Recovery of Copper from Secondary Sources Via Regeneration of Synergistic Reactive Extraction of D2EHPA-Cyanex 302 System

An alternative method for selectively extract copper (Cu) from mixture of secondary sources (especially zinc) from leached solution of waste Cu slag (WCS) has been developed using synergist extractants of D2EHPA and Cyanex 302. Under the optimal conditions, almost 100% of Cu was extracted using a synergist mixture of 0.01 M D2EHPA and 0.025 M Cyanex 302. Meanwhile, the Cu-loaded complexes were successfully stripped using 1.0 M acidic thiourea for Cu recovery. The selectivity factor of Cu over Zn in the extraction process is 23,900 at pH 1.45. Free-Cu solution was treated for zinc recovery using published formulation. This study includes mass transfer mechanism in Cu synergistic reactive extraction system and identifying kinetics of the complex formation at the interface. It is found that the reaction would typically involve a reduction process where Cu²⁺ is reduced to Cu⁺ at the interface of reaction. The extraction using regeneration of synergist organic phase was studied. The results showed the Cu extraction efficiency was consistently around 97% after four times of recycling. Thus, reactive extraction with synergistic D2EHPA-Cyanex 302 offers excellent prospects for the efficient recovery of Cu over Zn from the WCS leached solution.