Kinetic model of hot metal dephosphorization by liquid and solid coexisting slags

In most cases, hot metal dephosphorization slag is saturated with dicalcium silicate, and the partition ratio of phosphorus between dicalcium silicate and liquid slag is high. These results indicate the important role of solid dicalcium silicate in dephosphorization. In order to understand the reaction kinetics and obtain an optimum treatment method, it is very important to know the influence of solid phases in the slag. In this study, a new reaction model for hot metal dephosphorization considering the effects of dicalcium silicate and dissolution rate of lime is proposed. In the new dephosphorization model, in addition to the reaction rate between liquid slag and metal, the partition between dicalcium silicate and liquid slag and the dissolution rate of lime are also considered. The dephosphorization reaction of hot metal by the liquid slag phase was calculated by using the coupled reaction model. The calculated results demonstrated the importance of dicalcium silicate in dephosphorization. Also, in some cases, the dissolution rate of lime affected the dephosphorization behaviour.