Solvent extraction is the most important method for rare earth extraction and separation.Currently,di(2-ethylhexyl) phosphoric acid (HDEHP) and 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (HEH/EHP) are widely used in industrial production,but there are still obvious deficiencies that require further research to resolve.In this paper,the unsaponification extraction of light rare earth ions in a hydrochloric acid medium by di(2-ethylhexyl) phosphoric acid-di(1-methyl-heptyl) methyl phosphonate (HDEHP-P350) system was studied.The results show that the addition of P350 reduces the extraction capacity of HDEHP,and also greatly reduces the concentration of acidity required for the back-extraction.It still has a good separation factor for light rare earths without saponification,and the extractant is not easy to emulsify.With an aqueous phase of pH =2.85,and HDEHP mole fraction XHDEHP =0.9 (compared with O/A-2),the separation effect of light rare earth is the best,resulting in the separation coefficient βCe/La =3.39,βPr/Ce =1.67 and βNd/Pr =1.45,respectively.The loaded light rare earth ions extracted by HDEHP-P350 can be easily stripped when 2 mol/L HCl is used as the stripping agent.Finally,the extraction mechanism is discussed using a slope method,and the final structure of the extracted com-plex is determined to be RECl[(DEHP)2]2P350(o),based on a combination of infrared spectra and 1H NMR and 31p NMR analyses.

Wenjie Zhang;Dongxia Feng;Xian Xie;Xiong Tong;Yunpeng Du;Yang Cao

School of Land Resource Engineering,Kunming University of Science and Technology,Kunming 650093,China

稀土学报（英文版）

[1]Wenjie Zhang;Dongxia Feng;Xian Xie;Xiong Tong;Yunpeng Du;Yang Cao-.Solvent extraction and separation of light rare earths from chloride media using HDEHP-P350 system)[J].稀土学报（英文版）,2022(02):328-337

HDEHP,P350,HEH,unsaponification,heptyl,emulsify,XHDEHP,RECl,2P350,31p

Solvent,extraction,separation,light,earths,from,chloride,media,using,system,most,important,method,Currently,ethylhexyl,phosphoric,phosphonic,mono,ester,widely,used,industrial,production,but,there,still,obvious,deficiencies,that,further,research,resolve,In,this,paper,ions,hydrochloric,medium,by,methyl,phosphonate,was,studied,results,show,addition,reduces,capacity,also,greatly,concentration,acidity,required,back,It,good,without,extractant,not,easy,With,aqueous,phase,mole,fraction,compared,effect,best,resulting,coefficient,Ce,La,Pr,Nd,respectively,loaded,extracted,can,easily,stripped,when,HCl,stripping,agent,Finally,mechanism,discussed,slope,final,structure,plex,determined,combination,infrared,spectra,1H,NMR,analyses

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