Iranian Journal of Chemical Engineering (IJChE)

Abstract In this investigation, in order to study the effect of hydrodynamic parameters such as impeller speed and hold-up, two series of experiments have been performed with a single stage horizontal mixer-settler equipped with 2 four-blade impellers. In the first series, 15 experiments were carried out with toluene/water system and in the second series, 60 experiments were carried out with toluene/acetone/water system. Results show that in both systems, when the hold-up is constant, the mean drop size decreases with increasing impeller speed and when the impeller speed is constant, the mean drop size increases with increasing hold-up, however, these manners for any system are different quantitatively. It shows that with the addition of solute (acetone) concentration in the system, the mean drop size decreases. The experimental results were compared with the Desnoyer and Quadros models, of which the Quadros model has a little
deviation from Desnoyer model.

Abstract The effects and influences of various operational parameters on the efficiency of mixer-settlers are thoroughly studied in this paper. One of the most important factors in designing a mixer-settler is to obtain an optimum operational extraction and overall efficiency. These two factors are dependent on various parameters such as impeller shape, size and speed of impeller, baffle size, residence time, volumetric flow rates and the ratio of heavy to light phases. In this paper, the effect of impeller speed and volumetric flowrates of two phases on efficiency are studied. Also, the effect of hold-up of each stage upon stage efficiency is studied. According to the above experiments and achieved results, it can be concluded that in general, an increase in impeller speed and solvent amount results in an increase in extraction efficiency. Also, when hold-up of the dispersed phase decreases, the stage efficiency usually increases up to a certain point.