CHEMISORPTION - THE THERMODYNAMICALLY FAVORED PROCESS IN THE INTERACTION OF THIOL COLLECTORS WITH SULFIDE MINERALS

Voltammetric investigations show that chemisorption is the thermodynam ically favoured process in the interaction of thiol collectors with su lphide minerals, The potential dependence of chemisorption coverage is in accordance with the Frumkin adsorption isotherm, Chemisorbed thiol s render sulphide mineral surfaces hydrophobic and induce efficient fl otation of mineral particles. W-Visible, Fourier transform infrared, s urface-enhanced Raman scattering, and electron spectroscopic studies p rovide complementary information on the nature of the adsorbed species , X-ray photoelectron spectroscopic (XPS) studies of xanthate on galen a reveal sulphur environments associated with chemisorbed xanthate and lead xanthate but no oxidised sulphur derived from the galena substra te, This finding is explained by electrochemical studies that have sho wn the surface composition of oxidized galena to relax, Discrepancies between the results of conventional and synchrotron radiation excited XPS studies of the oxidation of galena are discussed. (C) 1997 Elsevie r Science B.V.