Use of “oily bubbles” and dispersants in flotation of molybdenite in fresh and seawater

Abstract

Molybdenite - as all inherently hydrophobic minerals – is floated with the use of water-insoluble oily collectors. Such collectors can be used in flotation either after emulsification in water, but can also be brought to the point of particle-to-bubble attachment on the surface of bubbles (as oily-bubbles). In this paper we are testing the effect of oily-bubbles and the dispersants sodium hexametaphosphate (SHMP) and sodium silicate (SS) on the flotation of moleybdenite in seawater in alkaline environment. The results show that molybdenite recovery increases when kerosene is supplied on the surface of bubbles which was particularly important in the flotation of molybdenite at pH > 9.5 in seawater. SHMP dispersant had a strong positive effect on the recovery of molybdenite at pH > 9.5, the pH range known to cause depression of the molybdenite flotation when pH is raised to depress pyrite and magnesium species precipitate as hydroxo-complexes/hydroxide. The combined effect of the oily bubbles and dispersants allows for the molybdenite recoveries to reach to similar values to those achieved when using fresh water. The results of induction time measurements indicate that the attachment of bubbles to molybdenite is significantly improved when the bubbles are coated with a layer of kerosene.