The flotation separation of galena from pyrite with 2-dialkylamino-s-triazine-4-thiol-6(1H)-thione sodium at pH ∼8.0: Emphasize on adsorption mechanism

To achieve an eco-friendly flotation separation of galena from pyrite under the low alkaline and depressant-free conditions, the triazine-dithione surfactants, such as 2-dimethylamino- s -triazine-4-thiol-6(1H)-thione sodium (DMN), 2-diethylamino- s -triazine-4-thiol-6(1H)-thione sodium (DEN) and 2-dibutylamino- s -triazine-4-thiol-6(1H)-thione sodium (DBN) were designed as the special collectors for galena. The micro-flotation results showed that the collecting capacity of these three collectors towards galena was in the order of DBN > DEN ≫ DMN, being consistent with their hydrophobization ability. In-situ AFM observed the aggregation of DBN on the whole surface of galena, which significantly enhanced the contact angle of galena. UV spectra and zeta potential recommended that the affinity of DBN towards lead ions and galena was much stronger than ferrous/ferric ions and pyrite. DFT (density functional theory) calculation revealed DBN’s two exo -S atoms were of its electron-donating center. And XPS confirmed the bonding interaction of the two exo -S atoms with Pb(Ⅱ) atoms on/in galena surface. DBN owned the mild electron-donating capacity and strong electron-accepting ability, and realized the eco-friendly flotation separation of galena from pyrite at pH ∼8.0.