MECHANISM OF SELECTIVE FLOTATION OF SODIUM-CALCIUM BORATES WITH ANIONIC AND CATIONIC COLLECTORS

The major boron minerals, colemanite and ulexite, are frequently found together in boron deposits. Similarities in their chemical compositio ns create problems in the selective flotation of these minerals, The s urface properties of the above boron minerals have been determined by solubility, microflotation, and zeta potential measurements using typi cal anionic and cationic surfactants. The isoelectric point (iep) of c olemanite is 10.5, while ulexite exhibits no iep in a practical pH, An ionic surfactants thus easily float colemanite but fail to float ulexi te at a natural pH, This knowledge is used to find the optimum conditi ons for the selective separation of colemanite from ulexite at a natur al pH of 9.3. Cationic surfactants work-well but are adversely affecte d by the presence of clay-type minerals in the boron ore which hinder the floatability of berates by the formation of a slime coating, The m echanism of slime coating onto boron minerals is also elucidated.