The effect on copper leaching from chalcopyrite concentrates by ball milling

In recent years, efficient production method for low grade copper ore is increasingly required because the quality of copper ore is decreasing. Objective of this study was enhancement of sulfuric acid leaching of copper using ball milling. To accomplish this, optimum conditions of solid/liquid ratio of slurry, air volume in the mill, rotation speed and ball diameter were investigated for copper leaching from copper concentrate in which pyrite and chalcopyrite were dominant components. As a result, final copper recovery after 24 hour was increased to over 30 wt% when ball milling and leaching were conducted at once in the optimum conditions; 60 rpm of rotational speed, 15 mm of ball diameter, 0.5 wt% of slurry concentration and 85 vol% of air volume, whereas it remained 14 wt% by simple beaker leaching test. This increase of copper recovery could not be achieved in wet ball milling using water followed by sulfuric leaching using beaker. Furthermore, two-step leaching, that is, dry ball milling followed by sulfuric leaching using beaker, was also tried. As a result, final copper recovery was raised to 80 wt% because chalcopyrite in copper ore was oxidized and easily leached out after dry ball milling in 24 hours.