Study of Sulfide Ore from the Perspective of the Hierarchical Oxidation and Asymmetric Corrosion Mechanism of Minerals: (I) Chalcopyrite

It is known that sulfide minerals are affected by the pulp oxygen content during flotation, while few studies have been conducted on the specific oxidation and kinetic processes. This study adopted DO, ICP, XPS and SEM-EDS measurements to reveal the oxidation–corrosion characteristics of chalcopyrite systematically because they dominate the surface properties and flotation behavior of minerals. The results confirm the hierarchical oxidation–asymmetric corrosion characteristics of chalcopyrite firstly. More precisely, the ore-forming elements Fe and Cu are prone to corrosion under acidic conditions while S is to corrosion under alkaline conditions, and pulp aeration could further enlarge their difference of corrosion rate. Owing to their asymmetric corrosion characteristics, a “metal-deficient and S-rich” layer and a “metal-rich and S-deficient” layer are generated under acidic and alkaline conditions, correspondingly. Surface etching further revealed that the hierarchical oxidation process of Cu, Fe and S sites are Cu(I)-S → Cu(II)-O, Fe(III)-S → Fe(III)-O → sulfate and S2−→ S22−→ Sn2−→ SO42−. Moreover, the oxidation–corrosion of chalcopyrite was non-uniform, and the micro-zone of oxidation and corrosion were greatly overlapping. Finally, the hierarchical oxidation and asymmetric corrosion model was established to further promote the understanding of the oxidation–corrosion process and its impact on surface properties.