate loading means 24, in this case conveyor belts 18 arranged in sequence.
  • the furnace 10 may also be loaded with other raw materials such as cast iron, iron briquettes, sponge iron, all loaded by means of the same conveyor belts 18 or by other loading means of a known type.
  • other raw materials such as cast iron, iron briquettes, sponge iron, all loaded by means of the same conveyor belts 18 or by other loading means of a known type.
  • the stirring means 19 locate the scrap 17 in a desired zone of a distribution surface 20, in this case shaped like a circular crown.
  • the stirring means 19 are stopped and the scrap 17 is unloaded by means of the appropriate unloading means (which are not shown here), either all at once or in several stages, so as to obtain a homogeneous distribution of the scrap 17 inside the first body 11.
  • the stirring means 19 are electromagnetic; according to a variant, the stirring means 19 are mechanical, for example of the vibratory type.
  • Both the first body 11 and the second body 12 are circular in section and their ratio of height to diameter is such as to allow the maximum possible exploitation of the heat generated by the discharge fumes to pre-heat the scrap 17 which is temporally stationed on the distribution surface 20 or in any other position on the upper portion of the first body 11.
  • the first body 11 and the second body 12 include respective lower zones 36 and 37 to contain the liquid metal, above which there are lateral cooling panels 33.
  • the scrap 17 is affected by the discharge fumes as they arrive from the first body 11 and the second body 12, and therefore the scrap 17 is preheated.
  • burners 22 arranged at one or two levels on the sidewall of the first body 11.
  • the first body 11 is also equipped with supersonic lances 23 to inject oxygen into the lower zone of the first body 11; and with tuyIER, which are not shown here, to blow oxygen into the liquid metal from the bottom.
  • the second body 12 is equipped with sources of alternative energy and with means designed to assist and accelerate the refining of the steel.
  • one embodiment of the invention includes the immission of additives, either powders or gases, which assist and accelerate the processes of desulphurization and decarburization of the molten metal.
  • the channel 13 enables the liquid metal to be transferred from the first body 11 to the second body 12 as soon as the liquid metal goes over an overspill level 25.
  • This level 25 is arranged in such a way that the liquid metal in the first body 11, at the moment it spills into the second body 12, has already completed a first step of refining and attained at least a first degree of dephosphorization and decarburization.
  • the channel 13 is equipped with the appropriate wear-resistant means which, apart from limiting the wear on the refractory material, assist the passage of the liquid metal.
  • the wear-resistant means are composed of a device 29 to generate a magnetic field suitable to raise the liquid metal from the bottom of the channel 13 as it passes through.
  • the wear-resistant means are mechanical and cooperate with the bottom of the channel 13.
  • Stirring means 27 are included in cooperation with the lower zones 36 and 37 of both bodies 11 and 12, in order to obtain an efficient mixing of the molten metal so as to achieve a homogeneous bath and an even temperature, and also to accelerate the chemical reactions.
  • the stirring means 27 are of the electromagnetic type and include spirals 28 inside the lower shell of the furnace 10. When the spirals 28 are fed, they generate a magnetic field which interacts with and mixes the liquid metal.
  • the stirring means 27 are of the mechanical or mixed type.
  • the steel is tapped from the second body 12 by means of a hole 30 situated on the bottom of the second body 12.
  • This tapping operation in one embodiment of the invention, is performed continuously.
  • the tapping is performed periodically at pre-determined intervals.
  • the hole 30 cooperates with tapping means, which are not shown here, suitable to open and close the hole 30 and thus regulate the flow of steel.
  • the tapping means are of the siphon type and cooperate with a hermetic door, for example of the sliding type.
  • the tapping means comprise a hermetic door and cooperate with appropriate cooling means; in this case heating means are included, for example, of the induction type, and are used to melt the metal which has solidified inside the hole 30.
  • the furnace 10 is also equipped, in correspondence with the first body 11, with a second hole 31 which can be used for cleaning operations, and a door 32 to remove the waste which accumulates on the surface of the molten metal.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Vertical, Hearth, Or Arc Furnaces (AREA)
  • Discharge Heating (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
EP97119472A 1996-11-13 1997-11-06 Four à arc électrique à double sole pour la fusion en continu Expired - Lifetime EP0843020B1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
ITUD960218 1996-11-13
IT96UD000218A IT1289021B1 (it) 1996-11-13 1996-11-13 Forno elettrico ad arco e relativo procedimento di fusione continua
ITUS960218 1996-11-13

Publications (2)

Publication Number Publication Date
EP0843020A1 true EP0843020A1 (fr) 1998-05-20
EP0843020B1 EP0843020B1 (fr) 2002-04-17

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Family Applications (1)

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EP97119472A Expired - Lifetime EP0843020B1 (fr) 1996-11-13 1997-11-06 Four à arc électrique à double sole pour la fusion en continu

Country Status (5)

