Optimizing the Crystalline State of Cu Slag by Na2CO3 to Improve Cu Recovery by Flotation

Abstract

Cu is the most important component in Cu slag, which is usually recovered by flotation. However, the crystalline state of Cu slag is not conducive to flotation, which limits the recovery of Cu. This study investigated the effect of Na2CO3 on the crystalline state of Cu slag and the recovery of Cu by flotation. The mechanism was investigated by thermodynamic, viscosity, X-ray diffraction (XRD) analyses and scanning electron microscopy (SEM). The results of thermodynamic, viscosity and XRD analysis demonstrate that Na2CO3 is beneficial for the transformation of fayalite to low-melting point materials, such as Na2SiO3, Na4SiO4 and NaFeSi3O6, thereby reducing the viscosity of Cu slag. Moreover, SEM results indicate that the addition of Na2CO3 during the melting modification process can promote the aggregation of Cu-bearing minerals and simplify its intercalation relationship with gangue minerals. The flotation results verify the above conclusions that at 10% Na2CO3, the Cu flotation recovery index is the best. Compared with that without Na2CO3, the use of Na2CO3 has resulted in increased Cu grade and recovery by 3.544% and 28.94%, respectively.