Experimental Determination of the Phase Diagram for CaO-SiO₂-MgO-10%Al₂O₃-5%TiO₂ System

Abstract

The phase diagrams of Ti-bearing slag have fundamental guiding significance for the comprehensive utilization of Ti resources. In this article, the pseudo-melting temperatures were determined by the single hot thermocouple technique (SHTT) and high equilibrium experiments for the specified contents of 5% to 15% MgO in the CaO-SiO₂-MgO-10%Al₂O₃-5%TiO₂ phase diagram system. The 1250°C to 1350°C liquidus lines were firstly calculated based on the thermodynamic equations in the specific primary crystal field. The phase equilibrium relationship was determined experimentally at 1300°C using the high temperature experimental technique followed by X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Energy Dispersive X-ray spectroscope (EDX) analysis, and the liquid Phase, liquid coexist with solid solution phase of (2CaO·MgO·2SiO₂, 2CaO·Al₂O₃·SiO₂)_ss were found. Therefore, the phase diagram was constructed for the specified region of the CaO-SiO₂-MgO-10%Al₂O₃-5%TiO₂ system, which was consistent with the existing phase diagram except for somewhat larger liquidus area at 1300°C. The comparison proved that the combination of liquidus temperature determination by SHTT and the high temperature experimental technique was enabled to construct the correct phase diagram for slag systems.