A future application of pulse plating–silver recovery from hydrometallurgical bottom ash leachant

In the current study, electrodeposition-redox replacement was applied to a hydrometallurgical solution with the main elements of Ca (13.8 g L⁻¹), Al (4.7 g L⁻¹), Cu (2.5 g L⁻¹), Zn (1.2 g L⁻¹), Fe (1.2 g L⁻¹), S (1 g L⁻¹), Mg (0.8 g L⁻¹), P (0.5 g L⁻¹) and Ag (3.5 ppm). The solution originated from the leaching experiment of incinerator plant bottom ash, which was dissolved into 2 M HCl media at T = 30 °C. The resulting deposit on the electrode surface was analysed with SEM-EDS and the observed Ag/(Cu + Zn) ratio (0.3) indicated remarkable enrichment of silver on the surface, when compared to the ratio of these elements (Ag/(Cu + Zn)) in the solution (6.8 × 10⁻⁵). The enrichment of Ag vs. (Cu + Zn) could be demonstrated to increase ca. 4500 fold compared to the ratio of the elements in solution.