The solubility and activity determination of NiO in the SiO₂-NiO-FeO system

A structural model for the liquid phase of silicate systems was used to obtain the SiO₂-NiO-FeO phase diagram and the NiO activities at 1573 and 1673 K. The NiO activities were determined experimentally by equilibrating a pure nickel crucible with an iron-silicate slag and CO-CO₂ gas mixture to produce pO₂ = 10^-6 and 10^-10 atm. The NiO activities obtained by the structural model are in good agreement with those obtained experimentally for strongly reduction conditions (10^-10 atm), due to the structural model consider only the iron in the divalent state. The Fe³⁺/Fe²⁺ ratio and the nickel oxide solubility were increased when the oxygen partial pressure and the temperature were increased.