Recent advances in lithium extraction from lithium-bearing clay minerals

The metallic element lithium (Li) has become a strategically prominent element in many fields which has caused significantly increased demand for Li-related resources. The main Li-bearing clay minerals in nature are lepidolite (polylithionite and trilithionite), zinnwaldite, masutomilite, swinefordite, hectorite, cookeite and jadarite. They have a relatively simple structure and are widely distributed in Asia and America, becoming a new Li resource. This review highlights the structures and properties of Li-bearing clay minerals and summarizes the advantages and deficiencies of five extraction methods. It was concluded that the main Li-bearing clay minerals have a 2:1 layered structure. The Li+ can enter the interlayer space in clay minerals and be fixed in the mineral crystals through mineralization or isomorphism. Among the extraction methods, acidification is a relatively mature technique that could achieve relatively low energy consumption and high extraction efficiency. Therefore, the acidification method is considered the main technique for Li extraction from Li-bearing clay minerals. However, the reaction mechanism, process optimization, equipment design, reagent recovery, and waste disposal need further improvement. Future recovery methods should pay more attention to the safe treatment and further reuse of residue and waste. This review presents the methods for extracting Li from Li-bearing clay minerals and a comparative discussion of the principles of the extraction methods reported in recent literature, which will provide significant insights into efficient Li extraction.