Apparatus and process for countercurrent liquid-fluid extraction

Claim 1

IN A PROCESS FOR COUNTERCURRENTLY CONTACTING A LIGHT FLUID WITH A RELATIVELY DENSE LIQUID WHICH IS SUBSEQUENTLY IMMISCRIBLE WITH THE LIGHT LIQUID IN A VERTICALLY ELONGATED COLUMN HAVING VERTICALLY SPACED PERFORATED PARTITIONS DIVIDING THE COLUMN INTO A PLURALITY OF CONTACT ZONES, THE METHOD WHICH COMPRISES INTRODUCING SAID DENSE LIQUIDS INTO THE UPPERMOST CONTACTING ZONE FOR DOWNWARD FLOW THROUGH THE COLUMN, INTRODUCING SAID LIGHT FLUID INTO THE LOWERMOST CONTACTING ZONE FOR UPWARD PASSAGE THROUGH THE COLUMN, MAINTAINING IN EACH OF THE CONTACTING ZONES A LOWER LAYER OF THE DENSE LIQUID AND AN UPPER LAYER OF THE LIGHT FLUID SEPARATED BY AN INTERFACE THEREBETWEEN, PASSING LIGHT FLUID IN SUBDIVIDED FORM FROM THE UPPER LAYER IN EACH OF SAID ZONES EXCEPT THE UPPERMOST THROUGH THE DENSE LIQUID LAYER IN THE NEXT HIGHER ZONE AND THEN INTO THE LIGHT FLUID LAYER IN THE LAST-NAMED ZONE, WITHDRAWING DENSE LIQUID AT THE INTERFACE IN EACH ZONE EXCEPT THE LOWERMOST AND PASSING THE SAME DOWNWARDLY THROUGH AND OUT OF CONTACT WITH THE DENSE LIQUID LAYER IMMEDIATELY BELOW SAID INTERFACE AND DOWNWARDLY THROUGH AND OUT OF CONTACT WITH THE LIQUID FLUID LAYER BELOW THE LAST-NAMED DENSE LIQUID LAYER INTO THE NEXT LOWER DENSE LIQUID LAYER IN THE COLUMN, MAINTAINING THE INTERFACE IN SAID LOWERMOST ZONE AT A SUBSTANTIALLY CONSTANT LEVEL WHEREBY THE INTERFACE IN EACH OF THE UPPER ZONES REMAINS AT A SUBTANTIALLY CONSTANT PREDETERMINED LEVEL, REMOVING THE CONTACTED LIGHT FLUID FROM SAID UPPERMOST ZONE AND FROM THE COLUMN, AND WITHDRAWING THE DENSE LIQUID FROM THE LOWERMOST ZONE AND FROM THE COLUMN.