EP0031776B1 - Kombiniertes Blasverfahren zum Frischen von Metallen im Konverter - Google Patents

Kombiniertes Blasverfahren zum Frischen von Metallen im Konverter Download PDF

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Publication number
EP0031776B1
EP0031776B1 EP80401847A EP80401847A EP0031776B1 EP 0031776 B1 EP0031776 B1 EP 0031776B1 EP 80401847 A EP80401847 A EP 80401847A EP 80401847 A EP80401847 A EP 80401847A EP 0031776 B1 EP0031776 B1 EP 0031776B1
Authority
EP
European Patent Office
Prior art keywords
blowing
oxygen
flow
bottom upwards
blown
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
EP80401847A
Other languages
English (en)
French (fr)
Other versions
EP0031776A1 (de
Inventor
Pierre Leroy
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.)
Creusot Loire SA
Original Assignee
Creusot Loire SA
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
Priority claimed from FR7931990A external-priority patent/FR2472616A1/fr
Priority claimed from FR8003091A external-priority patent/FR2475574A2/fr
Application filed by Creusot Loire SA filed Critical Creusot Loire SA
Priority to AT80401847T priority Critical patent/ATE3445T1/de
Publication of EP0031776A1 publication Critical patent/EP0031776A1/de
Application granted granted Critical
Publication of EP0031776B1 publication Critical patent/EP0031776B1/de
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

