PHOSPHORUS AND CHROMIUM EQUILIBRIUM DISTRIBUTIONS BETWEEN CAO-CAF2 SLAGS AND FE-CR-C-P MELTS

Equilibrium distribution ratios of phosphorus and chromium between molten CaO-CaF2 slags and Fe-Cr-C(sat.)-P melt were measured at 1400-degrees-C and at the prevailing low oxygen partial pressure determined by the experimental conditions, i.e. a(C) = 1 and p(CO) = 1 atm corresponding to log P(O2) = -16.11. The phosphate capacity of the slags was calculated. Phosphate capacity of CaO(sat)-CaF2 slag decreased with temperature. At 1400-degrees-C the relations found between phosphate capacity and slag composition are summarized as follows: X(CaO)/Z(CaF2) < 0.3:log C(PO43-) = 23.14 + 1.53 x (X(CaO)/X(CaF2)) X(CaO)/X(CaF2) > 0.3:log C(PO43-) = 23.70 Thermodynamic analysis suggested that CaO-CaF2-Cr2O3 slag double saturated with CaO and CaO . Cr2O3 should give the highest phosphorus distribution between the slag and crude stainless steel melts.