The Effect of Flux type and Oxygen Blowing on Simultaneous Removal of Phosphorus and Sulfur from Molten Iron

Abstract

This research was conducted to study the effect of lime based Flux with the composition of CaO-20%CaF₂-8%FeO on simultaneous removal of phosphorus and Sulfur from hot metal. The effects of Na₂O and oxygen blowing were also studied. The experiments were performed using an induction furnace and hot metal produced in Isfahan Steel Company in the temperature range 1350-1450 ºC. The results showed that simultaneous removal of these elements was possible. It was also indicated that addition of Na₂CO₃ as the supplier of Na₂O caused a considerable improvement in the removal process. This was mainly because of an increase in slag basicity and CO₂ gas evolution. Oxygen blowing into the melt improved the phosphorus removal slightly. However, an increase in melt temperature resulted in some sulfur return from slag to hot metal. On the other hand, increase in melt oxygen potential due to oxygen blowing decreased desulfurization to some extent. According to the results obtained, 35% and 75% decrease in phosphorus and sulfur content of the melt was achieved respectively. The initial silicon content of hot metal was found to be an important parameter. The results showed that the hot metal silicon content should be reduced to less than 0.15% before phosphorus removal starts.