The Application Research Of Ionic Liquids On Flotation Of Lithium And Strontium And Study On The Mechanism

The application research of ionic liquid used as flotation solvent in flotation separation was discussed in this paper. Series of alkyl-imidazolium hexafluoro phosphate ionic liquids [Cnmim]PF6(n=4⁸)was choosed as representative,and the conditions apply to flotation separation of ionic liquids used as flotation solvent were examined and optimized. With an aim of lowering the density of ionic liquids,three mesures were taken into account to choose the best condition in which ionic liquids apply to be used as flotation solvent.The three methods were changing the temparature of the system,adding organic diluent into ionic liquids and adding neutral electrolyte into waiting flotation solution.Then ionic liquids flotation technology was used for the separation of lithium in the salt lake brine,and also used for the enrich of strontium in the barium titanate material.Now,the separation of lithium from the salt lake brine has become a hot topic.The salt lake brine is rich in lithium resource in China,but the proportion of magnesium and lithium is also high in QingHai brine,so the difficulty of separation on lithium from the salt lake brine is big.The system of ionoc liquids and tributyl phosphate was choosed as flotation solvent and Fe³⁺ as trapping agent for the flotation separation of lithium from the salt lake brine,the best condition of flotation on lithium was founded.The recycle of the ionic liquids system was also discussed in the experiment. The result indicated:the recycle effects of ionic liquids in flotation experiment was better than in the extraction experiment and it was also better than the system of some traditional organic solvent. The flotation mechanism was discussed preliminarily:Li+ and Fe³⁺ formed associatedmatter of LiFeCl₄ first in the solution,and then LiFeCl₄ adhered to the air bubbles. The air bubbls ruptured when they reached the organic phase.Then LiFeCl₄ coordinated with chemical bond of TBP,and LiFeCl₄·2TBP was formed and stayed in the organic phase at last,and the separation of lithium was come true.The content of strontium is one of the most important chemical character in the electronic grade high-purity barium titanate material.The determination of trace strontium has low response rate if determined directly by penetration rate higher AAS, and lots of matrix interference makes the reliability of the method is reduced greatly. In the flotation experiment ILs-EA system was choosed as flotation solvent and HTTA as trapping agent for the flotation enrich of strontium in solution,and some experimental conditions were examined and optimized. Compared with traditional organic solvent EA,TBP,MIBK,CHCl3 and methylbenzene,the result showed when ILs was used as flotation solvent,effects on strontium was best.The flotation mechanism on strontium is Sr²⁺ + 2HTTA Sr(TTA)2 + 2H+, generated associatedmatter of Sr(TTA)2 adhered to the air bubbles, and the air bubbls ruptured when they reached the organic phase., and then stayed in the organic phase at last.Ionic liquids flotation method was used for the enrich and separation of Sr in the real BaTiO3 sample,after eliminating the interference of matrix effect and titanium,the experimental result was received: the content of Sr in 20ml sample solution was 28.5μg, RSD was 2.33%,the recoveries ranged from 96.2%⁹8.6%.