Application Of Synergistic Extraction System In The Separation Of Rare Earth And Thorium

Rare earth elements(REEs)are a group of 17 elements,involving the 15 lanthanides、scandium,yttrium,they are applied in many high-tech products because of their unique optical,electric and magnetic properties.Heavy rare earth elements(HREEs)were called "super monosodium glutamate" for manufacture,the country small reserves,low recycling rate,high value and low substitution.In the natural thorium(232Th)has important application on nuclear programs,in the south ion-absorbed type rare earth minerals there are low-level radioactive thorium mixed with in it.In this paper,the synergistic extraction and separation of HREE and Th has been investigated in detail with a view to the effective extraction and separation heavy rare earth elements and Th.Solvent extraction is an effective technology for industrial REE separation,Synergistic extraction is the most important research field in solvent extraction.The synergistic effect of extractants not only enhances the extraction efficiency but also improves the selectivity in some cases.Taking into account the possible synergistic effect,mixed extractants have attracted wide attentions for improving REE separation performances.The main disadvantage of CA-12 for the separation of hearvy rare is low separation factor,combined CA-12 and C272 can improve the separation selectivity of Y and HREE.CA-12 and C272 needed to be saponification,produced saponification wasterwater in the extraction process easily brings up environment pollution.Iron liquid can improve the problem as an novel green solvent,the research of new ABC-BIL synergistic extraction system has attracted interesting attention.Some defects in the experiment were analyzed,and the improvements were proposed.In this paper,Synergistic extraction of trivalent rare earth element(REE)from hydrochloride solution using mixtures of methyltrioctylammonium sec-octylphenoxy acetate([N1888][SOPAA])and trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylpentyl)phosphinate([P66614][BTMPP],Cyphos IL 104)has been investigated,the synergistic extraction and separation of RE has been investigated in detail,the result indicates that the IL based extraction system revealed pronouncedly synergistic effects in the extraction of Lu(Ⅲ).For demonstrating the mechanism of Lu(Ⅲ)extraction using[P66614][BTMPP]and[N1888][SOPAA],slope analysis method was used in this study.The slope indicates that the stoichiometry of[Ni888][SOPAA]with Lu(Ⅲ)is approximately 2:1,the stoichiometry of[P66614][BTMPP]with Lu(Ⅲ)is indicated to be approximately 4:1,extractants for Lu(Ⅲ)was indicated to be ion association.The interfacial properties of[P66614][BTMPP]and[N1888][SOPAA]system has been studied thoroughly,the effects of aqueous pH,the concentration of NaCl.The sequence of the separation factors of the combined[P66614][BTMPP]and[N1888][SOPAA]for HREE was achieved as follows:(3(Lu/Y)>β(Yb/Y)>β(Tm/Y)>β(Er/Y)>β(Ho/Y).It is an industrial challenge to separate Y and HREEs,because of the south ion-absorbed rare earth deposits has a abundant yttrium,Y and HREEs have similar physical and chemical properties and difficult to be separated,the problem is resolved using combined[P66614][BTMPP]and[Ni888][SOPAA]system.The loaded Lu(Ⅲ)could be full stripped when the acidities are larger than 1.0 mol/L.The results indicate this method has a potential application in heavy REE separation.A process for the separation of thorium(Th)from hydrochloride solution using combined Cyanex(?)572(C572)and C923 synergistic system has been developed.The result indicates that the combined C572 and C923 system revealed pronouncedly synergistic effects in the extraction of Th(Ⅳ).The slope indicates that the stoichiometry of C572 with Th(Ⅳ)is approximately 2:1,the stoichiometry of C923 with Th(Ⅳ)is indicated to be approximately 1:1.The interfacial properties of C572 and C923 system has been studied thoroughly,the effects of the concentration of HCl.