Definitions

  • the present invention relates to a process for introducing refining gas and brewing gas into metal refining converters, and more particularly into steelworks converters.
  • the second type of pure oxygen blowing in a steelworks converter consists in using nozzles, vertical or oblique, arranged in the refractory bottom of the converter, blowing from bottom to top, and made up of at least two concentric tubes, the (or) inner tube blowing an oxidizing gas, which can be pure oxygen, the outer tube being traversed by a protective agent of the nozzle against its wear in service.
  • the object of the present invention is to produce a mixed blowing, simultaneously from above and from below, which, combining the advantages of blowing by lance and blowing by nozzles, also makes it possible to significantly improve the life of the bottoms to nozzles thus used in such a mixed blowing.
  • the subject of the present invention is a process for blowing oxidizing gases, and in particular pure oxygen, for refining metals, and. more specifically for the refining of cast iron in a converter, by means of a hand from a lance blowing from top to bottom, and simultaneously on the other hand by means of protected nozzles blowing, vertically or obliquely, bottom to top, characterized both in that the quantity of oxygen blown from bottom to top by the nozzles is between 3% and 25% of the total quantity of oxygen necessary for refining the metal bath, in this that this oxygen is blown from bottom to top at practically constant flow or decreasing flow, that is to say at non-increasing flow, in that one can add to this oxygen blown from bottom to top a stirring gas, neutral or oxidant, the flow rate of which varies according to the various stages of blowing and may even be zero at certain times, so that the total amount of oxygen blown from bottom to top by the nozzles remains between 3% and 25% of the total amount of oxygen necessary for
  • the brewing gas can be a neutral gas, such as nitrogen or argon, or a mixture of argon, that is to say, argon containing a little oxygen and not containing all other than trace gases.
  • This brewing gas can also be an oxidizing gas, such as carbon dioxide or water vapor, the dissociation products of which other than oxygen (carbon monoxide for the first, hydrogen for the second) cause an effect. bath brewing.
  • an oxidizing gas such as carbon dioxide or water vapor
  • the flow rate of oxygen blown through the nozzles is kept constant throughout the duration of the blowing.
  • the flow of oxygen blown through the nozzles is at a decreasing flow throughout the duration of the blowing or only from a certain time. It can also be decreasing first, and constant thereafter.
  • a stirring gas there is added to the oxygen blown by the nozzles a stirring gas, and this for two periods: a first period of a few minutes at the critical moment of the decarburization projections which may be located in the second quarter of high phosphorus cast iron conversion, and in the third quarter into hematite cast iron; and a second period, quite short, of one to three minutes, towards the end of the blowing, at low carbon contents, period during which the instantaneous rate of wear of the nozzles increases rapidly if one blows from the pure oxygen.
  • the flow rate of oxygen blown through the nozzles is adjusted decreasingly, it may be advisable to compensate for the decrease in the flow rate of oxygen by an equal increase in the flow rate of the mixing gas, so that the Total gas flow blown from the nozzles from bottom to top remains constant.
  • the jets of oxygen blown from bottom to top have a diameter at most equal to 18 mm, and preferably at most equal to 12 mm, at the outlet of the nozzles. It is understood that these nozzles are protected against wear in a known manner by a protective peripheral agent, such as a hydrocarbon gas, or fuel oil, or water vapor, or car dioxide. gaseous or liquid bone, etc.
  • a protective peripheral agent such as a hydrocarbon gas, or fuel oil, or water vapor, or car dioxide. gaseous or liquid bone, etc.
  • the nozzles usually used in the processes of integral blowing from the bottom have a passage diameter for oxygen generally between 28 mm and 36 mm.
  • the protective agent of the nozzles against wear possibly participates in the stirring of the bath but only to a small extent, because the flow rate of the protective agent is always very low compared to the flow rate of blown oxygen.
  • the total amount of oxygen blown from bottom to top by the nozzles is between 3% and 10% of the total amount of oxygen necessary for refining the metal bath.
  • the pulverulent materials, such as lime powder or limestone powder, to be introduced into the metal bath are introduced in suspension in the oxygen of the lance, and as the latter does not represents that a fraction of the total oxygen necessary for the complete refining of the metal bath, the concentration of pulverulent matters in oxygen can be notably higher than in the processes of integral blowing by lance, which contributes, by cooling the oxygen reaction zone of the lance in the bath, to reduce the quantity of red fumes due to this oxygen.
  • the flow rate of oxygen blown from bottom to top, and, optionally, the flow rate of additional stirring gas are regulated at each instant as a function of the oxidation state of the slag, evaluated either by an overall estimate from known elements, or by dosing of samples taken by a sublance, with measurement of the bath temperature, or by means of a device for measuring the intensity of the sound produced by the converter , in order to control at all times the difference in the balance between slag and metal bath.
  • the number and the diameter of the nozzles are calculated as a function of the flow rates envisaged for the oxygen blown from bottom to top, with or without stirring gas, and for a usual pressure for blowing from the bottom, the total passage section oxygen in all the nozzles is generally between the thirtieth and a quarter of the passage section necessary in the blowing processes integrated from bottom to top through the nozzles.
  • the oxygen blown through the nozzles must represent 20% of the total oxygen, or 1/5
  • the protected nozzles blow 20% of the total oxygen required, or 13 Nm3 per ton of pig iron.
  • the red smoke is reduced ⁇ but not suppressed ⁇ due to this relatively high concentration of powder and also the use of castine powder.
  • Protected nozzles blowing 7% of total oxygen i.e. 4 Nm3 per ton of pig iron. They have a passage diameter for oxygen of 11 millimeters and are three in number. At a pressure of 10 8 effective Pascals, they are capable of a gas flow of 6.7 Nm3 / min per nozzle, or 20 Nm3 / min for the 3 nozzles.
  • This oxygen is accompanied by:
  • Red fumes are reduced, but to a lesser extent than in the previous example, because, on the one hand, the proportion of oxygen blown by the lance is higher than in the previous example, and d 'on the other hand it is a hematita cast iron, which requires less lime for its refining.
  • the joint effects of the small diameter of the nozzles, of the decrease in the oxygen flow rate per nozzle compared to a normal blast nozzle at the bottom, of the decrease in the oxygen flow rate at the end of blowing, and of the final addition of the stirring gas, during the period of greatest wear of the nozzles means that the behavior of the nozzles and of the bottoms is much improved compared to that of the nozzles and of the bottoms of processes with integral blowing from the bottom.
  • the improvement is also notable compared to known mixed processes.
  • a final advantage of the mixed blowing according to the invention can manifest itself in many cases, at the beginning of the blowing.
  • priming the oxygen jet of the lance, on the surface of a more or less frozen metal bath, more or less charged with scrap, lime, etc. is difficult.
  • the initiation of refining reactions by oxygen from the nozzles is always instantaneous.
  • a particular characteristic of the mixed blowing according to the invention consists in starting the blowing for a few seconds only with the oxygen from the nozzles blowing from bottom to top, regulated at a high flow rate, for example at the maximum of the oxygen pressure available , and then to introduce the oxygen from the lance, while then bringing the oxygen from the nozzles to its normal operating rate.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Carbon Steel Or Casting Steel Manufacturing (AREA)

Claims (11)

