Abstract:

The preparation of high-purity lithium carbonate from secondary lithium resources is of great significance for efficient resource utilization and green recycling. The conventional carbonation process typically uses CO₂ bubbling, but its low mass transfer efficiency and slow reaction rate restrict industrial application efficiency. To this end, this study used the CO₂ microbubble carbonization method to improve the mass transfer rate, focusing on the effects of reaction time, CO₂ gas flow rate and liquid-solid ratio on lithium carbonate conversion and CO₂ utilization, and constructed a dissolution reaction kinetic model. The results show that compared to the bubbling process, the microbubble carbonation method improves lithium carbonate conversion by approximately 20% and reduces carbonation time by about 56%. Under optimal conditions of a reaction time of 100 min, CO₂ flow rate of 120 ml/min, and liquid-solid ratio (ml/g) of 30∶1, lithium carbonate conversion reaches 99.91%, and CO₂ utilization rate achieves 94.10%. Kinetic calculations based on the shrinking core model indicate that the dissolution rate follows the film diffusion control model, with activation energy of -2.456 kJ/mol. This research provides fundamental data and process support for the deep carbonation dissolution process of crude lithium carbonate.

Key words: secondary lithium resources, crude lithium carbonate, CO₂ microbubbles, dissolution, kinetics

摘要：

二次锂资源制备高纯碳酸锂对于资源高效利用和绿色循环具有重要意义，上述过程一般采用CO₂鼓泡法进行碳化，但该过程传质效率低、反应速率慢，限制了其工业应用效率。为此，本研究采用CO₂微气泡碳化方法以提高传质速率，重点考察了反应时间、CO₂气体流量和液固比等因素对碳酸锂转化率和CO₂利用率的影响，并构建了溶解反应动力学模型。结果表明，微气泡碳化与鼓泡工艺相比，可使碳酸锂转化率提高约20%、碳化时间降低约56%；反应时间100 min、CO₂流量120 ml/min和液固比（ml/g） 30∶1条件下，碳酸锂转化率达到99.91%、CO₂利用率为94.10%；缩核模型动力学计算结果表明溶出速率符合膜扩散控制模型，该过程反应活化能为-2.456 kJ/mol。研究可为粗碳酸锂深度碳化溶解过程提供基础数据和工艺支撑。

关键词: 二次锂资源, 粗碳酸锂, CO₂微气泡, 溶解, 动力学