Abstract: A continuous, completely jacketed countercurrent centrifugal extractor of the type utilized to mix and separate two liquids that have different specific gravities and enter through separate inlets. The extractor has at least one overflow weir in a mixing zone between the inlet for the specifically lighter and the inlet for the specifically heavier liquid phase and a division of the mixing zone into mixing-and-separation compartments. Access channels empty into the vicinity of the inner surface of a drum jacket and into that of the heavier phase, to conduct the lighter phase out of the compartment inside the hub of a conveyor worm into the initial mixing-and-separation compartment. One or more overflow channels also empty into the vicinity of the heavier phase, in the overflow weir to divert the lighter phase separated in the initial mixing-and-separation compartment into another and subsequent mixing-and-separation compartment.