Lithium carbonate recovery from lithium-containing solution by ultrasound assisted precipitation

Lithium carbonate (Li₂CO₃), one of the most important lithium compounds, is usually prepared from lithium-containing solution. The lithium recovery rate and the purity of Li₂CO₃ are highly dependent on the lithium concentration. In order to get a high lithium recovery rate, high concentrated lithium-containing solution is required, while the purity of Li₂CO₃ can be low remaining a significant amount of impurities. Usually, it is not possible to obtain high purity Li₂CO₃ by single-step precipitation with a relatively high lithium recovery rate especially from a low concentrated lithium-containing solution. In this research, ultrasound is introduced to increase lithium recovery rate and prepare industrial grade Li₂CO₃. The research found that ultrasound can significantly reduce the polymerization of Li₂CO₃ crystal particles and promote dissociation of impurity ions. At the same time, ultrasound accelerates the nucleation process of Li₂CO₃ and boosts lithium recovery rate because of cavitation. The different parameters during the Li₂CO₃ precipitation process were systematically discussed. Under the optimized conditions, the lithium recovery rate can be increased by 12% with a global lithium recovery rate of 97.4%. Li₂CO₃ with a purity higher than industrial grade can be obtained by one-step precipitation. It demonstrates a potential pathway for effective lithium recovery from low concentrated lithium-containing solution and preparation of industrial grade Li₂CO₃.