Effects of the Chemical Compositions of Salars de Uyuni and Atacama Brines on Lithium Concentration during Evaporation

During L i recovery from salar brines, L i concentration is typically increased to about 60,000 mg L −1 by evaporation. We investigated the concentration changes of L i, N a, K , M g, C l, SO 4 , and B during evaporation of both natural U yuni and artificial Atacama brines. The U yuni brine exhibited a maximum L i concentration of 6810 mg L −1 at 31 days of evaporation, at which point the majority of the N a and K in the brine was removed. The L i concentration decreased with further evaporation due to precipitation as Li 2 SO 4 , such that the level at the 56 day mark was approximately 4130 mg L −1 . In contrast, the artificial Atacama brine showed no pronounced L i precipitation, even after 54 days, at which point the L i concentration was 21,800 mg L −1 . The initial concentrations of N a and K in the Atacama brine were higher than those in the U yuni brine, and the A tacama solution still retained K after 54 days of evaporation. The order of precipitation of cation species during the evaporation of both brines was: N a, followed by K , M g, and L i. Thus, L i precipitation in the Atacama brine might be prevented due to the more favored precipitations of N a and K , such that significant L i removal did not occur in this brine.