US3898077A - Process for refining metal melts - Google Patents

Process for refining metal melts Download PDF

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Publication number
US3898077A
US3898077A US321107A US32110773A US3898077A US 3898077 A US3898077 A US 3898077A US 321107 A US321107 A US 321107A US 32110773 A US32110773 A US 32110773A US 3898077 A US3898077 A US 3898077A
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US
United States
Prior art keywords
oxygen
melt
blown
stream
tuyeres
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 - Lifetime
Application number
US321107A
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English (en)
Inventor
Helmut Knuppel
Karl Brotzmann
Hans Georg Fassbinder
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.)
Eisenwerke Gesellschaf Maximilianshuette mbH
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Eisenwerke Gesellschaf Maximilianshuette mbH
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Filing date
Publication date
Priority claimed from DE19722200413 external-priority patent/DE2200413C3/de
Application filed by Eisenwerke Gesellschaf Maximilianshuette mbH filed Critical Eisenwerke Gesellschaf Maximilianshuette mbH
Application granted granted Critical
Publication of US3898077A publication Critical patent/US3898077A/en
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    • 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
    • C21C5/34—Blowing through the bath

Definitions

  • This invention relates to a process for the refining of metal melts, and particularly to the refining of pig iron to produce steel, by a process in which oxidizing gases, preferably pure oxygen, are surrounded by a liquid or gaseous protective medium and blown upon the metal bath.
  • the refining gas supply tuyeres usually consist of two concentric tubes, the refining gas being supplied through the central tube and the liquid or gaseous protective medium being made to pass through the annular spacing between the two tubes, and these tuyeres are inserted through the refractory masonry into the refining vessel, without requiring cooling by means of a circulatory cooling system.
  • the top oxygen blowing process does suffer from technical drawbacks. Among these are the following:
  • the high temperature at the focus of the oxygen lance produces increased iron evaporation and contamination of product as well asundesired formation of brown smoke and increased iron content in the slag.
  • Gaseous and/or liquid hydrocarbons are preferably used as the protective media.
  • crude benzol, propane, butane. natural gas or coke oven gas have been used.
  • the amounts of protective media with respect to the refining oxygen are relatively small and may amount to 7% .in volume when natural gas is used and 3% in volume when propane is used.
  • the protective medium prevents premature backburning of the tuyeres and an even burn-off of tuyeres and of the surrounding refractory masonry is achieved.
  • those tuyere pipes transmitting only oxygen burn back in funnel-shape very quickly and may cause converter breakdown during refining of a single melt. This has prevented industrial application of pure oxygen refining, without protective media..Oxygen used together with a properly metered amount of protective medium will cause an average wear in the tuyeres and in the refractory material of about 3 mm/melt.
  • the customary total time of refining is about 10 minutes. In order to supply during this time the required amount of about 1,200 n /min. STP of oxygen for a 200 ton converter, approximately 20 tuyeres with the indicated ,diameters of about 30 mm will be required.
  • the present invention is directed to the provision of a process for the refining of metal melts which will combine the advantages of the known refining processes in which oxygen is blown by means of a watercooled lance on the metal bath with the known refining process in which oxygen is introduced into a converter below the bath surface, in such manner that a new process will be obtained that does not suffer from the drawbacks of either of these known oxygen refining processes;
  • tuyeres for the supply of oxygen and protective medium are installed above the bath surface in the refractory lining of the converter mantle. It has been surprisingly discovered that tuyere-assemblies such as those which are being used for introducing oxygen and protective media underneath the bath surface when installed above the bath surface in the converter mantle masonry will burn back evenly together with the masonry and not, as had been expected on account of experience, at a rate approximately twice the rate of wear of the masonry in the tuyere region.
  • the arrangement of the tuyeres in the converter mantle may be effected at any height above the bath level. However the range from about to 100 cm above the bath surface was found to be particularly advantageous in practice.
  • the inclination angle of the tuyeres as measured from the horizontal tuyere position in the direction of the bath surface may also fluctuate within limits, the range from 10 to 60 having been found to be suitable.
  • the inclination angle of the tuyeres should be increased as their height above the bath surface increases.
  • tuyeres have been mounted at several different heights above the bath surface.
  • a preferred arrangement utilizes tuyeres located in two tuyere planes. First the tuyeres in the more elevated plane with respect to the bath surface are utilized in a new converter, and after approximately halfa campaign, the tuyeres in the lower-lying plane are utilized. The tuyere supply holes in the masonry that are not being used were plugged with refractory tamping clay or similar substances.
  • the bath level in the converter decreases appreciably as the wear of the refractory masonry increases while the metal charge remains the same, and this procedure with two planes of tuyeres provides the advantage of blowing oxygen from nearly the same height onto the melt during the entire converter campaign.
  • a further measure for improving blowing consists in loading the oxygen stream with fine-grained slagforming agents, in particular with lime.
  • fine-grained slagforming agents in particular with lime.
  • the use of a lime-loaded oxygen stream makes it possible to refine for instance a pig iron melt to steel in about 10 minutes without any kind of ejection.
  • Loading the oxygen stream with lime dust has proved particularly useful when refining lowphosphorus pig iron.
  • the lime dust loading should be varied during the entire refining period.
  • the sense of the invention further includes operating the tuyeres for introduction of oxygen with protective media not only in refining veessels such as the various types of steel-making converters, but also in the refining by means of metallurgical furnaces such as electric and Simens-Martin furnaces.
  • the process of the invention has been applied to pre-refining and to post-refining in transportation vessels for metal melts with good results.
  • the invention has been successfully applied to continuous steel making. In this installation the tuyeres were obliquely arranged in a groove-like furnace in order to stir the metal melt evenly.
  • the protective fluids which have been used in the practice of the present invention include those described in US. Pat. No. 3,706,549 and German Auslegeschriften Nos. 1,583,960 and 1,758,616 noted above.
  • Particularly preferred fluids are hydrocarbons, especially straight chain alkanes with fewer than five carbon atoms in the chain, e.g., methane (natural gas) or propane.
  • a process for refining metal melts in a refractory vessel which comprises:

