An apparatus is provided that is useful for effecting liquid-liquid extraction by contacting a first liquid medium with a substantially immiscible heavier second liquid medium. The apparatus includes either a single mixer-settler unit or two or more such mixer-settler units in series. Each mixer-settler unit includes a vertically extending settling tank. An elongated extraction column extends generally vertically upwardly through the settling tank bottom. The extraction column is open at its top with the top of the extraction column below the top of the settling tank. A mixer is provided in liquid communication with the extraction column for mixing the first and second liquid mediums together to form a dispersion of droplets of one of the liquid mediums in the other liquid medium and for pumping the liquid mediums through the apparatus. The dispersion flows from the mixer upwardly through the extraction column and out from its top into the settling tank. The first liquid medium separates from the dispersion, rises to the top of the settling tank and exits the settling tank from an outlet near the settling tank top. The second liquid medium separates from the dispersion, sinks to the bottom of the settling tank and exits the settling tank from an outlet near the settling tank bottom.
Liquid-liquid extraction apparatus includes an extractor unit where a first liquid contacts a second liquid so a component is transferred from the first liquid to the second liquid. The extractor unit has an inlet for the first liquid with the component in it, and an outlet for the first liquid from which the component has been removed. The extractor unit also includes an inlet for a second liquid to which component is transferred from the first, and an outlet for second liquid to which component has been transferred from the first liquid in the extractor unit. A separator having an inlet and a permeate outlet includes a semi-permeable membrane which forms a barrier between the separator inlet and the permeate outlet. The separator inlet is connected to one of the outlets of the extractor unit, and the semi-permeable membrane is permeable to most of the liquid flowing from that outlet. The membrane is substantially impermeable to any other entrained liquid, so only one liquid flows through the membrane and out the permeate outlet substantially free of any other liquid. A reject outlet opening into the separator on the same side of the membrane as the inlet permits removal from the separator liquid not passed by the membrane.
Liquid--liquid extraction apparatus includes a separator tank rotatable about an axis extending through the tank, a tank inlet for a mixture of two liquids of different densities and which are substantially insoluble in each other, a tank outlet on the axis of rotation for the light liquid, and a tank outlet spaced from the axis of rotation for the heavy liquid. In terms of method, a mixture of the two liquids is rotated about an axis extending through the mixture to cause the light liquid to concentrate at the axis of rotation, and to cause the heavy liquid to concentrate at the periphery of the rotating liquid. The light liquid is removed from the body of liquid along a flow path co-linear with the axis, and the heavy liquid is removed from the periphery of the rotating body of liquid.
