US3551140A - Controlled refining of pig iron - Google Patents

Controlled refining of pig iron Download PDF

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Publication number
US3551140A
US3551140A US3551140DA US3551140A US 3551140 A US3551140 A US 3551140A US 3551140D A US3551140D A US 3551140DA US 3551140 A US3551140 A US 3551140A
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United States
Prior art keywords
bath
slag
refining
penetration
pig iron
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English (en)
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Paul Emile Nilles
Etienne Marie Denis
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Centre de Recherches Metallurgiques CRM ASBL
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Centre de Recherches Metallurgiques CRM ASBL
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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
    • 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

  • the invention relates to a method for the dynamic control of the pig iron refining operation conducted in a solid bottom converter.
  • the general method of conducting a refining operation can be thought of in two complementary ways; on the one hand in a static way which starts from a precalculated theoretical amount of the elements necessary for entering into reaction or which should enter into reaction in the course of the refining operation being conducted, and on the other hand, in a dynamic way, by following as closely as possible the progress of the refining and guiding it as frequently as it appears to be desirable.
  • the static phase of the refining operation can be set out as follows:
  • Cooling additives such as scrap, ores and so on, of
  • the dynamic phase of the refining operation is the controlling of the steps of the operation to obtain at the end of the refining process a desired steel, having desired properties, while maintaining the various physical and chemico-physical reactions within the limits of a range which is considered to be correct.
  • This method has some disadvantages; in the first place it does not allow to intervene to a completely for the connection existing between the blowing conditions and the reactions which take place in the converter, and furthermore it is based on ideal graphs which are representative only of a portion of the reactions taking place in the converter. It follows from this that the corrective measures indicated by this method are often incomplete and sometimes inadequate.
  • the present invention has as its object a method for the dynamic control of the refining operation of pig iron making it possible to improve upon the incomplete and imprecise nature of the methods known theretofore. This method makes possible the control and regulation of the refining operation during its entire course.
  • the method forming the subject of the present invention is essentially characterized in that in accordance with a known method, and based preferably on theoretical bases, one determines the charge necessary to put into the furnace to carry out the required refining of a given pig iron, and in that, during the course of this refining operation, one automatically regulates the surfaces of penetration of the jet or jets of refining oxygen in such a way that the amount of carbon removed from the bath per unit of time follows a time-graph which is determined by prior calculation, and in that while maintaining the observance of this first condition, one also automatically reg- 3 ulates the blowing conditions in such a way that the amount of oxygen required per unit of time by the various constituents of the slag, also follows a time-graph determined by prior calculation.
  • the surface of penetration is a function of the amount of carbon escaping from the bath per unit of time and that the amount of O absorbed per unit of time by the various constituents of the slag, as well as the surface of penetration, is a function of the blowing conditions. It suflices accordingly, within the limits fixed by the operational conditions, to trace a curve or relationship which gives as a function of value of this surface of penetration the amount of carbon escaping from the bath as well as the curve or relationship which compares the blowing conditions to the amount of O
  • the principle of the present method consists in following these two graphs.
  • the operational conditions which influence the regulating characteristics of the surface of penetration there should be enumerated the capacity of the converter, its geometry, and the nature of the pig iron put into the furnace.
  • p Maximum penetration of the jet into the metallic bath on the axis of the jet. This depth of peneration represents the distance existing between the surface of the bath before injection and the lowest point of the surface of penetration (in metres).
  • A, B, C represents values which are a function of the parameters such as the temperature of the jet, the density of the oxygen, the density of the liquid and the distribution of rates in the jet of gas. These values A, B, C are known since the relations connecting the said values to the parameters are themselves well known. (II) The locality of the points of the jet for which the penetration p is lower than p is determined as a function of the radius r, representing the distance from the point considered to the axis of the jet.
  • p is replaced by p.
  • A is replaced by A, A having the value A.exp[ED(r/r') with an d.
  • the integration can be carried out by any known method.
  • the content in carbon of the molten bath is between 100% and of the initial carbon content of the pig iron.
  • blowing conditions which one can influence are the following:
  • apparatus For checking whether the rate of C removal from the bath is deviating from predetermined ideal conditions, apparatus is arranged by which it is possible in particular to take the following standard measurements:
  • the temperature of the converter fumes.
  • the content in oxygen of the converter fumes is the content in oxygen of the converter fumes.
  • the second condition imposed i.e. the amount if 0 absorbed by the slag at a particular time
  • the supply of O to the molten bath is modified in the sense desired.
  • the influence which the modifications of the rate of 0 could have had on the value of the surface of penetration is compensated.
  • the present method is able on the one hand to simultaneously regulate several values, each is a characteristic of an aspect of the state of progress of the refining process, which values are dependent on each other, and on the other hand the corrections which appear necessary are introduced in a permanent and automatic way, which rapidly reduces any deviation between theactual graph and the ideal graph.
  • a content in P of the steel corresponds at the temperature envisaged for the steel to each composition of slag calculated as a function of the Fe content of the slag.
  • a balance oxygen supplies the value of the volume of O necessary for the refining operation.
  • A varies from 260 to 130 imfi/min.
  • A0 remains constant at 180 mfi/min.
  • AC/At varies from 250 kg. to 160 kg./min.
  • A0 varies from 150 to 801m. /min.
  • AC/At remains constant at 120 kg./min.
  • A0 remains constant at 180 m. min.
  • AC/At varies from 180 to 50 kg./'min.
  • A0 varies from 250 to 400 m. min.
  • the graph AC/At is simply related to the depth of penetration of the O jet in the molten metal bath.
  • the attached figure shows as abscissae the duration of the refining in minutes, and as ordinates there are plotted (graph 1) the rate of decarbonisation in kg./min. and (graph II) the rate of 0 in mfi/min.
  • graph 1 the rate of decarbonisation in kg./min.
  • graph II the rate of 0 in mfi/min.
  • the two flat levels correspond to the injection of lime in each of the two phases; the interruption of these two graphs corresponds to the deslagging.
  • a method of controlling the refining of pig iron in a solid bottomconverter comprising the steps of:
  • step F automatically adjusting the actual quantity of O absorbed per unit of time by altering at least one of the parameters set forth in step F until the actual quantity of O coincides with the predetermined theoretical quantity per unit of time.
  • the weight of slag per metric ton of pig iron and the gross weight of lime per metric ton are calculated; the volume of required 0 necessary for refining is determined by calculating an oxygen balance; and the amount of pig iron to be used as Well as the cooling additives are calculated by solving a system of two equations with two unknowns, one representing the Fe balance and the other the thermal balance.
  • a method as claimed in claim 1 wherein for depths of penetration of the jet of 0 between 10% and of the height of the molten metal bath and for carbon content of the bath between and 15% of the initial carbon content of the pig iron, the adjusting of the surface of penetration is determined by a relation in which the surface of penetration of the jet is related to the amount of carbon removed from the bath per unit of time by a coefficient of proportionality K which is substantially constant.
  • a method as claimed in claim 1 wherein for depths of penetration of the jet of 0 between 10% and 75% of the height of the molten metal bath and for carbon content of the bath which is less than or equal to 15% of the initial carbon content of the pig iron, the adjustment of the surface of penetration is determined by a relation in which the surface of penetration of the jet is related to the amount of carbon removed from the bath per unit of time by a coefiicient of proportionality K decreasing substantially linearly from 1 to zero between the moment when the carbon content of the bath is 15% of the initial carbon content of the pig iron and when the carbon content of the bath corresponds to the final desired carbon content.

