Kinetics of droplets' sedimentation in a continuous gravity settler

Extraction experiments of phosphoric and chloric acids from isoamyl alcohol by water were conducted in an impinging-stream reactor with thin films (Berman & Tamir (AIChE J. 46 (2000) 769; Can. J. Chem. Eng. 79 (2001) 305)). Phase separation was achieved in a regular gravity settler shown in Fig. 1. Extraction efficiency of about 100% was achieved, and mass transfer coefficients were higher by comparison to regular devices by a factor of 100-200. The limiting zone in the settler was the "sedimentation zone", typical to the present chemical system as well as similar ones. A model was established for the "sedimentation zone". It is based on known theories of droplets' motion in a liquid, on a special method which was developed here to determine the fractions of the dispersion phase moving upwards and downwards, as well as on a new approach to determine the droplets diameters. Experimental results substantiated the validity of the suggested model.