Effect of Na2O and B2O3 on the distribution of P2O5 between solid solution and liquid phases slag

Abstract

With the development of multiphase slag system for hot-metal treatment to achieve better dephosphorization efficiency, it is very important to improve the distribution ratio of P2O5 between the solid solution (2CaO•SiO2-3CaO•P2O5) and liquid phase slag. This study was carried out to investigate the effects of Na 2O and B2O3 on P2O5 distribution ratio and morphologies of corresponding solid solutions in CaO-SiO2-Fe2O3-P2O5 slag system. The results indicated that the distribution ratio of P2O5 would be improved with the increase of Na2O content due to the formation of (2CaO•SiO2-Na2O•2CaO•P2O 5) solid solution with a similar morphology as that of reference solid solution (2CaO•SiO2-3CaO•P2O5) in the reference slag. While B2O3 plays an opposite role, it would not only reduce the phosphorus distribution ratio, but also change the morphology of its corresponding solid solution due to the formation of complex solid solution (2CaO•SiO2-Ca9.93(P 5.84B0.16O24) (B0.67O 1.79)). Besides, the effect of cooling rate on the size of the solid solution was also studied. It would provide an instructive way for the design of multiphase slag for hot metal treatment.