Minimum conditions for liquid-liquid mixing in continuous flow, pump-mix, agitated tanks

摘要

A study of mixture quality and performance was made by measuring the dependence of hold-up on impeller speed. Two turbine-type impeller designs, relating to industrial practice for metals extraction in mixer-settlers, were tested. The impellers were fitted with retreat, curved blades. A double shrouded, centrally located, impeller and a single shrouded, bottom located, impeller were compared. The impeller diameters were 177mm. The mixing vessel also reflected industrial practice being an unbaffled closed tank of square cross-section (300 x 300mm). The liquids were an aqueous phase containing 1percent by weight sodium sulphate and cumene as the organic phase. Aqueous and cumene dispersions were studied. Comparisons were made on the basis of the energy required to give a vessel hold-up equivalent to the flow ratio.