ELECTROKINETIC PROPERTIES OF SOME HYDRATED BORON MINERALS

Electrokinetic properties of a series of boron minerals, i.e., coleman ite, ulexite, inderite, and tunellite, are investigated using the micr oelectrophoresis technique. Colemanite exhibits an isoelectric point a t pH 10.5. Ulexite, inderite, and tunellite yield practically no isoel ectric point in the pH range of 7 to 11. While ulexite remains negativ ely charged, inderite and tunellite show positive charges in the pH ra nge studied. The potential determining ions for these minerals are the constituent lattice cations, Ca2+, Mg2+, and Sr2+, and the anion, B4O 72-. The H+ and OH- ions which indirectly control the ratio of HCO3-/C O32- are also the potential determining ions for the hydrated boron mi nerals studied. The electrokinetic results generally support the adsor ption of oppositely charged flotation collectors on boron minerals thr ough electrostatic attraction. (C) 1995 Academic Press, Inc.