卤水提锂多元新路径：技术、资源、环境和成本

传统沉淀法提锂生产周期长、不适用于低锂浓度卤水,盐湖提锂产量增长缓慢,难以满足新能源产业发展的需求。因此,开发高镁锂比卤水提锂新技术是锂产业发展的迫切需求。本文概述了吸附法、萃取法、膜法和电化学法等提锂新工艺的研究现状,发现铝基吸附剂已应用于工业生产,但其吸附容量显著地小于锰基和钛基吸附剂,而后两者的溶损和长吸附平衡时间是制约其产业化的关键。中性磷类萃取剂关注最多,但其易腐蚀和出现第三相;酰胺类萃取体系无腐蚀,已用于氯化物型卤水工业化提锂,但其稳定性需长期关注;并且萃取法工艺流程较长,酸碱消耗高。膜法无法深度除镁,需与其他方法相结合提锂,其水资源消耗量大。电渗析和“摇椅式”电化学实现了连续性提锂,加速了吸附速率,避免了洗脱剂的使用,其电耗随着优化提锂体系和工作条件的降低,电化学提锂将迎来广阔的产业前景。以上卤水提锂新工艺资源消耗和环境影响小于传统沉淀法,对高镁锂比盐湖具有显著的竞争优势,但各有弊端。因此,未来盐湖卤水提锂应加强多种新技术的集成与耦合,前移提锂过程,提升全流程锂的回收率和多种资源的综合开发。

Multiple new paths of extracting lithium from brine:Technology, resources, environment and cost

The traditional precipitation method for extracting lithium has a long production cycle, which is not suitable for brine with low lithium concentration. Therefore, the lithium output from salt lakes grows slowly and does not meet the needs of new energy industry. Therefore, there is an urgent need for the lithium industry to develop new technology for extracting lithium from brine with high magnesium lithium ratio. This paper summarizes the development of new lithium extraction processes such as adsorption, solvent extraction, membrane and electrochemical methods. It is found that aluminum based adsorbents have been used in industrial production, but its adsorption capacity is significantly smaller than that of manganese and titanium based adsorbents, and the dissolution loss and long adsorption equilibrium time of the latter two are the key factors restricting their industrialization. Neutral phosphorus extractant have attracted the most attention, but they easily corrode in the third phase. Corrosion free amide extraction system has been used to industrially extract lithium from chloride type brine, but its lack of stability demands continuing attention. Moreover, solvent extraction process has a long process flow and high acid and alkali consumption. The membrane method cannot fully remove magnesium, so it needs to be combined with other methods to extract lithium, which consumes a large amount of water resources. Electrodialysis and "rocking chair" electrochemistry realize continuous lithium extraction, accelerate the adsorption rate, and avoid the use of eluent. With the reduction of power consumption with the optimization of lithium extraction system and working conditions, electrochemical lithium extraction technology will usher in broad industrial prospects. The resource consumption and environmental impact of the above new process for extracting lithium from brine are less than that of the traditional precipitation method, which has significant competitive advantages for salt lakes with high magnesium lithium ratio, but each has its own disadvantages. Therefore, in future, lithium extraction from salt lake brine should strengthen the integration and coupling of a variety of new technologies to improve lithium extraction process, boost the lithium recovery rate and enable comprehensive utilization of various resources.