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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)
US3551140D 1966-10-11 1967-10-09 Controlled refining of pig iron Expired - Lifetime US3551140A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
LU52150A LU52150A1 (enrdf_load_stackoverflow) 1966-10-11 1966-10-11

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US3551140A true US3551140A (en) 1970-12-29

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US3551140D Expired - Lifetime US3551140A (en) 1966-10-11 1967-10-09 Controlled refining of pig iron

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US (1) US3551140A (enrdf_load_stackoverflow)
BE (1) BE704338A (enrdf_load_stackoverflow)
DE (1) DE1583228C2 (enrdf_load_stackoverflow)
FR (1) FR1548479A (enrdf_load_stackoverflow)
GB (1) GB1153938A (enrdf_load_stackoverflow)
LU (1) LU52150A1 (enrdf_load_stackoverflow)
NL (1) NL142453B (enrdf_load_stackoverflow)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3773497A (en) * 1972-03-02 1973-11-20 Steel Corp Steelmaking
US3871871A (en) * 1967-12-11 1975-03-18 Centre Nat Rech Metall Monitoring and control of pig iron refining
US4148629A (en) * 1976-08-04 1979-04-10 Vereinigte Osterreichische Eisen- Und Stahlwerk-Alpine Montan Aktiengesellschaft Process for controlling a steel refining process for steels having a carbon content within the range of 0.1 to 0.8 % by weight
US4474361A (en) * 1980-07-30 1984-10-02 Nippon Steel Corporation Oxygen-blown steelmaking furnace
US6228142B1 (en) * 1996-12-23 2001-05-08 Pohang Iron & Steel Co., Ltd. Apparatus for keeping optimal penetration depth formed at front end of oxygen tuyere and method for keeping the same

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113435037B (zh) * 2021-06-25 2022-08-26 马鞍山钢铁股份有限公司 一种判断300t转炉铸余冶炼前期倒渣时机的方法

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE753758C (de) * 1938-09-16 1952-07-21 Dortmund Hoerder Huettenver A Verfahren zur Beeinflussung des Schmelzverlaufes im Konverter
DE1433443B2 (de) * 1964-05-23 1972-01-27 Fried Krupp GmbH, 4300 Essen Verfahren zur ueberwachung und regelung der sauerstoffauf blasverfahren

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3871871A (en) * 1967-12-11 1975-03-18 Centre Nat Rech Metall Monitoring and control of pig iron refining
US3773497A (en) * 1972-03-02 1973-11-20 Steel Corp Steelmaking
US4148629A (en) * 1976-08-04 1979-04-10 Vereinigte Osterreichische Eisen- Und Stahlwerk-Alpine Montan Aktiengesellschaft Process for controlling a steel refining process for steels having a carbon content within the range of 0.1 to 0.8 % by weight
US4474361A (en) * 1980-07-30 1984-10-02 Nippon Steel Corporation Oxygen-blown steelmaking furnace
US6228142B1 (en) * 1996-12-23 2001-05-08 Pohang Iron & Steel Co., Ltd. Apparatus for keeping optimal penetration depth formed at front end of oxygen tuyere and method for keeping the same

Also Published As

Publication number Publication date
BE704338A (enrdf_load_stackoverflow) 1968-03-26
DE1583228C2 (de) 1975-01-09
NL142453B (nl) 1974-06-17
NL6713782A (enrdf_load_stackoverflow) 1968-04-16
GB1153938A (en) 1969-06-04
LU52150A1 (enrdf_load_stackoverflow) 1968-05-07
DE1583228B1 (de) 1974-05-30
FR1548479A (enrdf_load_stackoverflow) 1968-12-06

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