Due to its poor sulfidization effect and environmental issues, the traditional sulfidization–xanthate method faces challenges in chrysocolla flotation. Addressing these, our study pioneers a sulfidization-free approach using ammonium sulfate as an activator in an octyl hydroxamic acid (OHA) collector system. This innovation propels flotation recovery from 34.10 % to an impressive 98.43 %. Infrared spectroscopy and adsorption tests confirm that ammonium sulfate improves OHA’s adsorption on chrysocolla. X-ray photoelectron spectroscopy (XPS) analysis reveals a significant rise in C–C and C-N bonds related to OHA on the mineral surface post-activation. Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDS) analysis shows a rougher mineral surface with filamentous precipitates and a higher surface nitrogen atom concentration. Density Functional Theory (DFT) calculations elucidate NH3′s role in disrupting the hydration layer, exposing more Cu sites for enhanced OHA attachment. The Cu 2p shift observed on the mineral surface, along with state density analysis, further confirms the chemical adsorption of OHA on chrysocolla’s Cu sites facilitated by ammonium sulfate. This study introduces a novel NH3-enhanced OHA adsorption method, offering a promising strategy for the efficient flotation of chrysocolla.