First-principles study of differences in flotation behavior of quartz and muscovite

The flotation separation of quartz and muscovite, typical silicate minerals, is a notable challenge in mineral processing. Herein, first-principles calculations were employed to elucidate the fundamental causes of the differences between the flotation behaviors of the two minerals at the atomic scale. The electron transfer, chemical bonding information, projected density of states, and charge difference density of the two minerals were calculated through density functional theory and compared. The results suggest that quartz contains only SiO strongly polar covalent bonds, whereas the structure of muscovite is dominated by SiO covalent bonds, with the substitution of Si⁴⁺ with Al³⁺ introducing ionic AlO bonds. At the same time, K⁺ in the interlayer compensates for the charge imbalance through pure ionic bonds. The computed adsorption energies of the cationic trapping agent dodecyl amine on quartz and muscovite were −2.103 and −5.879 kcal/mol, respectively, which is a notable difference. In line with the findings of flotation studies, this suggests that dodecyl amine can be adsorbed on both quartz and muscovite, but the adsorption is stronger on muscovite.