A novel countercurrent liquid-liquid extractor is presented and illustrated with applications. The apparatus consists essentially of an assembly of mixer-settlers, feeders, reservoirs, and flow lines that are made of glass or other chemical resistant materials. In operation this multistage assembly rotates intermittently in one direction on a horizontal axis causing the immiscible phases to progress to opposite ends of the unit. Details for the construction of the extractor and its principles of operation are given. Extractors of this design are applicable to experimental work and to the preparation of pure compounds in quantity.
Wilhelm, Harley A. and Foos, Raymond A., "A countercurrent liquid-liquid extractor" (1954). Ames Laboratory ISC Technical Reports. 76.