An X-ray photoelectron spectroscopic investigation of chalcopyrite and pyrite surfaces after conditioning in sodium sulfide solutions

McCarron, J.J.; Walker, G. W.; Buckley, Alan N.

doi:10.1016/0301-7516(90)90064-6

Cited by 36 publications

(7 citation statements)

References 11 publications

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“…Fitting with an assumption of two doublets gives the positions of the S 2p 3/2 component for each doublet at 161.2 and 163.0 eV with the fwhm values of 1.35 and 1.85 eV, respectively. The doublet positioned at lower energy, i.e., 161.1 eV (component b), is characteristic for chalcopyrite sulfur, which is in agreement with a previous observation …”

Section: Resultssupporting

confidence: 92%

“…This indicates formation of surface intermediate species like metal-deficient sulfides 8 or polysulfides. , The presence of elemental sulfur was excluded on the basis of the observation that the S2p 3/2 peak at 163.0 eV is stable in ultrahigh vacuum (UHV), at room temperature during the measurement time. It was already demonstrated that the elemental sulfur in the outermost layer is not stable under UHV conditions at room temperature …”

Section: Resultsmentioning

confidence: 99%

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XPS Characterization of Chalcopyrite, Tetrahedrite, and Tennantite Surface Products after Different Conditioning. 1. Aqueous Solution at pH 10

et al. 1996

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Characterization of the surface products formed by the interaction of aqueous solution at pH 10 with mineral samples of chalcopyrite (CuFeS2), tetrahedrite (Cu12Sb4S13), and tennantite (Cu12As4S13) was carried out by X-ray photoelectron spectroscopy (XPS). The experimental data collected directly after treatment with aqueous solution and after successive sputtering have led us to determine the in-depth distribution of the different types of surface products formed by the diffusion of metal atoms from the bulk structure to the interface and their interaction with aerated water. In general, the following in-depth surface composition was found for the investigated mineral samples: (i) the outermost thin layer consists of hydrophilic species, mainly ferric or cupric (depending on the mineral sample) oxides/hydroxides and adsorbed water, (ii) the next layer is a sulfur-enriched structure with a gradually changing composition with hydrophobic properties which vary significantly among the minerals, and (iii) the innermost layer has a bulk mineral composition and structure. In the case of chalcopyrite the separation between the outermost hydrophilic layer (iron oxides/hydroxides) and the internal hydrophobic sulfur-rich layer is more pronounced than for other mineral samples. This is the reason that the outermost hydrophilic thin layer can be relatively easily removed mechanically and/or by dissolution during a strong agitation. This involves a strong increase in the hydrophobicity of chalcopyrite. In the case of tetrahedrite and tennantite the outermost hydrophilic layer consists mainly of copper oxides/hydroxides and it is not well separated from the rest of the surface structure. This implies that the two minerals remain hydrophilic. Tetrahedrite forms the copper oxides/hydroxides product much more quickly with a major amount of cupric species, whereas tennantite oxidation, under the same conditions, yields a small amount of cuprous surface species. The differences in surface composition of these three minerals, caused by the different mobilities of copper atoms in their crystalline structures, are vitally important for their separation in the presence of surfactants. It should be noted that although tetrahedrite and tennantite contain a significant amount of other elements, they are not concentrated in the outermost layer. On the contrary their surface concentrations are several times lower than those found for the bulk composition.

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Section: Resultssupporting

confidence: 92%

Section: Resultsmentioning

confidence: 99%

XPS Characterization of Chalcopyrite, Tetrahedrite, and Tennantite Surface Products after Different Conditioning. 1. Aqueous Solution at pH 10

et al. 1996

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“…The model of oxidation and reaction of iron-containing sulphides is now well established. 1,10,11,14,21 The development of Fe(II)-O species and, on oxidation, an Fe(III)-O overlayer predominantly as hydroxide species proceeds, leaving the underlying surface of the original mineral increasingly deficient in iron. The stoichiometry of this underlayer (measured by XPS or Auger spectrometry) on pyrrhotite can be observed to change from Fe 7 S 8 through Fe 2 S 3 to FeS 2 with extended reaction.…”

Section: Discussionmentioning

confidence: 99%

“…21 Dramatic evidence of the formation of islands of elemental sulphur has been provided by AFM imaging of galena oxidising in acid solution. The sulphur islands are directly correlated with an S 2p 3/2 component at 163.9 eV lost on evaporation at room temperature in a vacuum.…”

Section: Discussionmentioning

confidence: 99%

XPS of sulphide mineral surfaces: metal-deficient, polysulphides, defects and elemental sulphur

Smart

Skinner

Gerson

1999

Surf. Interface Anal.

