EIT Raw Materials RIS-DUSTREC: investigation and selection of furnace dust samples for valuable metals recovery

Abstract

Every year around 1.2 Mt of Electric Arc Furnace (EAF) dust and around 50 kt of Cupola Furnace (CF) dusts are generated in Europe. Both materials are classified as hazardous waste due to significant concentration of Zn, Cd, Cr, Ni and Pb, which burden the metallurgical industry, albeit their possibility to be considered as an alternative source of valuable metals. Around 30 steelworks in the East-Southeast European Regional Innovation Scheme (ESEE RIS) region exploit EAFs for scrap-based steelmaking. However, the dusts generated from the exhaust gases abatement cannot be profitably recycled due to the absence of recycling plants operating in these areas, which implies that the dust generators have additional costs due to the dust ransportation to the nearest Zn recovery plant, since presence of toxic substances prohibits their landfilling. Thanks to the extensive knowledge on the extraction of a wide range of compounds from steelmaking dusts, as well as the capacity of reutilisation of residues after extraction in the building and construction industry, the DustRec project aims at the recovery of all the economical compounds within the dusts (Zn, Pb, Cu, Fe and others) hence minimizing the final waste landfilling and generate an economically feasible process with improved environmental and societal impacts. The proposed approach includes several emerging techniques from innovative magnetic and gravity separation methods to new pyro- and hydro-metallurgical reprocessing technologies for the separated fractions. In this paper, eight different dusts from EAF and CF were collected all around the partners’ countries and chemically, thermally and physically characterized in order to select the most optimal samples to be reprocessed for improved valuable extractions. Due to their high concentration of ZnO and PbO, three EAF dusts were identified as promising raw materials while two CF dusts will be employed as co-adjuvant for magnetic fraction reduction and smelting. Preliminary hints about the next reprocessing steps are also revealed.