EP1530648A1 - Methods and device for decarbonising a steel melt - Google Patents

Methods and device for decarbonising a steel melt

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Publication number
EP1530648A1
EP1530648A1 EP03792199A EP03792199A EP1530648A1 EP 1530648 A1 EP1530648 A1 EP 1530648A1 EP 03792199 A EP03792199 A EP 03792199A EP 03792199 A EP03792199 A EP 03792199A EP 1530648 A1 EP1530648 A1 EP 1530648A1
Authority
EP
European Patent Office
Prior art keywords
molten steel
steel
oxygen
melt
blowing
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
EP03792199A
Other languages
German (de)
French (fr)
Other versions
EP1530648B1 (en
Inventor
Yuyou Zhai
Johannes Müller
Johannes Spiess
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.)
Primetals Technologies Austria GmbH
Original Assignee
Voest Alpine Industrienlagenbau 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 Voest Alpine Industrienlagenbau GmbH filed Critical Voest Alpine Industrienlagenbau GmbH
Priority to EP06020935A priority Critical patent/EP1764421A3/en
Publication of EP1530648A1 publication Critical patent/EP1530648A1/en
Application granted granted Critical
Publication of EP1530648B1 publication Critical patent/EP1530648B1/en
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
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/068—Decarburising
    • C21C7/0685—Decarburising of stainless steel
    • 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
    • C21C5/005—Manufacture of stainless steel
    • 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
    • C21C5/30—Regulating or controlling the blowing
    • C21C5/32—Blowing from above
    • 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
    • C21C5/30—Regulating or controlling the blowing
    • C21C5/35—Blowing from above and through the bath
    • 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
    • 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
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/068—Decarburising
    • 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
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/072—Treatment with gases
    • 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
    • F27D3/00—Charging; Discharging; Manipulation of charge
    • F27D3/16—Introducing a fluid jet or current into the charge

Definitions

  • the invention relates to a method and a device for decarburizing a molten steel in the course of the production of stainless steel in a metallurgical vessel, in particular in a converter, the molten steel being treated with oxygen and optionally an inert gas, in particular argon and / or nitrogen.
  • a process for decarburizing a steel melt in particular according to the AOD process, it is known to carry out decarburization by means of an acid inflation process above a carbon content of essentially 0.3% by weight in the steel melt using a corresponding top lance. If the steel melt has a carbon content of less than 0.3% by weight, decarburization is continued by the operation of underbath jets. However, the operation of the underbath jets generally results in insufficient mixing of the molten steel. Furthermore, there is high ferrostatic pressure in the area of the underbath jets, which has a negative effect on decarburization.
  • the present invention has for its object to avoid the disadvantages of the prior art and to develop a method according to the preamble of claim 1 and a device according to the preamble of claims 6 and 7, which realizes a particularly economical and efficient decarburization of the steel melt can be.
  • the metal bath is mixed particularly well.
  • This measure according to the invention significantly accelerates decarburization compared to the prior art.
  • the major part of the oxygen used by the inflator and the opening below the surface of the steel melt is in via the inflator with the steel melt Brought in contact.
  • This measure according to the invention significantly accelerates decarburization compared to the prior art.
  • just as much gas, in particular oxygen, is blown in through the opening below the surface of the molten steel. that a blockage of the opening is prevented and / or at the same time an adequate bath mixing is ensured.
  • the inflator has a blowing lance, and the oxygen is passed through the blowing lance onto the surface of the molten steel.
  • the blowing lance has a Laval nozzle, and the oxygen is passed through the Laval nozzle onto the surface of the molten steel.
  • Laval nozzles enable technically and economically efficient forms to achieve high flow velocities. Since a slag layer normally floats on the molten steel, the flow velocity of the gas stream directed to the same for the treatment of the molten steel is of crucial importance. Only a high gas velocity, as can be achieved particularly preferably by using a Laval nozzle, guarantees the contact of the gas stream, in particular the oxygen, with the steel melt, and thus sufficient mixing and decarburization of the steel melt.
  • a carbon limit of 0.2% by weight in particular a carbon content of 0.3% to 0.4% by weight, particularly preferably a carbon limit of 0.5% by weight, is used in the Steel melt oxygen through a blowing lance equipped with a first Laval nozzle with a flow rate D1 and below the carbon limit in the steel melt oxygen through a blowing lance equipped with a second Laval nozzle with a flow rate D2, where D2 ⁇ D1, passed onto the steel melt, in particular inflated.
  • the first and the second Laval nozzle each have different diameters.
  • the present invention relates to a method and a device for the combined top and bottom injection of 0 2 and / or inert gas into a metal vessel for the purpose of decarburizing a molten metal, in particular a molten steel, the required amount of 0 2 mainly is blown through one or more top lances, and the required adjustment of the 0 2 and / or inert gas blowing intensity is achieved by changing the lance configuration during operation, ideally by arranging and operating a second blowing lance. In this way, the optimal gas jet is ensured (thorough mixing of the metal bath) and the lance life is increased.
  • the second lance is designed for a lower blowing intensity or flow rate.
  • the specific blow rate of the second lance is set to a value in the range from 0.5 to 1 Nm 3 / (t * min).
  • the lance used has a Laval nozzle on the lance head.
  • oxygen and / or inert gas is blown onto the molten metal through the second top lance.
  • the second lance is operated at a lower C content in the melt with a lower blowing intensity.
  • the mixing ratio between oxygen and inert gas with which the molten metal is applied is adjusted during the process in accordance with the current C content of the melt.
  • the critical C content (starting point for the use of the second lance) depends above all on the process conditions, in particular the chemical composition and the temperature of the molten metal, and / or other thermochemical conditions.
