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

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 1 250°C to 1 350°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 1 300°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 1 300°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.