Breakthrough in the China's Separation Technology for Extraction of Rare Earth Elements

Separation technology of rare earth elements （REEs）, as the critical step in the separation process, had long been fraught with technical difficulty. A research project conducted by Baotou Shibo Rare Earth Extraction ＆ Equipment Co. Ltd., Baotou REE Research Institute, and Baotou Steel ＆ REE Group Hi-Tech Co. Ltd （Inner Mongolia）, has successfully solved the problem using a centrifugal extractor and advanced techniques to achieve a key breakthrough.

Studies on Expert System for Extraction of Rare Earths

An expert system has been developed,using LISP,for extraction of rare earths.The expert system was de- signed to mimic the deduction of chemists for rare earth separation.The knowledge base consists mainly of three parts:(1)the extractant solvents common use and the separations of the individual rare earths;(2)the recom- mendation of process for the separation of mixed rare earths with extraetant P507;(3)the evaluation of econo- my for planning to build a rare earth factory The knowledge base of this system was organized as files including frame files and rules.In addition,removing of the rules can be carried out in the file compiling window under the LISP environment.Both the forward-chaining and the reverse chaining were used simultaneously as the infer- ence strategies.The machine used was a microcomputer IBM PC-XT.

STUDY ON THE SEPARATION AND EXTRACTION MECHANISM OF RARE EARTH ELEMENTS BY MEANS OF REVERSED-PHASE PAPER CHROMATOGRAPHY

Reversed-phase paper chromatography technique is used for study on the extraction mechanism and sep- aration of rare earth elements.As the stationary phase,chromatographic paper strips are impregnated with a solution of monomyristyl phosphoric acid (MPA) in chloroform.Mineral acids are used as developers. The effect of concentration of acids and/or salts upon R_f has been investigated.According to the re- sults of R_f values for a given rare earth element in various acids,the order of extraction ability is HCl>HNO_3>H_2SO_4.A tetrad effect is clearly observed.for the R_f value of rare earth elements.The effects of other parameters on the R_f value,such as the quantities of extractant retained by the paper and the temperature are also examined.Based on the determination of the molar ratio of MPA to rare earth elements and the number of H^+ ions released in extraction reaction,a reasonable mechanism is proposed.The mutual separation of heavy rare earth elements will be better than that of the light rare earth group because of the larger separation coefficient of the former.A mixture of Ho-Er-Tm-Lu is successfully separated by the present method.

Study on separation technology of Pr and Nd in D_2EHPA-HCl-LA coordination extraction system

The separation coefficient of Nd/Pr was lower in D2EHPA-HCl system. Pointing to this problem,the effect of the acidity of feed and the concentration of lactic acid on the distribution ratio,separation coefficient and extraction capacity was investigated in unsaponified D2EHPA-HCl-LA system,and the regression equations were calculated in this paper. The results showed that the distribution ratio and separation coefficient both increased with decreasing of feed acidity and increasing of the lactic acid concentration,and the extraction capacity increased with increasing of lactic acid concentration in D2EHPA-HCl-LA system. When the pH value of the feed was 3.5 and lactic acid concentration was 0.6 mol/L,the max separation coefficient was 1.57,and the extraction capacity was 27.87 g/L.