铝基材料裂解盐湖卤水分离镁锂的热力学研究

Thermodynamic Study on Separating Magnesium and Lithium by Aluminum-Based Materials 

中文关键词:  盐湖卤水  基团贡献法  热力学  镁锂分离  铝基材料

英文关键词:Salt lake brine  Group contribution  Thermodynamic calculation  Separation of magnesium and lithium  Aluminum-based materials 

中文摘要:

      中国盐湖锂资源非常丰富,但由于镁锂比高、镁锂性质相似而使得二者难以分离,锂资源开发利用成本较高。采用组贡献法对LiCl·2Al(OH)₃·2H₂O的标准生成吉布斯自由能Δ_fGθ298.15K进行了估算,在热力学计算的基础上绘制了298.15K时Li-Al-Cl-H₂O系和Li-Mg-Al-Cl-H₂O系的电位-pH(φ-pH)图。计算结果表明,通过调控体系的pH,可使溶液中的Li⁺与Al形成沉淀而Mg²⁺仍留在溶液中,从而实现溶液中的镁锂分离。在理论计算的基础上进行了镁锂分离的验证实验,实验结果与热力学计算结果基本吻合,镁锂分离效果良好。

英文摘要:

      The lithium resources in salt lakes are abundant in China,due to the high ratio of magnesium to lithium and similar properties of magnesium and lithium,the separation of magnesium and lithium is difficult, which limits the utilization badly.In this paper,the standard Gibbs free energy Δ_fGθ298.15K of LiCl·2Al(OH)₃·2H₂O was estimated by the φ-pH diagrams of the Li-Al-Cl-H₂O system and Li-Al-Mg-Cl-H₂O system according to the thermodynamic calculation.The potential-pH diagrams showed that LiCl·2Al(OH)₃·2H₂O in solution had a larger stable region than Mg(OH)₂.In the experiment of separating magnesium and lithium,Li⁺ was coprecipitated with the reacted aluminum by regulating the pH of the solution,while Mg²⁺ remained in solution,thereby magnesium and lithium were separated.The experimental results were roughly consistent with the thermodynamic analysis.