A concept for the estimation of HETS for rare earth separations in extraction columns

An approach is proposed to estimate the height equivalent to a theoretical stage (HETS) for multicomponent rare earth separations in extraction columns. Based on the steady concentration profiles of rare earths in the two phases along the extraction column height and the separation factor, a graphical diagram is constructed to determine the number of theoretical stages. The ratio of the two component concentrations in the organic phase and the ratio of the two component concentrations in the aqueous phase times the separation factor are plotted against the height of the column. Rectangular steps are drawn between these two lines to determine the number of theoretical stages and thus HETS. The average HETS for Nd/Pr separation was in the range of 0.86-1.06 m under tested conditions.