1. Blasverfahren mit oxydierenden Gasen, insbesondere reinem Sauerstoff, zum Frischen von Metallen, insbesondere zum Frischen von - Stahlschmelze, in einem Konverter, mittels einerseits einer Lanze, die von oben nach unten bläst, und anderseits geschützten Düsen, die vertikal oder schräg von unten nach oben blasen, dadurch gekennzeichnet, daß gleichzeitig die von den Düsen von unten nach oben eingeblasene Sauerstoffmenge 3-25% der gasamten, zum Frischen des Metallbades erforderlichen Sauerstoffmenge beträgt, daß dieser Sauerstoff von unten nach oben in einer nicht ansteigenden Menge eingeblasen wird, daß diesem von unten nach oben eingeblasenen Sauerstoff zu bestimmten Zeitpunkten des Blasvorgangs ein neutrales oder oxydierendes Rührgas so zugesetzt wird, daß die gesamte, durch die Düsen von unten nach oben eingeblasene Sauerstoffmenge zwischen 3-25% der gesamten, zum Frischen des Metallbades erforderlichen Sauerstoffmenge verbleibt und die gesamte, durch die Düsen eingeblasene Sauerstoffmenge nicht ansteigt, und daß die von unten nach oben engeblasenen, gegebenenfalls mit einem Rührgas versetzten Sauerstoffstrahlen einen Durchmesser von höchstens 18 mm gemessen am Auslaß der Düsen aufweisen.
2. Blasverfahren nach Anspruch 1, dadurch gekennzeichnet, daß die durch die Düsen von unten nach oben eingeblasene Sauerstoffmenge während des gesamten Blasvorgangs konstant gehalten wird.
3. Blasverfahren nach Anspruch 1, dadurch gekennzeichnet, daß die durch die Düsen von unten nach oben eingeblasene Sauerstoffmenge während des desamten Blasvorgangs abnehmend geregelt wird.
4. Blasverfahren nach Anspruch 1, dadurch gekenzeichnet, daß die durch die Düsen von unten nach oben eingeblasene Sauerstoffmenge während der ersten Phase des Blasvorgangs konstant gehalten und während der zweiten Phase des Blasvorgangs abnehmend geregelt wird, oder umgekehrt.
5. Blasverfahren nach einem der Ansprüche 1-4, dadurch gekennzeichnet, daß das Rührgas dem durch die Düsen von unten nach oben eingeblasenen Sauerstoff während zweier bestimmter Perioden zugemischt wird: einer ersten Periode im kritischen Augenblick des Auswurfs (Kochen) bei der Entkohlung, einer zweiten Periode gegen Ende des Blasvorgangs.
6. Blasverfahren nach Anspruch 5, dadurch gekennzeichnet, daß die Rührgasmenge während der zweiten Periode gegen Ende der Umwandlung ansteigt.
7. Blasverfahren nach Anspruch 3 oder 4, dadurch gekennzeichnet, daß gegen Ende des Blasvorgangs das Ansteigen der Rührgasmenge so geregelt wird, daß dadurch genau die Verringerung der von unten nach oben eingeblasenen Sauerstoffmenge kompensiert wird, sodaß die Gesamtmenge konstant bleibt.
8. Blasverfahren nach einem der Ansprüche 1-7, dadurch gekennzeichnet, daß die gegebenenfalls mit einem Rührgas vermischten, von unten nach oben eingeblasenen Sausrstoffstrahlen einen Durchmesser von höchstens 12 mm, gemessen am Auslaß der Düsen, aufweisen.
9. Blasverfahren nach Anspruch 8, dadurch gekennzeichnet, daß die Gesamtmenge an durch die Düsen von unten nach oben eingeblasenem Sauerstoff 3-1096 der Gesamtmenge an Sauerstoff beträgt, die zum Frischen des Metallbades erforderlich ist.
10. Blasverfahren nach einem der Ansprüche 1-9, dadurch gekennzeichnet, daß die von unten nach oben eingeblasene Sauerstoffmenge und gegebenenfalls die zusätzliche Menge an Rührgas zu jedem Zeitpunkt in Abhängigkeit vom Oxydationszustand der Schlacke geregelt wird, um zu jedem Zeitpunkt die Abweichung vom Gleichgewicht zwischen Schlacke und Metallbad unter Kontrolle halten zu können.
11. Blasverfahren nach einem der Ansprüche 1-10, dadurch gekennzeichnet, daß zu Beginn des Blasvorgangs einige Sekunden lang nur Sauerstoff in großen Mengen durch die Düsen von unten nach oben eingeblasen wird, daß darauf der Sauerstoff durch die Lanze zugeführt wird und daß bald darauf die durch die Düsen eingeblasene Sauerstoffmenge auf ihren normalen Wert eingestellt wird.
EP80401847A 1979-12-28 1980-12-23 Kombiniertes Blasverfahren zum Frischen von Metallen im Konverter Expired EP0031776B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT80401847T ATE3445T1 (de) 1979-12-28 1980-12-23 Kombiniertes blasverfahren zum frischen von metallen im konverter.

