Optimization of copper and zinc extractions from polymetallic bulk concentrate and ferric iron bioregeneration under metallic stress

Polyphasic optimisation process for ferric iron mediated metal extraction with 50 mL system on COD digester showed 60% copper and 56% zinc extractions in only 30 and 90 min of contact time respectively. Optimum conditions were 90 °C reaction temperature, 10% (w/v) pulp density, pH 1.8 and 1.5% (w/v) Fe3+ concentration. The system was scaled up successfully to 5000 mL and as high as 80.81% copper and 54.0% zinc extractions were obtained in 30 and 90 min respectively without addition of any catalyst. The bioregeneration of Fe3+ iron from the leachate in shake flask study by developed iron oxidising consortium showed IOR of 396 mg/L/h in the presence of as high as 124.8, 21.0, 2.8 and 26.7 g/L total dissolved solids, total iron, copper and zinc respectively. The developed biofilm in down-flow packed bed column having UHMWPE plastic material as support matrix showed 3100 mg/L/h IOR, which is eight fold higher as compared to the best IOR obtained in shake flask study.

► Optimised parameters for Cu and Zn leaching from PBC are similar except reaction time.
► The leaching process for PBC successfully scaled up from 50 mL to 5000 mL.
► As high as 80.81% Cu and 54.00% Zn extractions were achieved in 5000 mL system.
► Consortium efficiently oxidise Fe2+ iron under acid and metal stress from leachate.
► Compare to flask packed bed column found 8 fold efficient for Fe3+ regeneration.