Thermodynamic modeling of the K-KCl and Mg-MgCl2 binary systems using the CALPHAD method

Abstract

The Calculation of Phase Diagrams (CALPHAD) method uses models that reproduce and predict phase equilibria and thermochemical behavior. To date, the CALPHAD approach has been applied to the KCl-MgCl2 psuedobinary only. The two-sublattice modified quasi chemical (MQM) model, already developed for the KCl-MgCl2 melt and used extensively within the CALPHAD community to represent molten salts, is extended in this work to include excess K and Mg. Phase relations calculated using the MQM is compared to experimentally observed behavior for the K-KCl binary system. Gaps in the experimental data are identified and recommendations are given for better understanding the thermochemistry and phase equilibria.