Date of Award


Degree Type


Degree Name

Doctor of Philosophy


This thesis examines the interaction of aqueous metal complexes, KAuCl{dollar}\sb4{dollar}, Na{dollar}\rm\sb3Au(S\sb2O\sb3)\sb2{dollar}, Na{dollar}\rm\sb2PdCl\sb4{dollar} and HgCl{dollar}\sb2{dollar}, with the surfaces of the sulphide minerals, FeS{dollar}\sb2{dollar}, PbS and (Zn,Fe)S. The aim of this work was to gain a better understanding of the role of sulphide minerals in controlling metal concentrations in ore depositing and other natural aqueous systems. Scanning electron microscopy (SEM) and the surface sensitive techniques of Auger electron spectroscopy, and in particular, X-ray photoelectron spectroscopy, provided information relating to the chemical and morphological changes occurring at the mineral surface. Atomic absorption spectroscopy was used to monitor solution concentrations.;KAuCl{dollar}\sb4{dollar} is reduced to Au(0) on all three sulphides. The sulphide mineral acts as the reducing agent. High resolution XPS of S 2p region indicated that PbS and (Zn,Fe)S are oxidised to polysulphides. Zn, Fe and Pb are released as the sulphide lattice is disrupted. Although polysulphides were detected on pyrite after long reaction times, soluble sulphate appears to be the major oxidation product. The difference in the oxidation state and amount of gold detected on pyrite and galena plates from solutions of Na{dollar}\rm\sb3Au(S\sb3O\sb3)\sb2{dollar}, suggest that the ability of the mineral to concentrate reduced gold will be a function of the reduction potential of the mineral and the gold complex.;Na{dollar}\rm\sb2PdCl\sb4{dollar} is also reduced to the metal by all three minerals. Detailed studies with pyrite show that the reduction is controlled by the solution concentrations of Cl{dollar}\sp-{dollar} and H{dollar}\sp+{dollar}. The non-uniformity of the reduction process is a result of surface control of the reaction. Adsorbed Pd(II) species were also detected. PbS and (Zn,Fe)S are oxidised to polysulphides, and palladium sulphides are also formed.;Three forms of sorbed Hg(II) were detected on PbS. It was possible to distinguish HgS from Hg{dollar}\rm\sb3S\sb2Cl\sb2{dollar} and another species associated with chloride, from the change in the S 2p spectra after desorption with ligands of varying desorbing strengths. Only weakly bound Hg(II) was detected on FeS{dollar}\sb2{dollar}.



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