Hydrometallurgical extraction of zinc from wastes: optimization, feasibility and practical sustainable approach

This research proposes a practical method for extracting zinc from leaching residues at ALZINC Ghazaouet - Tlemcen (Algeria), which can improve the yield of waste recovery during the wet treatment of zinc ore. The quality of the blende and calcine (grilled) in terms of elemental chemical composition was identified using X-ray fluorescence (XRF) and residues containing 20.02 wt% Zn and 20.24 wt% Fe were determined by volumetric analysis. The experimental protocol was established in two successive stages in order to optimise the operating conditions of the ammonium salt-based jarosite process. The best process yield with 17.02% zinc recovery from residues was obtained under operating conditions of pH 1.5 (190 g/L H₂SO₄), a temperature of 90 °C, 800 mg of (NH₄)₂SO₄ and a reaction time of 300 min. The microstructure and elemental distribution of the materials studied were examined using a scanning electron microscope (SEM) coupled with energy dispersive spectroscopy (EDS) and mapping. A qualitative analysis of the samples was performed using X-ray diffraction (XRD). This analysis, combined with Rietveld refinement, confirmed the effectiveness of the treatment thanks to the quality of the obtained product (Zinc), with a purity of 99.995% and an estimated average grain size of 11 μm.