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
  • Carbon Steel Or Casting Steel Manufacturing (AREA)
US321107A 1972-01-05 1973-01-04 Process for refining metal melts Expired - Lifetime US3898077A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19722200413 DE2200413C3 (de) 1972-01-05 Frischgefäß

Publications (1)

Publication Number Publication Date
US3898077A true US3898077A (en) 1975-08-05

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ID=5832394

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US321107A Expired - Lifetime US3898077A (en) 1972-01-05 1973-01-04 Process for refining metal melts

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US (1) US3898077A (OSRAM)
JP (1) JPS5213488B2 (OSRAM)
FR (1) FR2167713B1 (OSRAM)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4065298A (en) * 1974-12-28 1977-12-27 Nippon Kokan Kabushiki Kaisha Steel making process by oxygen top-blown converter

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2817584A (en) * 1954-05-25 1957-12-24 August Thyssen Hutte Ag And Do Method for refining pig iron
US2918365A (en) * 1953-08-10 1959-12-22 Yawata Seitetsu K K Method for controlling compositions of molten pig iron and slag in a blast furnace
US2962277A (en) * 1958-05-15 1960-11-29 Gen Electric Apparatus for continuous process of steel making
US2991173A (en) * 1959-02-27 1961-07-04 Siderurgie Fse Inst Rech Metal refining method and apparatus
US3212882A (en) * 1962-03-14 1965-10-19 Garfinkle Marvin Method and apparatus for oxygen steelmaking
US3459867A (en) * 1967-08-10 1969-08-05 Air Reduction Direct arc furnace
US3706549A (en) * 1968-02-24 1972-12-19 Maximilianshuette Eisenwerk Method for refining pig-iron into steel

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1194741A (fr) * 1957-04-18 1959-11-12 Procédé et dispositif pour l'exécution d'opérations métallurgiques, en particulier par affinage au vent
FR1231179A (fr) * 1959-04-09 1960-09-27 Procédé et dispositif d'affinage de la fonte

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2918365A (en) * 1953-08-10 1959-12-22 Yawata Seitetsu K K Method for controlling compositions of molten pig iron and slag in a blast furnace
US2817584A (en) * 1954-05-25 1957-12-24 August Thyssen Hutte Ag And Do Method for refining pig iron
US2962277A (en) * 1958-05-15 1960-11-29 Gen Electric Apparatus for continuous process of steel making
US2991173A (en) * 1959-02-27 1961-07-04 Siderurgie Fse Inst Rech Metal refining method and apparatus
US3212882A (en) * 1962-03-14 1965-10-19 Garfinkle Marvin Method and apparatus for oxygen steelmaking
US3459867A (en) * 1967-08-10 1969-08-05 Air Reduction Direct arc furnace
US3706549A (en) * 1968-02-24 1972-12-19 Maximilianshuette Eisenwerk Method for refining pig-iron into steel

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4065298A (en) * 1974-12-28 1977-12-27 Nippon Kokan Kabushiki Kaisha Steel making process by oxygen top-blown converter

Also Published As

Publication number Publication date
DE2200413A1 (de) 1973-07-26
DE2200413B2 (de) 1977-03-17
JPS48103413A (OSRAM) 1973-12-25
FR2167713B1 (OSRAM) 1976-04-30
FR2167713A1 (OSRAM) 1973-08-24
JPS5213488B2 (OSRAM) 1977-04-14

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