Reverse floc-flotation of talc from chalcopyrite by using polyvinyl acetate as a flocculant: Adsorption and bubble capture studies

Abstract

Chalcopyrite is often intergrown with talc, which, after grinding, forms ultrafine particles (<10 μm) that readily coat chalcopyrite surfaces, hindering flotation and causing significant losses in tailings. This study evaluates polyvinyl acetate (PVAc), a thermoplastic polymer, as a selective flocculant to enhance reverse flot ation separation of chalcopyrite from ultrafine talc. Flotation tests showed that at a PVAc dosage of 40 mg/L, talc can be effectively and selectively removed, enabling efficient separation. Laser particle size analysis and scanning electron microscopy-energy dispersive spectrometry (SEM-EDS) confirmed that PVAc promotes selective talc aggregation without affecting chalcopyrite. X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations revealed that hydrogen bonding between PVAc ester groups and surface hydroxyls on talc drives the flocculation, while chalcopyrite lacks suitable binding sites. PVAc adsorption also enhances talc hydrophobicity. Furthermore, particle-bubble coverage angle measurements and extended Derjaguin-Landau-Verwey-Overbeek (DLVO) theory theoretical calculations demonstrated that PVAc-induced flocculation increases attractive interactions between talc and bubbles, shifting the total interaction energy from repulsive to attractive and promoting bubble-particle attachment. This study clarifies the selective adsorption and flocculation mechanisms of PVAc and reveals the coupling of flocculation and flotation of ultrafine talc from a particle-bubble capture perspective, while expanding the potential of ester-based polymers for ultrafine mineral recovery.

Keywords

Chalcopyrite / Ultrafine talc / Polyvinyl acetate / Floc-flotation / Flocculant adsorption / Bubble capture

Acknowledgments

This work was supported by the National Natural Science Foun-dation of China (Nos. 52174239 and 52374259), the Program of China Scholarship Council (No. 202406080114), and Natural Sciences and Engineering Research Council of Canada (No. NSERC RGPIN 2024-04570).

Supplementary material

Supplementary data to this article can be found online at https://doi.org/10.1016/j.ijmst.2025.08.016.

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