US3376130A - Process for dephosphorization of pig iron particularly pig iron rich in phosphorus - Google Patents

Process for dephosphorization of pig iron particularly pig iron rich in phosphorus Download PDF

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Publication number
US3376130A
US3376130A US43666165A US3376130A US 3376130 A US3376130 A US 3376130A US 43666165 A US43666165 A US 43666165A US 3376130 A US3376130 A US 3376130A
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US
United States
Prior art keywords
slag
bath
phosphorus
pig iron
iron
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
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English (en)
Inventor
Kootz Theodor
Maas Heinz
Bengtsson Erik Axel
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.)
Stora Enso Oyj
Original Assignee
Stora Kopparbergs Bergslags AB
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
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Application filed by Stora Kopparbergs Bergslags AB filed Critical Stora Kopparbergs Bergslags AB
Application granted granted Critical
Publication of US3376130A publication Critical patent/US3376130A/en
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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
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/02—Dephosphorising or desulfurising
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • Steps used in these processes comprise maintaining a high basic slag, the addition of ores or slag fluxing means, limiting the temperature, control of the blast jet to a low velocity against the bath surface, providing an additional mechanical movement to the bath, addition of pulverized lime to the oxygen blast jet and others.
  • the refining of high phosphorus pig iron is carried out in a vessel which is stationary during the refining with oxygen being blown perpendicularly onto the bath surface and the oxygen usually contains ground lime.
  • a first phosphate slag is withdrawn when the percentage of carbon has been reduced to about 1%, at which time the percentage of phosphorus in the steels is in the range of 0.2%-O.3%.
  • the temperature must be far above 1500 C., as, for example, about 1600 C., in order to liquidize the highly basic slag.
  • These slags have a ratio of basicity, i.e., bases to acids, of at least 2.
  • the final slags which are preferably left in the refining vessel, are still more basic and usually have a ratio of basicity of 3 or more and their ferrous oxide content are high.
  • the decarburization reaction not only has to deliver the necessary heat, but in addition imparts a movement to the bath during decarburization by the gas evolved and thereby produces a thorough circulation.
  • the stirring exect of the decarburization reaction may not be necessary in principle to produce the dephosphorization reaction, in such methods where mechanical movement is imparted to the bath, as in a Kaldo furnace, it is always used.
  • Acid slag materials most suitable are SiO P 0 TiO A1 0
  • the process is particularly adapted for the refining of high phosphorus pig iron (above 1.5% P), such as pig iron for basic Bessemer. Furthermore it is necessary with this method to keep the temperature low, namely below 1500 C., preferably within the limits 1400 C. and 1450 C. This is not only because the dephosphorization will proceed better at so low a temperature, but also because at temperatures above 1500 C. such low basicity slags cannot be used in basic vessels as they tend to attack the lining and dissolve CaO and MgO therefrom.
  • This mechanical movement of the bath can be produced by impressing a rotary swinging movement upon the bath while contained in a vertical converter vessel, such as that resulting from an eccentric movement of the vessel about a vertical axis without rotation of the vessel about said axis.
  • Such a movement to the bath can also be produced by other rhythmic movement of the converter vessel in resonance with the swinging movement of the bath.
  • the process according to the invention also can be carried out in refining vessels classified as rotary either about a horizontal or inclined axis during the refining.
  • the required maximum temperature limit is maintained by adding cooling agents, such as scrap iron, before or during the refining.
  • the slag was maintained substantially constant during the entire course of blowing at 37%-39% CaO, 1%1.5% MgO, 6%-8% SiO 25%29% P 0 1%-2% A1 0 12%15% MnO, 8%-10% FeO.
  • the slag had low viscosity, and had a fine foam when the furnace was tilted, which collapsed quickly, did not retain any granules and could easily be removed.
  • a further surprising feature of this process was that the sulphur in the pig iron also was reduced by 50-60%, for instance, from 0.040% in the pig iron to 0.015- 0.020%, although slags which are acid from a metallurgical point of view do not take up very much sulphur. Also the content of nitrogen had decreased to below 0.002%.
  • the slag can be removed and a high percentage of very easily soluble phosphoric acid can be recovered which is a highly elfective fertilizer.
  • the pig iron is then decarburized in the usual way after repeated small additions of lime, preferably not more than 35 kg. lime per ton pig iron, until desired end percentage of carbon is attained. During this finishing refining the phosphorus percentage decreases to below 0.020%, the percentage of sulphur to about 0.010%, the percentage of nitrogen remaining unchanged below 0.002%, or decreasing further somewhat during the decarburization. It is cooled as required. The end slag obtained is preferably left in the converter for a subsequent heat.
  • a process for dephosphorizing a bath of moltenhigh phosphorus pig iron and producing slag having a high phosphorus content for use as a fertilizer comprising the steps of blowing oxygen onto the bath and a layer of slag floating on the top thereof, adding basic slag-forming material selected from the group consisting of calcium oxide, magnesium oxide, alkali metal oxide and mixtures thereof and acid slag forming material selected from the group consisting of silicon dioxide, titanium dioxide, aluminum oxide, phosphorus pentoxide and mixtures thereof, the proportions of said basic and acidic slag-forming materials being such during the entire blowing period as to maintain a ratio of basic to acidic materials in the slag in the range of 0.8 to 1.5 by weight, maintaining the bath at a temperature below 1500 C.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Carbon Steel Or Casting Steel Manufacturing (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
US43666165 1964-03-03 1965-03-02 Process for dephosphorization of pig iron particularly pig iron rich in phosphorus Expired - Lifetime US3376130A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE1964T0025740 DE1433649A1 (de) 1964-03-03 1964-03-03 Verfahren zum Entphosphoren von Roheisen,insbesondere Thomasroheisen

