Rotary Agitated Column Extractor contains some type of rotating mechanisms to agitate the liquids as they pass through the column. Many modern differential extractor employ this method of agitation for phase dispersion.
The heavy phase enters the top of the extractor and mixes with the light phase in the top mixing region, composed of a rotating disk.
The two phases then enter the external settling stage, where they separate. The heavy phase then travels down to the next mixing region.
This mixing-settling action continues down the length of the column. Individual mixing regions are separated by baffles, and the mixing and settling regions by a stator. A stator is a portion of a cylinder that separates the two regions while allowing transport between the two.
Baffled mixing segments are common to all rotary agitated column extractor. Turbine impellers rotate between a set of baffles, creating several mixing zones along the column length.
The mixed liquids move to the outside sets of stator baffles, where they can separate out and move up or down to the next stage. The baffles help reduce axial mixing, creating several mixing zones to increase mass transfer.
A baffle turbine impeller such as the Kuhni contactor or the Scheibel column promotes radial discharge within a compartment. The Scheibel and the Oldshue-Rushton columns are common designs.