Extraction of lithium from bittern

With tri-butyl-phosphate(TBP) as extraction reagent,mineral spirit(200#) as dilution reagent and FeCl3.6H2O as co-extraction reagent,the extraction of lithium from Qinghai salt lake was studied.The effect of TBP concentration on extraction rate,and the effect of phase ratio on extraction rate and distribution ratio were analysed.The results show that the concentration of hydrogen ion in water phase is a very important factor,and a proper concentration of hydrogen ion not only ensures that lithium ion enters into organic phase and decreases the complexing of hydrogen ion and organic solvent,but also assures iron ion against hydrolyzing.The optimum parameters in the solvent extraction process are as follows: the phase ratio is 1.5,the molar ratio of Fe3+ to Li+ is 1.3,TBP concentration is 60%,the concentration of hydrogen ion in water phase is 0.05 mol/L.Under the above conditions,the extraction rate of lithium can reach 80%,the separating effect of lithium with magnesium is good,and a high pure Li2CO3 can be made from the extracting solution after washing and demagnesium deeply.