Extraction of Copper from Chalcopyrite Using Alkaline Glycine-Ammonia Solutions

Chalcopyrite is well known as being refractory to conventional leaching approaches at atmospheric pressure. The current study investigated a hybrid approach using aqueous ammonia as a pH modifier for glycine-based lixiviant systems to leach copper from chalcopyrite while maintaining surface refreshment using ceramic media at room temperature. The glycine-ammonia system exhibited significantly better copper extraction than the traditional glycine-NaOH system. A copper extraction of 91.5% was achieved after 72 h of leaching by using 0.71 M ammonia, at a Gly:Cu molar ratio of 4:1, by using a solid content of 1%, with a ceramic media: solid ratio of 3:5 and at ambient temperature. Adding ceramic beads during leaching led to a breakup of particles and a refreshment of particles' surfaces that significantly improved the copper extraction. At a solid content of 10%, oxygen is essential for leaching; a copper extraction of 95.4% was achieved with oxygen injection, while only 33.4% copper extraction was obtained without introducing oxygen. A kinetic analysis indicates that the leaching rate is limited by combined liquid film diffusion and diffusion through the product layer. A conceptual flowsheet is proposed, where chalcopyrite concentrate can be extracted by a leaching-grinding process and copper can be recovered by a solvent extraction-electrowinning circuit.

Automated summary

In this study, a hybrid approach using aqueous ammonia as a pH modifier and ceramic media was employed to leach copper from chalcopyrite. The glycine-ammonia system showed significantly better copper extraction compared to the traditional glycine-NaOH system. Adding ceramic beads during leaching improved copper extraction by breaking up particles and refreshing particle surfaces. Oxygen injection was essential for achieving high copper extraction at a solid content of 10%.