EP0032343B1 - Procédé de brassage pneumatique d'un bain de métal en fusion - Google Patents

Procédé de brassage pneumatique d'un bain de métal en fusion Download PDF

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Publication number
EP0032343B1
EP0032343B1 EP80401859A EP80401859A EP0032343B1 EP 0032343 B1 EP0032343 B1 EP 0032343B1 EP 80401859 A EP80401859 A EP 80401859A EP 80401859 A EP80401859 A EP 80401859A EP 0032343 B1 EP0032343 B1 EP 0032343B1
Authority
EP
European Patent Office
Prior art keywords
stirring
bath
fluid
injection device
molten 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.)
Expired
Application number
EP80401859A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0032343A1 (fr
Inventor
Pierre Vayssiere
Jean-Claude Grosjean
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.)
Institut de Recherches de la Siderurgie Francaise IRSID
Original Assignee
Institut de Recherches de la Siderurgie Francaise IRSID
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 Institut de Recherches de la Siderurgie Francaise IRSID filed Critical Institut de Recherches de la Siderurgie Francaise IRSID
Priority to AT80401859T priority Critical patent/ATE18438T1/de
Publication of EP0032343A1 publication Critical patent/EP0032343A1/fr
Application granted granted Critical
Publication of EP0032343B1 publication Critical patent/EP0032343B1/fr
Expired 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
    • C21C5/28—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
    • 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

