Synergistic activation of smithsonite with copper-ammonium species for enhancing surface reactivity and xanthate adsorption

Abstract

Copper ions (Cu2+) are usually added to activate the sulfidized surface of zinc oxide minerals to enhance xanthate attachment using sulfidization xanthate flotation technology. The adsorption of Cu2+ and xanthate on the sulfidized surface was investigated in various systems, and its effect on the surface hydrophobicity and flotation performance was revealed by multiple analytical methods and experiments. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) characterization demonstrated that the adsorption of Cu2+ on sulfidized smithsonite surfaces increased the active Cu—S content, regardless of treatment in any activation system. The sulfidized surface pretreated with NH4+–Cu2+ created favorable conditions for the adsorption of more Cu2+, significantly enhancing the smithsonite reactivity. Zeta potential determination, ultraviolet (UV)-visible spectroscopy, Fourier transform-infrared (FT-IR) measurements, and contact angle detection showed that xanthate was chemically adsorbed on the sulfidized surface, and its adsorption capacity in various systems was illustrated from qualitative and quantitative aspects. In comparison to the Na2S–Cu2+ and Cu2+–Na2S–Cu2+ systems, xanthate exhibited a higher adsorption capacity on sulfidized smithsonite surfaces in NH4+–Cu2+–Na2S–Cu2+ system. Hence, activation with Cu2+–NH4+ synergistic species prior to sulfidization significantly enhanced the mineral surface hydrophobicity, thereby increasing its flotation recovery.