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dc.contributor.authorAsta, M. P.
dc.contributor.authorPérez López, Rafael 
dc.contributor.authorRomán Ross, G.
dc.contributor.authorIllera, V.
dc.contributor.authorCama, J.
dc.contributor.authorCotte, M.
dc.contributor.authorTucoulou, R.
dc.identifier.citationAsta, M.P, Pérez López, R., Román Ross, G., Illera, V., Cama, J.,Cotte, M., Tucoulou, R. "Analysis of the iron coatings formed during marcasite and arsenopyrite oxidation at neutral-alkaline conditions". Geologica Acta. Vol. 11, n. 4,, págs. 465-481, (2013). DOI: 10.1344/105.000002062en_US
dc.description.abstractIn order to study the nature of the precipitates formed on arsenopyrite and marcasite after reacting with neutral to alkaline solutions, a combination of techniques including Scanning Electron Microscope-Energy Dispersive Spectroscopy (SEM-EDS), X-ray Photoelectron Spectroscopy (XPS) and synchrotron-based techniques such as micro-X-Ray diffraction (μXRD) and Micro-X-ray Absorption Near Edge Structure (μXANES) have been used. The results showed that the oxidation of marcasite and arsenopyrite under neutral to alkaline conditions leads to the formation of an Fe rich coating which seems to prevent the oxidation of these sulphides. SEM observations confirmed the presence newly-formed phases after the sulphides reaction under the studied conditions. XPS analysis showed that iron, sulphur and arsenic in the case of the arsenopyrite are in oxidized states in the sulphide surfaces. The microscale analysis of the S and Fe speciation performed by μXANES suggested that due to the sulphide oxidation an increase in the oxidation state of those elements took place together with an increase of the sulphate content in the surface layer (grain boundary). Micro-X-ray diffraction results indicated that goethite (α-FeOOH) is the only crystalline newly-formed phase when the reaction occurs at pH 12 whereas at lower pH the products formed on the sulphide surfaces seem to be poorly crystalline and they do not contribute to the diffraction effects in the XRD diagrams.en_US
dc.description.sponsorshipThis research was supported by the project REN 2003-09590-C04-02 from the Spanish Government. MPA has received economical support from the Spanish Ministry of Science and Innovation through a Research Contract from the "Juan de la Cierva" Subprogram. RPL thanks the Spanish Ministry of Science and Innovation and the "Ramon y Cajal" Subprogram (MICINN-RYC 2011). Albert Soler and Angels Canals from the Departament de Cristal center dot lografia, Mineralogia i Diposits Minerals of Universitat de Barcelona supplied the arsenopyrite and marcasite samples. We wish to express our gratitude to Javier Perez, Vanessa Ouro, Rafel Bartroli, Eva Pelegri, Eva Prats, Ana Dominguez and Josep Elvira for their technical assistance. We are indebted to Lorenzo Calvo for his assistance in XPS analyses and to Xavier Llovet who assisted in the obtainment of EMP analyses at the Serveis Tecnics of Universitat de Barcelona. The constructive comments of the Editor, Dr. Josep M. Soler, Dr. Majzlan and an anonymous reviewer have considerably improved the original manuscript. We gratefully acknowledge the support of this study by a grant of the European Synchrotron Radiation Facility (ESRF; proposal EC-632).en_US
dc.publisherUniversitat de Barcelonaen_US
dc.rightsAtribución-NoComercial-SinDerivadas 3.0 España*
dc.subject.otherSulphide oxidationen_US
dc.subject.otherIron phasesen_US
dc.subject.otherNeutral-basic pHen_US
dc.titleAnalysis of the iron coatings formed during marcasite and arsenopyrite oxidation at neutral-alkaline conditionsen_US
dc.relation.projectIDinfo:eu-repo/grantAgreement/Spanish Government [2003-09590-C04-02]en_US

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