Effect of polyethylene oxide on flotation of molybdenite fines

The processing of low-grade deposits of molybdenite is becoming more urgent with the gradual depletion of high-grade molybdenite ores in China. Low flotation efficiency has been suffered due to finer sizes liberation resulted from finely disseminated nature of low-grade ores and crystal anisotropy. In this study, kerosene was used to collect the molybdenite fines with different sizes, but even high dosage of kerosene could not achieve high flotation recovery for molybdenite particles with finer sizes. However, the presence of polyethylene oxide (PEO) considerably increased the flotation efficiency of molybdenite. The mechanism of PEO effect on the molybdenite flotation was studied by molecular dynamics simulation, Atomic Force Microscopy (AFM), Focused Beam Reflectance Measurement (FBRM), etc. Molecular dynamics calculation shows PEO molecules were more susceptible to (010) plane than (001) plane, thereby promoting the adsorption of PEO on the finer molybdenite particles. The wettability results indicate molybdenite particles become more hydrophobic in the presence of PEO, especially for the edge planes. Thereby the attachment time between bubbles and molybdenite particles reduced significantly. Moreover, in PEO solution, larger attractive forces were detected between molybdenite surfaces at > 100 nm, agreeing with the rapid formation of large flocs in the molybdenite suspension. Thus, PEO not only improves the surface hydrophobicity but also induces the flocculation of fine particles, both of which improve the flotation performances of molybdenite fine particles.