A New Application of Solvent Extraction to Separate Copper from Extreme Acid Mine Drainage Producing Solutions for Electrochemical and Biological Recovery Processes

Abstract Over the last decade, AMD waters have gained more attention as a potential source of metals due to emerging need recover or recycle from secondary resources. Metals recovery supports sustainability and development circular economy with benefits for resource conservation environment. In this study, five extractants (Acorga M5640, LIX 54, 622, 622 N, 864) diluted (15% (v/v)) in Shell GTL 2.5% (v/v) octanol were compared evaluated Cu an extreme sample (5.3 ± 0.3 g/L Cu) collected at inactive São Domingos Mine Iberian Pyrite Belt Portugal. Of extractants, Acorga M5640 showed best selective efficiency. Further tests that 30% extractant was able selectively extract ≈ 96.0% one extraction step all remaining (to below detection) three steps. Among different stripping agents tested, 2 M sulfuric acid most efficient, 99% stripped, recyclability organic phase confirmed successive cycles stripping. Furthermore, contact time revealed kinetics allows transfer 97% 15 min, aqueous ratios demonstrated maximum loading capacity 16 phase. Raising concentration solution (2 acid) 46 through striping steps elemental using traditional electrowinning. Finally, biological approach by adding supernatant sulfate-reducing bacteria culture make molar biogenic sulfide copper; over 1.75 resulted precipitation than 95% covellite nanoparticles. Graphical