Country Link
EP (1) EP0843020B1 (fr)
AT (1) ATE216433T1 (fr)
DE (1) DE69712020D1 (fr)
ES (1) ES2172727T3 (fr)
IT (1) IT1289021B1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999000522A1 (fr) * 1997-06-27 1999-01-07 Voest-Alpine Industrieanlagenbau Gmbh Installation et dispositif pour la production de metal en fusion
EP1181492A1 (fr) * 1999-05-18 2002-02-27 Danieli Technology, Inc. Four a arc electrique a chargement continu en matieres ferreuses et coulee semi-continue de metal en fusion
CN107218812A (zh) * 2017-06-20 2017-09-29 浙江今飞凯达轮毂股份有限公司 铸造用节能保温炉
CN110343869A (zh) * 2019-08-09 2019-10-18 新乡市华瑞电源材料有限公司 连通式电解熔铅锅及其使用方法
CN110425893A (zh) * 2019-08-16 2019-11-08 中冶赛迪工程技术股份有限公司 电炉加料涵道与电炉的连接结构以及电炉系统

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1482929A (fr) * 1966-04-01 1967-06-02 Siderurgie Fse Inst Rech Procédé d'élaboration d'un métal au four électrique
EP0240485A1 (fr) * 1986-03-17 1987-10-07 VOEST-ALPINE Industrieanlagenbau GmbH Installation pour la fabrication d'acier de ferraille
EP0451323A2 (fr) * 1990-04-09 1991-10-16 BLUFIN S.r.l. Procédé pour le préchauffage de ferraille par pyrolyse de résidus résineux avec la récupération totale de son énergie et amélioration du cycle de fabrication d'acier
EP0548041A2 (fr) * 1991-11-18 1993-06-23 Voest-Alpine Industrieanlagenbau Gmbh Four à arc électrique pour la production d'acier
EP0626549A1 (fr) * 1993-05-27 1994-11-30 Sollac S.A. Four métallurgique de fusion tel qu'un four électrique d'aciérie et procédé utilisant un tel four
WO1996019592A1 (fr) * 1994-12-21 1996-06-27 Arcmet Technologie Gmbh Unite metallurgique basculante constituee de plusieurs recipients
WO1996032505A1 (fr) * 1995-04-10 1996-10-17 Voest-Alpine Industrieanlagenbau Gmbh Procede et installation de production de fontes en fer selon le procede de fusion en zones multiples

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1482929A (fr) * 1966-04-01 1967-06-02 Siderurgie Fse Inst Rech Procédé d'élaboration d'un métal au four électrique
EP0240485A1 (fr) * 1986-03-17 1987-10-07 VOEST-ALPINE Industrieanlagenbau GmbH Installation pour la fabrication d'acier de ferraille
EP0451323A2 (fr) * 1990-04-09 1991-10-16 BLUFIN S.r.l. Procédé pour le préchauffage de ferraille par pyrolyse de résidus résineux avec la récupération totale de son énergie et amélioration du cycle de fabrication d'acier
EP0548041A2 (fr) * 1991-11-18 1993-06-23 Voest-Alpine Industrieanlagenbau Gmbh Four à arc électrique pour la production d'acier
EP0626549A1 (fr) * 1993-05-27 1994-11-30 Sollac S.A. Four métallurgique de fusion tel qu'un four électrique d'aciérie et procédé utilisant un tel four
WO1996019592A1 (fr) * 1994-12-21 1996-06-27 Arcmet Technologie Gmbh Unite metallurgique basculante constituee de plusieurs recipients
WO1996032505A1 (fr) * 1995-04-10 1996-10-17 Voest-Alpine Industrieanlagenbau Gmbh Procede et installation de production de fontes en fer selon le procede de fusion en zones multiples

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999000522A1 (fr) * 1997-06-27 1999-01-07 Voest-Alpine Industrieanlagenbau Gmbh Installation et dispositif pour la production de metal en fusion
US6264883B1 (en) 1997-06-27 2001-07-24 Voest-Alpine Industrieanlagenbau Gmbh Plant for the production of metal melts
EP1181492A1 (fr) * 1999-05-18 2002-02-27 Danieli Technology, Inc. Four a arc electrique a chargement continu en matieres ferreuses et coulee semi-continue de metal en fusion
EP1181492A4 (fr) * 1999-05-18 2004-11-17 Danieli Technology Inc Four a arc electrique a chargement continu en matieres ferreuses et coulee semi-continue de metal en fusion
CN107218812A (zh) * 2017-06-20 2017-09-29 浙江今飞凯达轮毂股份有限公司 铸造用节能保温炉
CN107218812B (zh) * 2017-06-20 2023-05-23 浙江今飞凯达轮毂股份有限公司 铸造用节能保温炉
CN110343869A (zh) * 2019-08-09 2019-10-18 新乡市华瑞电源材料有限公司 连通式电解熔铅锅及其使用方法
CN110425893A (zh) * 2019-08-16 2019-11-08 中冶赛迪工程技术股份有限公司 电炉加料涵道与电炉的连接结构以及电炉系统
CN110425893B (zh) * 2019-08-16 2024-05-14 中冶赛迪工程技术股份有限公司 电炉加料涵道与电炉的连接结构以及电炉系统

Also Published As

Publication number Publication date
IT1289021B1 (it) 1998-09-25
ES2172727T3 (es) 2002-10-01
DE69712020D1 (de) 2002-05-23
EP0843020B1 (fr) 2002-04-17
ATE216433T1 (de) 2002-05-15
ITUD960218A1 (it) 1998-05-13
ITUD960218A0 (it) 1996-11-13

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