Recovery of lithium from alkaline brine by solvent extraction with β-diketone

Abstract

Lithium recovery from alkaline brines by counter-current method using β-diketone was investigated. By comparing effect of different co-extractants and diluents on lithium extraction, HBTA-TOPO-kerosene system was determined as the extraction system.In extraction process, 0.4mol/L HBTA and 0.3mol/L TOPO in kerosene performed as extractant and three theoretical stages were required to reach 95% extraction according to McCabe Thiele diagram. 1mol/L HCl and 3mol/L HCl solution were used as scrubbing agent and stripping agent respectively. In regeneration stage, 2mol/L NaOH was used as regeneration agent to remove free acid entrained in organic phase and exchange H+ of hydroxyl. Bench experiments indicated that the respective number of extraction, scrubbing, stripping and regeneration were 3, 1, 2 and 1 stage.A 7-stage extraction process was conducted in a mixer-settler for 30h to reach stable state, average extraction rate of lithium was 96% and lithium concentration in stripping solution was 15g/L. Concentration of impurity ions in stripping liquor was <1g/L. No third phase or emulsification was observed during the operation. In summary, HBTA-TOPO-kerosene extraction system was verified an effective method to recovery lithium from alkaline brine.