Titre du document / Document title

Microstructural investigation of the formation of the calcioferrites

Auteur(s) / Author(s)

DURAK J. ⁽¹⁾ ; MADIGOU V. ⁽²⁾ ; CESARI C. ⁽²⁾ ; JASIENSKA S. ⁽¹⁾ ; NIHOUL G. ⁽²⁾ ; OREWCZYK J. ⁽¹⁾ ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

⁽¹⁾ Zakład Inżynierii i Analiz Materiałów, WMilM, al. Mickiewicza 30, 30-059 Kraków, POLOGNE
⁽²⁾ Laboratory MMI, University of Toulon, BP 132, 83957 La Garde, FRANCE

Résumé / Abstract

The production process of steel is essentially governed by the reduction of iron oxides in blast furnace. However, during this main operation, formation of others phases like ferrites occurs due to the presence of impurities (Ca, Mn, Mg ...). These compounds have a non negligible influence on the control of the reduction mechanism. The aim of this study is to characterize and localize which type of calcioferrite appears during the reduction of calciomagnetite. The samples were obtained from a mixture of Fe₃O₄ and CaO which was sintered during 3 hours at 1100°C (1). The chemical formula of the materials is Fe_3-xCa_xO₄ with 0.04≤x≤0,16. The temperature of the reduction process increased of 6°/mn and was maintained at 1200°C during 2 hours in different CO/CO₂ gas flows. In a first step, we have examined the initial material Fe_3-xCa_xO₄ which has a spinel structure with a partial substitution of Fe³⁺ by Ca²⁺ on the tetrahedral sites (in the operating conditions, the limit of the solubility of Ca²⁺ in the magnetite is about x = 0.11). During the reduction mechanism, depending on the experimental conditions, Fe₃O₄transforms in Fe_1-x-yCa_yO and Fe can be seen on the SEM images. During first step of the reduction process the formation of the wustite with a network of pores was observed. In the second step, the formation of ferrite takes place because the solubility of Ca²⁺ in iron is less than in wüstite and magnetite. The type of the calcioferrite varies the local concentration of Ca²⁺. Presents of calcioferrites is mainly an effect of the reduction of the claciomagnetite to iron, but some part is also due to reduction processes occurring in separately precipitated ferrites phases.

Revue / Journal Title

Archives of metallurgy   ISSN 0860-7052   CODEN ARMEER 

Source / Source

1998, vol. 43, n^o1, pp. 45-51 (8 ref.)

Langue / Language

Anglais

Editeur / Publisher

Polish Scientific Publishers, Warszawa, POLOGNE  (1987) (Revue)

Mots-clés anglais / English Keywords

Microstructure ; Ferrite ; Steel ; Iron oxide ; Blast furnace performance ; Chemical reduction ; Blast furnace ; Reaction mechanism ; Calcium oxide ; Scanning electron microscopy ; Experimental study ; Pig iron manufacture ;

Mots-clés français / French Keywords

Microstructure ; Ferrite ; Acier ; Fer oxyde ; Marche haut fourneau ; Réduction chimique ; Haut fourneau ; Mécanisme réaction ; Calcium oxyde ; Microscopie électronique balayage ; Etude expérimentale ; Elaboration fonte ;

Mots-clés espagnols / Spanish Keywords

Microestructura ; Ferrita ; Acero ; Hierro óxido ; Funcionamiento alto horno ; Reducción química ; Alto horno ; Mecanismo reacción ; Calcio óxido ; Microscopía electrónica barrido ; Estudio experimental ; Elaboración fundición ;

Localisation / Location

INIST-CNRS, Cote INIST : 8643, 35400007544191.0040