Impact of Environmental Issues on Iron Removal Process Evolution in Electrolytic Zinc Production

At the end of the sixties new iron precipitation techniques as jarosite, goethite or hematite brought about the new generation of electrolytic zinc plants, thereby terminating the multitude of existing neutral leach residue treatment schemes. Since the eighties, increasing environmental impact considerations urge the conversion of these contaminated waste generating precipitation processes to techniques which either produce environmentally acceptable residues or minimize their formation thereby generating iron-bearing byproducts. Technologies identified and economically assessed include the hematite process either suitably improved or with subsequent upgrading, the iron extraction process and the direct smelting of neutral leach residue to slag and fumed zinc oxide.