Progress in liquid/liquid extraction. Liquid/liquid extraction continues to increase in importance. Classical areas of application, such as aromatic chemistry, hydrometallurgy, and reprocessing of spent nuclear fuels are being supplemented by new uses in biotechnology, in pharmaceutical production, and in water treatment. This upswing would be unthinkable without intensified R & D in chemistry and process engineering. Deeper knowledge of the physical chemistry of solvents permits purposeful choice of solvents for special separation tasks, advances in engineering elucidation of flow and mass transfer in proven and in newly designed extractors creates a basis for calculation or at least assessment criteria for the choice and operating behaviour of equipment. Yet much remains to be clarified. This article describes the current state of the art in the analysis of flow and mass transfer in countercurrent gravity feed columns with and without pulsation or agitator energy and in centrifugal extractors. A brief look at new designs demonstrates that scientific knowledge gave birth to the new ideas expressed therein.

Unpulsierte Siebbodenkolonnen fur die Fliissig/Fliissig-Extraktion zeichnen sich durch relativ einfache Bauweise und geringen Energie-Eintrag aus. Sie ermoglichen hohe flachenbezogene Durchsatze. Bisher wurden als Einbauten Lochbleche rnit Ablaufschachten ahnlich wie in der Rektifiziertechnik verwendet. Sie sorgen fur eine geordnete Stromungsfuhrung, indem die Dispersphase an jedem Boden zerteilt wird und vor dem nachstfolgenden Boden wieder koalesziert , wahrend die kontinuierliche Phase durch Ablaufschichte Verteiluncl der Tropfengrone dp /rnm