The effect of redox control on the continuous bioleaching of chalcopyrite concentrate

• Redox potential controlled electrochemically in continuously operated system.
• Bioleaching tests carried out at high pulp density (15%) under controlled redox conditions.
• The copper extraction increased with the redox control up to 79%.
• The formation of jarosite reduced by electrochemical control of redox potential.

A continuous bioleaching process was developed for the dissolution of chalcopyrite concentrate with electrochemically redox control. Therefore, using a flotation concentrate containing 46% chalcopyrite and 23% pyrite, bioleaching tests were carried out at 47 °C with 15% pulp density under controlled and uncontrolled redox conditions. To increase the copper recovery in contrast to the conventional bioleaching (∼39.62%), the effect of redox potential on the chalcopyrite bioleaching was investigated by electrochemically controlled bioleaching. The results showed that by controlling the redox potential, faster copper leach kinetics could be achieved. At last, reducing the redox potential from high levels to optimum window (420–440 mV SCE) caused an increase in copper recovery from around 39% to higher than 69% (over 25 g/L Cu2+).