  • the working position and the blow rate of the lances used are set accordingly during the operation of the decarburization process.
  • the dimensions of the lower bath nozzles can be designed to be smaller if the bath is mixed sufficiently than is the case with the method known from the prior art.
  • an oxygen / inert gas mixture in particular with a blowing rate of 0.1 to 0.3 Nm 3 / (t * min), is introduced in the area of the under bath nozzles to keep the nozzles free.
  • the under bath nozzles are arranged on the bottom or on the side wall of the metallurgical vessel.
  • the underbath jets are designed as classic jets and / or sink stones.
  • the top lance equipped with a Laval nozzle head is used for decarburization during a first process step.
  • the top lance With a carbon content of 0.3% by weight in the molten steel, the top lance is switched off and the further decarburization is continued by blowing in oxygen and, if appropriate, inert gas via one or more sub-bath nozzles.
  • the lance is used for approx. 15 - 25% of the total process time.
  • This reaction is strongly influenced by the partial pressure of CO.
  • the CO partial pressure is suppressed by introducing inert gas (Ar / N 2 ) into the molten steel.
  • inert gas Ar / N 2
  • this introduction is carried out by one or more sub-bath jets and / or a top lance.
  • the decarburization condition in the under bath nozzle is more unfavorable because of the ferrostatic pressure via the under bath nozzle. It is therefore proposed according to the invention to support further decarburization by blowing (top-blowing) and to intensify the mixing.
  • the admixture of inert gas is to be restricted in a range specified by the process requirement in order to minimize the inert gas consumption, in particular the Ar / N 2 consumption.
  • the total gas flow through the lance should be selected so that a high wear of the lance head and / or nozzle is avoided and a high utilization of the injected gas is ensured.
  • the invention relates to a method and a device for decarburization in a refractory-lined vessel, which is preferably in converter form, in the metal manufacturing industry, preferably in the steel and stainless steel producing industries.
  • the process according to the invention ensures the optimum mixing that occurs with combined blowing (top + bottom) in a corresponding vessel, in particular a converter, and thus also an improved C transport for CO formation, and, on the other hand, that in the inflation process (top lance -Blowing) lower CO partial pressure, and the decarburization conditions, which are therefore more favorable compared to bottom blowing, are used.
  • Bottom blowing is by definition a blowing in of a treatment gas below the surface of the molten metal.
  • top blowing is the blowing up of treatment gas onto the surface of the molten metal.
  • the decarburization in a metal vessel is divided into two process stages.
  • the first stage during which the addition of oxygen determines the rate of the chemical reaction taking place, decarburization takes place at a higher C content by means of combined top and bottom blowing, thus minimizing the amount of gas which is introduced into the metal bath through the bottom nozzles will prevent the floor nozzles from moving.
  • a second process step below a critical carbon content in the bath which for example in the case of chromium-containing melts is between 0.3-0.4% by weight of carbon in the steel melt, the mass transfer process taking place during the decarburization determines the reaction rate.
  • the ⁇ 2 bubble intensity is reduced accordingly.
  • the required amount of 0 2 becomes preferred Embodiment of the method according to the invention mainly blown through the top lance, preferably with the addition of inert gas.
  • a second appropriately designed lance is installed and used according to a special embodiment of the method according to the invention, the design of the lance head (with a Laval nozzle) is configured precisely for the requirements in this phase.
  • the lance used during the first bubble stage can be changed by mechanical adaptation (changeover or changeover) in such a way that the required blowing intensity and the required gas jet character can be fulfilled.
  • the mixing ratios between 0 2 and inert gas through the second lance are adjusted during the decarburization depending on the C content.
  • the lower bath nozzles are acted upon with an inert gas mixture in order to prevent the nozzles from moving or closing and to ensure optimal bath mixing.
  • a reduction phase can follow, in which the inert gas is blown through the lower bath nozzles and / or top lance.
  • the Laval nozzle has a mechanical and / or electromagnetic device for changing the characteristics of the Laval nozzle with regard to the set characteristic flow rate, for example by changing the cross section of the nozzle.
  • the top lance is used for decarburization up to a carbon content of 0.3% by weight in the steel melt, from a carbon content of 0.3% by weight in the steel melt, the 0 2 injection is carried out exclusively via floor nozzles
  • a first lance is used for decarburization up to a carbon content of 0.3% by weight in the steel melt.
  • a second lance for inflating an Ar / N 2/0 2 - used mixture is used for decarburization up to a carbon content of 0.3% by weight in the steel melt.
  • the gas flow (Ar / N / 0 2 ) prevailing in the bottom blowing during the second process step is minimized with regard to the premise of preventing the nozzles from closing.
  • Fig. 1 shows a device for treating a molten steel
  • the device 1 shows a device for decarburizing a molten steel using the AOD process.
  • the device 1 has a metallurgical vessel 2, in particular a converter, in which there is a steel melt 3, in particular a melt of a, preferably chromium-rich, stainless steel.
  • a slag 4 floats on the molten steel 3.
  • the steel melt 3 is treated through floor nozzles 5 with a treatment gas which generally contains oxygen and optionally an inert gas, in particular with one or more of the gases: oxygen, nitrogen, argon or air.
  • a first blowing lance 6 is operated, through which a treatment gas, in particular oxygen or an oxygen inert gas Mixture, particularly preferably an oxygen-argon mixture, with which molten steel is brought into contact.
  • a second method step 1 ' which corresponds to decarburization at a carbon content, preferably at or below 0.3% by weight, in the steel melt
  • the steel melt 3' in the metallurgical vessel 2 ' is again supplied with a treatment gas via one or more bottom nozzles 5'
  • the second lance 7' is in operation, which differs from the first lance 6 'in that this lance, which in turn is preferably equipped with a Laval nozzle, for a different, in particular smaller one .
  • Flow rate of treatment gas is designed.
  • the slag 4 ' is at least partially pushed back by the molten steel due to the operation of the blowing lance 7'.
  • the blowing lance 6 ' remains out of operation during the second process step.

