Zinc and lead sorption on the surface of CuFeS2 during flotation: a fluorescence REFLEXAFS study

The structural environment of Pb and Zn sorbed from solution onto the surfa ce of chalcopyrite has been studied by XAS both before and after the additi on of xanthate. Initially the Pb is bonded as a Pb-O species to the surface sulfur atoms, probably via the hydrophobic S-rich species. After the addit ion of xanthate, the oxygen bonded to the Pb is displaced and the Pb is coo rdinated to 4 S atoms. The Zn, in contrast, is initially coordinated only t o oxygen atoms on the surface, probably via a Fe(OH)(x)-type species and af ter xanthate addition it is bonded to ca. 1 O atom and 3 S atoms, the latte r provided by the xanthate. These observations help explain the loss of sel f-flotation of chalcopyrite in the presence of metal ions and the action of the xanthates in restoring its flotability. (C) 1999 Elsevier Science B.V. All rights reserved.