369

187

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This paper reviews evidence for the assignments of components of the S 2p XPS spectra from sulphide mineral surfaces under different conditions of preparation, oxidation and reaction. Evidence from other techniques confirming assignment of high‐binding‐energy S 2p components to metal‐deficient sulphide surfaces, polysulphides, elemental sulphur and electronic defect structures is considered for specific cases. Reliable assignment of S 2p3/2 components at 163.6–164.0 eV to elemental sulphur Sn0 can be confirmed by evaporative loss at 295 K and/or observation of S–S bonding by x‐ray absorption fine structure (XAFS), x‐ray diffraction or vibrational spectroscopy. Assignment to polysulphides Sn2− at 162.0–163.6 eV requires confirmation of S–S bonding by XAFS or vibrational spectroscopy. Metal‐deficient lattices can be represented as electronic defects (e.g. vacancies) or restructured surface phases confirmed by diffraction or XAFS evidence. High‐binding‐energy S 2p3/2 components can also result from Cu(I) substitution into ZnS with associated oxidation of sulphur as electronic defect sites without S–S bonding, metal deficiency or restructuring. This assignment is confirmed by XAFS evidence. Copyright © 1999 John Wiley & Sons, Ltd.

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“…Surface analysis of natural enargite mineral can provide important information for a better understanding of this material with respect to various industrial applications as different as, for instance, ore processing by floating for copper exploitation 1 or the possibility of solar energy conversion due to the semiconductive properties of this material. 2 The knowledge of surface reactivity and compounds formed at the mineral surface is vitally important in the mineral industry for copper exploitation.…”

Section: Introductionmentioning

confidence: 99%

XPS analysis of an electrochemically modified electrode surface of natural enargite

Velásquez

Ramos-Barrado

Córdova

et al. 2000

Surf. Interface Anal.

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A natural enargite (Cu 3 AsS 4 ) electrode has been studied by cyclic voltammetry (CV) and XPS. Cyclic voltammetry was carried out in a preparation chamber filled with Ar gas and coupled to the spectrometer in order to analyse by XPS, quasi-in situ, the electrochemically modified electrode surface. By CV, different potentials of oxidation and reduction were applied to the electrode in a disodium tetraborate decahydrate electrolyte solution of pH 9.2 at room temperature. Cycling in the anodic direction, XPS analysis has shown that at Y500 mV the electrode surface is oxidized to CuO, CuSO 4 and As 2 O x (x = 3; 5) and the corresponding hydroxides and polysulphide are formed, whereas at lower oxidation potentials the Cu 2p and As 3d photoelectron peaks do not alter. However, with increasing oxidation potential up to Y200 mV a new contribution in the S 2p signal and Cu loss indicate the formation of non-stoichiometric (metal-deficient) enargite and polysulphides in the electrode surface. Cycling then from Y500 mV in the cathodic direction until −800 mV, we observe with increasing reduction potential a reverse process in the S 2p signal and Cu concentration. Furthermore, even at Y200 mV the reduction from Cu(II) to Cu(I) occurs and no sulphate species are observed any more. These observations indicate that the copper concentration at the electrode surface is a sweep-direction-independent function of applied potential and that the oxide species formed at the electrode surface are only stable by application of high oxidation potentials. For comparison, the surfaces of the fractured mineral and the original polished electrode surface were also studied.

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An X-ray photoelectron spectroscopic investigation of chalcopyrite and pyrite surfaces after conditioning in sodium sulfide solutions

Cited by 36 publications

References 11 publications

XPS Characterization of Chalcopyrite, Tetrahedrite, and Tennantite Surface Products after Different Conditioning. 1. Aqueous Solution at pH 10

XPS Characterization of Chalcopyrite, Tetrahedrite, and Tennantite Surface Products after Different Conditioning. 1. Aqueous Solution at pH 10

XPS of sulphide mineral surfaces: metal-deficient, polysulphides, defects and elemental sulphur

XPS analysis of an electrochemically modified electrode surface of natural enargite

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