Phosphorus Distribution between Molten Iron and Slags of the System CaO-MgO-Fe_tO-SiO₂

Abstract

Experiments were made to obtain phosphorus distribution ratio between molten iron and CaO-MgO-Fe_tO-SiO₂ slag in a magnesia crucible at the temperatures of 1550°C and 1600°C. The results showed that the phosphorus transfer between iron and slag was so fast that the phosphorus equilibrium was maintained with the dissolution of magnesia from the crucible into the slag. The equations for phosphorus partitions obtained in this study are as follows.
log[(%P₂O₅)/[%P]²·(%Fe_tO)⁵]=0.143[%CaO)+0.55(%MgO)]+13980/T+16.08
log[(%P)/[%P]·(%T.Fe)^5/2]=0.065[%CaO)+0.55(%MgO)]+12230/T-10.08
These equations could be applied to CaO-MgO-Fe_tO-SiO₂ slags which were not saturated with magnesia as well as those saturated. The variation of the activity coefficients of Fe_tO and P₂O₅ with the theoretical optical basicity of slags was also discussed.