Abstract
SiO2-Fe2O3-CaO (SFC) is believed to be the transition phase during the SiO2-Fe2O3-CaO-Al2O3 (SFCA) formation process. The effect of SiO2 on the mechanical property and reduction of the CaO-Fe2O3-SiO2 system was inspected in this study. Experiments were carried out under air at 1200 °C with different amounts of SiO2 mixed with Fe2O3 and CaO. The mechanical properties and reduction of samples were studied. Results indicate that the hardness of samples gradually increases with the increase of SFC content. That may be caused by SiO2 solid solution in calcium ferrite. The larger the amount and smaller size of acicular calcium ferrites in samples, the greater the fracture toughness. The solid solution of SiO2 in calcium ferrite is beneficial to decrease the initial reduction temperature. The apparent activation energy values of the samples with the different content of SiO2 from 0% to 5% are 167.23, 84.36, 87.90, 96.02, 92.44 and 107.83 kJ·mol−1, respectively. The microstructure of lump samples after reduction consists of four phases, i.e., CF (CaFe2O4), SFC, calcio-wüstite (CW) and Fe. It was not difficult to find the Fe in the samples reduced from CW. Scanning electron micrograph images have revealed that the acicular-like calcium ferrites are more easily reduced than the platy-like ones.
Highlights
Under the pressures of the decreases of high-quality iron ore, the iron and steel enterprises in China turn to use low-quality ores
The grained calcium ferrites are gradually transformed into the column or acicular calcium ferrites with SiO2 added, as shown in samples no.1 to samples nos.2 and 3
This was a fundamental study of the effect of SiO2 on the mechanical property and reduction mechanism of calcium ferrite in iron ore sinter
Summary
Under the pressures of the decreases of high-quality iron ore, the iron and steel enterprises in China turn to use low-quality ores. The SFCA phase (SiO2 -Fe2 O3 -CaO-Al2 O3 ) is regarded as a desirable bonding phase for fluxed sinter [1,2]. Compared with grained or plate-like calcium ferrite, fine acicular calcium ferrite has higher microhardness, and it can prevent crack extension effectively. That makes acicular calcium ferrite better the compressive strength and metallurgical properties than grained or plate-like calcium ferrite [12,13]. The effect of SiO2 on the mechanical property and reduction of calcium ferrite will be investigated. We include the following methods: the samples of hardness and fracture toughness test, powder non-isothermal reduction and block isothermal reduction This will contribute to more deeply understanding the effect of SiO2 on the properties of calcium ferrite and sinter
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
