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Wu S.,China Minmetals Beijing Research Institute of RE Co. | Wu S.,Peking University | Cheng F.,China Minmetals Beijing Research Institute of RE Co. | Cheng F.,Peking University | And 3 more authors.
Journal of Rare Earths | Year: 2013

Solvent extraction based on mixer-settler is the major industrial method of rare earth (RE) separation. In the mixer-settler extraction process, due to the insufficient settling time in normal circumstances, backmixing of the aqueous phase could have significant impact on the process of RE extraction separation. Therefore on the basis of the extraction equilibrium and mass balance of the mixer-settler extraction process, here we developed a mathematic expression of the aqueous phase backmixing in a two-component separation process, and obtained a quantitative analysis of the backmixing effect on the purification process by the approximations according to certain hypotheses. Two extraction systems of La/Ce and Pr/Nd separation were chosen as the examples to analyze the backmixing effect, and the results showed that the aqueous backmixing had greater influence in the scrubbing segment than in the extraction segment, especially in the system with a high separation factor such as La/Ce separation. Therefore it was suggested that the aqueous backmixing effect should be well attended in the design and application of RE extraction separation. © 2013 The Chinese Society of Rare Earths.


Cheng F.,China Minmetals Beijing Research Institute of RE Co. | Wu S.,China Minmetals Beijing Research Institute of RE Co. | Wu S.,CAS Beijing National Laboratory for Molecular | Liao C.,China Minmetals Beijing Research Institute of RE Co. | And 2 more authors.
Journal of Rare Earths | Year: 2013

Impurity components decrease stage by stage in a cascade of rare earth (RE) extraction separation, and adjacent stage impurity ratio (ASIR) which is defined as the ratio of an impurity's contents in the aqueous/organic phase of two adjacent stages can be used to evaluate the capacity of impurity removal for the two stages. On the basis of extraction equilibrium and mass balance, the ASIR in a two-component extraction separation was deducted and its simplified expressions were given for different process sections according to reasonable assumptions. The calculation simulation was then carried out to obtain the ASIR distribution in the cascade. The results showed that in both the extraction and scrubbing sections the ASIR principally increased with the decrease of the molar proportion of the impurity but along with a flat appearing in the purification zone located in the middle of the cascade. The ASIR intuitively exhibits the running status of RE extraction separation and purification, which could provide a theoretic guide for investigating the influence factors of RE extraction separation process in practical industry. © 2013 The Chinese Society of Rare Earths.


Liao C.,China Minmetals Beijing Research Institute of RE Co. | Liao C.,CAS Beijing National Laboratory for Molecular | Wu S.,China Minmetals Beijing Research Institute of RE Co. | Wu S.,CAS Beijing National Laboratory for Molecular | And 5 more authors.
Journal of Rare Earths | Year: 2013

After a review on the conventional separation process of rare earths (RE), hyperlink extraction technology was introduced and a potential process was proposed for clean separation of RE. A great amount of acid, base and water was consumed in the conventional RE separation process which included the procedures of raw material dissolving, extraction separation and precipitation. Therefore hyperlink extraction technology had been developed, by which the repeated consumption of acid and base could be avoided during the extraction process. And based on the theory and successful applications of the hyperlink extraction technology, we proposed the integral hyperlink process in which the intermediate acid resulted in individual procedures would be recycled and reused after being treated. The proposed process would make it feasible to consume no chemicals except for oxalic acid, and so could be a promising clean separation technology with a significant reduction on consumption and emission. © 2013 The Chinese Society of Rare Earths.


Cheng F.-X.,China Minmetals Beijing Research Institute of RE Co. | Wu S.,China Minmetals Beijing Research Institute of RE Co. | Wu S.,CAS Beijing National Laboratory for Molecular | Liu Y.,China Minmetals Beijing Research Institute of RE Co. | And 5 more authors.
Separation and Purification Technology | Year: 2014

A novel solvent countercurrent extraction separation technology which can dramatically save the use of acid and alkali during multi-component separation using acidic extractants, hyperlink extraction technology, has been widely applied in rare earth industry in recent years. AB/BC extraction separation is one of the important formations of hyperlink process, and is therefore discussed in this article with the target to develop the optimization theory of hyperlink extraction process. The study revealed that it can result minimum amounts of both extracting solvent and scrubbing agent solution for a given AB/BC separation using aqueous feed only when the ratio between the flowrate of central component B leaving aqueous outlet to that leaving organic outlet reaches an optimum value. This optimum flowrate ratio of B component can be decided merely by the separation factors between the components but regardless of feed composition. The minimum amount of extracting solvent can be calculated by the feed composition together with the separation factors, while that of scrubbing agent solution is only determined by the separation factor of A/C pair and irrelevant to the feed composition and the separation factors of the other pairs as well. Meanwhile the composition of aqueous stream leaving feed stage is totally same as that of the feed when the separation system is given the minimum amounts of extracting solvent and scrubbing agent solution after steady state has been reached. © 2014 Elsevier B.V. All rights reserved.


Cheng F.,China Minmetals Beijing Research Institute of RE Co. | Zhang B.,China Minmetals Beijing Research Institute of RE Co. | Wu S.,China Minmetals Beijing Research Institute of RE Co. | Wu S.,CAS Beijing National Laboratory for Molecular | And 5 more authors.
Journal of Rare Earths | Year: 2013

Computer simulation of the preparation process loading rare earth (RE) directly from acidic extractant and RE chloride was established using MATLAB software. The mechanism of the extraction reaction was assumed, and then an experiment was conducted to confirm the mechanism and the apparent equilibrium constant of the reaction was determined as well. Owing to the involvement of H+ ion in the reaction between acidic extractant and RE chloride, the computer simulation of the process was more complicated than that of the extraction only between different rare earths. In the present work, MATLAB software was therefore introduced to handle the resolution of the complicated processing equation, and the simulation was performed by varying some key parameters including feed composition and phase ratio, etc. Consequently this work presented a simple method to simulate the H+ ion involved countercurrent extraction process of rare earths and also provided the practical references for the relative process designing. © 2013 The Chinese Society of Rare Earths.

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