Critical thermodynamic evaluation of oxide systems relevant to fuel ashes and slags: Potassium oxide–magnesium oxide–silica

The K2O–MgO–SiO2 system has been thermodynamically assessed. The modified associate species model was applied to the liquid phase while the solubility of SiO2 in K2MgSiO4 has been treated with a multi-sublattice model. The resulting new databank was used for the representation of the phase equilibria in the ternary system including several quasi-binary sections of the ternary diagram. The calculated phase relations are in good agreement with the experimental data. The phase equlibria in the unmeasured region were proposed on the basis of the obtained new databank. •K2O–MgO–SiO2 system was thermodynamically assessed.•Modified associate species model was used for the liquid phase.•Gibbs energy data for 6 ternary compounds are generated.•Solubility of SiO2 in K2MgSiO4 is added to the dataset.•Calculated phase equilibria are in good agreement with the experimental data.