Copper nitrate for galena activation: A surface chemistry study of xanthate adsorption

The efficient recovery of lead by selective flotation of galena (PbS) is crucial, yet often hindered by its insufficient inherent hydrophobicity, necessitating surface activation. While copper sulfate (CuSO₄) is a conventional activator, the potential and mechanistic details of alternative copper salts, particularly copper nitrate (Cu(NO₃)₂), remain largely unexplored for galena activation. This study, for the first time, systematically investigates copper nitrate (Cu(NO₃)₂) as an activator for galena, focusing on its impact on surface chemistry and subsequent potassium ethyl xanthate (KEX) adsorption. Copper sulfate (CuSO₄) was employed as a well-established benchmark to evaluate the relative activation power of Cu(NO₃)₂. A suite of analytical techniques, including X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Energy-Dispersive X-ray Spectroscopy (EDS), was utilized to characterize the induced surface modifications.

Results demonstrate that Cu(NO₃)₂ facilitates KEX adsorption, leading to the formation of copper-xanthate complexes. This was supported by characteristic XRD peaks (e.g., at 2θ = 24.37°, 18.40°) and FTIR absorption bands (e.g., at 1197 cm⁻¹). SEM imaging revealed moderate surface roughening, and EDS analysis confirmed copper deposition at an atomic concentration of 0.11 %. In comparison, the benchmark CuSO₄ activation resulted in more extensive copper-xanthate formation, indicated by significantly more intense XRD and FTIR signals (e.g., 2θ = 19.63°, 28.35°), more pronounced morphological changes, a higher copper deposition of 0.39 %, and a corresponding sulfur enrichment to 50.70 % S.

These findings establish Cu(NO₃)₂ as a viable, albeit less potent activator than CuSO₄ under the studied conditions (0.11 % vs. 0.39 % Cu deposition). This research provides the first detailed surface-chemical evidence of this activation, quantifying elemental changes and highlighting the differential impact of the counterion. This work contributes foundational knowledge for optimizing flotation schemes to improve the efficiency and sustainability of lead ore processing.