Mechanism and performance of anionic polyacrylamide in selective flocculation separation of fine quartz-muscovite

Conventional separation processes often encounter issues such as redundant separation steps and low separation efficiency when treating fine quartz and muscovite, owing to the similar particle sizes and properties. To address these problems, this study explored the feasibility of enhancing gravity separation through the flocculation effects. Using the specific “bridging” capability of anionic polyacrylamide (APAM), the efficient separation of fine quartz and muscovite was achieved under near-neutral conditions. Sedimentation experiments were conducted to compare the flocculation behaviors of the two minerals using different types of polyacrylamide (PAM). The selective flocculation behavior and adsorption mechanism of APAM on the two minerals were systematically analyzed using XRD, XRF, microscopic observation, Zeta potential, FTIR and XPS. The results showed that APAM could effectively flocculate fine muscovite but had a weaker coagulation effect on quartz. When the APAM concentration reached 100 mg/L, the difference in sedimentation recovery rates between the two minerals was 78.8 ± 2.5%. In mixed mineral systems, after sedimentation separation, the suspension product contained 88.49 ± 0.23% quartz with a recovery rate of 63.30 ± 0.23%, whereas the sediment product contained 60.19 ± 0.12% muscovite with a recovery rate of 81.84 ± 0.12%. Mechanistic studies indicated that APAM specifically binds to the muscovite surface via hydrogen bonding and electrostatic adsorption, whereas its interaction with quartz is relatively weak. Furthermore, this study constructed a selective adsorption model to illustrate the dynamic process by which APAM separates quartz and muscovite under natural conditions.