Abstract

Decarburization of molten steel (3), especially in stainless steel production in a metallurgical vessel (2) and particularly a converter, involves treatment with oxygen and an inert gas if required and especially argon and/or nitrogen. To decarburize molten steel with carbon content of =0.3 wt.%, the gas is introduced through an opening (5) below the molten steel level and a blower lance (6, 7) over the molten steel surface, to bring the gas into contact with the metal.

Description

Verfahren und Vorrichtung zur Entkohlung einer StahlschmelzeMethod and device for decarburizing a molten steel
Die Erfindung betrifft ein Verfahren sowie eine Vorrichtung zur Entkohlung einer Stahlschmelze im Zuge der Herstellung von rostfreiem Stahl in einem metallurgischen Gefäß, insbesondere in einem Konverter, wobei die Stahlschmelze mit Sauerstoff und gegebenenfalls einem Inertgas, insbesondere Argon und/oder Stickstoff, behandelt wird.The invention relates to a method and a device for decarburizing a molten steel in the course of the production of stainless steel in a metallurgical vessel, in particular in a converter, the molten steel being treated with oxygen and optionally an inert gas, in particular argon and / or nitrogen.
Bei einem Verfahren zur Entkohlung einer Stahlschmelze, insbesondere nach dem AOD-Verfahren, ist bekannt, oberhalb eines Kohlenstoffgehaltes von im wesentlichen 0,3 Gew % in der Stahlschmelze unter Benützung einer entsprechenden Top-Lanze eine Entkohlung mittels eines Saueraufblasprozesses durchzuführen. Unterhalb von 0,3 Gew% Kohlenstoffgehalt in der Stahlschmelze wird die Entkohlung durch den Betrieb von Unterbaddüsen fortgesetzt. Durch den Betrieb der Unterbaddüsen folgt im Allgemeinen jedoch eine unzureichende Durchmischung der Stahlschmelze. Weiters herrscht im Bereich der Unterbaddüsen ein hoher ferrostatischer Druck, der sich negativ auf die Entkohlung auswirkt.In a process for decarburizing a steel melt, in particular according to the AOD process, it is known to carry out decarburization by means of an acid inflation process above a carbon content of essentially 0.3% by weight in the steel melt using a corresponding top lance. If the steel melt has a carbon content of less than 0.3% by weight, decarburization is continued by the operation of underbath jets. However, the operation of the underbath jets generally results in insufficient mixing of the molten steel. Furthermore, there is high ferrostatic pressure in the area of the underbath jets, which has a negative effect on decarburization.
Der vorliegenden Erfindung liegt die Aufgabe zugrunde, die Nachteile aus dem Stand der Technik zu vermeiden und ein Verfahren gemäß dem Oberbegriff des Anspruchs 1 sowie eine Vorrichtung gemäß dem Oberbegriff des Anspruchs 6 und 7 zu entwickeln, womit eine besonders wirtschaftliche und effiziente Entkohlung der Stahlschmelze verwirklicht werden kann.The present invention has for its object to avoid the disadvantages of the prior art and to develop a method according to the preamble of claim 1 and a device according to the preamble of claims 6 and 7, which realizes a particularly economical and efficient decarburization of the steel melt can be.
Diese Aufgabe wird entsprechend dem erfindungsgemäßen Verfahren nach dem kennzeichnenden Teil des Anspruchs 1 sowie entsprechend der erfindungsgemäßen Vorrichtung nach dem kennzeichnenden Teil der Ansprüche 6 und 7 gelöst.This object is achieved according to the inventive method according to the characterizing part of claim 1 and according to the inventive device according to the characterizing part of claims 6 and 7.
Durch den gemeinsamen Betrieb der Unterbaddüse und der Toplanze erfolgt eine besonders gute Durchmischung des Metallbades.Due to the joint operation of the lower bath nozzle and the top lance, the metal bath is mixed particularly well.
Durch diese erfindungsgemäße Maßnahme wird die Entkohlung gegenüber dem Stand der Technik wesentlich beschleunigt.This measure according to the invention significantly accelerates decarburization compared to the prior art.
Nach einer besonderen Ausführungsform des erfindungsgemäßen Verfahrens wird bei der Entkohlung der Stahlschmelze unterhalb eines Kohlenstoffgehaltes von 0,3 Gew% in der Stahlschmelze, der überwiegende Teil des durch die Aufblasvorrichtung und die Öffnung unterhalb der Oberfläche der Stahlschmelze eingesetzten Sauerstoffs über die Aufblasvorrichtung mit der Stahlschmelze in Kontakt gebracht.According to a particular embodiment of the method according to the invention, when the steel melt is decarburized below a carbon content of 0.3% by weight in the steel melt, the major part of the oxygen used by the inflator and the opening below the surface of the steel melt is in via the inflator with the steel melt Brought in contact.
Durch diese erfindungsgemäße Maßnahme wird die Entkohlung gegenüber dem Stand der Technik wesentlich beschleunigt.This measure according to the invention significantly accelerates decarburization compared to the prior art.
Nach einer bevorzugten Ausfuhrungsform des erfindungsgemäßen Verfahrens wird durch die Öffnung unterhalb der Oberfläche der Stahlschmelze gerade soviel Gas, insbesondere Sauerstoff, eingeblasen, dass eine Blockade der Öffnung verhindert und/oder gleichzeitig eine ausreichende Baddurchmischung sichergestellt wird.According to a preferred embodiment of the method according to the invention, just as much gas, in particular oxygen, is blown in through the opening below the surface of the molten steel. that a blockage of the opening is prevented and / or at the same time an adequate bath mixing is ensured.
Nach einer weiteren besonderen Ausführungsform des erfindungsgemäßen Verfahrens weist die Aufblasvorrichtung eine Blaslanze auf, und wird der Sauerstoff durch die Blaslanze auf die Oberfläche der Stahlschmelze geleitet.According to a further particular embodiment of the method according to the invention, the inflator has a blowing lance, and the oxygen is passed through the blowing lance onto the surface of the molten steel.
Nach einer weiteren besonderen Ausführungsform des erfindungsgemäßen Verfahrens weist die Blaslanze eine Lavaldüse auf, und wird der Sauerstoff durch die Lavaldüse auf die Oberfläche der Stahlschmelze geleitet.According to a further special embodiment of the method according to the invention, the blowing lance has a Laval nozzle, and the oxygen is passed through the Laval nozzle onto the surface of the molten steel.
