SURFACTANT-ENHANCED ELECTROOSMOTIC DEWATERING OF MINERAL ULTRAFINES

The rate and extent of electroosmotic dewatering of mineral ultrafines are dependent on the surface charge density which is quantitatively measured by the zeta potential. This research tailors the surface electrical properties of a naturally uncharged ochre (iron oxide) mineral slurry by altering the concentration of potential determining hydroxide ions to facilitate electroosmotic dewatering. The adsorption of hydroxide ions (9 x 10(-4) to 9 x 10(-3) M) onto the iron oxide surface provides the necessary increase in zeta potential; however, the resulting electrostatic dispersion of the particles severely limits the hydraulic permeability. Subsequent addition of cetyl trimethyl ammonium bromide (5 x 10(-4) to 5 x 10(-3) M), a cationic surfacant, reflocculates the particles, while maintaining sufficient zeta potential to generate an electroosmotic effect. Hydraulic performance of the treated slurries is characterized by measurement of flow rate data and specific resistance determination. Further characterization of the electrokinetic properties through electrophoretic mobility studies verifies the proposed adsorption mechanism.