Resource utilization of copper slag: The enhanced sulfidization mechanism of Pb2+/NH4+ system on copper oxide in copper slag and its impact on flotation performance

Abstract

The hydrophilic nature of the copper oxide phase in copper slag (CS) often results in low recovery using traditional sulfidization flotation methods. This study explored the influence of Pb²⁺/NH₄⁺ on the flotation efficiency and its activation mechanism during the sulfidization flotation of copper oxide. Analytical techniques including microcalorimetry, scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM–EDS), time–of–flight secondary ion mass spectrometry (ToF–SIMS), and X–ray photoelectron spectroscopy (XPS) revealed that the treatment of Pb²⁺/NH₄⁺ enhanced the reaction between sodium sulfide and the copper oxide surface. This modification facilitated the formation of sulfide compounds such as lead–sulfur (Pb–S) and copper–sulfur (Cu–S). The formation of these sulfide products enabled the surface of copper oxide to exhibit more active sites for collector adsorption, thereby enhancing its hydrophobicity and flotation performance. Further confirmation from Fourier transform infrared spectroscopy (FT–IR) and ToF–SIMS analysis revealed that Pb²⁺/NH₄⁺ significantly enhanced the adsorption of collectors on the copper oxide surface, thereby enhancing its hydrophobicity. Micro–flotation experiments demonstrated that the incorporation of Pb²⁺\NH₄⁺ enhanced copper oxide recovery from 40 % to 91 %, which validated their effective activation role in copper oxide flotation.