Chemical Engineering Problems 4.9.4 Consider the liquid/liquid stage extraction process with an immiscible solvent shown in Figure P4.9.4. Note that stream W enters the first stage containing X, weight fraction of material A and solvents enters the last stage (1) containing Y., weight fraction of material A. As the solvent flows through the process, it retains more A, thus extracting A from W. Stage Stage 2 Stage i Stage N-1 Stage N S Y, Y w X, XN- X-1 Figure P4.9.4 Countercurrent extraction process. fraction of A in W (X). Assuming that each stage is operated at the same temperature , the relationship For each stage (i), we assume equilibrium between the weight fraction of A in S (Y) and the weight between X and Y can be given as Y = KX