Influence of mechanical activation on the alkaline leaching of enargite concentrate

In this study the alkaline leaching of enargite Cu₃AsS₄ (El Indio, Chile) in the medium of sodium sulphide was investigated. The rate of leaching can be influenced by the pre-treatment consisting of mechanical activation of the concentrate in a stirring ball mill (attritor). The XRD and XPS methods used to characterize the bulk and surface properties of the solid phase after leaching have shown that arsenic extraction from enargite leads to its transformation to covellite CuS. On the basis of the value of experimental activation energy (62 kJmol^-) we can conclude that a chemical reaction is the rate-determining process of the reaction between Cu₃AsS₄ and Na₂S. The applied procedure represents a potentionality of de-arsenification of sulphidic concentrates and preparation of a charge convenient for further processing, e.g., by pyro-treatment.