Publications (1)

Publication Number Publication Date
US3376130A true US3376130A (en) 1968-04-02

Family

ID=7552277

Family Applications (1)

Application Number Title Priority Date Filing Date
US43666165 Expired - Lifetime US3376130A (en) 1964-03-03 1965-03-02 Process for dephosphorization of pig iron particularly pig iron rich in phosphorus

Country Status (6)

Country Link
US (1) US3376130A (da)
BE (1) BE660381A (da)
DE (1) DE1433649A1 (da)
FR (1) FR1425195A (da)
GB (1) GB1097512A (da)
LU (1) LU48051A1 (da)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3473917A (en) * 1966-08-25 1969-10-21 Bot Brassert Oxygen Technik Ag Basic steelmaking process
EP0043238A1 (en) * 1980-06-28 1982-01-06 Kawasaki Steel Corporation Method of dephosphorizing molten pig iron
EP0170407A1 (en) * 1984-06-27 1986-02-05 The BOC Group, Inc. Agents for the removal of impurities from a molten metal and a process for producing same
JP2013181215A (ja) * 2012-03-01 2013-09-12 Jfe Steel Corp 溶銑吹錬処理の制御方法および制御装置
JP2013181216A (ja) * 2012-03-01 2013-09-12 Jfe Steel Corp 溶銑吹錬処理の制御方法および制御装置

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2391280A2 (fr) * 1977-05-17 1978-12-15 Sumitomo Metal Ind Procede de dephosphoration de la fonte liquide

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2668759A (en) * 1952-05-22 1954-02-09 Inland Steel Co Steelmaking process
US2671018A (en) * 1952-03-31 1954-03-02 Huettenwerk Oberhausen Ag Process for the production of basic bessemer steel low in nitrogen
US2693411A (en) * 1951-12-26 1954-11-02 Cremer Frederick Method of purifying molten pig iron
US2781256A (en) * 1953-11-23 1957-02-12 United States Steel Corp Process for the rapid removal of sulphur and silicon from pig iron
US2789046A (en) * 1955-02-01 1957-04-16 Mannesmann Ag Process of making steel from pig iron
GB817786A (en) * 1956-08-16 1959-08-06 Stora Kopparbergs Bergslags Ab Method of refining phosphorus-containing pig iron
GB946964A (en) * 1960-12-22 1964-01-15 Halbergerhuette Ges Mit Beschr Dephosphorization of melts of ferrous metals
US3136626A (en) * 1960-08-19 1964-06-09 Lorraine Laminage Method of refining cast-iron
US3172756A (en) * 1965-03-09 Process of dephosphorizing pig iron

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3172756A (en) * 1965-03-09 Process of dephosphorizing pig iron
US2693411A (en) * 1951-12-26 1954-11-02 Cremer Frederick Method of purifying molten pig iron
US2671018A (en) * 1952-03-31 1954-03-02 Huettenwerk Oberhausen Ag Process for the production of basic bessemer steel low in nitrogen
US2668759A (en) * 1952-05-22 1954-02-09 Inland Steel Co Steelmaking process
US2781256A (en) * 1953-11-23 1957-02-12 United States Steel Corp Process for the rapid removal of sulphur and silicon from pig iron
US2789046A (en) * 1955-02-01 1957-04-16 Mannesmann Ag Process of making steel from pig iron
GB817786A (en) * 1956-08-16 1959-08-06 Stora Kopparbergs Bergslags Ab Method of refining phosphorus-containing pig iron
US3136626A (en) * 1960-08-19 1964-06-09 Lorraine Laminage Method of refining cast-iron
GB946964A (en) * 1960-12-22 1964-01-15 Halbergerhuette Ges Mit Beschr Dephosphorization of melts of ferrous metals

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3473917A (en) * 1966-08-25 1969-10-21 Bot Brassert Oxygen Technik Ag Basic steelmaking process
EP0043238A1 (en) * 1980-06-28 1982-01-06 Kawasaki Steel Corporation Method of dephosphorizing molten pig iron
EP0170407A1 (en) * 1984-06-27 1986-02-05 The BOC Group, Inc. Agents for the removal of impurities from a molten metal and a process for producing same
JP2013181215A (ja) * 2012-03-01 2013-09-12 Jfe Steel Corp 溶銑吹錬処理の制御方法および制御装置
JP2013181216A (ja) * 2012-03-01 2013-09-12 Jfe Steel Corp 溶銑吹錬処理の制御方法および制御装置

Also Published As

Publication number Publication date
LU48051A1 (da) 1965-04-23
DE1433649A1 (de) 1969-05-14
GB1097512A (en) 1968-01-03
BE660381A (da) 1965-08-26
FR1425195A (fr) 1966-01-14

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