Experimental phase relations between MgO-saturated magnesium-aluminate spinel (MgAl2O4) and CuOx-rich liquid

Experimental phase equilibrium data for the Cu-O-Al₂O₃-MgO system is required to improve the performance of MgAl₂O₄-containing refractories and slagging in non-ferrous smelting. In this work, the phase relations of MgAl₂O₄ in the Cu-O-Al₂O₃-MgO system were studied experimentally in air within a temperature range of 1100–1400 °C using the equilibration and quenching method. The chemical compositions of the phases in the quenched samples were determined using electron probe microanalysis (EPMA). Less than 1 wt% of Al₂O₃ or MgO were found in the oxide liquid phase, whereas the solid MgAl₂O₄ and MgO phases contained up to 23 wt% and 30 wt% of ‘Cu₂O’, respectively. Discrepancies between these results and the corresponding calculated values generated by the MTDATA 6.0 software and Mtox database Version 8.2 ranged from 3 wt% to 19 wt%. The results of this work indicate that the MgAl₂O₄ spinel is chemically stable in the presence of a CuO_x-rich liquid under the conditions studied.