Distribution of P2O5 between solid solution and liquid phase in dephosphorization slag of CaO–SiO2–FeO–P2O5–Na2O system

Abstract

A multi-phase slag containing Na2O is potential to efficiently dephosphorize high-P hot metal. After dephosphorization, the generated slag with high P2O5 content is regarded as a P resource. Because P2O5 was mainly concentrated in the 2CaO·SiO2–3CaO·P2O5 solid solution, the recovery of P from dephosphorization slag primarily depends on the separation of the solid solution from other phases. The distribution ratios of P2O5 between solid solution and liquid phase in the CaO–SiO2–FeO–P2O5–Na2O slag system were investigated. The results indicated that the addition of Na2O facilitated the enrichment of P2O5 in the solid solution because it increased not only the distribution ratio of P2O5 but also the mass fraction of the solid solution. The distribution ratio of P2O5 was independent of the P2O5 content in slag. A higher P2O5 content in slag resulted in higher P2O5 and Na2O contents in the solid solution. The distribution ratio of P2O5 increased with the total Fe content in the liquid phase, regardless of the valence of Fe. An increase in the FeO content in slag brought a higher P2O5 content in the solid solution. As slag basicity increased, the distribution ratio of P2O5 increased, but the P2O5 content in the solid solution decreased.