“…Mechanical agitation can promote the mass transfer rate and extractor efficiency because it increases interfacial area between the two immiscible liquids and new surfaces and high turbulence which increase mass transfer coefficients (Takahashi et al, 1993a;Horvoth and Hartland, 1985).Varieties of stirring extractors are known such as MIXCO, Kühni, RDC, ARD, QVF and mixer-settlers. As drop size decreases with agitation speed, however, the relative velocity between the dispersed phase and continuous phase decreases, which makes the throughput small (Kirou et al, 1988). Moreover, axial mixing, which lowers the stage efficiency, becomes significant at high agitation speed.…”