First‐Principles Molecular Dynamics Study on Ionic Structure and Transport Properties of NaCl‐MgCl₂‐CaCl₂ Ternary Molten Salt System

Abstract

The carbochlorination in molten salt is an effective method for titanium extraction form low-grade titanium slag with a high calcium and magnesium content. However, in industrial practice, the fluidity of molten salt will gradually decrease with the increase of CaCl 2 content. It is important to elucidate the influencing mechanism of CaCl 2 content on the microstructure and diffusion properties of molten salt for the rational selection of a molten salt system and clean utilization of titanium slag. In this study, the densities of molten salt systems with different CaCl 2 contents are measured according to the Archimedes principle. Then, using the first-principles molecular dynamics (FPMD) method, the ionic structure and transport properties of NaCl-MgCl 2 -CaCl 2 ternary molten salt systems under different CaCl 2 contents are qualitatively and quantitatively described by determining the partial radial distribution functions (PRDF), coordination number (CN), angular distribution functions (ADF), and diffusion coefficient (DC). The results show that with the addition of CaCl 2 , Ca 2+ ion complexed with Cl − ion to form larger ionic clusters, which reduced the proportion of free Cl − ion and restricted the diffusion of Cl − ion.