Activities of FeO and P₂O₅ in Dephosphorization Slags Coexisting with Solid Solutions between Di-calcium Silicate and Tri-calcium Phosphate

Abstract

Towards better understanding of the phosphorus removal from hot metal with low-basicity slags, electrochemical technique incorporating MgO-stabilized zirconia was conducted to measure simultaneously the activities of FeO and P 2 O 5 within heterogeneous CaO-SiO 2 -P 2 O 5 -FeO slags. The FeO activity was fairly insensitive to the variation of Ca 3 P 2 O 8 content in solid solutions between Ca 2 SiO 4 -Ca 3 P 2 O 8 , while the P 2 O 5 activity increased with an increase in Ca 3 P 2 O 8 content. By using the present values for activities, phosphorus distribution ratios were estimated between molten slag and carbon-saturated iron. The relationship between phosphorus distribution ratio and FeO content in molten slag was consistent with the phase diagram of the pseudo-ternary CaO-(SiO 2 + P 2 O 5 )-FeO system.

Activities of P₂O₅ in Solid Solutions between Di-calcium Silicate and Tri-calcium Phosphate at 1573 K

“…. l og( ) Figure 8(c) also shows the P 2 O 5 activities in the threephase region of CS + < C 2 S-C 3 P > ss + Liquid 15) and the two-phase coexistence of < C 2 S-C 3 P > ss + Liquid. 16) It could be concluded here that the values for a P O 2 5 in CS + < C 2 S-C 3 P > ss + Liquid were slightly lower than those in CS + < C 2 S-C 3 P > ss due to dissolution of iron oxide into < C 2 S-C 3 P > ss (See Fig.…”

Reevaluation and Measurements of Fe<i>_x</i>O Activities in Fe<i>_x</i>O–CaO–SiO₂ Pseudo-ternary System at 1573 K

“…The solid line represents log[mass%P] Fe calculated when the oxygen partial pressure is determined by the equilibrium between Fe x O in slag and metallic iron. The equilibrium phosphorus concentrations measured in the laboratory investigations [52][53][54] are also plotted in Fig. 9.…”

Thermochemical Properties of Copper-Iron-Sulfur Alloy as Reference Metallic Phase for Analyzing Resulfurization

“…Some thermochemical studies on dephosphorization slags at temperature of hot metal pre-treatment have been conducted by the present authors. 13,14) The experimental apparatus is schematically illustrated in Fig. 1.…”