Optimization of lithium extraction solar pond in Zabuye Salt Lake: Theoretical calculation combined with field experiments

Abstract

This research optimized the structure of lithium extraction solar ponds to enhance the crystallization rate and yield of Li₂CO₃. Using the response surface methodology in Design-Expert 10.0.3, the authors conducted experiments to investigate the influence of four factors related to solar pond structure on the crystallization of Li₂CO₃ and their pairwise interactions. Computational Fluid Dynamics (CFD) simulations of the flow field within the solar pond were performed using COMSOL Multiphysics software to compare temperature distributions before and after optimization. The results indicate that the optimal structure for lithium extraction from the Zabuye Salt Lake solar ponds includes UCZ (Upper Convective Zone) thickness of 53.63 cm, an LCZ (Lower Convective Zone) direct heating temperature of 57.39°C, a CO₃^2- concentration of 32.21 g/L, and an added soda ash concentration of 6.52 g/L. Following this optimized pathway, the Li₂CO₃ precipitation increased by 7.34% compared to the initial solar pond process, with a 33.33% improvement in lithium carbonate crystallization rate. This study demonstrates the feasibility of optimizing lithium extraction solar pond structures, offering a new approach for constructing such ponds in salt lakes. It provides valuable guidance for the efficient extraction of lithium resources from carbonate-type salt lake brines.