Influence of mechanical activation on the alkaline leaching of enargite concentrate

In this study the alkaline leaching of enargite Cu3AsS4 (El Indio, Chile) i n the medium of sodium sulphide was investigated. The rate of leaching can be influenced by the pre-treatment consisting of mechanical activation of t he concentrate in a stirring ball mill (attritor), The XRD and XPS methods used to characterise the bulk and surface properties of the solid phase aft er leaching have shown that arsenic extraction from enargite leads to its t ransformation to covellite CuS, On the basis of the value of experimental a ctivation energy (62 kJmol(-1)) 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 sulp hidic concentrates and preparation of a charge convenient for further proce ssing, e.g., by pyro-treatment. (C) 2000 Elsevier Science B.V. All rights r eserved.