LIQUID-LIQUID EXTRACTION

摘要

The invention provides a process and apparatus for liquid-liquid extraction in which a first liquid phase is passed continuously through a series of extraction stages (10) whilst a second liquid phase is passed continuously through the series in counter-current to the first phase. In each stage the second phase is dispersed as by a sieve plate (11) and then allowed to coalesce into a settled body (14) from which the second phase is withdrawn and passed to the next adjacent stage. The invention is characterised by the fact that the flows of the two phases in each stage are generally transverse to each other. Preferably the first phase flows through the series of stages under gravity whilst the second phase is pumped (16) from stage to stage to control its inter-stage transfer. The invention combines the features of separate control of residence time characteristics of an extraction column with the safety aspects inherent in a mixer/settler battery.