New insights into chalcopyrite leaching enhanced by mechanical activation

Mechanical activation has been applied prior to leaching to improve copper extraction from chalcopyrite. Results showed that 86% copper was extracted within 2 h from chalcopyrite ground with sodium chlorite at 500 rpm, at pH 1.0 (sulfuric acid) and 348 K, greater than from leaching of unground (4.5% copper extraction) and ground chalcopyrite without sodium chlorite (13.5% extraction). Size reduction, structural modification and phase transformation were suggested as three mechanisms for improved copper extraction rate, with the last mechanism found to be dominant. Two leaching steps were proposed, for the first time, for chalcopyrite ground with sodium chlorite, including the first stage primarily determined by the dissolution of copper chlorite formed via a solid state reaction during grinding with chalcopyrite and the second stage dominated by the dissolution of unconverted chalcopyrite. This study suggests that grinding of chalcopyrite with sodium chlorite is beneficial to highly efficient copper extraction from chalcopyrite. [Display omitted] •Cu extraction from CuFeS2 was increased from 4.5% to 86% after grinding with NaClO2;•CuFeS2 co-ground with NaClO2 produced water soluble CuCl2;•Two leaching stages were proposed for CuFeS2 co-ground with NaClO2;•Three activation mechanisms were clearly identified for CuFeS2 co-ground with NaClO2.