Nickel and iron removal from concentrated chloride solutions by electrowinning

In this paper a new electrolytic concept for electrowinning of iron or iron alloys from concentrated chloride solutions is presented. The new electrolytic equipment has been developed and scaled up from laboratory to pilot prototypes with commercial size electrodes. Process operating conditions have been established in continuous runs at bench and pilot plant scale. The technology has shown a remarkable capacity to produce alloys of a wide range of compositions simply by adjusting the operating parameters. The substitution of iron-based solid wastes as jarosite, goethite or hematite, by saleable iron or iron alloy plates provide both economic and environmental attractiveness. Operating and equipment costs are described to give an introductory idea of the process economy. This emerging technology could be implemented in many processes in which iron and other non-ferrous metals (nickel, cobalt, chromium, zinc...) are either harmful impurities to be removed, or valuable metals to be recovered as a marketable iron alloy. Potential applications of this technology are: regeneration of spent etching liquors, iron removal from aqueous effluents, nickel recovery as nickel-iron alloy from concentrates without previous smelting, and others.