The oxidation of copper sulfide minerals during grinding and their interactions with clay particles

In this study, the mechanism which underpins the different interactions of chalcopyrite, a primary copper sulfide mineral, and chalcocite, a secondary copper sulfide mineral, with bentonite, a clay mineral, during the grinding with stainless steel media was investigated by a range of techniques including XPS (X-ray Photoelectron Spectroscopy) analysis, electrokinetic studies and Cryo-SEM (Scanning Electron Microscope) measurements. It was found that during grinding chalcocite was heavily oxidized but chalcopyrite was slightly oxidized. As a result of the different extent of mineral surface oxidation, chalcopyrite remained negatively charged but chalcocite became positively charged after grinding leading to the different interactions with bentonite particles. This study provides a guideline to improve the extraction of copper sulfide minerals in the presence of clay minerals, an important issue in mineral processing.

During grinding, the extent of oxidation of chalcopyrite, a primary copper sulfide mineral, and chalcocite, a secondary copper sulfide mineral is different. Chalcopyrite is slightly oxidized, while chalcocite is strongly oxidized, resulting in different interactions with bentonite, a clay mineral.Figure optionsDownload as PowerPoint slideHighlights
► Chalcocite is more oxidized than chalcopyrite during normal grinding.
► Oxidation alters the surface property of chalcopyrite and chalcocite.
► Chalcopyrite remains electrostatically repulsive from bentonite during grinding.
► Chalcocite becomes electrostatically attractive to bentonite during grinding.