Definitions

  • the present invention relates to the operations of pneumatic stirring of a bath of molten metal by injecting a gas under the surface of the bath.
  • a handicap of this technique results from the fact that very often pneumatic stirring is useful or sought after, for the treatment of metal, only temporarily while the injection of gas, which provides this stirring, is necessary permanently to avoid that the molten metal clogs the injection device by solidifying it.
  • the injection device is calibrated so as to obtain an optimal gas flow rate for stirring, the minimum flow rate necessarily to be observed outside of the stirring periods for protecting the injection device against the risk of blockage constitutes a substantial economic penalty which may not be justified for metallurgical reasons.
  • the object of the present invention is to remedy these difficulties.
  • the subject of the invention is a process for pneumatically stirring a bath of molten metal by introducing an inert fluid by means of an injection device opening out under the surface of the bath, according to which the effect brewing is only sought temporarily and characterized in that, outside the brewing periods, the injection device is supplied with an inert fluid in the gaseous state, and in that, during the brewing periods, the inert gaseous fluid is replaced with an inert fluid in the liquid state capable of vaporizing easily on contact with the molten metal.
  • the fluids injected respectively in gaseous form and in liquid form can be either of the same chemical nature or of different chemical natures.
  • the fluid injected in liquid form has a density / molecular mass ratio of high value.
  • the method of the invention can be implemented both with an injection device constituted by nozzles opening out under the surface of the molten metal bath as with an injection device constituted by a plurality of refractory parts, selective and oriented internal permeability, incorporated into the bottom of the container containing the molten metal bath.
  • an injection device constituted by nozzles opening out under the surface of the molten metal bath
  • an injection device constituted by a plurality of refractory parts, selective and oriented internal permeability, incorporated into the bottom of the container containing the molten metal bath.
  • Such permeable refractory parts have been described in patent application EP-0 021 861, in the name of the applicant.
  • the invention therefore consists, in its essential characteristics, of modifying during operation the physical state of the stirring fluid - and possibly also its chemical nature - so as to inject a protective gas into the device. injection when the stirring of the bath is not necessary and to inject a stirring liquid when this need occurs.
  • the invention provides an elegant solution to the problem posed by making it possible to reconcile the apparently contradictory imperatives of minimizing the protection flow and optimizing the stirring flow by means of the same injection device.
  • FIG. 1 there is shown at 1 the converter with the lance 2 for blowing oxygen from above.
  • the bottom 3 of the converter is provided with nozzles 4.
  • the nozzles 4 consist of a central tube 5, through which liquid or gaseous nitrogen passes, and of an external tube 6 concentric with the tube 5 and defining with the tube 5 an annular space into which a cooling fluid is injected.
  • the tubes 5 are connected to a manifold 7 supplied, either with liquid nitrogen coming from the source 8, or with gaseous nitrogen coming from the source 9.
  • the placing of the manifold 7 in communication with the source 8 or with the source 9 takes place using the three-way valve symbolized at 10.
  • the annular spaces defined between the tubes 5 and 6 are connected to a source 11 coolant through a line 12.
  • the generally adopted criterion consists in obtaining a sonic velocity of the gas at the nose of the nozzle. Under these conditions, the minimum protection flow is close to 10 1 of nitrogen per second and this flow is obtained under a pressure of 2 ⁇ 10 5 Pascal.
  • the treatment of the bath begins with stirring with nitrogen. Nitrogen in the liquefied state is then substituted for the previously blown nitrogen gas. Under the maximum pressure of 15. 105 Pascal, the flow of liquid nitrogen passing through the nozzle is 0.2 1 / sec. approximately which, on contact with the molten metal in the converter vaporizes rapidly, providing a gas flow rate close to 120 IIsec., which corresponds to the value sought for efficient stirring.
  • the maximum gas flow rate that can be reached per nozzle is only 60 l / sec. about.
  • the process according to the invention makes it possible, in the case of nitrogen mixing, to double the mixing flow at a given protection flow, or, expressed differently, to reduce the protection flow for half for a flow of brewing given.
  • FIG. 2 there is shown at 1 the converter with the lance 2 for blowing oxygen from above.
  • the permeable refractory pieces 13 are placed in the bottom 3 of the converter.
  • Each piece 13 is constituted by an assembly 14 of refractory plates maintained laterally by a metal casing 15 completed by a closure plate 16.
  • the pieces 13 are connected by conduits 17 to a nurse 7 supplied, either with liquid nitrogen coming from the source 8, or with gaseous nitrogen coming from the source 9.
  • the nurse 7 is placed in communication with the source 8 or with the source 9 using of valve 10.
  • nitrogen gas is injected at a minimum flow rate of less than 1 l / sec. ; this flow rate is obtained at a pressure of approximately 10 5 Pascal.
  • nitrogen is then injected in the liquid state at a rate of approximately 0.3 l / sec. ; this flow rate is obtained at a pressure of approximately 6 ⁇ 10 5 Pascal.
  • the liquid nitrogen vaporizes quickly and provides a gas flow close to 200 l / sec.
  • the gaseous and liquid fluids are of different chemical nature.
  • the shielding gas can be argon and the brewing liquid liquid nitrogen, whose cost price is lower than that of liquid argon and whose injection after the refining period, that is to say in a highly oxidized metal bath, no longer presents a great risk of nitriding of the latter.
  • this passage from argon to liquid nitrogen makes it possible to achieve a flow rate of vaporized gas which, as we have seen, could not be obtained with liquid argon.
  • This single source is then connected to the injection device by two parallel circuits, one of which includes an evaporator and which are activated alternately using a “bypass”, depending on whether one wishes to blow the gas or inject the brewing liquid.
  • the invention is not limited to liquefied gases, but extends to any fluid in the liquid state under standard conditions of temperature and pressure, but insofar as it is obviously not not harmful to the development of the metal to be brewed.
  • mixtures of fluids of different chemical natures are also possible.
  • a brewing fluid which. per unit volume in the liquid state, provides the largest volume of gas by vaporization on contact with the molten metal.
  • liquefied gases appear to be entirely suitable.
  • the method according to the invention makes it possible to reduce the brewing period compared to the known technique. This is an appreciable advantage, in particular on the thermal level. because studies made by the inventors have shown that the cooling of a steel bath in a converter during brewing is less the result of the blowing of the brewing fluid than the calorific losses caused by the expectations for sampling and the duration of agitation of the bath, although these losses diminish when the converter capacity increases.
  • stirring liquid can be under standard conditions of temperature and pressure, a gas which has been liquefied prior to its injection, the opposite is quite possible with regard to the shielding gas .
  • the protective gas of the injection device is. under normal conditions of temperature and pressure, a liquid which has been vaporized prior to its passage through the injection device.
  • the protection of the injection device with a gas originating from the prior vaporization of a liquid is combined with stirring of the bath by injection of a liquid originating from a previously liquefied gas. , which makes it possible to have a high flow rate of stirring gas, while reducing to a certain extent the cooling of the bath outside the brewing periods.
  • the invention is not limited, as regards its applications, to mixing in a converter, but extends to other fields, such as the processing of steel in a ladle, and more generally, to any treatment.
  • pneumatic stirring of a bath of molten metal by injecting a stirring fluid under the surface of the bath.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
  • Carbon Steel Or Casting Steel Manufacturing (AREA)
  • Manufacture Of Alloys Or Alloy Compounds (AREA)
  • Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
  • Mixers With Rotating Receptacles And Mixers With Vibration Mechanisms (AREA)
  • Manufacture And Refinement Of Metals (AREA)
EP80401859A 1980-01-02 1980-12-23 Procédé de brassage pneumatique d'un bain de métal en fusion Expired EP0032343B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT80401859T ATE18438T1 (de) 1980-01-02 1980-12-23 Verfahren zur gasspuelung eines metallschmelzbades.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8000083A FR2473064A1 (fr) 1980-01-02 1980-01-02 Procede de brassage pneumatique d'un bain de metal en fusion
FR8000083 1980-01-02

