Simulation of Evaporation Ponds for Brine Concentration in the Lithium Industry

Abstract

The Pitzer model was integrated with ion massbalances to simulate brine composition and predict the precipitationof salts during evaporation using the Salar de Atacama brinecomposition. Adding CaCl2 induces early gypsum (CaSO4·2H2O)precipitation, reduces the sulfate content, and prevents late-stagesulfate salt formation. The thermodynamic approach was thenintegrated with the seasonal evaporation rate, estimated with thePenman model, within a mass balance framework for a single pond.Halite (NaCl) and gypsum remained in equilibrium, while KClremained undersaturated for most of the year, showing sensitivity toinventory volume and seasonality. In a three-pond system, KClreached saturation in the last pond, while gypsum precipitated earlyand halite formed continuously throughout the system. Pulsed feedflow strategies adapted to seasonal changes effectively controlled the KCl saturation location. This integrated approach offers insightinto salt behavior and supports the optimization of pond design and operation in lithium extraction.