Wang Huaiyou, Zhang Jia, Liu Xu, Ge Haiwen, Luo Zhibo, Wang Min
Key Laboratory of Green and High-end Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences Xining 810008 PR China.
Qinghai Provincial Key Laboratory of Resources and Chemistry of Salt Lakes Xining 810008 PR China.
RSC Adv. 2025 Jun 30;15(28):22376-22385. doi: 10.1039/d5ra02716k.
The tail liquid generated from lithium carbonate production in salt lake brine is termed lithium-bearing mother liquor. This mother liquor exhibits a complex composition, with the Li concentration typically around 1.5 g L, representing a significant lithium resource. Preparing lithium phosphate (LiPO) from this mother liquor is critical for efficient lithium recovery. However, the lack of data on the thermodynamic behavior and LiPO crystallization in such complex solutions has hindered the high-efficiency recovery of lithium resources. In this study, the solubility of LiO in sodium carbonate solutions was determined using the dynamic dissolution equilibrium method. The effects of temperature and sodium carbonate concentration on solubility were analyzed, and experimental data were correlated using an exponential equation. Results indicated that the solubility of LiPO in pure water and sodium carbonate solutions increases with temperature and sodium carbonate concentration. The supersolubility of LiPO in LiCl-NaCO electrolyte solutions was measured turbidimetric analysis, and the metastable zone width (MSZW) was determined. The supersolubility of LiPO significantly decreased with rising temperature. In contrast, supersolubility initially increased and then decreased with higher NaCO concentrations, with reactant concentration being the decisive factor driving the crystallization reaction. Furthermore, the MSZW narrowed at elevated temperatures. Thermodynamic functions (Δ , Δ , and Δ ) for the dissolution process were calculated the van't Hoff equation, confirming that LiPO dissolution is a spontaneous and endothermic process. Based on solubility and supersolubility data, a novel process was developed to prepare battery-grade LiPO (purity: 99.80%) from salt lake mother liquor. The results of Raman, FTIR, TG and SEM suggested that the prepared lithium phosphate was pure phase. This study provides fundamental physicochemical data and theoretical insights for the efficient separation and extraction of lithium resources from lithium precipitation mother liquor.
盐湖卤水中碳酸锂生产产生的尾液称为含锂母液。该母液成分复杂，锂浓度通常约为1.5 g/L，是一种重要的锂资源。从该母液中制备磷酸锂（LiPO）对于高效回收锂至关重要。然而，缺乏关于此类复杂溶液中热力学行为和LiPO结晶的数据阻碍了锂资源的高效回收。本研究采用动态溶解平衡法测定了LiO在碳酸钠溶液中的溶解度。分析了温度和碳酸钠浓度对溶解度的影响，并使用指数方程关联实验数据。结果表明，LiPO在纯水和碳酸钠溶液中的溶解度随温度和碳酸钠浓度的增加而增加。通过比浊分析测量了LiPO在LiCl-NaCO电解质溶液中的过溶解度，并确定了亚稳区宽度（MSZW）。LiPO的过溶解度随温度升高而显著降低。相比之下，过溶解度随着NaCO浓度的升高先增加后降低，反应物浓度是驱动结晶反应的决定性因素。此外，MSZW在高温下变窄。根据范特霍夫方程计算了溶解过程的热力学函数（Δ 、Δ 和Δ ），证实LiPO溶解是一个自发的吸热过程。基于溶解度和过溶解度数据，开发了一种从盐湖母液中制备电池级LiPO（纯度：99.80%）的新工艺。拉曼光谱、傅里叶变换红外光谱、热重分析和扫描电子显微镜的结果表明，制备的磷酸锂为纯相。本研究为从锂沉淀母液中高效分离和提取锂资源提供了基础物理化学数据和理论见解。
