A Review of Fluorine-free Mold Flux Development

摘要

More than 95% of crude steel has been produced through the process of continuous casting technology, in which mold flux plays important roles inside the mold. As conventional mold flux system contains certain amount of fluorides that tend to be evaporated and cause the corrosion of casting facilities and environmental pollutions etc. It is urgent to optimize the mold flux composition without fluorides for the continuous casting process. In this review paper, the substitutes for fluorides in mold flux are summarized via two main strategies: TiO_2 and B_2O_3 based additives. Among them, CaO-SiO_2-Al_2O_3-Na_2O-B_2O_3 based fluoride-free (F-free) mold flux system shows great potential to replace conventional mold flux that can be widely used in the process of continuous casting, as the precipitated phase-Ca_(11)Si_4B_2O_(22) has the most similar crystallization behavior to cuspidine in conventional mold flux, which can effectively control the horizontal heat transfer and reduce the occurrence of longitudinal cracks. This paper would provide technical guidance and research direction for the design and study of efficient environment-friendly F-free mold flux.