Counter current diffusion extractor

A counter current extractor comprising:

• an elongate housing in the form of a trough or tube and having an inlet at or adjacent one end and an outlet at or adjacent the other end, the longitudinal axis of the housing being inclined upwardly from the one end to the other end, a screw conveyor having at least one substantially helical flight disposed within the housing and rotatable about its longitudinal axis for moving material to be extracted, which has been introduced into the housing through the inlet, from the said one end to the said other end of the housing, means for introducing an extracting liquid into the said other end of the housing in a manner such that introduced fluid will flow down the housing to the one end thereof and in counter current with the material being extracted, drive means for causing the screw conveyor to rotate and for causing the direction of rotation of the screw conveyor to be intermittently reversed while providing a net forward motion of material to be extracted from the one end to the other end, and means being provided for withdrawing extracting liquid from the housing at a point at or adjacent the one end thereof, for heating the withdrawn liquid, and for returning the heated liquid into the housing such that the returned heated liquid will contact the material being extracted.