Research On The Mechanism Of Ionic Liquid-Based System For Lithium Extraction From Lithium Deposition Mother Liquor

With the development of new energy industry,the demand for lithium salt products,especially lithium carbonate,has achieved "explosive" growth.There 1s still a high concentration of lithium in the lithium deposition mother liquor produced by the lithium carbonate production process,which will cause waste if it is discharged directly.However,the existing technologies such as precipitation of sodium by freezing method,precipitation of lithium by precipitation process have some disadvantages such as high energy consumption,complex process,easy introduction of impurity ions and so on,which are not suitable for industrial application.The solvent extraction method is considered to be an efficient recovery technology for lithium resources in the mother liquord due to its advantages of convenient operation and large production volume.However,the properties of mother liquor,such as alkaline,high ionic strength,low lithium/sodium ratio set a higher request to the structure and properties of the extractant.The aim of this paper is to improve the effect of solvent extraction on the recovery of lithium from lithium deposition mother liquor.According to the characteristics of lithium extraction from mother liquor,different extractants were selected and extraction systems were optimized.The influencing factors and laws of lithium extraction in different extraction systems were investigated.The thermodynamics and kinetics studies of the corresponding lithium extraction process were carried out and the mechanism of lithium extraction was proposed.In this paper,the single-stage extraction efficiency of Li+ can reach 97.83%when kerosene and ?-diketone,which have excellent extraction ability under alkaline conditions,are firstly selected as extraction system.Secondly,in order to avoid the use of volatile organic solvents,the hydroxyl-functionalized imidazolium ionic liquid was used as both solvent and extractant,and the lithium extraction efficiency reached 96.56%under the conditions predicted by the BBD model of the response surface method.Finally,four keto-functionalized ionic liquids were designed and synthesized by incorporating the structural characteristics of ?-diketone into ionic liquid.The extraction efficiency of lithium can reach 91.47%under optimized conditions.