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WO1979000700A1 - Procede pour reduire et traiter thermiquement du fer spongieux - Google Patents

Procede pour reduire et traiter thermiquement du fer spongieux Download PDF

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Publication number
WO1979000700A1
WO1979000700A1 PCT/EP1979/000012 EP7900012W WO7900700A1 WO 1979000700 A1 WO1979000700 A1 WO 1979000700A1 EP 7900012 W EP7900012 W EP 7900012W WO 7900700 A1 WO7900700 A1 WO 7900700A1
Authority
WO
WIPO (PCT)
Prior art keywords
iron
atmosphere
aftertreatment
sponge
sponge 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.)
Ceased
Application number
PCT/EP1979/000012
Other languages
German (de)
English (en)
Inventor
E Bjoerklund
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.)
SSAB AB
Original Assignee
SSAB Svenskt Stal 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
Publication date
Application filed by SSAB Svenskt Stal AB filed Critical SSAB Svenskt Stal AB
Publication of WO1979000700A1 publication Critical patent/WO1979000700A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B13/00—Making spongy iron or liquid steel, by direct processes
    • C21B13/0086—Conditioning, transformation of reduced iron ores

Definitions

  • the present invention relates to a process for post-treatment, in particular post-reduction and heat treatment, of sponge iron, in particular sponge iron produced by the Höganäs process or a similar process for direct steel production.
  • the sponge iron is obtained in the form of a tube with a chemical composition that mainly depends on the analysis of the iron ore silt used. Because during the reduction carbon is present, the temperature in the tunnel furnace and the residence time of the muffle in it determine how far the reduction goes and how high the carbon content in the sponge iron becomes. If the degree of reduction is greater than 95%, the carbon content is normally above 0.10%, the degree of reduction being defined as the ratio between metallic iron and the total amount of iron.
  • the sponge In the previous processes for producing iron powder from sponge iron, the sponge is cut up, ground and magnetically separated, after which various types of post-treatments, such as reduction and heat treatment, are carried out on the magnetically separated fraction. The fraction is then ground again and sieved.
  • the object of the present invention is the post-treatment, in particular post-reduction and heat treatment, of iron sponge without prior comminution.
  • the method according to the present invention is characterized in that the sponge iron is subjected to the post-treatment unbroken and / or in coarse fragments. This eliminates the grinding process and simpler material handling.
  • the aftertreatment is preferably carried out in a neutral atmosphere carried out.
  • This neutral atmosphere can be an inert gas atmosphere, in particular a nitrogen atmosphere and / or a slightly reducing atmosphere.
  • a nitrogen atmosphere which contains 1 to 101, in particular approximately 5%, hydrogen is preferably used as the aftertreatment atmosphere.
  • the aftertreatment according to the invention can be carried out at elevated temperatures, preferably at temperatures between approximately 700 ° C. and approximately 1200 ° C., in particular between approximately 800 ° C. and approximately
  • Sponge iron is preferably used, the proportion of metallic iron of which is greater than approximately 70% by weight, in particular greater than approximately 90% by weight and advantageously approximately 95% by weight.
  • the degree of reduction, i.e. the ratio of metallic Fe to the total amount of Fe can be increased.
  • the aftertreatment is advantageously carried out until the proportion of metallic iron reaches a value above approximately
  • the sponge iron heated during its manufacture in the rotary or tunnel furnace is not yet completely cooled, while avoiding oxidation during transfer. transferred into the aftertreatment atmosphere, since partial or complete reheating can then be omitted.
  • a generally tubular body made of sponge iron is obtained, for example, with an inside diameter of about 20 to 40 cm and a wall thickness of about 3 to 8 cm, in particular 5 to 6 cm and a length of about 2 m, for example.
  • the tubular sponge iron is heated to 800-1200 ° C., in particular without completely cooling and removing the residues of coke breeze and limestone, in a neutral, for example nitrogen or reducing atmosphere, so that the degree of reduction in iron is not reduced.
  • final reduction and heat treatment are obtained in one step during the aftertreatment according to the invention.
  • the warming time depends, among other things, on the composition of the sponge iron, the carbon content and the desired composition of the finished iron powder.
  • the heating in the aftertreatment according to the invention can take place both with gaseous, liquid or solid fuels and also with electrical energy, for example by electrical resistance heating by means of a heating element, electrical resistance heating by means of sponge iron as resistance or by induction heating of the iron sponge.
  • the carbon content in the sponge iron is used for post-reduction, which increases the degree of reduction of the sponge iron.
  • the heat treatment improves the state of free iron in the sponge iron in a manner similar to annealing, as is particularly advantageous when the sponge iron is used for powder metallurgical purposes.
  • the present invention enables the post-reduction and heat treatment of sponge iron without prior grinding, this can be necessary for powder production Crushing, grinding, magnetic separation and sieving can be carried out in direct succession after the treatment of the sponge iron.
  • the residues of coke breeze and limestone located on the sponge iron surface do not have to be removed, or only to the extent necessary for the access of the neutral or slightly reducing atmosphere to the sponge iron or the contacting of this atmosphere the sponge iron is required in the aftertreatment according to the invention.
  • the residues of coke breeze and limestone or the like, which are still present after the aftertreatment according to the invention, after cooling the iron sponge bodies or the fragments of the iron sponge bodies, can be removed from them in a conventional manner, e.g. mechanically.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Geology (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Abstract

