Reactive Crystallization Process of Li2CO3 from LiCl and Na2CO3 Mechanism and Modeling

The main process to obtain lithium carbonate from brines is based on the reaction of lithium chloride with sodium carbonate. The present work seeks to find the most favorable conditions to produce lithium carbonate from industrial lithium chloride brines and sodium carbonate solutions. To this end, a 400 mL mechanically stirred batch crystallizer was employed to feed the sodium carbonate solution over the lithium brine in stoichiometric amounts. The reaction temperature (55–85 °C), stirring rate (300–400 rpm), and LiCl and Na2CO3 concentrations (1.54–2.53 mol/L) were varied. Primary homogeneous and heterogeneous nucleation zones of Li2CO3 were determined as functions of the degree of supersaturation and temperature. Crystal growth likely has a two-dimensional (2D) nucleation-mediated mechanism. A temperature increase enhances the Li2CO3 crystallization yield, slightly increases its purity, and generates a small particle size reduction. A rise in chemical concentration makes the crystallization yield and particle sizes increase, while it also produces lower purity percentages from the product. An increase in stirring rate causes a slight improvement in product purity, a small decrease in size, and no significant effect on crystallization yield.