Study On The Synergistic Extraction Of Light Rare Earth By N263-P507 System

In order to eliminate the problems of excessive acidity and saponification of water phase in the extraction process of traditional extraction system,and to find a new green synergistic extraction system,this paper first discusses the extraction effect of several synergistic extraction systems for La Ce Pr Nd in Light Rare Earth.The extraction effect of N263-P507 system is better than that of single P507 system,saponification P507system,N1923-P507 system and TBP-P507 system,N263 was selected as the suitable synergistic agent.At the same time,in order to evaluate the actual effect of synergistic extraction,the effects of P507 mole fraction,oscillation time,V_o/V_a,pH,rare earth concentration on the distribution ratio of La,Ce,Pr and Nd in N263-P507 system were studied.The results show that the distribution ratio of rare earth extracted by N263 and P507 alone increases with the increase of their concentration,the ability of extracting light rare earth by P507and N263 is greater than that by any other extractant alone,and the synergistic coefficient R of La,Ce,Pr,Nd is greater than 1,indicating that N263-P507 system has a positive synergistic effect,and the maximum synergistic coefficient can be obtained when the mole fraction of P507 is about 0.5（volume ratio is 1:1）.The maximum synergistic coefficient values are 5.1,3.3,2.2 and 3.2,respectively.The N263-P507system has a positive positive synergy.7 min of oscillation time,1/2 of V_o/V_a,3.5 of pH,and the maximum distribution ratio of La,Ce,Pr,Nd was 1.2,1.2,1.3,1.35.The effects of oscillation time,V_o/V_a,pH,and rare earth concentration on the separation coefficient were studied.The results showed that the separation coefficient was proportional to the rare earth concentration,and there was no regularity between the oscillation time and the separation coefficient.When the rare earth concentration was0.52mol/L,pH value is 3.5,the oscillation time is 7 min,and V_o/V_a is 1/1,the best separation conditions are obtained,The maximum separation coefficients of Ce/La,Pr/Ce,and Nd/Pr are 7.4,4.1,and 3.2,respectively.The separation coefficients of rare earth in N263-p507 system are compared with those in P507 system,saponified P507 system and N235-p507 system.The results show that the separation coefficients of Ce/La and Nd/Pr in N263-p507 system are increased by 3.32 and 1.63 respectively compared with those in traditional P507 system,and Pr/Ce is not much different.The effect of N263-p507 system on the separation of Nd/Pr was slightly higher than that of other systems,and there was no obvious rule in other systems.Subsequently,The influence of N263-P507 system on the stripping performance was studied.The results showed that 5 mol/L hydrochloric acid was used as the stripping agent at room temperature,the stripping time was 8 min,V_o/V_a was 1/1,and the stripping rate of La Ce Pr Nd was higher.Finally,the change of extraction process was analyzed in detail by infrared spectrum,and the mechanism of synergistic action was discussed.N263,as a co extractant,has a good ability to extract hydrogen ions,which can help P507 to solve the problem of acidity in water phase.The appearance of N-H bond indicates the existence of R₄NH⁺.The reaction of P=O bond and RE³⁺,the formation of P-O-RE group and the fracture of P507 dimer shows the exist form of P507 in the extract.The coordination mode of N263-P507 system to La Ce Pr Nd is the same.The extraction mechanism is that P507 in N263-P507 system releases H⁺,after quaternary amine salt combines with protons in P507 to form cations,and then combines with rare earth anion to form R₄NH⁺·RECl^-.