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

Abstract

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 Na 2 CO 3 concentrations (1.54–2.53 mol/L) were varied. Primary homogeneous and heterogeneous nucleation zones of Li 2 CO 3 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 Li 2 CO 3 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.