Effect of Al₂O₃ on the Melting, Viscosity, and Phosphorus Distribution of CaO–SiO₂–Fe₂O₃–P₂O₅ Slag System

An investigation is conducted to study the effect of Al2O3 on the melting, viscosity, and phosphorus distribution of CaO–SiO2–Fe2O3–P 2 O 5 slag system by using Single Hot Thermocouple Technique and rotating cylinder viscometer. The results show that with the addition of Al 2 O 3 content, the melting temperature range of slag system is first reduced and then increased, as the added Al 2 O 3 may react with CaO to form different compounds with varied melting points. The slag viscosity increases with the addition of Al 2 O 3 content, due to the fact that the polymerization degree of the melt slag is getting increased. Besides, the addition of Al 2 O 3 can improve the mass percentage of P 2 O 5 in the solid phase, but it may reduce the dephosphorization capacity of the slag due to the reduction of the total solid phase solution (2CaO · SiO 2 –n3CaO · P 2 O 5 ) precipitation. The results of this study can elucidate the effect of Al 2 O 3 on the property of dephosphorization slag and provide guidelines for the new slag design to achieve a better hot metal dephosphorization efficiency.