WO2003070990A1 - Procede pour la decarburation profonde d'aciers en fusion - Google Patents

Procede pour la decarburation profonde d'aciers en fusion Download PDF

Info

Publication number
WO2003070990A1
WO2003070990A1 PCT/EP2003/001799 EP0301799W WO03070990A1 WO 2003070990 A1 WO2003070990 A1 WO 2003070990A1 EP 0301799 W EP0301799 W EP 0301799W WO 03070990 A1 WO03070990 A1 WO 03070990A1
Authority
WO
WIPO (PCT)
Prior art keywords
oxygen
blowing
steel
decarburization
vacuum container
Prior art date
Application number
PCT/EP2003/001799
Other languages
German (de)
English (en)
Inventor
Eric Perrin
Francois Stovenot
Christian Schrade
Original Assignee
Vai Fuchs Gmbh
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 Vai Fuchs Gmbh filed Critical Vai Fuchs Gmbh
Priority to BRPI0307897A priority Critical patent/BRPI0307897A2/pt
Priority to US10/505,610 priority patent/US20050109161A1/en
Priority to AU2003210336A priority patent/AU2003210336A1/en
Priority to KR1020047012963A priority patent/KR100889073B1/ko
Priority to EP03742571A priority patent/EP1476584A1/fr
Priority to JP2003569881A priority patent/JP2005517812A/ja
Publication of WO2003070990A1 publication Critical patent/WO2003070990A1/fr

Links

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
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/10—Handling in a vacuum
    • 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
    • C21C5/28—Manufacture of steel in the converter
    • C21C5/42—Constructional features of converters
    • C21C5/46—Details or accessories
    • C21C5/4606—Lances or injectors

