Effect of the Size of the Mineral in the Zeta Potential (ζ): Molybdenite Case

The effect of grinding in molybdenite ore with respect to the zeta potential (ζ) was studied in this work. In relation to the investigations carried out on this topic and in accordance with that carried out in this work, the results obtained confirm that in molybdenite particles, as the face/edge ratio decreases, from its original size of 19.1% to -20 µm, up to 70% at -20 µm after grinding, the zeta potential (ζ) increases. Likewise, a variation of the zeta potential (ζ) is achieved in the same direction as the pH increases; the values obtained are negative but increase in absolute magnitude. The magnitude of the values obtained, specifically the increase in the zeta potential (ζ), with increasing grinding and pH, is due to the fact that finer grinding generates a greater number of edges. It is at these edges that the surface charge of the molybdenite particles originates from oxygenated sites, causing the formation of molybdate ions (MoO4-2) and hydromolybdates (HMoO4-1). Based on the above, and correlated with results from other investigations, it can be established that a decrease in the face-edge ratio of molybdenite particles generates an increase in the absolute value of the zeta potential (ζ), which in turn causes a decrease in flotation efficiency.