The Effect of CaF2 Content in Hot Metal Pretreatment Flux Based on Lime

Abstract

This research was conducted for the purpose of studying the effect of CaF2 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 40, 30, 20 and 10 percent calcium fluoride were prepared and hot metal pretreatment experiments were done in an induction furnace at the temperature range of 1350-1450°C. The obtained results indicated that by using the flux containing 30 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 20 percent CaF2 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 20 percent fluorine was introduced as a providing optimum condition. The results have been studied with respect to CaO-CaF2 equilibrium phase diagram, as well as the effect of CaF2 amount on phosphate capacity and lime efficiency of slag.