Procede de post-traitement en particulier de post-reduction et de traitement thermique de fer spongieux applique en particulier a du fer spongieux prepare d'apres la methode de Hogana ou une methode analogue de preparation directe de l'acier dans lequel le fer spongieux en entier et/ou grossierement partage subit un post-traitement dans une atmosphere neutre et/ou reductrice, en particulier une atmosphere d'azote contenant de 1 a 10% d'oxygene.
PCT/EP1979/000012 1978-03-03 1979-03-02 Procede pour reduire et traiter thermiquement du fer spongieux Ceased WO1979000700A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE7802421A SE7802421L (sv) 1978-03-03 1978-03-03 Forfarande for efterreduktion och vermebehandling av jernsvamp
SE7802421 1978-03-03

Publications (1)

Publication Number Publication Date
WO1979000700A1 true WO1979000700A1 (fr) 1979-09-20

Family

ID=20334170

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP1979/000012 Ceased WO1979000700A1 (fr) 1978-03-03 1979-03-02 Procede pour reduire et traiter thermiquement du fer spongieux

Country Status (2)

Country Link
SE (1) SE7802421L (fr)
WO (1) WO1979000700A1 (fr)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2545932A (en) * 1948-05-26 1951-03-20 Allied Chem & Dye Corp Two-stage conversion of iron oxide into iron
DE1171623B (de) * 1961-11-24 1964-06-04 Huettenwerk Oberhausen Ag Verfahren zur Herstellung dichten, wenig poroesen oder porenfreien Eisenpulvers aus Eisenschwamm
US3414402A (en) * 1967-06-16 1968-12-03 Hydrocarbon Research Inc Beneficiation of low grade iron ores
GB1219674A (en) * 1968-10-07 1971-01-20 British Iron Steel Research Process for the production of iron powder from aman oxide
DE2343040A1 (de) * 1973-08-25 1975-03-13 Thyssen Niederrhein Ag Verfahren zur herstellung von eisenpulver

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2545932A (en) * 1948-05-26 1951-03-20 Allied Chem & Dye Corp Two-stage conversion of iron oxide into iron
DE1171623B (de) * 1961-11-24 1964-06-04 Huettenwerk Oberhausen Ag Verfahren zur Herstellung dichten, wenig poroesen oder porenfreien Eisenpulvers aus Eisenschwamm
US3414402A (en) * 1967-06-16 1968-12-03 Hydrocarbon Research Inc Beneficiation of low grade iron ores
GB1219674A (en) * 1968-10-07 1971-01-20 British Iron Steel Research Process for the production of iron powder from aman oxide
DE2343040A1 (de) * 1973-08-25 1975-03-13 Thyssen Niederrhein Ag Verfahren zur herstellung von eisenpulver

Also Published As

Publication number Publication date
SE7802421L (sv) 1979-09-04

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