Thermal and Spectroscopic Feature of the Cu3AsS4 Enargite Oxidation Up to 800°C. Implications in the Arsenic Evolution

The thermal oxidation of enargite (Cu₃AsS₄) from Chuquicamata (Chile), has been studied between RT and 800°C. Enargite samples were heated in air atmosphere and analyzed by means of several physicochemical techniques such as XRPD, SEM-EDS, FTIR, XPS and chemical analysis. A surface digenite formation was observed in a first step. The XPS technique was particularly useful to correlate the copper oxidation with the As-O-Cu interaction, responsible for the continuous and slow As evolution up to temperatures higher than 600°C. These results must be considered of interest to reduce the negative environmental impact of the technological copper production from valuable Cu-ores where enargite is present.