The role of galena associated with silver-enhanced pyrite in the kinetics of chalcopyrite leaching during the Galvanox™ process

The effects of silver ions, galena, and pyrite on the kinetics of chalcopyrite leaching have been studied. In addition, the effects of galena and pyrite pretreated with silver ions have been investigated. It has been found that the addition of silver ions, pyrite, and pyrite pretreated with silver ions accelerates the rate of chalcopyrite leaching significantly. The addition of galena has minimal effect on the kinetics of chalcopyrite leaching. Considering the high cost of silver, the possibility of recycling these catalysts was also examined. The results indicate that direct recycling of silver ions as a catalyst is not feasible; however, silver-enhanced pyrite can be efficiently recycled to subsequent leaching tests. Secondary Electron Microscopy and Electron Diffraction X-ray techniques were applied to study the morphology and elemental composition of residues after completion of leaching experiments. In this study, formation of a porous sulfur layer around chalcopyrite was observed in both the presence and absence of catalysts indicating that acceleration of the rate of chalcopyrite leaching in the presence of catalysts is not due to the alteration of morphology of sulfur around chalcopyrite.