Phase equilibria of slag systems “FeO”-SiO2-CaO-Al2O3 and “FeO” -SiO2-CaO-MgO at 1200 °C and p(O2) of 10-7 kPa
(1. Faculty of Materials, Metallurgy and Chemistry, Jiangxi University of Science and Technology, Ganzhou 341000, China;
2. National Rare Earth Functional Material Innovation Center, Ganzhou 341000, China;
3. School of Metallurgy and Environment, Central South University, Changsha 410083, China;
4. Sustainable Minerals Institute, The University of Queensland, Brisbane 4072, Australia)
2. National Rare Earth Functional Material Innovation Center, Ganzhou 341000, China;
3. School of Metallurgy and Environment, Central South University, Changsha 410083, China;
4. Sustainable Minerals Institute, The University of Queensland, Brisbane 4072, Australia)
Abstract: High-temperature experiments were carried out for the slag systems of “FeO”-SiO2-CaO-Al2O3 and “FeO”-SiO2-CaO-MgO at 1200 °C and p(O2) of 10-7 kPa. The equilibrated samples were quenched, and the phase compositions were measured by electron probe microanalysis (EPMA). A series of pseudo-ternary and pseudo-binary phase diagrams are constructed to demonstrate their applications in copper smelting process and evaluation of the thermodynamic database. Spinel and tridymite are identified to be the major primary phases in the composition range related to the copper smelting slags. It is found that the operating window of the smelting slag is primarily determined by wFe/wSiO2 ratio in the slag. Both MgO and Al2O3 in the slag reduce the operating window which requires extra fluxing agent to keep the slag to be fully liquid. Complex spinel solid solutions cause inaccurate predictions of the current thermodynamic database.
Key words: phase equilibrium; “FeO”-SiO2-CaO-Al2O3 slag system; “FeO”-SiO2-CaO-MgO slag system; oxygen partial pressure; copper smelting slag; FactSage