Acting mechanism of F, K, and Na in the solid phase sintering reaction of the Baiyunebo iron ore

The effect of F, K, and Na on the solid phase reaction of the Baiyunebo iron ore was investigated by differential thermal analysis (DTA) and X-ray diffraction (XRD). It has been identified that alkaline elements K and Na in the Baiyunebo ore instigate the formation of low melting point compounds Na₂SiO₃ and Na₂O·Fe₂O₃ and the generation of molten state in the solid phase sintering. Element F in the Baiyunebo ore facilitates the formation of cuspidine compound 3CaO·2SiO₂·CaF₂ in the solid phase reaction. The cuspidine compound is kept in solid as one of the final products through the entire sintering process due to its high melting point. In the sintering process, CaF₂ and SiO₂ react with CaO first and form 3CaO·2SiO₂·CaF₂ and 3CaO·2SiO₂, so the formation of ferrites, Na₂O·Fe₂O₃, and 2CaO·Fe₂O₃ is inhibited.