Investigation into the heap leaching of copper ore from the Disele deposit

Heap leaching of malachite–atacamite ores with high silica gangue using sulphuric acid is reported. The base metals were present in the ores in copper rich nodules with a network of fine strings rich in cobalt and manganese along the quartz grain boundaries. It was observed that leaching of copper was quicker and the corresponding recovery of copper was consistently higher when the ore particle was finer. The recovery of copper measured at different leaching times revealed that the efficiency of the process was better enhanced by refinement of the ore particle size than by increasing the concentration of sulphuric acid in the lixiviant from 60 to 120 g/L. Iron contamination in the pregnant leach solution (PLS) subsequently increased as the initial acid concentration in the lixiviant increased. The water loss during the heap leaching process was higher when the ore particle size was finer and when the concentration of sulphuric acid in the lixiviant was higher. Leaching residues typically contained 92% SiO2 and 4% muscovite.