Phase equilibria in the CaO-“FeO”-AlO1.5 system in equilibrium with Fe metal

Experimental and thermodynamic modelling investigation of the phase equilibria in the CaO-“FeO”-AlO 1.5 system in equilibrium with Fe metal has been undertaken to characterise the thermochemistry of slag in pyrometallurgical processes. Phase equilibria data at 1100-1615°C were obtained using equilibration of synthetic mixtures with predetermined compositions in Fe foil/wire or Al 2 O 3 crucibles, quenching, and electron probe X-ray microanalysis of the phases. Phase equilibria and liquidus isotherms in the lime (CaO), wustite (FeO x ), spinel (FeAl 2 O 4 ), corundum (Al 2 O 3 ), calcium aluminates (CaAl 2 O 4 = CA, CaAl 4 O 7 = CA 2 , CaAl 12 O 19 = CA 6 , Ca 3 Al 2 O 6 = C 3 A, Ca 12 Al 14 O 33 = mayenite), dicalcium ferrite (Ca 2 (Fe,Al) 2 O 5 = C 2 F, brownmillerite), and calcium iron aluminate (Ca 3 FeAl 4 O 10 = C 3 FA 2 , found for the first time) primary phase fields were revealed. The experimental results were used to develop a thermodynamic database for describing the CaO-“FeO”-AlO 1.5 system. Also, the composition of solid phases versus slag composition was analysed through the experimental results and thermodynamic database developed in this study.