Effect of Al2O3 Addition on the Phase Equilibria Relations of CaO-SiO2-5 wt%MgO-Al2O3-TiO2 System Relevant to Ti-bearing Blast Furnace Slag

The influence of Al2O3 addition up to 30 wt% on equilibria phase relations of Ti-bearing slag system with w(CaO)/w(SiO2) of 1.00 was investigated at 1 300 degrees C and 1 400 degrees C by classical high temperature thermodynamic equilibria technique followed by XRD (X-Ray diffraction) and SEM-EDX (Scanning Electron Microscope and Energy Dispersive X-ray Fluorescence scope) analysis. Experimental results indicated that with the increase of Al2O3 addition the equilibria solid phases gradually change from melilite solid solution and perovskite to Al Ti diopside solid solution, spinel, and pseudobrookite solid solution. Moreover, comparisons with the predictions by Factsage 7.2 revealed that the calculated equilibria phase relations were only well agreed with experimental results below 20 wt% Al2O3 and TiO2, while great deviations presented when Al2O3 content higher than 20 wt%. Based on experimental and calculated results, the 1 300 degrees C and 1 400 degrees C liquidus lines as well as the predicted primary crystal phase boundary lines were constructed for specific composition range of CaO-SiO2-5wt%MgO-Al(2)O3-TiO2 system.