Simulation of Evaporation Ponds for Brine Concentration in the Lithium Industry

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