A comprehensive review of processing strategies for iron precipitation residues from zinc hydrometallurgy

Comprehensive amounts of valuable elements are lost due to the disposal of waste materials which are generated during the hydrometallurgical production of zinc. Those wastes, mainly jarosite or goethite, are predominantly immobilized and disposed on open landfills whereby the contained elements are not extracted. Several strategies were investigated to face increasing needs regarding ecological and economical improvements of the current situation. This review compares processes for immobilization and hydro-, as well as pyrometallurgical treatments of iron precipitation residues. The Jarofix process to immobilize jarosite waste is widely used to generate a product with good elution properties for subsequent safe disposal. It is the only accepted and used method for the dedicated treatment of jarosite, resulting in significant losses of valuable metals and land use in the course of the disposal procedure. A few pyrometallurgical processes are in operation which use top submerged lance reactors or waelz kilns for the co-treatment of jarosite waste on industrial scale. However, a broad variety of hydrometallurgical and pyrometallurgical strategies for the utilization of iron precipitation residues was pursued solely on a laboratory scale. Due to intensifying ecological restrictions and the geographic concentration of critical elements like indium, silver, gallium and germanium, the recycling of jarosite and goethite is constantly being more focused. This literature review gives a comprising overview on strategies which were developed for the processing of those waste materials.