Hydrometallurgical processing of EAF steelmaking fumes

Electric an: furnace dust generated during the production of steels is regarded as hazardous waste because of the presence of leachable elements such as Cr, Pb, Cd.... Different processes are available according to the management policy chosen by the steelmaker: disposal, recycle and/or recovery. The feasibility of an hydrometallurgical Zn recovery process on fumes generated during the pyrometallurgical treatment of EAF dust has been investigated. The recovery of metallic iron, chromium and nickel as molten metal provides fumes very rich in zinc oxide (63.1%) and poor in zinc ferrite. This secondary dust is still an hazardous waste and represents the raw material for the recovery of Zn and Pb. The waste material is first leached in 1.5 M sulphuric acid at 30 degrees C to provide a Zn, Fe and Mn rich aqueous solution and a Pb and Ca sulphate rich sludge. The iron is eliminated by precipitation because is harmful to the following electrowinning process. The filtered and purified leached solution is acidified in order to obtain good electrowinning conditions. A pure cathodic deposit of zinc is then produced in an electrolytic cell at laboratory scale.