Author(s)

Fuxiang Cheng¹, Sheng Wu^1,2, Yan Liu¹, Songling Wang¹, Bo Zhang¹, Chunsheng Liao^1,2*, Chunhua Yan²

¹China Minmetals (Beijing) Research Institute of RE Co., Ltd., Beijing, China.
²Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, PKU-HKU Joint Lab on Rare Earth Materials and Bioinorganic Chemistry, Peking University, Beijing, China.

A significant development in the theory of countercurrent extraction will be presented in this article. New expressions of the term in countercurrent extraction process analysis, “Adjacent Stage Impurity Ratio” (ASIR), are deduced. Furthermore, based on the term together with mass balance and extraction equilibrium, the conditions where a given countercurrent extraction separation operation can have minimum amounts of both extracting solvent and scrubbing agent solution can be estimated, and the equations of the two minimum amounts can be deduced. It was found that the equations for a two-component separation using a single aqueous or organic feed are exactly the same as they appeared in the theory initially established in 1970s. Unlike its earlier version, the present derivation does not involve feed-stage-composition hypothesis, and also has the advantage of dealing with a double-feed system where both aqueous and organic feeds are simultaneously employed whereas the earlier theory can only analyze a separation using a single aqueous or organic feed.

Theory of Countercurrent Extraction, Minimum Amount of Extracting Solvent, Two-Component Separation, Adjacent Stage Impurity Ratio

Cheng, F. , Wu, S. , Liu, Y. , Wang, S. , Zhang, B. , Liao, C. and Yan, C. (2014) Minimum Amount of Extracting Solvent of a Separation of Two Rare Earth Components. Advances in Materials Physics and Chemistry, 4, 275-283. doi: 10.4236/ampc.2014.412030.