Durch Lavaldüsen sind in technisch und wirtschaftlich effizienter Form hohe Strömungsgeschwindigkeiten realisierbar. Da auf der Stahlschmelze im Normalfall eine Schlackenschicht aufschwimmt, ist die Strömungsgeschwindigkeit des zur Behandlung der Stahlschmelze auf dieselbe gerichteten Gasstromes von entscheidender Bedeutung. Erst eine hohe Gasgeschwindigkeit, wie sie besonders bevorzugt durch Anwendung einer Lavaldüse erzielbar ist, garantiert den Kontakt des Gasstromes, insbesondere des Sauerstoffes mit der Stahlschmelze, und damit eine ausreichende Durchmischung und Entkohlung der Stahlschmelze.Laval nozzles enable technically and economically efficient forms to achieve high flow velocities. Since a slag layer normally floats on the molten steel, the flow velocity of the gas stream directed to the same for the treatment of the molten steel is of crucial importance. Only a high gas velocity, as can be achieved particularly preferably by using a Laval nozzle, guarantees the contact of the gas stream, in particular the oxygen, with the steel melt, and thus sufficient mixing and decarburization of the steel melt.
Nach einer weiteren besonderen Ausführungsform des erfindungsgemäßen Verfahrens wird oberhalb eines Kohlenstoffgrenzgehaltes von 0,2 Gew% , insbesondere oberhalb eines Kohlenstoffgehalts von 0,3 Gew% bis 0,4 Gew%, besonders bevorzugt oberhalb eines Kohlenstoffgrenzgehaltes von 0,5 Gew%, in der Stahlschmelze Sauerstoff durch eine mit einer ersten Lavaldüse ausgestatteten Blaslanze mit einer Durchflussmenge Dl und unterhalb des Kohlenstoffgrenzgehaltes in der Stahlschmelze Sauerstoff durch eine, mit einer zweiten Lavaldüse ausgestatteten Blaslanze mit einer Durchflussmenge D2, wobei D2<D1, auf die Stahlschmelze geleitet, insbesondere aufgeblasen.According to a further particular embodiment of the process according to the invention, a carbon limit of 0.2% by weight, in particular a carbon content of 0.3% to 0.4% by weight, particularly preferably a carbon limit of 0.5% by weight, is used in the Steel melt oxygen through a blowing lance equipped with a first Laval nozzle with a flow rate D1 and below the carbon limit in the steel melt oxygen through a blowing lance equipped with a second Laval nozzle with a flow rate D2, where D2 <D1, passed onto the steel melt, in particular inflated.
Nach einer besonderen Ausführungsform der Erfindung weisen die erste und die zweite Lavaldüse jeweils unterschiedliche Durchmesser auf.According to a special embodiment of the invention, the first and the second Laval nozzle each have different diameters.
Nach einer besonderen Ausführungsform betrifft die vorliegende Erfindung ein Verfahren und eine Einrichtung zur kombinierten Top- und Boden-Einblasung von 02 und/oder Inertgas in ein Metallgefäß zum Zwecke der Entkohlung einer Metallschmelze, insbesondere einer Stahlschmelze, wobei die erforderliche 02-Menge hauptsächlich durch eine oder mehrere Top-Lanzen eingeblasen wird, und die erforderliche Anpassung der 02- und/oder Inertgas-Blasintensität durch die Änderung der Lanzenkonfiguration während des Betriebes, idealerweise durch Anordnung und Betrieb eine zweiten Blaslanze realisiert wird. Auf diese Weise erfolgt eine Sicherung des optimalen Gasstrahles (gute Durchmischung des Metallbades) und eine Erhöhung der Lanzenlebensdauer. Nach einer besonderen Ausführungsform der Erfindung wird die zweite Lanze auf eine niedrigere Blasintensität bzw. Durchflussmenge ausgelegt. Nach einer besonderen Ausführuπgsform der Erfindung ist die spezifische Blasrate der zweiten Lanze auf einen Wert im Bereich von 0,5 bis 1 Nm3/(t*min) eingestellt. Nach einer besonderen Ausführungsform der Erfindung weist die verwendete Lanze am Lanzenkopf eine Laval-Düse auf.According to a particular embodiment, the present invention relates to a method and a device for the combined top and bottom injection of 0 2 and / or inert gas into a metal vessel for the purpose of decarburizing a molten metal, in particular a molten steel, the required amount of 0 2 mainly is blown through one or more top lances, and the required adjustment of the 0 2 and / or inert gas blowing intensity is achieved by changing the lance configuration during operation, ideally by arranging and operating a second blowing lance. In this way, the optimal gas jet is ensured (thorough mixing of the metal bath) and the lance life is increased. According to a special embodiment of the invention, the second lance is designed for a lower blowing intensity or flow rate. According to a special embodiment of the invention, the specific blow rate of the second lance is set to a value in the range from 0.5 to 1 Nm 3 / (t * min). According to a special embodiment of the invention, the lance used has a Laval nozzle on the lance head.
Nach einer weiteren Ausführungsform der Erfindung wird durch die zweite Top-Lanze Sauerstoff und/oder Inertgas auf die Metallschmelze aufgeblasen.According to a further embodiment of the invention, oxygen and / or inert gas is blown onto the molten metal through the second top lance.
Nach einer zusätzlichen Ausführungsform der Erfindung wird die zweite Lanze bei niedrigem C- Gehalt in der Schmelze mit einer niedrigeren Blasintensität betrieben. Nach einer weiteren besonderen Ausfuhrungsform wird das Mischungsverhältnis zwischen Sauerstoff und Inertgas mit welchem die Metallschmelze beaufschlagt wird während dem Prozess entsprechend dem aktuellen C-Gehalt der Schmelze angepasst. Nach einer besonderen Ausführungsform der Erfindung hängt der kritische C- Gehalt (Startpunkt für den Einsatz der zweiten Lanze) vor allem von den Verfahrensbedingungen, insbesondere der chemischen Zusammensetzung und der Temperatur der Metallschmelze, und/oder anderen thermochemischen Bedingungen ab.According to an additional embodiment of the invention, the second lance is operated at a lower C content in the melt with a lower blowing intensity. According to a further special embodiment, the mixing ratio between oxygen and inert gas with which the molten metal is applied is adjusted during the process in accordance with the current C content of the melt. According to a particular embodiment of the invention, the critical C content (starting point for the use of the second lance) depends above all on the process conditions, in particular the chemical composition and the temperature of the molten metal, and / or other thermochemical conditions.
Nach einer besonderen Ausführungsform der Erfindung wird die Arbeitsposition und die Blasrate der verwendeten Lanzen während dem Betrieb des Entkohlungsverfahrens entsprechend eingestellt.According to a particular embodiment of the invention, the working position and the blow rate of the lances used are set accordingly during the operation of the decarburization process.
