Copper leaching from waste electric cables by biohydrometallurgy

• At optimal process conditions, copper extraction above 90% was achieved in 1 day.
• The Fe2+ bio-oxidation by Acidithiobacillus ferrooxidans is not enough competitive.
• The Fe3+ concentration is the more significant parameter investigated.
• A temperature of 35 °C is the best compromise between kinetics and acid consumption.
• The activation energy Ea of the copper dissolution reaction is 20.4 kJ.

This study examines the leaching of copper from waste electric cables by chemical leaching and leaching catalysed by Acidithiobacillus ferrooxidans in terms of leaching kinetics and reagents consumption. Operational parameters such as the nature of the oxidant (Fe3+, O2), the initial ferric iron concentration (0–10 g/L) and the temperature (21–50 °C) were identified to have an important influence on the degree of copper solubilisation. At optimal process conditions, copper extraction above 90% was achieved in both leaching systems, with a leaching duration of 1 day. The bacterial leaching system slightly outperformed the chemical one but the positive effect of regeneration of Fe3+ was limited. It appears that the Fe2+ bio-oxidation is not sufficiently optimised. Best results in terms of copper solubilisation kinetics were obtained for the abiotic test at 50 °C and for the biotic test at 35 °C. Moreover, the study showed that in same operating conditions, a lower acid consumption was recorded for the biotic test than for the abiotic test.