Abstract: In order to investigate the influence of clay minerals on pyrite flotation in seawater,the flotation tests of pyrite were carried out with different kaolinite content. Zeta potential,pulp foam layer and other tests were further conducted to reveal the mechanisms. The results showed that low kaolinite content did not influence pyrite flotation in seawater while high kaolinite content depressed the pyrite flotation in seawater. Further mechanisms indicated that kaolinite slime can readily cover the surface of pyrite particles or form entrainment to enter into concentrate,further reducing pyrite flotation recovery. DLVO theoretical calculation showed that the kaolinite face mainly covered pyrite surface under weakly acidic condition. Differently,kaolinite interfered with pyrite flotation by mechanical entrainment under weakly alkaline conditions. The research revealed the adverse conditions of pyrite flotation in seawater,providing importantly theoretical support to achieve an efficient flotation of pyrite in seawater,which is helpful to expand the application of high saline water such as seawater in the field of mineral flotation.

Key words: kaolinite,pyrite,seawater,flotation