The pyrometallurgy of enargite: A literature update

Although several hydrometallurgical treatment options for dirty copper sulfide concentrates have been developed in recent years, these processes have not been implemented by industry. Attention has therefore shifted to pyroprocessing such concentrates in order to provide clean feed for the well-established sulfide smelting process. In this paper, recent publications on pyrometallurgical processing of enargite and gold concentrates have been reviewed, which indicate that little has been added to already existing knowledge of the thermal behavior of enargite. The arsenic fix-roast approach using Na2CO3 and Ca(OH)2 to capture the arsenic during roasting does not seem to be a practical approach due to insufficient capture and also the complexity of the subsequent phase separations. A more pragmatic approach would be further development of neutral/reductive roast of enargite concentrates in order to produce clean feed for the existing smelters and to convert arsenic into its sulfides which are more stable and compact than its oxides. Potentially high temperatures (>650°C) required for effective arsenic removal from enargite concentrates has represented a significant barrier for the development of roasting equipment. This calls for further development of pyroprocessing strategies through a better understanding of the thermodynamics of the Cu-As-S-(O) system. The results of recent research indicate that the mysterious role of pyrite, always present in enargite concentrates in thermal transformation of enargite, has been largely underestimated and not well understood. This necessitates a thorough understanding of the even more complicated Cu-Fe-As-S-(O) system. •High temperature processing of enargite concentrates•Arsenic volatilization issues•Different roasting strategies•Phase stability diagrams•Recent developments