Fractal model-based crystal pillar structure simulation and mechanism analysis of impurity migration process in layer melt crystallization

Layer melt crystallization (LMC) is regarded as a green purification technique and is widespread in the separation of isomers. Based on the highly efficient separation, this work combined the experiments and models to explore the crystal pillar structure and impurity migration. Firstly, we established the crystallization process kinetic model to reveal the crystal growth rules and pointed out the correlations of growth rate and supercooling degree. Then the fractal porous model was used to analyze the crystal pillar structure, where the fractal characteristics tended to the Euclidean geometric features with porosity increase in both crystallization and sweating processes. Next, we simulated the melt seepage rate through the pore channel, where the modeling results showed high consistency with the experiments. Finally, the effects of pore structure, kinetics, and sweating intensity on the separation and impurity migration in both crystallization and sweating processes were revealed, to guide the technical design.