Advance review on occurrence state and leaching of lithium in sedimentary bauxite (aluminum) deposits, China

Bauxite-associated type Li resource is mainly discovered in the sedimentary bauxite (aluminum) deposits forming areas, especially Northern Guizhou-Southern Chongqing, Western Henan and Central Guizhou, China. This paper reviews the enrichment mechanism and occurrence states of Li in sedimentary bauxite (aluminum) deposits. The Li in these deposits is derived from underlying carbonate rock, and the favorable sedimentary environment, e.g., alternation climate of dry and humid, the marine-continental transitional zone with reduction-weak oxidation and low salinity, is conducive to the Li enrichment in these deposits. Li is mainly hosted by independent mineral (i.e., cookeite), partly adsorbed by montmorillonite, and rarely adsorbed by illite/kaolinite. Furthermore, the leaching methods and affecting factors of Li from bauxite-associated type Li resource are summarized. Acid solution is the main leaching solution, but its excessive use can generate abundant acidic residues, which have hazards to the environment. Thereby, leaching solution with little or no acid has been recommended. The affecting factors of Li leaching are the calcination temperature, leaching temperature, leaching time, liquid–solid ration and mineral particle size. The above summary deepens the understanding of the enrichment mechanism and occurrence states of Li in the sedimentary bauxite (aluminum) deposits, and has the potential to promote Li resource, initially considered uneconomical, become an important economic source of Li.