Temperature Variation, Complex Formation, and Creation of Supersaturation During Reaction Crystallization of Lithium Carbonate in Aqueous Lithium Chloride Solution by Feeding Sodium Carbonate Solution at Constant Rate
Keshra Sangwal, Ewa Mielniczek‐BrzóskaABSTRACT
Experimental results of the variation of temperature T s of water and aqueous LiCl solution with the feeding Na 2 CO 3 solution at a constant rate R B during the reaction crystallization of Li 2 CO 3 are presented and discussed from the standpoint of the creation of supersaturation in the solution. The origin of the variation of temperature of water and LiCl solution with the feeding of Na 2 CO 3 solution from consideration of chemical reactions, the relationship of temperature T s and pH of water and LiCl solution with the feeding of Na 2 CO 3 solution, and the nature of complexes existing in the solution and their role in the creation of supersaturation are analyzed and discussed. Analysis of variation of temperature T s and pH of LiCl solution with the feeding duration t of Na 2 CO 3 solution shows that the minimum temperature T min is associated with the creation of solubility of Li 2 CO 3 in the solution due to the formation of HCO 3 − ions by the hydrolysis of CO 3 2− ions required for the formation of neutral solvated Li 2 CO 3 0 associates, followed by subsequent insignificant increase in T s due to the formation of practically constant concentration of neutral solvated Li 2 CO 3 0 associates, independent of the concentration c B of Na 2 CO 3 solution, for the onset of three‐dimensional (3D) nucleation.