Minimum amount of extracting solvent for AB/BC countercurrent separation using aqueous feed

• Published in: Separation and purification technology 2014-06, Vol.131, p.8-13
• Main Authors: Cheng, Fu-Xiang, Wu, Sheng, Liu, Yan, Wang, Song-Ling, Zhang, Bo, Liao, Chun-Sheng, Yan, Chun-Hua
• Format: Article
• Language: English
• Subjects: 3-Component separation; Countercurrent extraction; Extraction; Hyperlink process; Minimum amount of extracting solvent; Optimization; Outlets; Rare earth metals; Rare earths; Scrubbing; Separation; Solvents; Steady state
• ISSN: 1383-5866; 1873-3794
• DOI: 10.1016/j.seppur.2014.04.031

•Greatly advancing countercurrent extraction theory.•Giving the condition on which AB/BC separation uses minimum extracting solvent.•Giving the equation of minimum amount of extracting solvent for AB/BC separation.•Presenting a theoretical basis for optimizing a multi-component separation. 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.