Diosmin as a green depressant for selective flotation separation of chalcopyrite from pyrite: Adsorption mechanism and performance

Lime and cyanide are frequently employed as depressants in the flotation process of Cu–Fe sulfide minerals; nevertheless, their application often raises environmental issues and poor selectivity. In this research, the introduction of the semi-synthetic flavonoid Diosmin (Dio) was proposed as an innovative and eco-friendly depressant aimed at achieving the selective chalcopyrite-pyrite flotation separation. Micro-flotation experiments demonstrated that Dio exhibited excellent selective depression toward pyrite. When the dosage was set at 40 mg/L, the recovery of pyrite was controlled below 10%, whereas the flotation performance of chalcopyrite remained largely unaffected, with recoveries exceeding 90%. Zeta potential measurements, contact angle analysis, and atomic force microscopy revealed that Dio could adsorb onto the surfaces of both minerals, with a significantly stronger affinity for pyrite. Moreover, Dio pretreatment effectively inhibited the subsequent collector from adsorbing on the pyrite surface, thereby markedly reducing its floatability. Further insights from FT-IR, XPS, and local electrochemical impedance spectroscopy indicated that Dio interacted preferentially with Fe active sites on the pyrite surface through chemisorption, while exerting a negligible influence on the surface properties of chalcopyrite. These findings demonstrate that Dio functions as an efficient depressant for pyrite and provides a promising green alternative for the flotation separation of chalcopyrite and pyrite.