Abstract: An extraction unit of the type having successively in the flow direction of the liquid, a mixer, a pre-settler and a settler, the pre-settler and the settler being separated from each other by several successive perforated partition walls, the perforations of each partition wall being laterally unaligned with the perforations of the following partition wall, the lower section of the mixer having inlets for the heavy phase and the light phase and a mechanical stirrer for mixing the heavy phase and the light phase to form a dispersion, and the upper section having at least one opening for directing the dispersion from the mixer to the pre-settler, the upper section of the settler having members for removing the separated light phase as an overflow from the settler, the lower section of which has an opening for the removal of the separated heavy phase from the settler as a controlled flow, and between the settler and the mixer there are pipes for returning part of the separated heavy and light phase from the set

Abstract: A process for removing zinc from an aqueous solution of a nickel salt by liquid-liquid extraction using as the extraction agent an organic phosphoric acid dissolved in an organic solvent, adding a strongly oxidizing substance at an elevated temperature to the aqueous phase emerging from the extraction to precipitate the cobalt as a hydroxide and decompose the organic phase left in the aqueous phase and to adsorb it into the cobalt hydroxide precipitate, and finally separating it from the pure aqueous nickel salt solution.