A novel vitamin E-based xanthate collector for chalcopyrite-quartz mineral flotation

In this study, a novel vitamin E-based xanthate, α-tocopherol polyethylene glycol 400 succinate xanthate (TPGS-X) was compared with potassium amyl xanthate (PAX) for the flotation of synthetic and natural chalcopyrite-quartz ores at medium (P 80 < 140 µm) and coarse (P 80 > 170 µm) sizes. TPGS-X was expected to improve chalcopyrite hydrophobicity and recovery due to the bulkier hydrophobic α-tocopheryl group. The water contact angle on chalcopyrite increased from 68° to 99° with 0.03 mM TPGS-X, compared to a maximum of 92° with 0.5 mM PAX. Increasing xanthate concentrations led to hydrophobicity reversal on the chalcopyrite surface, with contact angles decreasing below the pristine mineral value. This was attributed to bilayer formation, supported by adsorption isotherm studies of PAX and TPGS-X on chalcopyrite. Flotation studies also show that a hydrophobic reversal occurs past a critical PAX and TPGS-X dose. The maximum chalcopyrite recovery with TPGS-X occurred at 5 to 10 times lower molar concentrations relative to PAX for the synthetic medium-sized ore and the natural ores. At the optimal doses, TPGS-X outperformed PAX in final recovery for the natural coarse-sized (84 % vs 81 %) and natural medium-sized (56 % vs 48 %) ores at similar grades. TPGS-X outperformed PAX in grade for the synthetic medium-sized (18 % vs 15 %) ores at similar final recovery. For the synthetic coarse-sized samples, TPGS-X outperformed PAX in both final recovery (85 % vs 78 %) and grade (16 % vs 13 %). Furthermore, TPGS-X demonstrated greater chemical stability than PAX, with ∼ 3 % degradation observed after 216 h at pH 9, compared to > 50 % degradation of PAX.