Publications (2)

Publication Number Publication Date
EP0032343A1 EP0032343A1 (fr) 1981-07-22
EP0032343B1 true EP0032343B1 (fr) 1986-03-05

Family

ID=9237192

Family Applications (1)

Application Number Title Priority Date Filing Date
EP80401859A Expired EP0032343B1 (fr) 1980-01-02 1980-12-23 Procédé de brassage pneumatique d'un bain de métal en fusion

Country Status (8)

Country Link
US (1) US4382817A (OSRAM)
EP (1) EP0032343B1 (OSRAM)
JP (1) JPS56102689A (OSRAM)
AT (1) ATE18438T1 (OSRAM)
AU (1) AU535747B2 (OSRAM)
CA (1) CA1159653A (OSRAM)
DE (1) DE3071475D1 (OSRAM)
FR (1) FR2473064A1 (OSRAM)

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2501722B1 (fr) * 1981-03-11 1986-08-14 Siderurgie Fse Inst Rech Procede de brassage pneumatique d'un bain metallique
US4780133A (en) * 1986-11-10 1988-10-25 Lazcano Navarro Arturo Process to improve the refining of liquid metals by natural gas injection
SE8702338L (sv) * 1987-06-05 1988-12-06 Aga Ab Gasspolning av smaelta i skaenk
FR2632971B1 (fr) * 1988-06-17 1993-09-03 Vallourec Procede de traitement des aciers liquides par injection de gaz a travers le fond de poche
FR2635789B1 (fr) * 1988-08-29 1993-04-23 Air Liquide American Procede d'elaboration d'acier a faible teneur en azote dans un four poche
SE463876B (sv) * 1989-05-29 1991-02-04 Aga Ab Saett vid behandling av en smaelta med gas samt anordning foer saadan behandling
FR2807066B1 (fr) * 2000-03-29 2002-10-11 Usinor Procede de brassage pneumatique du metal liquide en poche
DE102009049896A1 (de) * 2009-01-22 2010-08-05 Sms Siemag Ag Impulsspülung mit Inertgas beim BOF- und AOD-Konverterprozess
CN111957251A (zh) * 2020-09-01 2020-11-20 云南锡业股份有限公司锡业分公司 一种液体金属搅拌装置及其使用方法

Family Cites Families (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1189971A (fr) * 1956-10-19 1959-10-08 Arbed Procédé de fabrication d'acier
BE609232A (fr) * 1961-10-16 1962-04-16 Centre Nat Rech Metall Perfectionnements aux procédés d'affinage de la fonte
GB1253581A (en) * 1968-02-24 1971-11-17 Maximilianshuette Eisenwerk Improvements in processes and apparatus for making steel
US4001009A (en) * 1969-04-03 1977-01-04 Hannsgeorg Bauer Process for the manufacture of steels with a high chromium content
BE752893A (fr) * 1969-07-08 1970-12-16 Forges De La Loire St Chamond Procede et dispositif de refroidissement d'une tuyere de convertisseur d'affinage
BE742079A (OSRAM) * 1969-11-21 1970-05-21
US3819165A (en) * 1972-12-08 1974-06-25 Maximilianshuette Eisenwerk Device for blowing-in oxygen through the refractory lining of a metallurgical converter
AT337736B (de) * 1973-02-12 1977-07-11 Voest Ag Verfahren zum frischen von roheisen
US3854932A (en) * 1973-06-18 1974-12-17 Allegheny Ludlum Ind Inc Process for production of stainless steel
FR2322202A1 (fr) * 1975-08-29 1977-03-25 Siderurgie Fse Inst Rech Procede d'elaboration d'acier par soufflage d'oxygene
JPS5810967B2 (ja) * 1976-06-01 1983-02-28 新日本製鐵株式会社 転炉の操業方法
US4174212A (en) * 1978-03-10 1979-11-13 A. Finkl & Sons Co. Method for the refining of steel

Also Published As

Publication number Publication date
FR2473064B1 (OSRAM) 1983-11-10
ATE18438T1 (de) 1986-03-15
CA1159653A (fr) 1984-01-03
EP0032343A1 (fr) 1981-07-22
AU535747B2 (en) 1984-04-05
JPS56102689A (en) 1981-08-17
US4382817A (en) 1983-05-10
AU6588480A (en) 1981-08-06
DE3071475D1 (en) 1986-04-10
FR2473064A1 (fr) 1981-07-10

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