Silico-ferrite of Calcium and Aluminum (SFCA) Iron Ore Sinter Bonding Phases: New Insights into Their Formation During Heating and Cooling

Webster, Nathan A. S.; Pownceby, Mark I.; Madsen, Ian C.; Kimpton, Justin A.

doi:10.1007/s11663-012-9740-5

Cited by 165 publications

(183 citation statements)

References 27 publications

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“…hematite. This is qualitatively in agreement with the thermodynamic modeling and with the findings of Webster et al 5 .…”

Section: Phase Characterizationsupporting

confidence: 93%

“…This is a strong indication that the SFCA phases form during cooling of the sinter bed, after the formation of magnetite. This is confirmation of the findings of Webster et al 5 who found that SFCA forms after melting and magnetite crystallization. However, no evidence could be found for the solid state formation of SFCA species during heating below the melting temperature, but this could be due to the sharp temperature gradient between samples 5 and 6; significant melting has already started in sample 5 with 36% melt.…”

Section: Phase Quantificationsupporting

confidence: 92%

“…The SFCA phases are not stable in the presence of melt; this was conclusively shown by Webster et al 5 . This is confirmed by this study, as can be seen in Table 2, and in Figure 5.…”

Section: Phase Characterizationmentioning

confidence: 63%

“…This is probably due to the absence of thermodynamic data for the SFCA phases. Nevertheless CaFe 2 O 4 was reported as an intermediate phase (event 5) by Webster et al 5 .…”

Section: Liquid Compositionmentioning

confidence: 97%

“…To evaluate the reactions taking place during sintering, fine-grained synthetic mixtures were examined by in situ high-temperature X-ray diffraction in air and at slightly reducing conditions 4,5,6 using laboratory and synchrotron sources. These studies, although not quite representing actual sintering conditions, are valuable in that they established the temperature conditions where the major phases magnetite, hematite and the silico-ferrite binding phases, SFCA (silico ferrite of calcium and aluminium)and SFCA-I, form.…”

Section: Introductionmentioning

confidence: 99%

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Variation of the redox conditions and the resultant phase assemblages during iron ore sintering

Berg

Villiers

Cromarty

2016

International Journal of Mineral Processing

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Highlights• The oxygen potential in a sinter bed is measured by a zirconia oxygen probe to be ~ 0.01 atm.• This oxygen potential in the sinter is appreciably more oxidizing than previous estimates.• The contents of a quenched sinter pot show that at the flame front, only magnetite and slag are present.• SFCA phases only form to a limited extent at the top of the quenched bed.• Thermodynamic modeling at a pO 2 of 0.01 atm is in qualitative agreement with the phase analysis of the sinter pot. AbstractThe oxygen potential prevailing during iron ore sintering was measured with a zirconia sensor in a series of sinter pot experiments. This was done to get a better indication of the redox conditions during commercial sintering. It was found that the pO 2 is appreciably more oxidizing than previously assumed, with a minimum value of ~0.01 atm. It is concluded that this value represents the oxygen potential of the gas phase and it is therefore a mixture of combustion gas and downdraft air. The contents of a quenched sinter pot where the reactions were interrupted with the flame front situated midway through the sinter bed were investigated. X-ray diffraction analysis, using an internal standard to quantify the amorphous slag phase, revealed that at the flame front only magnetite and slag was present. SFCA phases only formed at the top of the bed after the flame front had passed. Thermodynamic modeling of the phases at equilibrium agree qualitatively with the phase analysis and explained the extensive presence of magnetite and melt, as well as the formation of calcium ferrite phases during cooling below 1100°C.

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