Multiscale separation mechanisms of novel eco-friendly depressants in hematite reverse flotation

This study delves into the separation mechanism of hematite from quartz in reverse flotation using quercetin as a novel eco-friendly depressant. Micro-flotation tests were combined with molecular dynamics simulations. The underlying separation mechanisms were then elucidated through multi-scale analyses, including FTIR, XPS, AFM, and optical microscopy. Results show quercetin effectively separates hematite and quartz at pH 10, yielding a TFe grade of 63.44 % and recovery of 89.72 % in the mixed ore concentrate. Compared to neutral conditions, the concentrate grade increased by 1.21 %, with the recovery rate decreasing by only 0.24 %. FT-IR analysis showed that the surface of hematite treated with quercetin, a novel eco-friendly depressant, exhibited hydroxyl group peaks characteristic of quercetin. XPS analysis further indicated that the hydroxyl groups in quercetin chemically adsorbed onto the Fe on the hematite surface. AFM analysis revealed that after treatment with quercetin, the vertical fluctuation range of the cross-sectional height of hematite was relatively large, and the hematite surface exhibited several flaky protuberances. Molecular dynamics calculations show a significant peak near 2 Å for the interaction between the –OH in quercetin and Fe on hematite, and a peak near 3 Å for the interaction between the –NH₂ in DDA and O on quartz. These results are consistent with flotation tests results, indicating the accuracy of the molecular dynamics simulation calculations. This study offers an eco-efficient selective depressant for hematite and gangue mineral separation, with theoretical and practical significance for the sustainable development of clean mines.