A case study of the separation of copper-gold sulfide ore from pyrite using a novel flotation reagent scheme: Insight from first-principles calculations

Due to many problems such as pipe blockage, environmental pollution, and the difficulty of recovering precious metals, caused by extensive use of lime, the conventional program using lime (CaO) as the inhibitor and xanthates (e. g., sodium butylxanthate) (BX) as the collector has become increasingly restricted in use, and lime-free flotation processes are increasingly advocated. In this study, a novel process with Z200 as the collector and pyrogallic acid (PGA) as the inhibitor was innovatively proposed and applied to separate copper-gold sulfide ore and pyrite in Hubei Province, China. In laboratory experiments, this new reagent system achieved a substantially better separation of copper-gold sulfide ore and pyrite than the conventional process program. First-principles calculations based on density functional theory (DFT) were used to understand the separation mechanism of the new reagent scheme. The DFT simulations showed that PGA had a much stronger depression effect on pyrite than chalcopyrite, whereas Z200 exhibited a stronger collecting ability for chalcopyrite than pyrite, which together explains the effectiveness of the new reagent system at the molecular level. This work sheds some new light on the potential of adopting new and eco-friendly reagent schemes in the utilization of mineral resources.