Nach einer besonderen Ausführungsform der Erfindung sind die Dimensionen der Unterbaddüsen bei ausreichender Baddurchmischung kleiner auslegbar als das bei aus dem Stand der Technik bekannten Verfahren der Fall ist. Nach einer besonderen Ausführungsform der Erfindung wird im Bereich der Unterbaddüsen ein Sauerstoff-ZInertgasgemisch, insbesondere mit einer Blasrate von 0,1 bis 0,3 Nm3/(t*min), zur Freihaltung der Düsen eingeleitet.According to a special embodiment of the invention, the dimensions of the lower bath nozzles can be designed to be smaller if the bath is mixed sufficiently than is the case with the method known from the prior art. According to a special embodiment of the invention, an oxygen / inert gas mixture, in particular with a blowing rate of 0.1 to 0.3 Nm 3 / (t * min), is introduced in the area of the under bath nozzles to keep the nozzles free.
Nach einer besonderen Ausführungsform der Erfindung sind die Unterbaddüsen am Boden oder an der Seitenwand des metallurgischen Gefäßes angeordnet.According to a special embodiment of the invention, the under bath nozzles are arranged on the bottom or on the side wall of the metallurgical vessel.
Nach einer besonderen Ausführungsform der Erfindung sind die Unterbaddüsen als klassische Düsen und/oder Spülsteine ausgeführt.According to a special embodiment of the invention, the underbath jets are designed as classic jets and / or sink stones.
Bei einem aus dem Stand der Technik bekannten AOD-L oder K-OBM-S Prozess wird die mit einem Laval-Düsenkopf ausgestattete Top-Lanze während eines ersten Verfahrensschrittes zur Entkohlung eingesetzt. Bei einem Kohlenstoffgehalt von 0,3 Gew% in der Stahlschmelze wird die Top-Lanze abgeschaltet und die weitere Entkohlung durch Einblasen von Sauerstoff und gegebenenfalls Inertgas über eine oder mehrere Unterbaddüsen fortgesetzt. Die Einsatzdauer der Lanze beträgt demnach je nach dem Eingangskohlenstoffgehalt in der Vorschmelze ca. 15 - 25 % der gesamten Prozesszeit.In an AOD-L or K-OBM-S process known from the prior art, the top lance equipped with a Laval nozzle head is used for decarburization during a first process step. With a carbon content of 0.3% by weight in the molten steel, the top lance is switched off and the further decarburization is continued by blowing in oxygen and, if appropriate, inert gas via one or more sub-bath nozzles. Depending on the input carbon content in the premelt, the lance is used for approx. 15 - 25% of the total process time.
Die Entkohlung folgt der Reaktion:Decarburization follows the reaction:
Cr203 + 3C -» 2Cr + 3COCr 2 0 3 + 3C - »2Cr + 3CO
Diese Reaktion wird stark durch den CO-Partialdruck beeinflusst. Um die Entkohlung zu begünstigen, wird der CO-Partialdruck durch Einleitung von Inertgas (Ar/N2) in die Stahlschmelze unterdrückt. Diese Einleitung erfolgt nach dem Stand der Technik durch eine oder mehrere Unterbaddüsen und/oder eine Top-Lanze.This reaction is strongly influenced by the partial pressure of CO. To promote decarburization, the CO partial pressure is suppressed by introducing inert gas (Ar / N 2 ) into the molten steel. According to the prior art, this introduction is carried out by one or more sub-bath jets and / or a top lance.
Im Vergleich zum Aufblasen des Behandlungsgaseε (Top-Lance-Blowing) ist die Entkohlungsbedingung bei der Unterbaddüse wegen des ferrostatischen Druckes über die Unterbaddüsen ungünstiger. Es wird deshalb erfindungsgemäß vorgeschlagen, die weitere Entkohlung durch Aufblasen (Top-blowing) zu unterstützen und die Durchmischung zu intensivieren.In comparison to the inflation of the treatment gas (top lance blowing), the decarburization condition in the under bath nozzle is more unfavorable because of the ferrostatic pressure via the under bath nozzle. It is therefore proposed according to the invention to support further decarburization by blowing (top-blowing) and to intensify the mixing.
Hierbei könnte man nach einer besonderen Ausführungsform der Erfindung beispielsweise eine bestimmte Inertgasmenge zum dem über die Lanze einzuleitendem 02 beimischen, wodurch die für den Betrieb der Lavaldüse der Blaslanze erforderliche Gasmenge bereitgestellt werden kann. Die Inertgasbeimischung ist in einem durch den Prozessbedarf vorgegebenen Bereich einzuschränken, um den Inertgasverbrauch, insbesondere den Ar/N2-Verbrauch, zu minimieren. Der gesamte Gasdurchfluss über die Lanze ist dabei so auszuwählen, dass ein hoher Lanzenkopf- und/oder Düsenverschleiß vermieden wird, und eine hohe Ausnutzung des eingeblasenen Gases sichergestellt wird.Here, according to a particular embodiment of the invention, one could, for example, add a certain amount of inert gas to the 0 2 to be introduced via the lance, as a result of which the amount of gas required for operating the Laval nozzle of the blowing lance can be provided. The admixture of inert gas is to be restricted in a range specified by the process requirement in order to minimize the inert gas consumption, in particular the Ar / N 2 consumption. The total gas flow through the lance should be selected so that a high wear of the lance head and / or nozzle is avoided and a high utilization of the injected gas is ensured.
Die Erfindung bezieht sich auf ein Verfahren und eine Vorrichtung zur Entkohlung in einem mit feuerfest-ausgemauerten Gefäß, welches vorzugsweise in Konverterform vorliegt, in der Metallherstellungsindustrie, vorzugsweise in der Stahl- und Edelstahl erzeugenden Industrie. Durch das erfindungsgemäße Verfahren wird einerseits die bei kombiniertem Blowing (Top + Bottom) in einem entsprechendem Gefäß, insbesondere einem Konverter, auftretende optimale Durchmischung und somit auch ein verbesserter C-Transport zur CO-Bildung, und andererseits der bei dem Aufblasverfahren (Top-Lance-Blowing) niedrigere CO-Partialdruck, und die im Vergleich zum Bottom-Blowing somit günstigere Entkohlungsbedingung ausgenützt.The invention relates to a method and a device for decarburization in a refractory-lined vessel, which is preferably in converter form, in the metal manufacturing industry, preferably in the steel and stainless steel producing industries. The process according to the invention, on the one hand, ensures the optimum mixing that occurs with combined blowing (top + bottom) in a corresponding vessel, in particular a converter, and thus also an improved C transport for CO formation, and, on the other hand, that in the inflation process (top lance -Blowing) lower CO partial pressure, and the decarburization conditions, which are therefore more favorable compared to bottom blowing, are used.
Als Bottom-Blowing wird definitionsgemäß ein Einblasen eines Behandlungsgases unterhalb der Oberfläche der Metallschmelze bezeichnet. Als Top-BIowing wird definitionsgemäß ein Aufblasen von Behandlungsgas auf die Oberfläche der Metallschmelze bezeichnet.Bottom blowing is by definition a blowing in of a treatment gas below the surface of the molten metal. By definition, top blowing is the blowing up of treatment gas onto the surface of the molten metal.
