Influence of alumina and magnesia on phase equilibria in the system Fe‐CaO‐FeOn‐SiO2 at 1600 °C

The phase relations in the systems CaO‐FeO_n‐SiO₂‐Al₂O₃ and CaO‐FeO_n‐SiO₂‐MgO at 1600 °C saturated with liquid iron are described. The phase conditions in the quaternary system with aluminium oxide are so far rather unknown. An addition of aluminium oxide makes the calciumsilicates and lime saturation areas move towards the CaO corner thus enlarging the homogeneous liquidus space accordingly. Aluminium oxide can be considered as a flux in this case. The fields of different solid solutions in the system CaO‐FeO_n‐SiO₂‐MgO were taken into account. Some additional (2 to 4)‐phase areas occur with increasing MgO content. This causes the precipitation of magnesiowustite which dominates the system accordingly. The changed phase relations strongly influence the direction of tie‐lines and their length. Therewith, the correlation between liquid phase and solid phase, calculated via lever rule, is influenced, too.