Recovery of Lithium Using Tributyl Phosphate in Methyl Isobutyl Ketone and FeCl3

Lithium recovery from salt-lake brines was explored using the extraction equilibria of lithium with tributyl phosphate (TBP) in methyl isobutyl ketone (MIBK), with FeCl3 coextractant, for various volume concentrations of TBP, molar ratios of Fe to Li, and volume ratios of the organic to aqueous phases. Washing and stripping equilibria of magnesium and lithium ions with HCl, NH4Cl, and LiCl/HCl and NH4Cl/HCl combinations were investigated. The extraction of lithium ions from salt-lake brines was successful. NH4Cl was a suitable washing agent for magnesium ions but not for stripping lithium ions into the aqueous phase. HCl can wash magnesium ions and strip lithium ions but corrodes equipment. The LiCl/HCl and NH4Cl/HCl combinations reduced equipment corrosion and washed and stripped magnesium and lithium ions, respectively, at appropriate volume ratios. MIBK loss was reduced using high-salinity solutions and large volume ratios during extraction and adjusting the volume ratio and overall chloride-ion concentration during washing/stripping.