Recent trends in the processing of enargite concentrates

The copper industry is witnessing great interest in the development and utilization of copper-arsenic deposits. While most plants tend to use traditional processing technologies, the depletion of conventional copper ores has created competition for designing and implementing new process alternatives for the treatment of copper-arsenic ores containing minerals such as enargite, luzonite, and tennantite. Nevertheless, the downstream processing of high-arsenic copper concentrates represents a significant metallurgical challenge in terms of both arsenic separation and also its stabilization in an environmentally benign form that fulfills the current and future environmental policies. Smelters are subject to penalties on high arsenic-bearing copper concentrates. While reductive roasting can drive-off the arsenic from enargite concentrates to an acceptable level suitable for smelting (<0.5 wt.%), this option has generally been viewed as unacceptable due to environmental conflicts and the lack of a market for arsenic trioxide. The lack of a suitable pyrometallurgical option has led to several proposed hydrometallurgical treatments of enargite concentrates. Hydrometallurgical options include either selective arsenic dissolution to produce a clean copper concentrate or collective leaching of copper and arsenic. Both options with various conditions and lixiviants are discussed and evaluated. In this review, alkaline sulfide leach (ASL), sulfate-and chloride-based leach systems, high temperature pressure oxidation (HTPOX), sodium hypochlorite leach, bio-leach/oxidation, nitrogen species catalyzed pressure oxidation, Cominco Engineering Services Limited, Intec, HydroCopper™ and Fluobor® processes are outlined. Pyrometallurgical process strategies have also been briefly reviewed. Among all processing options, ASL, HTPOX, Fluobor® and reductive roasting processes are given special attention with specific flowsheets for enargite concentrates discussed. © 2014 Taylor and Francis Group, LLC.