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
FR7931990A FR2472616A1 (fr) 1979-12-28 1979-12-28 Procede de soufflage mixte pour l'affinage des metaux au convertisseur
FR7931990 1979-12-28
FR8003091A FR2475574A2 (fr) 1980-02-12 1980-02-12 Procede de soufflage mixte pour l'affinage de la fonte acier au convertisseur " d'acierie "
FR8003091 1980-02-12

Publications (2)

Publication Number Publication Date
EP0031776A1 EP0031776A1 (de) 1981-07-08
EP0031776B1 true EP0031776B1 (de) 1983-05-18

Family

ID=26221519

Family Applications (1)

Application Number Title Priority Date Filing Date
EP80401847A Expired EP0031776B1 (de) 1979-12-28 1980-12-23 Kombiniertes Blasverfahren zum Frischen von Metallen im Konverter

Country Status (7)

Country Link
US (1) US4328031A (de)
EP (1) EP0031776B1 (de)
AU (1) AU541719B2 (de)
BR (1) BR8007499A (de)
CA (1) CA1157658A (de)
DD (1) DD154026A5 (de)
DE (1) DE3063382D1 (de)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4599107A (en) * 1985-05-20 1986-07-08 Union Carbide Corporation Method for controlling secondary top-blown oxygen in subsurface pneumatic steel refining

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1151053A (fr) * 1956-05-29 1958-01-23 Procédé de conversion de fonte en acier
FR1344238A (fr) * 1962-04-16 1963-11-29 Cie Des Ateliers & Forges De L Procédé et dispositifs d'élaboration de l'acier
FR1478478A (fr) * 1966-03-03 1967-04-28 Loire Atel Forges Fond de convertisseur d'aciérie et procédé d'élaboration de l'acier mettant en oeuvre un tel fond
FR2217422A1 (de) * 1973-02-12 1974-09-06 Voest Ag
FR2322202A1 (fr) * 1975-08-29 1977-03-25 Siderurgie Fse Inst Rech Procede d'elaboration d'acier par soufflage d'oxygene

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2158140A1 (en) * 1971-11-05 1973-06-15 Creusot Loire Steel making - by top and bottom blowing oxygen with a fluid contg hydrocarbons
US3854932A (en) * 1973-06-18 1974-12-17 Allegheny Ludlum Ind Inc Process for production of stainless steel
GB1586762A (en) * 1976-05-28 1981-03-25 British Steel Corp Metal refining method and apparatus
DE2737832C3 (de) * 1977-08-22 1980-05-22 Fried. Krupp Huettenwerke Ag, 4630 Bochum Verwendung von im Querschnitt veränderlichen Blasdüsen zur Herstellung von rostfreien Stählen

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1151053A (fr) * 1956-05-29 1958-01-23 Procédé de conversion de fonte en acier
FR1344238A (fr) * 1962-04-16 1963-11-29 Cie Des Ateliers & Forges De L Procédé et dispositifs d'élaboration de l'acier
FR1478478A (fr) * 1966-03-03 1967-04-28 Loire Atel Forges Fond de convertisseur d'aciérie et procédé d'élaboration de l'acier mettant en oeuvre un tel fond
FR2217422A1 (de) * 1973-02-12 1974-09-06 Voest Ag
FR2322202A1 (fr) * 1975-08-29 1977-03-25 Siderurgie Fse Inst Rech Procede d'elaboration d'acier par soufflage d'oxygene

Also Published As

Publication number Publication date
BR8007499A (pt) 1981-06-30
DE3063382D1 (en) 1983-07-07
EP0031776A1 (de) 1981-07-08
AU541719B2 (en) 1985-01-17
AU6538480A (en) 1981-07-02
US4328031A (en) 1982-05-04
DD154026A5 (de) 1982-02-17
CA1157658A (fr) 1983-11-29

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