Utilization of Galvanizing Flue Dust Residue: A Sustainable Approach towards Complete Material Recycling

During hot-dip galvanization, wastes such as bottom dross, zinc ash, spent pre-treatment solutions, and galvanizing flue dust (GFD) are generated. In scientific publications, research devoted to GFD waste recycling is absent, and companies generating this waste require a solution to this complex problem. GFD is often landfilled in hazardous waste landfills. However, it is possible to process this waste hydrometallurgically, where GFD is first leached, the solution is refined, and finally, zinc metal is obtained by electrowinning. During specific environmentally friendly leaching, not all solid GFD is dissolved, and the aim of this study is to process the remaining solid GFD residue. The analysis shows that the GFD residue material mainly contains zinc (42.46%) in the form of oxides, but there is also a small amount of polluting elements such as Al, Fe, and Pb. This study examines the leaching of the samples in HCl and H2SO4 under different conditions with the aim of obtaining a solution with a high concentration and high leaching efficiency of zinc. The L/S ratio of 3, 4 M H2SO4, and ambient temperature proved to be optimal for the leaching of the GFD residue, where 96.24% of zinc was leached out, which represents a zinc concentration of 136.532 g/L.