Erfindungsgemäß wird die Entkohlung in einem Metallgefäß in zwei Verfahrensstufen unterteilt. Während der ersten Stufe, während der die Sauerstoffzugabe die Geschwindigkeit der ablaufenden chemischen Reaktion bestimmt, erfolgt die Entkohlung bei höherem C-Gehalt durch kombiniertes Top- und Bottom-Blowing, wobei die Gasmenge, welche durch die Bodendüsen in das Metallbad eingeleitet wird, so minimiert wird, dass ein Verlegen der Bodendüsen verhindert wird. Während einer zweiten Verfahrensstufe unterhalb eines kritischen C-Gehaltes im Bad, welcher beispielsweise bei chromhaltigen Schmelzen zwischen 0.3-0.4 Gew% Kohlenstoff in der Stahlschmelze beträgt, bestimmt der im Rahmen der Entkohlung ablaufende Stofftransportvorgang die Reaktionsgeschwindigkeit. Um die Oxidation der Metallelemente im Bad zu minimieren und die gezielte Prozesstemperatur sicherzustellen, wird die θ2-Blasenintensität dementsprechend reduziert. Während der zweiten Verfahrensstufe wird die erforderliche 02-Menge nach einer bevorzugten Ausführungsform des erfindungsgemäßen Verfahrens hauptsächlich durch die Top-Lanze, vorzugsweise unter Beimischung von Inertgas, eingeblasen.According to the invention, the decarburization in a metal vessel is divided into two process stages. During the first stage, during which the addition of oxygen determines the rate of the chemical reaction taking place, decarburization takes place at a higher C content by means of combined top and bottom blowing, thus minimizing the amount of gas which is introduced into the metal bath through the bottom nozzles will prevent the floor nozzles from moving. During a second process step below a critical carbon content in the bath, which for example in the case of chromium-containing melts is between 0.3-0.4% by weight of carbon in the steel melt, the mass transfer process taking place during the decarburization determines the reaction rate. In order to minimize the oxidation of the metal elements in the bath and to ensure the targeted process temperature, the θ 2 bubble intensity is reduced accordingly. During the second stage of the process, the required amount of 0 2 becomes preferred Embodiment of the method according to the invention mainly blown through the top lance, preferably with the addition of inert gas.
Da sich die während des zweiten Verfahrensschrittes gewünschte Gas-Durchflussmenge bzw. die gewünschte Blasintensität durch die Blaslanze von jener des ersten Verfahrensschrittes unterscheidet, wird nach einer besonderen Ausführungsform des erfindungsgemäßen Verfahrens eine zweite entsprechend ausgelegte Lanze installiert und eingesetzt, wobei die Auslegung des Lanzenkopfs (mit einer Laval-Düse) genau für die Erfordernisse in dieser Phase konfiguriert ist. Nach einer weiteren bevorzugten Ausführungsform kann erfindungsgemäß die während der ersten Blasenstufe eingesetzten Lanze durch mechanische Anpassung (Umschaltung bzw. Umstellung) so verändert werden, dass die erforderliche Blasintensität sowie der geforderte Gasstrahlcharakter erfüllt werden kann. Die Mischungsverhältnisse zwischen 02 und Inertgas durch die zweite Lanze werden während der Entkohlung je nach dem C-Gehalt angepasst. Die Unterbaddüsen werden dabei nach einer besonderen Ausführungsform mit einem OJlnertgas-gemisch beaufschlagt, um ein Verlegen oder Zugehen der Düsen zu verhindern und eine optimale Baddurchmischung zu sichern. Nachdem der erforderliche C-Gehalt im Bad erreicht ist, kann eine Reduktionsphase folgen, wobei das Inertgas durch die Unterbaddüsen und/oder Toplanze eingeblasen wird.Since the gas flow rate or the desired blowing intensity during the second process step differs from that of the first process step through the blowing lance, a second appropriately designed lance is installed and used according to a special embodiment of the method according to the invention, the design of the lance head (with a Laval nozzle) is configured precisely for the requirements in this phase. According to a further preferred embodiment, according to the invention the lance used during the first bubble stage can be changed by mechanical adaptation (changeover or changeover) in such a way that the required blowing intensity and the required gas jet character can be fulfilled. The mixing ratios between 0 2 and inert gas through the second lance are adjusted during the decarburization depending on the C content. According to a special embodiment, the lower bath nozzles are acted upon with an inert gas mixture in order to prevent the nozzles from moving or closing and to ensure optimal bath mixing. After the required C content in the bath has been reached, a reduction phase can follow, in which the inert gas is blown through the lower bath nozzles and / or top lance.
Nach einer besonderen Ausführungsform der Erfindung weist die Lavaldüse eine mechanische und/oder elektromagnetische Einrichtung zur Veränderung der Charakteristik der Lavaldüse hinsichtlich der eingestellten charakteristischen Durchflussmenge, beispielsweise durch Veränderung des Querschnittes der Düse, auf.According to a special embodiment of the invention, the Laval nozzle has a mechanical and / or electromagnetic device for changing the characteristics of the Laval nozzle with regard to the set characteristic flow rate, for example by changing the cross section of the nozzle.
Entsprechend einer besonderen Ausführungsform der Erfindung ist nachfolgend ein nichteinschränkender Vergleich zwischen den Versuchsergebnisse einer nach dem Stand der Technik durchgefühlten rostfreien Stahlerzeugung (konventionelles AOD-Verfahren) und einer nach dem vorgeschlagenen erfindungsgemäßen Verfahren durchgeführten rostfreien Stahlerzeugung:According to a particular embodiment of the invention, the following is a non-restrictive comparison between the test results of stainless steel production (conventional AOD process) carried out according to the prior art and stainless steel production carried out according to the proposed process according to the invention:
Ausgangsbedingungen:Initial conditions:
Vorschmelze: 3% C, 18.3% Cr, 3.5% NiPremelt: 3% C, 18.3% Cr, 3.5% Ni
Abstichzielanalyse: 0.04%C, 18.3% Cr, 8.1% Ni, N < 450 ppm,Target analysis: 0.04% C, 18.3% Cr, 8.1% Ni, N <450 ppm,
Abstichgewicht: 1201Tap weight: 1201
Umschaltpunkt N2 => Ar: 0.08% CSwitchover point N 2 => Ar: 0.08% C
Verfahren nach dem Stand der Technik: Standard AOD Verfahren mit einem Stahlbadhöhe: 1.8 mState-of-the-art process: Standard AOD process with a steel bath height: 1.8 m
