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| Format: | Artículo científico |
| Language: | en |
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Universitat de Barcelona
2013
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| Online Access: | https://www.redalyc.org/articulo.oa?id=50529511006 |
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Table of Contents:
- Analysis of the iron coatings formed during marcasite and arsenopyrite oxidation at neutral-alkaline conditions M.P. Asta R. Pérez-López G. Román-Ross V. Illera J. Cama M. Cotte R. Tucoulou Ciencias de la Tierra Neutral basic pH Marcasite Iron phases Arsenopyrite In 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 of 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. 2013 artículo científico 1695-6133 https://www.redalyc.org/articulo.oa?id=50529511006 en http://www.redalyc.org/revista.oa?id=505 Geologica Acta: an international earth science journal application/pdf Universitat de Barcelona Geologica Acta: an international earth science journal (España) Num.4 Vol.11