Mass Transfer Behavior of Phosphorus from the Liquid Slag Phase to Solid 2CaO·SiO₂ in the Multiphase Dephosphorization Slag

Abstract

The mass transfer behavior of phosphorus in the multiphase dephosphorization slag at 1623 K (1350 °C) is investigated in this article by adding the reagent P₂O₅ powders into the CaO-FeO_t-SiO₂ slag saturated with a directly precipitated 2CaO·SiO₂ phase. The results show that the phosphorus was first quickly dissolved and transferred from the liquid slag to the precipitated solid 2CaO·SiO₂ particle; then it reacted with the solid 2CaO·SiO₂ particle to form (2CaO·SiO₂-3CaO·P₂O₅) solid solution at the edge of a large solid particle. The further diffusion of phosphorus from the formed (2CaO·SiO₂-3CaO·P₂O₅) solid solution reaction layer into the core of the 2CaO·SiO₂ particle is the limiting step during the enrichment-phosphorus process. It is observed that the enrichment-phosphorus process is changed when the amount of added P₂O₅ content is increased and the formed solid solution phase is torn and peeled off from the surface of the 2CaO·SiO₂ particle. In addition, the study shows that the solid solution structure is changed and becomes more compacted with the addition of P₂O₅ content, leading to the increment of solid solution density.