Bacterial heap leaching of covellite

This study investigates the bacterial heap leaching of covellite from a chalcocite ore containing 0.5% Cu(tot). Leaching was conducted under varying temperatures (10-20°C) and acid-ferric bacterial conditions. The dissolution of copper was shown to rely on the rate of sulphide oxidation by ferric ion, revealing a chemically controlled dissolution pattern characterized by an activation energy of 78.09 kJ/mol. The primary oxidant, ferric iron, is generated through bacterial activity, which is measured both directly by bacterial counts in effluent solutions and indirectly by ferric iron levels. Results indicated a heap oxidative capacity of approximately 0.07-0.15 kg Fe³⁺/t/day at 20°C, decreasing to about 0.03 kg Fe³⁺/t/day at 10°C, though significant bacterial activity persisted at lower temperatures despite lag times. These findings highlight the importance of bacterial inoculation and temperature management in the design and operation of heap leaching processes for secondary copper sulphides. This research suggests that interventions are crucial for optimizing copper recovery from low-temperature environments.