Definitions

  • the invention relates to a method for decarburizing molten steel in an RH system, in which the steel is circulated from a vessel into a vacuum container placed under vacuum and back into the vessel and by means of a distance from the bath surface of the in the vacuum container Blast lance in the adjacent steel bath is blown with oxygen or an oxygen-containing gas onto the steel bath.
  • Such an RH system is shown in Fig. 1 of the drawing and consists of a vessel 1, on which a vacuum container 2 is placed to carry out the decarburization process, which dips into the steel in the vessel with two dip tubes 8 extending from its bottom.
  • the vacuum container 2 is connected at its nozzle 3 to a vacuum pump, not shown, so that due to the vacuum set in the vacuum container 2 in this way, a circulation of the steel from the vessel 1 into the vacuum container 2 and from this back into the vessel 1.
  • This circulation can be supported by introducing an inert gas such as argon into one of the dip tubes 8 via an injection device 4.
  • An oxygen jet 6 is blown onto the bath surface 7 of the steel bath in the vacuum container 2 via a blowing lance 5 which is arranged to be movable in the vacuum container 2.
  • This oxygen blowing in the context of the RH process can be useful for various reasons.
  • a first reason is that the oxygen content dissolved in a batch of melt in the vessel is not sufficient to bring about the required decarburization in a natural way; the invention described below is based on this fact.
  • Further reasons can be that the temperature of the batch is too low, so that by "refreshing" the batch with oxygen, more oxygen is taken up than is required for decarburization, this additionally taken up oxygen usually being set off via aluminum, which leads to an increase in temperature leads, or that decarburization should be accelerated by oxygen bubbles even in the event that there is sufficient oxygen for natural decarburization.
  • the usual pale processes are set in such a way that an unspecified amount of oxygen is blown onto the bath surface at a predetermined, fixed vacuum pressure until the required degree of decarburization of the batch is reached.
  • the runs Blow process usually with an excess of oxygen.
  • a method of the generic type mentioned at the outset is described, for example, in EP 0 347 884 B1; in the known method, the blowing of oxygen into the vacuum container of the RH system is used essentially to minimize the thermal losses of the decarburized steel in the vacuum container by the fact that the CO released by the decarburization is also greater than that following the decarburization phase the excess oxygen supplied is afterburned, so that the heat thus obtained can be used for the process.
  • the blowing in of oxygen or an oxygen-containing gas, in particular for afterburning is> 5% of the boundary conditions (CO + C0 2 )
  • the object of the invention is to provide a process for decarburizing molten steel with which low end carbon contents can be achieved in the steel, and with which the need for oxygen to be injected can be set lower. This object is achieved, including advantageous refinements and developments of the invention, from the content of the patent claims, which follow this description.
  • the invention provides in detail that, starting with the increase in CO due to natural decarburization due to the oxygen dissolved in the steel bath and present in the system, there is a CO in the vacuum container based on a ratio of
  • the invention takes into account the knowledge that due to the natural decarburization, oxygen should be introduced into the molten steel as early as possible, in order to react to the carbon dissolved in the molten steel to CO and from the melt with a sufficient supply of oxygen in the molten steel escape in gaseous form and thus increase the efficiency of oxygen blowing.
  • the invention uses the approach that the required for the decarburization of a batch taking into account oxygen suppliers such as ladle slag or steel bears adhering in the vacuum container for the oxygen required per unit weight of the batch is known as the ratio of the initial carbon content of the melt to the initial oxygen content of the melt sizes can be traced back and is therefore available as a calculation basis for the amount of oxygen to be blown in, so that the total amount of oxygen required (0 En d D eci) taking into account the size (G C ) of the batch to be decarburized and the final oxygen content to be set in the batch at the end of the blowing process
  • a final oxygen content of between 200 ppm and 400 ppm, on average of 300 ppm in the batch is generally set, and if the final oxygen content is less than 200 ppm, the decarburization process is unnecessarily prolonged because too little oxygen If the final oxygen content is above 400 ppm, the need for deoxidizing agents to bind the oxygen in the melt
  • the beginning of the blowing process is determined as a starting pressure to be determined as a function of the initial carbon content of the melt in such a way that the amount of oxygen to be blown in is introduced until the mentioned afterburning has been reached and the decarburization by means of oxygen blowing before starting one under Excess oxygen occurring after combustion is completed.
  • the first step for the implementation of the method according to the invention for each batch of a melt to be decarburized is the calculation of the amount of oxygen to be injected as a function of the
  • Initial carbon content and the initial oxygen content in the melt are dependent on plant-specific conditions, since the oxygen requirement required for the decarburization is already partially covered by process-related oxygen sources such as steel bears adhering to the vacuum container or existing ladle slag. Since RH systems usually process melts with a largely identical composition depending on the product groups, there are no substantial deviations during the operation of an RH system, so that the system-specific conditions can be determined by carrying out test series including the acquisition of measurement data and in one have the footing function recorded.
  • batches with an initial carbon content C in and an initial oxygen content 0 in to be recorded are to be decarburized by inflating oxygen, the oxygen content of the melt being determined on a sample taken shortly before the decarburization process and the amount actually blown up to this point Amount of oxygen to be recorded.
