ZETA POTENTIAL OF ULTRAFINE SULFIDE SURFACE AND FLOATABILITY OF MINERALS

Abstract

The paper shows the results obtained in experimental studies of zeta potential of ultrafine sulfides (chalcopyrite, tennantite, galena, sphalerite, pyrite, pyrrhotite); floatability of mono-mineral flotation grade sulfide fractions (–0,1 + 0,05 mm) in the mechanical flotation cell; floatability of sludges (–0,041 + 0,010 mm) in the Hallimond tube with adsorption under foamless flotation conditions. The method for preparation of ultrafine powders and sulfhydryl collectors for zeta potential measurement is provided. The paper studies zeta potential of mineral particle surface and insoluble forms of sulfhydryl collectors in the pH range from 2,0 to 12,5 (acidic medium was prepared using H2SO4, alkali medium was prepared using NaOH or Ca(OH)2). The obtained zeta potentials of sulfides were different for sodium hydroxide and lime media. In NaOH medium at pH> 9,5 zeta potential values of all sulfides were negative; in Ca(OH)2 medium at pH > 11 they had positive zeta potential values (1–18 mV); chalcopyrite zeta potential values are positive in the studied range pHCa(OH)2 = 9,0÷12,5. Isoelectric points were identified for chalcopyrite (pH = 6,5 and 8,8), tennantite (pH = 3,0), sphalerite (pH = 5,1 and 6,4), pyrite (pH = 3,1 and 8,9) and pyrrhotite (pH = 7,0) in sulfuric acid and sodium hydroxide medium; for tennantite and sphalerite (pH = 12,0), galena (pH = 11,2), pyrite (pH = 9,5 and 11,2), pyrrhotite (pH = 9,5 and 12,1) in lime medium. Measurements of zeta potential values of ultrafine sulfide particles make it possible to define more exactly the mechanism of interaction between sulfhydryl collectors and sulfides, associate non-selective extraction of sulfide sludges in high-alkali lime medium with the electrostatic component contribution during adhesion of ultrafine sulfide particles on bubbles and their mechanical removal to the froth.