In this study, ethylene diamine phosphate (EDP) was employed as an activator to improve the sulfidization and flotation of chrysocolla. The micro-flotation experiment results indicated that EDP could greatly increase the flotation recovery of chrysocolla. BET and TEM measurements confirmed that the porous structure of the chrysocolla’s surface would lead to large amounts of the reagents. ICP-AES analysis revealed that the addition of EDP caused more active Cu sites formed on the chrysocolla’s surface, enhancing the adsorption of S²⁻ on its surface. Meanwhile, a redox reaction occurred between the S²⁻ and [Cu(en)₂]²⁺ ions causing the Cu, S, and N in the solution to counter-adsorb onto the chrysocolla’s surface by forming new complexes. During this reaction, the Cu(II) species reduced to Cu(I) species and the sulfide ions in the form of S²⁻, S₂²⁻, S_n²⁻, and SO₄²⁻ appeared on the mineral surface. The zeta potential measurements further revealed that the EDP-activated chrysocolla surfaces adsorbed more sulfide species and xanthate species, thereby improving the floatability of the chrysocolla.

The crystal of hemimorphite is a non-conductor. The Si–O bond in the crystal is strong, whereas the Zn–O bond is weak. These properties lead to the easy breakage of the Zn–O bond in the crushing process of hemimorphite. Thus, the interaction between minerals and polar water molecules is strong, and natural floatability of ores is poor. This study systematically investigated the characteristics of hemimorphite and its action mechanism with Na₂CO₃. Results of SEM-EDS showed that the surface of hemimorphite dissolved after interacting with Na₂CO₃, and the contents of Si and O decreased, whereas Zn and C increased. XPS analysis showed that the carbonate group was detected. The interaction between CO₃²⁻ and hemimorphite was calculated using the first principles calculation based on density functional theory. The results indicate that an O atom in CO₃²⁻ interacted with Zn²⁺ from the (100) plane of hemimorphite. The interaction between Zn and O atoms was not strong, and the Zn atoms were not completely displaced, which was proven by density of state analysis and the EDS and XPS results. The Mulliken population showed that the O–Zn bond was the atomic bonding of CO₃²⁻ with Zn²⁺ and exhibited properties of ionic bonds. Thus, hemimorphite transformed to smithsonite-like mineral (ZnCO₃) when acting with CO₃²⁻.