Efficient Molybdenite-Talc flotation separation Mediated by the Synergistic chelation and hydrophobic effect of a novel heterocyclic inhibitor

Separating talc from molybdenite is notoriously difficult in practice, mainly because both minerals share a strong natural hydrophobicity and readily undergo hetero-coagulation. To overcome the shortcomings of conventional depressants, such as poor selectivity and molecular entanglement, this study developed a novel heterocyclic depressant, (Z)-5,6,7,8-tetrahydro-1,2,3-oxy-sulfur-azacyclic octanedione (TOD). TOD combines a carbon chain backbone with sulfonate groups, which allows it to selectively depress talc through a dual mechanism: hydrophobic engagement and specific chelation of magnesium ions. Density functional theory (DFT) and molecular dynamics simulation (MDS) results reveal that TOD adsorbs on the basal plane of talc via hydrophobic attraction and concurrently chelates Mg sites along the edges. In situ optical microscopy and Extended Derjaguin-Landau-Verwey-Overbeek (EDLVO) theory further support that TOD disrupts hydrophobic attraction between molybdenite and talc particles, markedly reducing their tendency to adhere. Contact angle, zeta potential, Fourier transform infrared spectrometer (FTIR), and adsorption measurements consistently demonstrate that TOD adsorbs preferentially onto the talc basal plane. This adsorption significantly reduces talc’s hydrophobicity and drops its surface potential below –35  mV, shifting the talc–molybdenite system from aggregation toward dispersion. In micro-flotation tests with sodium isobutyl xanthate as collector, TOD created a 39.26% recovery gap between talc and molybdenite, demonstrating strong selective depression and promising potential for industrial application.