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What is an Annular Centrifugal Contactor?

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:
  1. Flows of immiscible liquids enter the annular mixing region
  2. Mixing occurs and dispersion forms in annulus by shear induced by the spinning rotor
  3. Stationary vanes under rotor break rotation and force liquid into the hollow rotor
  4. Rotor acts as centrifuge separating phases and pumps fluid upward
  5. Phases flow over weirs into collector rings and out
Here is a flash animation of how this works (this and others can be found at 

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.