Crystallography of the High-Temperature Ca2SiO4-Ca3P2O8 Solid Solutions

Abstract

The crystallography of the Ca2SiO4-Ca3P2O8 solid solutions in the dephosphorization slag in current steelmaking process was determined in this study. Understanding the physical and chemical properties of these Ca2SiO4-Ca3P2O8 solid solutions is a preliminary step towards understanding the role of the Ca2SiO4-Ca3P2O8 solid solutions in the dephosphorization process. The range of Ca3P2O8 in the Ca2SiO4-Ca3P2O8 solid solutions synthesized for analysis varied from 10 to 90 mol pct, with an incremental increase of 10 mol pct per solid solution. In solid solutions with a Ca3P2O8 content of up to 40 mol pct, the crystal structure at 1773 K was found to be hexagonal, while the solid solutions with a Ca3P2O8 content over 70 mol pct had a trigonal structure. The silicocarnotite solid solutions observed when the Ca3P2O8 content was 50 to 60 mol pct were likely formed by phase transformation during cooling. In the stable solid solution with a Ca3P2O8 content of 50 to 60 mol pct at 1773 K before the occurrence of transformation, the crystal structure is trigonal since it is in the Ca3P2O8-rich range. A linear increase in the lattice parameters c of the solid solutions in the range of (0, 40 mol pct) and (70 mol pct, 100 mol pct) was found with increasing Ca3P2O8 content. The lattice parameter a, however, was almost independent of the Ca3P2O8 content in the solid solutions.