Investigation of Effects of SiO 2 Content and Cooling Rate on Crystallization in Fe 2 O 3 -CaO-SiO 2 System Using In Sit
- PDF / 5,748,475 Bytes
- 9 Pages / 593.972 x 792 pts Page_size
- 96 Downloads / 127 Views
TRODUCTION
SINTER is a major Fe source used extensively in Blast Furnace processes worldwide. The chemical and physical properties of sinter are crucial factors that affect the operating stabilities of blast furnaces.[1–3] Sinter is primarily composed of hematite (Fe2O3), magnetite (Fe3O4), calcium ferrite (mainly silico-ferrite of calcium and alumina (SFCA)), and a slag phase; among them, Fe2O3 and SFCA are in present in the highest proportions.[4] The quality of sinter is largely determined by the phase proportions of SFCA, which is a low-melting-point bonding-phase formed during the sintering process.[5,6] Increased understanding of the compositional and thermal stability domains of SFCA phases and their formation mechanisms can improve the efficiency of the sintering process, allowing the determination of the optimal sintering conditions required to produce high-quality products based on the chemical composition and physical characteristics of a given sinter mixture.[7] TAE JUN PARK, JOON SUNG CHOI, and DONG JOON MIN are with the Department of Materials Science and Engineering, Yonsei University, 50, Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea. Contact e-mail: [email protected] Manuscript submitted October 18, 2018.
METALLURGICAL AND MATERIALS TRANSACTIONS B
Webster and Pownceby et al.[8,9] found that a ternary phase appeared during the formation of SFCA. Al2O3 was confirmed to form a solid solution with calcium ferrite by the substitution of Al3+ for Fe3+ before the formation of complex SFCA. This finding proved that the formation of complex SFCA could not occur without SiO2 participation. Research on the crystal structure of silico-ferrite of calcium(SFC) provides a deeper understanding of the structure of SFCA. The SFC phase was identified by Hamilton et al.,[10] who recognized this as an alumina-free equivalent of SFCA within a compositional range in the CaOÆ3FeO (CF3) and 4CaOÆ3SiO2 (C4S3) pseudobinary phase diagram in the Fe2O3-CaO-SiO2 system. The compositions of SFC distributed along a line connecting the phases of CaOÆ3Fe2O3 (CF) and C4S3 with the maximum solid solution range of SFC occurring between of 7.0 and 11.7 wt pct C4S3.[11–14] In a recent study on the structure and formation mechanism of SFC, Ding et al.[15–17] examined the effect of SiO2 on the formation of SFC, which is the precursor phase of SFCA, suggesting that Si4+ can replace Fe3+ located in octahedral layers of the binary calcium ferrite to form SFC. The reaction between CaFe2O4 and the SFC depresses the melting temperature. However, previous studies of structure changes under static conditions provided insufficient information to reflect non-equilibrium and heterogeneous conditions with rapid temperature changes and various chemical compositions in the actual sintering process.
In this study, the crystallization behaviors, microstructures, and reduction properties of the Fe2O3CaO-SiO2 system were investigated in the non-equilibrium state with different cooling rates and SiO2 contents. The results of this work are expected to f
Data Loading...
