Study on Reaction Mechanism of Reducing Dephosphorization of Fe-Ni-Si Melt by CaO-CaF2 Slag

In the present study, the dephosphorization of Fe-Ni-Si melt by CaO-saturated CaO-CaF 2 slag was investigated, from which it was found that the dephosphorization efficiency increases as increasing the silicon content, meanwhile the increase rate becomes rapid when the silicon content is more than 10 mass pct. By analyzing the phase compositions of the dephosphorization slag of a high silicon Fe-Ni-Si melt, it was first found the dephosphorization products change with the silicon content. When Si contents are 10.5, 31.48, 34.71, and 43.15 mass pct, the de-P products are Ca 2 P 2 , Ca 10+ x Si 12−2 x P 16 , Ca 4 SiP 4 , and Ca 10+ x Si 12−2 x P 16 , as well as Ca 4 SiP 4 , respectively. The corresponding dephosphorization mechanism can be described as ( 2 x ) ( CaO ) + ( x + 2 y ) [ Si ] + 2 z [ P ] = x ( SiO 2 ) + 2 ( Ca x Si y P z ) .