Selective separation of hematite from quartz in reverse flotation using tea polyphenols: Experimental and molecular insights

TP enables the selective flotation separation of hematite from quartz. • TP is selectively chemisorbed onto the hematite surface. • TP is a natural, biodegradable, and water-soluble depressant. This paper investigated the selective depression of hematite by tea polyphenols (TP) in a cationic collector dodecylamine (DDA) system. Micro-flotation results indicate that, under natural pH conditions, when the DDA concentration was 2 × 10 -4 mol/L and the TP concentration was 2 × 10 -3 mol/L, the artificially mixed ore achieved satisfactory flotation indexes: an iron grade of 65.68% and a recovery of 87.75%. Contact angle test results indicate that TP could significantly reduce the hydrophobicity of hematite surfaces while exerting a minor effect on quartz. FTIR and XPS analyses indicate that TP was chemisorbed on the surface of hematite. Frontier molecular orbital analysis shows that the phenolic hydroxyl group served as the primary reactive site of the TP molecule. Molecular dynamics simulation results reveal that TP exhibited stronger interaction with hematite than with quartz, with interaction energies of approximately −56.44 kcal/mol and −27.80 kcal/mol, respectively. Therefore, TP, as a selective and biodegradable depressant for hematite, is expected to be applicable to the flotation separation of hematite and quartz. Download: Download high-res image (96KB) Download: Download full-size image