  • the desired final oxygen content for example, 300 ppm, is determined for the individual sample batches, whereby depending on the deviation of the actual oxygen content measured in the drawn sample from the reference value (300 ppm) upwards or downwards, the actually inflated oxygen quantity determined by measurement is to be converted or corrected for a blow quantity Q actual (only) based on the final oxygen content used as a reference quantity.
  • the curve to be laid in the coordinate system through the measurement points obtained can be mathematically calculated using a polynomial equation of the type
  • FIG. 3 shows a corresponding exemplary embodiment for determining the polynomial equation associated with an RH system, 8 test batches having been subjected to a decarburization process on the RH system on which it is based.
  • the graphical representation of the measurement results shown in FIG. 3 leads to the polynomial describing the curve laid through the reference points
  • the need for the oxygen to be introduced via the blowing lance as a function of the analysis values C in 1 and 0 ini of the analysis of each individual batch to be decarburized can thus be achieved for a retracted RH system which has been tested with regard to the polynomial equation to be used Determine the melt.
  • a naturally occurring secondary combustion occurs initially due to a low CO volume in the exhaust gas and relatively high proportions of oxygen from residual air and leaks, even without the separate blowing in of oxygen, the subsequent combustion rate being due to the further course of the process of rising CO emissions, however, is decreasing.
  • the start pressure P s ta r t for the release of the blowing process is largely dependent on the initial carbon content in the melt.
  • FIG. 4 shows the procedure explained above using an exemplary embodiment, with a total of 12 batches being driven.
  • the curve to be drawn through the measuring points leads to the polynomial equation
  • a delay between the start of the cycle and the start of inflation must be taken into account when determining the start pressure for the release of the blowing process.
  • This period spans triggering the automated process, lance travel and switching from inert gas operation to oxygen blowing operation.
  • time delays of up to 45 seconds can occur. Insofar as this time span can also be expressed as the difference in pressure at the start of the cycle and at the start of oxygen blowing , this differential pressure must be taken into account when determining P 3 tare .
  • the duration of the blowing process must be checked in addition to the determination of the oxygen demand by monitoring the afterburning, since a limit value for the end of the blowing process is a post-combustion rate of 30%, above which the blowing of oxygen cannot be observed in view of the metallurgy and the decarburization rate is more efficient, but as in the prior art would only serve to minimize the thermal losses of the decarburized steel in the vacuum container.
  • a limit value for the end of the blowing process is a post-combustion rate of 30%, above which the blowing of oxygen cannot be observed in view of the metallurgy and the decarburization rate is more efficient, but as in the prior art would only serve to minimize the thermal losses of the decarburized steel in the vacuum container.
  • the oxygen blowing during the decarburization phase leads to a partial afterburning of the CO released from the steel bath, even if the other operating parameters are optimally set.
  • the post-combustion rate during oxygen blowing is directly related to the release of CO from the
  • the ratio of the afterburning increases more or less depending on the decarburization rate, whereby it is obvious that the afterburning increases during the oxygen blowing if the decarburization rate and thus the CO release decrease.
  • the optimal operating range for blowing in the oxygen therefore begins when the Limit pressure P s tart / the optimal operating range is extended with a higher initial carbon content of the melt.
  • the monitoring of the vacuum pressure present in the vacuum container can serve as an indication, in particular at the end of the oxygen blowing, in order to maintain an optimal output of the oxygen with a low post-combustion.
  • the pressure level within the vacuum container is related to the amount of gas released at a defined suction power of the vacuum pump, the CO content in the exhaust gas during the treatment process being dependent on
  • the efficiency of the oxygen blowing also depends on the introduction of the oxygen into the molten steel, since it is not, as in the prior art, that the released CO is caused above the bath level, but the blown-in oxygen in the molten steel is to be dissolved in order to be able to react with the Melt to react with dissolved carbon.
  • the oxygen output i.e. the ratio of the oxygen dissolved in the melt bath to the oxygen blown onto the bath surface depends in individual cases essentially on the level of the
  • this oxygen output can be set at about 80 to 90%, so that in the practical implementation for the blowing process the calculated oxygen quantity O ⁇ has to be increased accordingly, taking into account the aforementioned oxygen output.
  • the oxygen output is also influenced by the formation of the blow nozzle, which is to act on the bath surface with a compact oxygen jet at high speed on a small surface so that the oxygen penetrates sufficiently deeply into the molten steel which is kept in motion by the circulation.
  • a blowing jet having a supersonic speed is generated in the blowing nozzle designed as a Laval nozzle, which ideally remains as a slim cylinder until it hits the bath surface and does not fan out.
  • the distance between the blow nozzle and the steel bath level must also be set accordingly, which is between 2.5 meters and 5.5 meters in the known frame.
  • a blowing nozzle which is changeable in its configuration by means of a displaceable adjusting cone is provided, which is shown in a schematic illustration in FIG. 2 of the drawing. If the adjusting cone 11 is in the position indicated by position 1, this means a fully open nozzle cross-section 12 with which the Laval nozzle 10 operates in accordance with the defined design point. Is the Setting cone 11 in position 2, the nozzle geometry is designed for a significantly lower back pressure; however, the throughput through the nozzle will decrease if the admission pressure remains constant.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Treatment Of Steel In Its Molten State (AREA)