Ablauf: Die Top-lanze wird bis zu einem Kohlenstoffgehalt von 0,3 Gew% in der Stahlschmelze zur Entkohlung eingesetzt, ab einem Kohlenstoffgehalt von 0,3 Gew% in der Stahlschmelze erfolgt die 02 Eindüsung ausschließlich über Bodendüsen Gesamtbehandlungszeit: 55.2 min. Ar: 8,5 Nm3/t Si: 13 kg/t Kalk: 51 kg/t Feuerfest: circa 12 kg/t Cr-Ausbringung: 98%Process: The top lance is used for decarburization up to a carbon content of 0.3% by weight in the steel melt, from a carbon content of 0.3% by weight in the steel melt, the 0 2 injection is carried out exclusively via floor nozzles Total treatment time: 55.2 min. Ar: 8.5 Nm 3 / t Si: 13 kg / t lime: 51 kg / t refractory: approx. 12 kg / t Cr output: 98%
Erfindungsgemäßes Verfahren:Method according to the invention:
Ablauf: Eine erste Lanze wird bei der Entkohlung bis zu einem Kohlenstoffgehalt von 0,3 Gew % in der Stahlschmelze eingesetzt. Nachfolgend wird eine zweite Lanze zum Aufblasen eines Ar/N2/02 - Gemisches verwendet.Process: A first lance is used for decarburization up to a carbon content of 0.3% by weight in the steel melt. Next, a second lance for inflating an Ar / N 2/0 2 - used mixture.
Der während des zweiten Verfahrensschrittes herrschende Gasfluß (Ar/N /02) bei dem Bottem- Blowing wird hinsichtlich der Prämisse, ein Zugehen der Düsen zu verhindern, minimiert.The gas flow (Ar / N / 0 2 ) prevailing in the bottom blowing during the second process step is minimized with regard to the premise of preventing the nozzles from closing.
Gesamtbehandlungszeit: 49.3 min.Total treatment time: 49.3 min.
Ar: 7.2 Nm3/tAr: 7.2 Nm3 / t
Si: 8.6 kg/tSi: 8.6 kg / t
Kalk: 31 kg/tLime: 31 kg / t
Feuerfest: 8 kg/tFireproof: 8 kg / t
Cr-Ausbringung: 98,4%Cr output: 98.4%
Im Folgenden wird ein nicht einschränkendes Ausführungsbeispiel der Erfindung anhand einer Zeichnung näher erläutert. Es zeigt:A non-restrictive exemplary embodiment of the invention is explained in more detail below with reference to a drawing. It shows:
Fig. 1 eine Vorrichtung zur Behandlung einer StahlschmelzeFig. 1 shows a device for treating a molten steel
In Fig. 1 ist eine Vorrichtung zur Entkohlung einer Stahlschmelze nach dem AOD-Verfahren dargestellt. Die Vorrichtung 1 weist dabei ein metallurgisches Gefäß 2, insbesondere einen Konverter auf, in welchem sich eine Stahlschmelze 3, insbesondere eine Schmelze eines, vorzugsweise chromreichen, rostfreien Stahls befindet. Auf der Stahlschmelze 3 schwimmt eine Schlacke 4 auf. Die Stahlschmelze 3 wird durch Bodendüsen 5 mit einem Behandlungsgas, welches im allgemeinen Sauerstoff und gegebenenfalls ein Inertgas enthält, insbesondere mit einem oder mehreren der Gase: Sauerstoff, Stickstoff, Argon oder Luft, behandelt. Weiters wird eine erste Blaslanze 6 betrieben, durch welche ebenfalls ein Behandlungsgas, insbesondere Sauerstoff oder ein Sauerstoff-Inertgas- Gemisch, besonders bevorzugt ein Sauerstoff-Argon-Gemisch, mit der Stahlschmelze in Kontakt gebracht wird. Wie anhand der schematischen Zeichnung ersichtlich, wird durch das Aufblasen des Behandlungsgases auf die Stahlschmelze, wenn dieses mit einer geeignet hohen Geschwindigkeit, wie das beispielsweise durch Anwendung einer Lavaldüse erreicht werden kann, geschieht, die Schlacke zurückgedrängt. Damit ist ein optimaler Kontakt des Behandlungsgases mit der Stahlschmelze gewährleistet. Eine ausreichende Intensität des durch die Lavaldüse der Blaslanze auf die Metallschmelze gerichteten Gasstromes sorgt zudem für eine gute Durchmischung der in dem Gefäß enthaltenen Flüssigkeiten. Eine zweite bereitgestellte Lanze 7 wird in dem ersten Verfahrensschritt, der im wesentlichen einer Entkohlung bei einem Kohlenstoffgehalt von über 0,3 Gew% entspricht, nicht eingesetzt.1 shows a device for decarburizing a molten steel using the AOD process. The device 1 has a metallurgical vessel 2, in particular a converter, in which there is a steel melt 3, in particular a melt of a, preferably chromium-rich, stainless steel. A slag 4 floats on the molten steel 3. The steel melt 3 is treated through floor nozzles 5 with a treatment gas which generally contains oxygen and optionally an inert gas, in particular with one or more of the gases: oxygen, nitrogen, argon or air. Furthermore, a first blowing lance 6 is operated, through which a treatment gas, in particular oxygen or an oxygen inert gas Mixture, particularly preferably an oxygen-argon mixture, with which molten steel is brought into contact. As can be seen from the schematic drawing, by blowing up the treatment gas onto the molten steel, when this occurs at a suitably high speed, as can be achieved, for example, by using a Laval nozzle, the slag is pushed back. This ensures optimal contact of the treatment gas with the molten steel. A sufficient intensity of the gas stream directed through the Laval nozzle of the blowing lance onto the molten metal also ensures that the liquids contained in the vessel are thoroughly mixed. A second lance 7 provided is not used in the first process step, which essentially corresponds to decarburization with a carbon content of more than 0.3% by weight.
In einem zweiten Verfahrensschritt 1', welcher einer Entkohlung bei einem Kohlenstoffgehalt vorzugsweise bei oder unterhalb von 0,3 Gew% in der Stahlschmelze entspricht, wird der Stahlschmelze 3' in dem metallurgischen Gefäß 2' wiederum über eine oder mehrere Bodendüsen 5' ein Behandlungsgas zugeführt. Im Gegensatz zum Verfahrensschritt 1, ist im zweite Verfahrensschritt 1' die zweite Lanze 7' in Betrieb, die sich gegenüber der ersten Lanze 6' dadurch unterscheidet, dass diese Lanze, die wiederum bevorzugt mit einer Lavaldüse ausgestattet ist, für eine unterschiedliche, insbesondere kleinere, Durchflussmenge an Behandlungsgas ausgelegt ist. Wiederum wird die Schlacke 4' durch den Betrieb der Blaslanze 7' von der Stahlschmelze zumindest teilweise zurückgedrängt. Die Blaslanze 6' bleibt während des zweiten Verfahrensschrittes außer Betrieb. In a second method step 1 ', which corresponds to decarburization at a carbon content, preferably at or below 0.3% by weight, in the steel melt, the steel melt 3' in the metallurgical vessel 2 'is again supplied with a treatment gas via one or more bottom nozzles 5' , In contrast to method step 1, in second method step 1 'the second lance 7' is in operation, which differs from the first lance 6 'in that this lance, which in turn is preferably equipped with a Laval nozzle, for a different, in particular smaller one , Flow rate of treatment gas is designed. Again, the slag 4 'is at least partially pushed back by the molten steel due to the operation of the blowing lance 7'. The blowing lance 6 'remains out of operation during the second process step.

