China Nonferrous Metallurgy

In nature, lithium-bearing clay minerals primarily include lepidolite (polylithionite and trilithionite), zinnwaldite, hectorite, saponite, and others. This article reviews the structure and properties of lithium-bearing clay minerals and compares treatment processes such as acidification and alkalization. Studies indicate that most lithium-bearing clay minerals have a 2∶1 layered structure, where a layer of aluminum-oxygen octahedra is sandwiched between two layers of silicon-oxygen tetrahedra. This structure provides space for the intercalation of lithium ions. Lithium ions can be fixed in the interlayer positions of the mineral crystals through mineralization or isomorphous substitution, thereby achieving lithium enrichment. Currently, the treatment processes for lithium-bearing clay minerals mainly include acidification and alkalization methods. Both methods rely on chemical reactions between acids or bases and the lithium in the minerals to dissociate lithium ions from the mineral structure, enabling lithium extraction. However, these methods also face several challenges that need to be addressed. In terms of reaction mechanisms, the current understanding of the microscopic processes of acid-mineral interactions is not yet thorough, which limits the potential for further process optimization. In process optimization, improving lithium extraction rates, reducing acid consumption, and shortening reaction times are key areas of research. In equipment design, existing setups may not fully meet the specific requirements of acidification methods. Additionally, reagent recovery and waste treatment are significant factors restricting the large-scale application of acidification methods. Therefore, efficiently recovering reagents and safely managing waste are critical challenges that need to be addressed in the future.