When operating as a centrifugal extractor for performing liquid-liquid extractions, a feed solution, containing one or more solutes (shown in yellow), and an immiscible solvent (shown in blue) with a different density than that of the feed solution are fed to the mixing chamber located on the bottom of the centrifuge housing.

A rotating agitator disc mixes the two immiscible liquids into a dispersion (shown in green). Different agitator disc designs can be used depending upon the liquids' interfacial tension. The efficient mixing creates a large interfacial area between the two liquids to ensure maximum mass transfer of the solutes.

The dispersion is aspirated into the centrifuge bowl by a turbine located on the bottom of the rotating bowl. The liquids are separated by the centrifugal force generated by the rotating bowl. The heavier liquid (shown in yellow) occupies the outer portion of the bowl. The light liquid (shown in blue) occupies the inner portion of the bowl.

The position of the liquid / liquid interphase is regulated by a heavy phase weir. Interchangeable heavy phase weirs of different diameters accommodate a wide range of density ratios. The heavy phase underflows to a static receiving chamber. The light phase overflows to a separate static receiving chamber.

The liquids are discharged by gravity to the next BXP centrifugal extractor or to downstream equipment. For multi-stage extraction processes, Rousselet Robatel Model BXP centrifugal extractors can be installed in series to provide the required number of stages. No interstage pumps are required between the extractors.

The external interstage piping allows liquids to be fed into or routed out of the extraction process (main extraction, scrubbing, back-extraction) as required for optimum flexibility.