基于动态降温结晶工艺的盐湖卤水镁锂分离研究

Study on Separation of Magnesium and Lithium from Salt Lake Brine Based on Dynamic Cooling Crystallization Process 

中文关键词:  盐湖卤水  分 离  非平衡  动 态  结 晶

英文关键词:Salt lake brine  Separation  Non-Equilibrium  Dynamic  Crystallization

中文摘要:

      青海盐湖卤水锂资源储量丰富,高镁锂比卤水存在镁锂分离难的问题。基于非平衡动态降温过程中不同盐组分结晶行为存在差异的原理,开展了强制分离高镁锂比卤水的研究,考察了卤水镁锂比、降温速率、流体状态和卤水温度对镁锂分离效果的影响,并分析了结晶过程中镁锂分离的介稳性特点。结果表明,通过非平衡动态降温结晶析出MgCl₂·6H₂O,可以实现卤水脱镁和镁锂分离,当降温速率为-1.25 ℃/min、卤水温度在70 ℃至50 ℃范围内,镁锂比在10∶1~80∶1时,镁锂分离因子最高可达到1.876,结晶的MgCl₂·6H₂O纯度最高为99.42%。非平衡动态降温结晶工艺相较于经典的盐田工艺,最多可将锂损失率从模拟盐田工艺的38.39%降至7.56%。该工艺为盐湖卤水镁锂分离提供了一条新的思路,也为后续高纯锂盐的制备奠定了基础。

英文摘要:

      Qinghai salt lake brine with rich lithium resources,and high magnesium-lithium ratio has the problem of difficult separation of magnesium-lithium from the brine.Based on the principle of the difference in crystallization behavior of different salt components during the non-equilibrium dynamic cooling process,this paper carried out a study on the forced separation of brine with a high magnesium-lithium ratio,and investigated the effect of brine magnesium-lithium ratio,cooling rate,fluid state and brine temperature on the separation of magnesium-lithium.The effect and the metastability characteristics of magnesium-lithium separation during the crystallization process were analyzed.The results show that by non-equilibrium dynamic cooling and crystallization to precipitate MgCl₂·6H₂O,brine demagnesium and magnesium-lithium separation can be realized.When the cooling rate is -1.25 ℃/min,the brine temperature is in the range from 70 ℃ to 50 ℃,the magnesium-to-lithium ratio is 10∶1 to 80∶1,the maximum separation factor of magnesium and lithium can reach 1.876,and the maximum purity of crystallized MgCl₂·6H₂O is 99.42%.Compared with the classic salt field process,the non-equilibrium dynamic cooling crystallization process can reduce the lithium loss rate from 38.39% of the simulated salt field process to 7.56% at most.This process provides a new idea for the separation of magnesium and lithium from salt lake brine,and also lays a foundation for the subsequent preparation of high-purity lithium salts.