Abstract

L'invention concerne un procédé pour la décarburation d'acier fondu dans une installation RH. Le procédé selon l'invention est caractérisé en ce que, lorsque commence dans le réservoir sous vide (2) l'augmentation du CO libéré par décarburation naturelle en raison de l'oxygène présent dans le système et dissous dans le bain d'acier, on insuffle une quantité d'oxygène calculée en fonction de la teneur initiale en carbone et de la teneur initiale en oxygène de la matière fondue. Une pression initiale, calculée en fonction de la teneur initiale en carbone, est déterminée pour le début de l'opération d'insufflation.
PCT/EP2003/001799 2002-02-22 2003-02-21 Procede pour la decarburation profonde d'aciers en fusion WO2003070990A1 (fr)

Priority Applications (6)

Application Number Priority Date Filing Date Title
BRPI0307897A BRPI0307897A2 (pt) 2002-02-22 2003-02-21 processo para a descarbonização profunda de massas fundidas de aço.
US10/505,610 US20050109161A1 (en) 2002-02-22 2003-02-21 Method for deep decarburisation of steel melts
AU2003210336A AU2003210336A1 (en) 2002-02-22 2003-02-21 Method for deep decarburisation of steel melts
KR1020047012963A KR100889073B1 (ko) 2002-02-22 2003-02-21 강철 용융물의 심층 탈탄 방법
EP03742571A EP1476584A1 (fr) 2002-02-22 2003-02-21 Procede pour la decarburation profonde d'aciers en fusion
JP2003569881A JP2005517812A (ja) 2002-02-22 2003-02-21 溶鋼を深脱炭する方法

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP02004014 2002-02-22
EP02004014.3 2002-02-22

Publications (1)

Publication Number Publication Date
WO2003070990A1 true WO2003070990A1 (fr) 2003-08-28

Family

ID=27741107

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2003/001799 WO2003070990A1 (fr) 2002-02-22 2003-02-21 Procede pour la decarburation profonde d'aciers en fusion

Country Status (8)

Country Link
US (1) US20050109161A1 (fr)
EP (1) EP1476584A1 (fr)
JP (1) JP2005517812A (fr)
KR (1) KR100889073B1 (fr)
CN (1) CN1650035A (fr)
AU (1) AU2003210336A1 (fr)
BR (1) BRPI0307897A2 (fr)
WO (1) WO2003070990A1 (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101441187B (zh) * 2008-12-22 2012-02-08 辽宁科技学院 一种rh真空精炼顶枪喷粉测试装置及方法
JP6337681B2 (ja) * 2014-08-12 2018-06-06 新日鐵住金株式会社 溶鋼の減圧精錬方法
CN105463210A (zh) * 2015-12-26 2016-04-06 杨伟燕 一种高杂质铜精矿的冶炼方法
CN106979452A (zh) * 2017-04-20 2017-07-25 常州汇丰粉末冶金有限公司 含油轴承真空注油机及其注油方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0347884A2 (fr) * 1988-06-21 1989-12-27 Kawasaki Steel Corporation Procédé pour le dégazage et la décarburation sous vide avec compensation de la baisse de la température
JPH0459913A (ja) * 1990-06-29 1992-02-26 Kawasaki Steel Corp 減圧下における溶融金属の酸素吹錬方法

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100270113B1 (ko) * 1996-10-08 2000-10-16 이구택 극저탄소강의 용강 제조장치

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0347884A2 (fr) * 1988-06-21 1989-12-27 Kawasaki Steel Corporation Procédé pour le dégazage et la décarburation sous vide avec compensation de la baisse de la température
JPH0459913A (ja) * 1990-06-29 1992-02-26 Kawasaki Steel Corp 減圧下における溶融金属の酸素吹錬方法

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
KLEIMT B ET AL: "DYNAMISCHES MODELL FUR DEN VAKUUM-UMLAUF-PROZESS ZUR ENTKOHLUNG VONSTAHLSCHMELZEN DYNAMIC MODEL OF THE VACUUM CIRCULATION PROCESS FOR STEEL DECARBURISATION", STAHL UND EISEN, VERLAG STAHLEISEN GMBH. DUSSELDORF, DE, vol. 115, no. 8, 15 August 1995 (1995-08-15), pages 75 - 81,143, XP000520380, ISSN: 0340-4803 *
PATENT ABSTRACTS OF JAPAN vol. 016, no. 261 (C - 0950) 12 June 1992 (1992-06-12) *

