An annular centrifugal contactor is a compact, combined mixer/centrifuge device that is used for solvent extraction (a.k.a liquid-liquid extraction) processes such as can be employed for recycling used nuclear fuel. The centrifugal contactor was originally developed at Argonne National Laboratory in (conjunction with Savannah River and others) in the early 70's and has been under ongoing development at Argonne and elsewhere since then.
A centrifugal contactor operates as follows:
For a very excellent review of centrifugal contactor technology please see:
LEONARD, R. “Design Principles and Applications of Centrifugal Contactors for Solvent Extraction,” in Ion Exchange and Solvent Extraction: A Series of Advances (B.A. Moyer, Ed.), 563-616, 2010.
Centrifugal contactors can also be used for oil/water separations--a commercial manufacturer of centrifugal contactors with this as the primary focus is CINC Industries. Some large CINC contactor units were sold to BP to help with clean-up of the Deepwater Horizon oil spill in 2010.