Wetting Behavior of Calcium Ferrite Slags on Cristobalite Substrates
- PDF / 4,151,087 Bytes
- 15 Pages / 593.972 x 792 pts Page_size
- 13 Downloads / 184 Views
mes, many iron and steel enterprises are using low-grade ores with large contents of gangue minerals, which results in a frequent fluctuation in the chemical composition and a reduced sinter strength. The quality of high-basicity sinters is largely determined by the phase proportion of silico-ferrite of calcium and alumina (SFCA) as adhesive phases, because of their high mechanical strength, high reducibility, and slow degradation.[1–6] The usage of low-grade ores also influences the liquid phase formation, assimilation, and solidification of SFCA during the sintering process. In high-basicity sinters, calcium ferrite (CF), as a significant initial adhesive phase, is first generated in the sintering raw materials.[7–10] Subsequently, the liquid phase flows, wets, and spreads along the surface of the solid particles, including iron ore concentrates and gangue minerals. SiO2, as the first predominant component of gangue, mostly determines the chemistry and formation of SFCA. Hamilton et al.[11] first identified
MINGRUI YANG, XUEWEI LV, RUIRUI WEI, JIAN XU, and CHENGUANG BAI are with the School of Materials Science and Engineering, Chongqing University, No. 174 Shazhengjie, Shapingba, Chongqing 400044, China. Contact e-mail: [email protected] Manuscript submitted October 18, 2017.
METALLURGICAL AND MATERIALS TRANSACTIONS B
the SFC phase and recognized this as an alumina-free equivalent of SFCA with a compositional range located along the CF3-C4S3 pseudobinary. Pownceby et al.[12–15] systematically studied the solid solution limits and thermal stability of silico-ferrites of calcium (SFC) and its alumina-doped equivalent SFCA; they found that SFC forms a solid solution along the trend line between the theoretical end-members CF3 and C4S3. Guo et al.[16,17] did extensive work on the formation mechanism of a SFC and its crystal structure. They found that the process of Si solution is closely related to the presence of a Ca channel composed of a Ca octahedron in the crystal structure of the SFC. The formation of the SFC is dominated by solid-state reactions in the SFC ternary system. The chemical composition of binary calcium ferrite is Ca2.5Fe15.5O25 and approximately Ca2Fe12O20. The SFC formation mechanism involves SiO2 dissolution in the CF slag. Lv and Yu[18] studied the dissolution kinetics of SiO2 in a CaO-Fe2O3-SiO2 slag. They found that the dissolution rate increased with increasing rotation speed and temperature. Further, they calculated the diffusion coefficient and activation energy of SiO2 during the dissolution process. Interfacial properties at the solid-liquid interface play an important role in the iron and steel-making process. Wettability, which can be characterized by the contact angle, is important for assimilation in sintering process. As for slag-oxide wetting system, Chung et al.[19] studied the dissolutive wetting and spreading phenomena
between Al2O3 substrate and CaO-Al2O3 non-saturated and saturated slags. It was found that the spreading rate of the non-saturated slag was faster than that of the saturated
Data Loading...
