One of the big challenges of the solvent extractionSolvent extraction unit of the hydrometallurgical operationOperation of “La Société du Terril de Lubumbashi” in the Democratic Republic of CongoDemocratic republic of congo is the processingProcessing of a leach solution containing a relatively high level of ironIron (Fe) impurityImpurity in the electrolytic beneficiation of copperCopper (Cu). The raw material is a granular white alloy containing mostly Fe, Cu, cobaltCobalt (Co), germanium and silverSilver. The leachingLeaching strategy includes two steps. The bulk of the Fe is leached in a primary step together with Co. Cu is leached in a secondary leachingLeaching step together with germanium. This secondary leach solution contains up to 40 g/L of Fe, depending on the concentration of Fe in the fed white alloy. The solvent extractionSolvent extraction mixers and settlers were sized to minimize the aqueous entrainmentEntrainment of the leach solution in the loaded organic. A washing stage of this loaded organic was included to mitigate the transfer of Fe among other impuritiesImpurity. Cu selectivity of the extractant over Fe is evaluated to be above 3000. A formal electrolyteElectrolyte bleed, and moreover a subsidiary portion of that bleed that would be recycled to the washing stage to make it run more as an Fe scrubbing rather than a physical washing stage was not fully anticipated in the designDesign. We have run a mass balance exercise across the wash-strip-electrowinningElectrowinning circuit to quantify the electrolyteElectrolyte bleed required to control Fe concentration in the electrolyteElectrolyte around 1.5 g/L. The importance of a washing/scrubbing stage and a small electrolyteElectrolyte bleed is outlined.