The activation role of Mg2+in the lepidolite flotation using NaOL

Metal ions commonly emerge as effective activators in the flotation of silicate minerals using anionic collectors, yet the underlying interaction mechanisms remain not well-understood. In this paper, the activation role of magnesium ions (Mg2+) in the flotation of lepidolite, using sodium oleate (NaOL) as the collector, was systematically explored. Flotation tests on single minerals reveal that the activation capacity for lepidolite of Mg2+ significantly outperforms Ca2+, achieving a remarkable recovery efficiency of over 85 % at pH 8. In contrast, the recovery of quartz remains consistently below 15 % across the tested conditions. Experiments with artificially mixed minerals demonstrate that a satisfactory flotation separation of lepidolite from quartz is achieved using Mg2+/NaOL with a molar ratio of 1:3 at pH 8, resulting in an impressive selectivity index (SI) of 18.84. Fourier transform infrared spectroscopy (FTIR) analysis and zeta potential results indicate that NaOL effectively adsorbs on the Mg2+-activated lepidolite surface through electrostatic attraction. Adsorption tests show that NaOL enhances the adsorption equilibrium of Mg2+ on the lepidolite surface, potentially due to the formation and adsorption of Mg-OOCR colloid. Furthermore, the interaction of Mg2+ with NaOL and lepidolite surface is more robust than that of Ca2+, while the single metal ions exhibit negligible activation effects on quartz. X-ray photoelectron spectroscopy (XPS) analysis further indicates that NaOL primarily interacts with O, F, and Al sites on the lepidolite surface under the mediation of the Mg atom.