Abstract

This study investigates the hydrometallurgical recovery of valuable metals from copper shaft furnace dust (SFD), a complex industrial waste containing approximately 40 wt.% Zn, 16 wt.% Pb, and 1 wt.% Cu. In contrast to conventional inorganic leaching processes that rely on aggressive acids and bases, this research explores the use of deep eutectic solvents (DESs) as eco-friendly and selective lixiviants. Deep eutectic solvents based on choline chloride combined with citric acid and lactic acid were evaluated as leaching media for metal recovery from SFD. The effects of temperature, leaching time, stirring intensity, and the DES:SFD ratio on metal extraction were systematically investigated. Analytical characterization of the raw material, leaching residues, and pregnant leach solutions was performed using Atomic Absorption Spectroscopy (AAS), X-ray Fluorescence Spectrometry (XRF), and Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy (SEM–EDS). The experimental results demonstrated efficient recovery of Zn, Pb, Cu, and Sn under mild leaching conditions. For the citric acid–choline chloride system, the highest extraction efficiency was obtained at 60 °C using a DES:SFD ratio of 30, whereas increasing the temperature to 70–80 °C did not significantly improve metal extraction. The lactic acid–choline chloride system exhibited different leaching behaviour, with the highest recoveries achieved after short leaching times. These findings indicate that DES-based systems represent a promising, sustainable alternative for the selective leaching of heavy metals such as Zn, Pb, Cu, and Sn, from metallurgical secondary raw materials, contributing to the development of greener circular economy practices.

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