The Effect of CaF۲ Content in Hot Metal Pretreatment Flux Based on Lime

This research was conducted for the purpose of studying the effect of CaF۲ content in the composition of hot metal pretreatment flux, based on lime. It was followed in regards to the importance of fluorine amount decrease in hot metal pretreatment and steel making processes. For this purpose, lime based fluxes including ۴۰, ۳۰, ۲۰ and ۱۰ percent calcium fluoride were prepared and hot metal pretreatment experiments were done in an induction furnace at the temperature range of ۱۳۵۰-۱۴۵۰°C. The obtained results indicated that by using the flux containing ۳۰ percent calcium fluoride, simultaneous removal of phosphorous and sulfurous are in the highest level which is known as a result of slag making with suitable liquid phase volume and adequate basicity. On the other hand, a flux with ۲۰ percent CaF۲ caused a small fall in the refining process results. In regards to the harmful effects of fluorine on refractory walls and considering environmental issues, a flux including ۲۰ percent fluorine was introduced as a providing optimum condition. The results have been studied with respect to CaO-CaF۲ equilibrium phase diagram, as well as the effect of CaF۲ amount on phosphate capacity and lime efficiency of slag.