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.