Controlled Solidification of Liquids Within the SFC Primary Phase Field of the “Fe{sub 2}O{sub 3}”-CaO-SiO{sub 2} System in Air

Journal Article · Sun Dec 15 04:00:00 EST 2019 · Metallurgical and Materials Transactions. B, Process Metallurgy and Materials Processing Science

DOI:https://doi.org/10.1007/S11663-019-01689-8· OSTI ID:22933418

Jak, E.; Hayes, P. C. ^[1]

---

1. The University of Queensland, Pyrometallurgy Innovation Centre (PYROSEARCH), School of Chemical Engineering (Australia)

To provide fundamental information on the phases and microstructures formed during sintering, a liquid with a bulk composition within the silico ferrite of calcium (SFC) primary phase field in the ternary “Fe{sub 2}O{sub 3}”-CaO-SiO{sub 2} system in air was solidified at a controlled rate. Samples of a bulk composition with a CaO/SiO{sub 2} ratio of 4.00 and 69.24 wt pct Fe{sub 2}O{sub 3}, were cooled from 1623 K (1350 °C) at 2 K/s, with samples quenched at temperatures between 1513 K (1240 °C) to 1453 K (1180 °C). The silico ferrite of calcium and aluminium I (SFCA-I) and Ca{sub 7.2}Fe{sub 0.8}{sup 2+}Fe{sub 30}{sup 3+}O{sub 53} phases were observed to form an intergrowth (‘SFC-I’) rather than the anticipated SFC phase. Solidification was found to occur in three stages, Liquid + ‘SFC-I’, Liquid + ‘SFC-I’ + C{sub 2}S + CF{sub 2}, and C{sub 2}S + CF{sub 2} + CF, where C{sub 2}S denotes dicalcium silicate, CF denotes calcium ferrite and CF{sub 2} denotes calcium diferrite. The phases formed and the solidification sequence differ from those predicted under equilibrium and Scheil–Gulliver Cooling. Although not directly applicable to industrial operations, this research clearly shows that the formation of both the SFCA and SFCA-I phase in iron ore sinters is controlled by kinetic processes rather than equilibrium conditions.

• OSTI ID: 22933418
• Journal Information: Metallurgical and Materials Transactions. B, Process Metallurgy and Materials Processing Science, Journal Name: Metallurgical and Materials Transactions. B, Process Metallurgy and Materials Processing Science Journal Issue: 6 Vol. 50; ISSN 1073-5615; ISSN MTBSEO
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AIR
ALUMINIUM
ALUMINIUM COMPOUNDS
CALCIUM OXIDES
CALCIUM SILICATES
FERRITES
IRON ORES
IRON OXIDES
KINETICS
LIQUIDS
MICROSTRUCTURE
SILICON OXIDES
SINTERING
SOLIDIFICATION