Influence of CAO and Sio 2 on the reducibility of wüstite using H 2 and co gas

Wan Ho Kim, Young Seok Lee, In Kook Suh, Dong Joon Min

Research output: Contribution to journalArticle

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Abstract

CaO- (0-20 mass%) and SiO 2-containing (0-30 mass%) wüstite ('FeO') compacts were isothermally reduced at 1 273 K under CO and H 2 gas. Prior to reduction, the phase of dicalcium ferrite (Ca 2Fe 2O 5) and fayalite (Fe 2SiO 4) was equilibrated with 'FeO' at 1 273 K under 50%CO/50%CO 2 and identified using X-ray diffraction and scanning electron microscopy. The rate of reduction for CaO-containing 'FeO' compacts under both H 2 and CO increased up to the vicinity of 2.5 mass% CaO, and then decreased with higher CaO dependent on the formation of an intermediate phase of dicalcium ferrite. For SiO 2-containing 'FeO', the rate decreased with SiO 2 additions. When the dense fayalite is present reduction using CO was limited, while considerable reduction was observed using H 2. The reduction was affected by three distinct reduction mechanisms of interfacial chemical reaction, gaseous mass transport, solid state diffusion of oxygen or a combination of these individual mechanisms termed the mixed control. The contribution of each mechanism with the content of CaO or SiO 2 affecting the reduction behavior was determined. The compact porosity increased when CaO was added to approximately 2.5 mass% and subsequently decreased with higher CaO, but continuously decreased with SiO 2 additions. The ratio of the effective diffusivity (De) to molecular interdiffusivity (D) was highest at the vicinity of 2.5 mass% CaO and thus the maximum reduction rate was obtained when the porosity was highest.

Original languageEnglish
Pages (from-to)1463-1471
Number of pages9
JournalISIJ International
Volume52
Issue number8
DOIs
Publication statusPublished - 2012 Aug 30

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Gases
Carbon Monoxide
Ferrite
Porosity
Chemical reactions
Mass transfer
Oxygen
X ray diffraction
Scanning electron microscopy

All Science Journal Classification (ASJC) codes

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

Cite this

Kim, Wan Ho ; Lee, Young Seok ; Suh, In Kook ; Min, Dong Joon. / Influence of CAO and Sio 2 on the reducibility of wüstite using H 2 and co gas. In: ISIJ International. 2012 ; Vol. 52, No. 8. pp. 1463-1471.
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abstract = "CaO- (0-20 mass{\%}) and SiO 2-containing (0-30 mass{\%}) w{\"u}stite ('FeO') compacts were isothermally reduced at 1 273 K under CO and H 2 gas. Prior to reduction, the phase of dicalcium ferrite (Ca 2Fe 2O 5) and fayalite (Fe 2SiO 4) was equilibrated with 'FeO' at 1 273 K under 50{\%}CO/50{\%}CO 2 and identified using X-ray diffraction and scanning electron microscopy. The rate of reduction for CaO-containing 'FeO' compacts under both H 2 and CO increased up to the vicinity of 2.5 mass{\%} CaO, and then decreased with higher CaO dependent on the formation of an intermediate phase of dicalcium ferrite. For SiO 2-containing 'FeO', the rate decreased with SiO 2 additions. When the dense fayalite is present reduction using CO was limited, while considerable reduction was observed using H 2. The reduction was affected by three distinct reduction mechanisms of interfacial chemical reaction, gaseous mass transport, solid state diffusion of oxygen or a combination of these individual mechanisms termed the mixed control. The contribution of each mechanism with the content of CaO or SiO 2 affecting the reduction behavior was determined. The compact porosity increased when CaO was added to approximately 2.5 mass{\%} and subsequently decreased with higher CaO, but continuously decreased with SiO 2 additions. The ratio of the effective diffusivity (De) to molecular interdiffusivity (D) was highest at the vicinity of 2.5 mass{\%} CaO and thus the maximum reduction rate was obtained when the porosity was highest.",
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Influence of CAO and Sio 2 on the reducibility of wüstite using H 2 and co gas. / Kim, Wan Ho; Lee, Young Seok; Suh, In Kook; Min, Dong Joon.

In: ISIJ International, Vol. 52, No. 8, 30.08.2012, p. 1463-1471.

Research output: Contribution to journalArticle

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AB - CaO- (0-20 mass%) and SiO 2-containing (0-30 mass%) wüstite ('FeO') compacts were isothermally reduced at 1 273 K under CO and H 2 gas. Prior to reduction, the phase of dicalcium ferrite (Ca 2Fe 2O 5) and fayalite (Fe 2SiO 4) was equilibrated with 'FeO' at 1 273 K under 50%CO/50%CO 2 and identified using X-ray diffraction and scanning electron microscopy. The rate of reduction for CaO-containing 'FeO' compacts under both H 2 and CO increased up to the vicinity of 2.5 mass% CaO, and then decreased with higher CaO dependent on the formation of an intermediate phase of dicalcium ferrite. For SiO 2-containing 'FeO', the rate decreased with SiO 2 additions. When the dense fayalite is present reduction using CO was limited, while considerable reduction was observed using H 2. The reduction was affected by three distinct reduction mechanisms of interfacial chemical reaction, gaseous mass transport, solid state diffusion of oxygen or a combination of these individual mechanisms termed the mixed control. The contribution of each mechanism with the content of CaO or SiO 2 affecting the reduction behavior was determined. The compact porosity increased when CaO was added to approximately 2.5 mass% and subsequently decreased with higher CaO, but continuously decreased with SiO 2 additions. The ratio of the effective diffusivity (De) to molecular interdiffusivity (D) was highest at the vicinity of 2.5 mass% CaO and thus the maximum reduction rate was obtained when the porosity was highest.

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