Multi-ion diffusion model and application to solid dissolution in CaO–Al₂O₃–SiO₂ melts

A general multi-ion diffusion model for liquid slag is developed for silicate melts by combining the tracer diffusivities of ions and chemical potentials from the CALculation of PHAse Diagrams thermodynamic database. For the demonstration of the model, the tracer diffusivities of Ca, Al, Si, and O ions in CaO–Al₂O₃–SiO₂ melts were optimized as functions of temperature and composition using available isotope experimental data. The present model successfully simulates liquid-junction diffusion in the CaO–Al₂O₃–SiO₂ system and the dissolution of solid SiO₂ and Al₂O₃ particles in CaO–Al₂O₃–SiO₂ melts. Furthermore, the model can be readily expanded to multicomponent systems, making it potentially applicable to refractory dissolution in liquid slag and various other diffusion-controlled high temperature processes involving liquid oxide melts.