Effects of nonpolar oil on hydrophobic flocculation of hematite and rhodochrosite fines

It is shown that a small amount of kerosene addition greatly enhances the hydrophobic flocculation of hematite and rhodochrosite fines rendered hydrophobic by the adsorption of oleate ions. This effect is not only closely related to kerosene concentration, but also to the hydrophobicity of mineral particles. Using the tilting plate technique, the hydrophobic adhesion force of the mineral particles was determined, indicating that kerosene addition increases the force by about 280-fold as compared to that without kerosene, and that this force is an exponential function of the particle contact angle. Flocculation kinetics studies, along with hydrophobic adhesion force measurements, reveal that the positive effect of kerosene on hydrophobic flocculation is mainly due to an increase in the strength of flocs, and thus the flocs can support greater floc-rupture force field from turbulent flows. (C) 1999 Elsevier Science S.A. All rights reserved.