Slip velocity within mixer and through the column has been measured in a pilot plant Hanson mixer-settler column by using three different liquid-liquid systems with and without mass transfer conditions. The effects of agitation speed, dispersed and continuous phase flow rates, interfacial tension and mass transfer on slip velocity have been investigated under a variety of operating conditions. Two empirical correlations for prediction of the slip velocity within mixer and through the column are recommended in terms of physical properties of liquid systems and operating variables excluding holdup. The prediction of slip velocities from the presented correlations is in good agreement with experimental results.La vitesse de glissementà l'intérieur du mélangeur et dans la colonne aété mesurée dans une colonne de mélangeur-décanteur Hanson en installation pilote en utilisant trois systèmes liquide-liquide différents avec et sans conditions de transfert de masse. Les effets de la vitesse d'agitation, des taux d'écoulement des phases dispersées et continues, de la tension interfaciale et du transfert de masse sur la vitesse de glissement ont etéétudiés sous une variété de conditions de fonctionnement. Deux corrélations empiriques pour la prédiction de la vitesse de glissementà l'intérieur du mélangeur et dans la colonne sont recommandées en termes de propriétés physiques des systèmes liquides et de variables de fonctionnement excluant la retenue. La prédiction des vitesses de glissementà partir des corrélations présentées s'accorde toutà fait avec les résultats expérimentaux.

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-The volumetric overall mass transfer coefficients in a pilot plant Hanson mixer-settler extraction column of seven stages have been measured using toluene-acetone-water system. The effects of agitation speed and dispersed and continuous phases flow rates on volumetric overall mass transfer coefficients have been investigated. The results show that the volumetric overall mass transfer coefficient increases with increase in agitation speed and reaches a maximum. After having reached its maximum, it falls with further increase in agitation speed. It was found that the volumetric overall mass transfer coefficient increases with increase in dispersed phase flow rate, while it decreases with increase in continuous phase flow rate. By using interfacial area, the overall mass transfer coefficients for continuous and dispersed phases are determined from volumetric coefficients. An empirical correlation for prediction of the continuous phase overall mass transfer coefficient is proposed in terms of Sherwood and Reynolds numbers. Also the experimental data of the column investigated are compared with data for various extraction columns. Comparison between theoretical models and experimental results for the dispersed phase mass transfer coefficient shows that these models do not have enough accuracy for column design. Using effective diffusivity in the Gröber equation results in more accurate prediction of overall mass transfer coefficient. The prediction of overall mass transfer coefficients from the presented equations is in good agreement with experimental results.