Evaluation of Cyanide Leaching Behavior of Typical Associated Copper Minerals in Gold Concentrates Based on Solution Chemistry and Interfacial Physicochemical Properties Analysis

Abstract

Copper minerals associated with gold concentrates are expelled alongside cyanide tailings. During cyanide leaching, prolonged exposure to cyanide alters the surface properties of minerals significantly, complicating copper recovery. This study focuses on the typical copper minerals in gold concentrates, including chalcopyrite, bornite, chalcocite, and malachite, to thoroughly examine the cyanide pulp properties and interface changes before and after cyanidation, using methods like leaching experiments, contact angle measurements, and analyses via FT − IR, XPS, and ToF-SIMS. Pulp chemical analysis revealed that copper minerals significantly deplete cyanide and dissolved oxygen. Surface analysis reveals that cyanidation enhances the wettability of copper minerals, transitioning them from hydrophobic to hydrophilic, thereby hindering the adsorption of flotation agents. The shift may result from CN⁻ adsorption and the creation of hydrophilic compounds like CNO⁻, SCN⁻, CuCN, and CuSCN instead of iron-cyanide complexes. Further ToF-SIMS deep sputtering analysis shows that cyanide can infiltrate the surface layer of copper minerals, spreading into the bulk phase and contaminating the surface. The contaminated film’s thickness ranges from approximately 2.8–15 nm on copper mineral surfaces, complicating the copper mineral’s physicochemical properties and impacting copper recovery efficiency.