Also Published As

Publication number Publication date
BRPI0307897A2 (pt) 2016-06-21
EP1476584A1 (fr) 2004-11-17
JP2005517812A (ja) 2005-06-16
AU2003210336A1 (en) 2003-09-09
CN1650035A (zh) 2005-08-03
KR100889073B1 (ko) 2009-03-17
US20050109161A1 (en) 2005-05-26
KR20040091653A (ko) 2004-10-28

Similar Documents

Publication Publication Date Title
DE1433443B2 (de) Verfahren zur ueberwachung und regelung der sauerstoffauf blasverfahren
DE2737832B2 (de) Verwendung von im Querschnitt veränderlichen Blasdüsen zur Herstellung von rostfreien Stählen
EP0198910A1 (fr) Procede et dispositif de detection des scories.
DE2733750C2 (de) Verfahren zum Einstellen des Kohlenstoffgehalts eines Stahls
EP1809774A2 (fr) Production d'acier inoxydable faisant partie du groupe des aciers ferritiques aisi 4xx dans un convertisseur aod
DE2944771C2 (de) Verfahren zum Frischen von Stahl
DE60132358T2 (de) Sauerstoffblasverfahren und aufwärtsblasende lanze für sauerstoffblaskonverter
WO2003070990A1 (fr) Procede pour la decarburation profonde d'aciers en fusion
DE3204632C2 (fr)
DE2803239A1 (de) Verfahren zur herstellung von nichtrostendem stahl mit extrem niedrigem kohlenstoffgehalt
DE2651922C3 (de) Verfahren zum Steuern des Frischablaufs beim Frischen von Roheisen
EP2099940B1 (fr) Procédé de régulation de l'émission de monoxyde de carbone dans un procédé de fusion métallurgique
DE1583228C2 (de) Verfahren zur Überwachung und selbsttätigen Regelung des in einem Sauerstoff-Aufblaskonverter durchgeführten Frischvorganges von Roheisen
DE2745722B2 (de) Verfahren zur Herstellung von kohlenstoff- und stickstoffarmem Stahl
DE19832701B4 (de) Verfahren zur Erzeugung von Stahl
DE3105999C2 (de) Bodendüse für einen Sauerstoff-Aufblas-Konverter
DE2450196A1 (de) Verfahren zum vakuumfrischen von stahl
DE1433443C (de) Verfahren zur Überwachung und Regelung der Sauerstoffaufblasverfahren
DE102013111059A1 (de) Verfahren zur Ermittlung der Effektivität der Zufuhr von Inertgas über eine Bodenspülung in einem Konverterprozess
DE2729071C3 (de) Verfahren zum Steuern des Frischverlaufs beim Frischen von Roheisen
DE1583318B1 (de) Verfahren zur Ermittlung des Kohlenstoffgehalts einer Stahlschmelze in einem Sauerstoffaufblaskonverter
DE1433439C (de) Verfahren zur selbsttätigen Regelung eines Sauerstoffaufblasverfahrens
AT514132B1 (de) Verfahren zur Bestimmung von Reaktionsdaten eines Reaktionsablaufs
DE2210172A1 (de) Verfahren und Vorrichtung zur Steuerung des Kohlenstoffgehaltes bei einem Verfahren zur Stahlherstellung
DE2458532A1 (de) Verfahren und vorrichtung zur steuerung kinetischer energie

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NO NZ OM PH PL PT RO RU SC SD SE SG SK SL TJ TM TN TR TT TZ UA UG US UZ VC VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LU MC NL PT SE SI SK TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
WWE Wipo information: entry into national phase

Ref document number: 1020047012963

Country of ref document: KR

Ref document number: 2003569881

Country of ref document: JP

WWE Wipo information: entry into national phase

Ref document number: 2003742571

Country of ref document: EP

WWE Wipo information: entry into national phase

Ref document number: 2003210336

Country of ref document: AU

WWE Wipo information: entry into national phase

Ref document number: 10505610

Country of ref document: US

WWE Wipo information: entry into national phase

Ref document number: 20038091054

Country of ref document: CN

WWP Wipo information: published in national office

Ref document number: 1020047012963

Country of ref document: KR

WWP Wipo information: published in national office

Ref document number: 2003742571

Country of ref document: EP

REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

ENP Entry into the national phase

Ref document number: PI0307897

Country of ref document: BR

Kind code of ref document: A2

Effective date: 20040823