EFFECT of Pb2+ on the flotation of molybdenite in the presence of sulfide ion

Although Na2S doesn't depress the flotation of molybdenite, as the most utilized depressant, its effect on the flotation of molybdenite in the case where Pb2+ is involved has not been investigated yet. In this work, the flotation behavior of molybdenite in Pb2+ solution with or without Na2S was investigated. The mechanism was also studied by Zeta potential measurement, SEM-EDX, AFM and XPS analysis. The results indicated Pb2+ depressed the flotation of molybdenite, and Na2S enhanced the depression effect significantly. The depression effect depended on pH in both Pb2+ and Pb2+-Na2S solutions. In Pb2+ solution, the depression is mainly due to formation of PbS on molybdenite surface. While in Pb2+-Na2S solutions, the deterioration of flotation was majorly attributed to coating of strongly hydrophilic Pb(OH)(2) precipitate on molybdenite surface.