Minimum Amounts of Extracting Solvent of (A1A2∙∙∙At−1)/(A2A3∙∙∙At) Countercurrent Extraction Separation

Minimum amounts of extracting solvent and scrubbing agent solution (denoted as Smin and Wmin respectively) mean the theoretical minimal requirements for chemicals to achieve a specified separation duty, and therefore attract more concerns in the process design of countercurrent extraction separation. Over the past decade, hyperlink extraction technology has been widely used in rare earth separation industry in China with the target to decrease chemical consumption as well as pollution discharges. However, the equations of Smin and Wmin derived in the earlier version of the theory of countercurrent extraction can only be correctly applied to two-component separation and become invalid for hyperlink processes. It is significant to develop new aspects of the theory for design of the hyperlink processes. The separation of (A1A2···At－1)/(A2A3···At) is the basic configuration in the hyperlink processes differently from in conventional processes, where A1, A2, ···, At represent different kinds of rare earth ions with the same number of valence. The separations of two and three components have been discussed and the equations of Smin and Wmin are derived in our previous works. Nevertheless, it is still significant, especially for rare earth separations, to investigate the separations with more components. The present article will therefore focus on developing new expressions for Smin and Wmin applied to the (A1A2···At﹣1)/(A2A3···At) separation. Also a five-component separation case is simulated according to the derived equations. This work is an essential part of the new theory to design the hyperlink extraction processes.