Claims

Patentansprüche: claims:
1. Verfahren zur Entkohlung einer Stahlschmelze im Zuge der Herstellung von rostfreiem Stahl in einem metallurgischen Gefäß, insbesondere in einem Konverter, wobei die Stahlschmelze mit Sauerstoff und gegebenenfalls einem Inertgas, insbesondere Argon und/oder Stickstoff, behandelt wird, dadurch gekennzeichnet, dass bei der Entkohlung der Stahlschmelze unterhalb eines Kohlenstoffgehaltes von 0,3 Gew. % in der Stahlschmelze Sauerstoff und gegebenenfalls Inertgas, insbesondere Argon und/oder Stickstoff, über eine Öffnung unterhalb der Oberfläche der Stahlschmelze sowie über eine oberhalb der Oberfläche der Stahlschmelze angeordnete Aufblasvorrichtung mit der Stahlschmelze in Kontakt gebracht wird.1. A process for decarburizing a steel melt in the course of the production of stainless steel in a metallurgical vessel, in particular in a converter, the steel melt being treated with oxygen and, if appropriate, an inert gas, in particular argon and / or nitrogen, characterized in that the Decarburization of the molten steel below a carbon content of 0.3% by weight in the molten steel, oxygen and possibly inert gas, in particular argon and / or nitrogen, via an opening below the surface of the molten steel and via an inflator arranged above the surface of the molten steel with the molten steel in Is brought into contact.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass bei der Entkohlung der Stahlschmelze unterhalb eines Kohlenstoffgehaltes von 0,3 Gew% in der Stahlschmelze, der überwiegende Teil des durch die Aufblasvorrichtung und die Öffnung unterhalb der Oberfläche der Stahlschmelze eingesetzten Sauerstoffs über die Aufblasvorrichtung mit der Stahlschmelze in Kontakt gebracht wird.2. The method according to claim 1, characterized in that in the decarburization of the steel melt below a carbon content of 0.3% by weight in the steel melt, the major part of the oxygen used by the inflator and the opening below the surface of the steel melt via the inflator with the molten steel is brought into contact.
3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass die Aufblasvorrichtung eine Blaslanze aufweist, und der Sauerstoff durch die Blaslanze auf die Oberfläche der Stahlschmelze geleitet wird.3. The method according to claim 1 or 2, characterized in that the inflator has a blowing lance, and the oxygen is passed through the blowing lance onto the surface of the molten steel.
4. Verfahren nach Anspruch 3, dadurch gekennzeichnet, dass die Blaslanze eine Lavaldüse ausweist, und der Sauerstoff durch die Lavaldüse auf die Oberfläche der Stahlschmelze geleitet wird.4. The method according to claim 3, characterized in that the blowing lance has a Laval nozzle, and the oxygen is passed through the Laval nozzle onto the surface of the molten steel.
5. Verfahren nach einem oder mehreren der Ansprüche 1 bis 4, dadurch gekennzeichnet, dass oberhalb eines Kohlenstoffgehaltes von 0,3 Gew% in der Stahlschmelze Sauerstoff durch eine mit einer ersten Lavaldüse ausgestatteten Blaslanze mit einer Durchflussmenge Dl und unterhalb eines Kohlenstoffgehaltes von 0,3 Gew% in der Stahlschmelze Sauerstoff durch eine, mit einer zweiten Lavaldüse ausgestatteten Blaslanze mit einer Durchflussmenge D2, wobei D2<D1, auf die Stahlschmelze aufgeblasen wird.5. The method according to one or more of claims 1 to 4, characterized in that above a carbon content of 0.3 wt% in the steel melt oxygen through a blowing lance equipped with a first Laval nozzle with a flow rate Dl and below a carbon content of 0.3 % By weight in the molten steel through a blowing lance equipped with a second Laval nozzle with a flow rate D2, where D2 <D1, is blown onto the molten steel.
6. Anlage zur Entkohlung einer Stahlschmelze bei der Herstellung von rostfreiem Stahl mit einem metallurgischen Gefäß (2) zur Aufnahme der Schmelze (3), welches im Bereich des Bodens und/oder seitlich im unteren Bereich des Gefäßes (2) zumindest eine Öffnung zur Einleitung von Sauerstoff und gegebenenfalls Inertgas, insbesondere Argon und/oder Stickstoff, aufweist und mit einer im oberen Teil des Gefäßes (2), zum Aufblasen von Sauerstoff und gegebenenfalls Inertgas, insbesondere Argon und/oder Stickstoff, auf die Oberfläche der Stahlschmelze (3), geeignet angeordneter, mit zumindest einer Lavaldüse ausgestatteter, Aufblasvorrichtung, dadurch gekennzeichnet, dass die Aufblasvorrichtung eine mechanische und/oder elektromagnetische Einrichtung aufweist, durch welche die Durchflussmenge der Lavaldüse veränderbar ist. Anlage zur Entkohlung einer Stahlschmelze bei der Herstellung von rostfreiem Stahl mit einem metallurgischen Gefäß (2) zur Aufnahme der Schmelze (3), welches im Bereich des Bodens und/oder seitlich im unteren Bereich des Gefäßes zumindest eine Öffnung zur Einleitung von Sauerstoff und gegebenenfalls Inertgas, insbesondere Argon und/oder Stickstoff, aufweist und mit einer im oberen Teil des Gefäßes zum Aufblasen von Sauerstoff und gegebenenfalls Inertgas, insbesondere Argon und/oder Stickstoff, auf die Oberfläche der Stahlschmelze geeignet angeordneten Aufblasvorrichtung, dadurch gekennzeichnet, dass die Aufblasvorrichtung zumindest zwei Blaslanzen (6, 7)mit jeweils zumindest einer Lavaldüse aufweist, wobei sich die Lavaldüsen der verschiedenen Blaslanzen durch unterschiedliche Auslegung hinsichtlich der Durchflussmenge unterscheiden, und die Blaslanzen unabhängig voneinander zur Entkohlung der Stahlschmelze (3) einsetzbar sind. 6. Plant for the decarburization of a molten steel in the production of stainless steel with a metallurgical vessel (2) for receiving the melt (3), which has at least one opening for introduction in the region of the bottom and / or laterally in the lower region of the vessel (2) of oxygen and optionally inert gas, in particular argon and / or nitrogen, and with one in the upper part of the vessel (2) for blowing oxygen and optionally inert gas, in particular argon and / or nitrogen, onto the surface of the molten steel (3), suitably arranged, equipped with at least one Laval nozzle, characterized in that the inflator has a mechanical and / or electromagnetic device through which the flow rate of the Laval nozzle can be changed. Plant for the decarburization of a molten steel in the production of stainless steel with a metallurgical vessel (2) for receiving the melt (3), which has at least one opening in the region of the bottom and / or laterally in the lower region of the vessel for introducing oxygen and possibly inert gas , in particular argon and / or nitrogen, and having an inflator suitably arranged in the upper part of the vessel for inflating oxygen and optionally inert gas, in particular argon and / or nitrogen, onto the surface of the molten steel, characterized in that the inflator has at least two blowing lances (6, 7) each with at least one Laval nozzle, the Laval nozzles of the various blowing lances differing in terms of the flow rate, and the blowing lances can be used independently of one another for decarburizing the steel melt (3).
EP03792199A 2002-08-21 2003-07-15 Methods and device for decarbonising a steel melt Expired - Lifetime EP1530648B1 (en)

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EP06020935A EP1764421A3 (en) 2002-08-21 2003-07-15 Device for decarbonising a steel melt

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AT12502002 2002-08-21
AT0125002A AT411530B (en) 2002-08-21 2002-08-21 Decarburization of molten stainless steel in a converter involves delivering the treatment gas through an opening below the molten level and blower lances above it, to mix the gas thoroughly through the molten metal
PCT/EP2003/007634 WO2004018714A1 (en) 2002-08-21 2003-07-15 Methods and device for decarbonising a steel melt

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DE102009049896A1 (en) * 2009-01-22 2010-08-05 Sms Siemag Ag Pulse flushing with inert gas in the BOF and AOD converter process
DE102014222727A1 (en) * 2014-11-06 2016-05-12 Sms Group Gmbh Method and device for producing a stainless steel

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JPS5589395A (en) * 1978-12-26 1980-07-05 Sumitomo Metal Ind Ltd Gasification of solid carbonaceous material and its device
JPS6040486B2 (en) * 1979-07-03 1985-09-11 住友金属工業株式会社 steel refining method
JPS6063307A (en) * 1983-09-14 1985-04-11 Kawasaki Steel Corp Converter steel making method of dead soft steel
LU86322A1 (en) * 1986-02-25 1987-09-10 Arbed OXYGEN BLOWING LANCE
LU88023A1 (en) * 1991-10-30 1993-05-17 Arbed Blow lance
JPH06158142A (en) * 1992-11-24 1994-06-07 Sumitomo Metal Ind Ltd Vacuum decarburization refining apparatus for high chrome steel
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EP1764421A3 (en) 2007-12-26
AU2003257462A1 (en) 2004-03-11
RU2319750C2 (en) 2008-03-20
CN1675383A (en) 2005-09-28
EP1764421A2 (en) 2007-03-21
ATE363546T1 (en) 2007-06-15
EP1530648B1 (en) 2007-05-30
ATA12502002A (en) 2003-07-15
AT411530B (en) 2004-02-25
RU2005107698A (en) 2005-09-10
CN100532581C (en) 2009-08-26
WO2004018714A1 (en) 2004-03-04
DE50307383D1 (en) 2007-07-12

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