Recycling of cupola furnace dust: Extraction and electrodeposition of zinc in deep eutectic solvents

Abstract

The dust waste formed during cast iron making in cupola furnace is rich in zinc and iron. High zinc content hinders recycling of this dust in iron/steel-making processes, and large amounts of cupola dust are landfilled although the dust contains some environmentally harmful elements such as Pb and Cr. This paper presents preliminary results of a novel recycling approach to recover zinc from cupola dust. The dust was firstly dissolved in a deep eutectic solvent (DES) composed of 1 M choline chloride:1.5 M urea:0.5 M ethylene glycol. The DES extracted 38 wt% of Zn present in the dust when stirred for 48 h at 60 °C. The resultant electrolyte was then subjected to cyclic voltammetry (CV) measurements to characterize its electrochemical behaviour. Bulk zinc layers were electrodeposited with a high current efficiency from the DES electrolyte via application of moderate static reductive potentials. SEM/EDX investigations showed that Zn layers deposited at moderate reductive potentials revealed high purity with fine and smooth morphology. The approach presented was suggested to be promising because it enables direct electrowinning of valuable Zn. Furthermore, the Fe-rich dust residue with lower Zn content can be recycled in cupola furnace or in other iron/steel-making processes.