Prediction of Leachate Quality for a Gossan Dump, Angostura, Spain
The Iberian Pyrite Belt (IPB) is one of the largest of the world’s massive sulfide provinces. Since the Chalcolithic era, gossans formed from massive sulfide mineralization have been worked for copper , silver and gold. Consequently many historical mine s
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Abstract The Iberian Pyrite Belt (IPB) is one of the largest of the world’s massive sulfide provinces. Since the Chalcolithic era, gossans formed from massive sulfide mineralization have been worked for copper, silver and gold. Consequently many historical mine sites have abandoned dumps of gossanous material. One such example is located at Angostura, a historical copper mine which operated from 1906 to 1931. The aims of this study are to determine the mineralogical hosts of environmentally significant elements (As, Ba, Bi, Co, Cu, Hg, Mo, Sb, Se, Ni, Pb, Zn) in gossanous waste rocks dumped adjacent to the Angostura open cut, using geochemical, optical, SEM-MLA and laser ablation techniques. Our findings demonstrate that the gossan materials are enriched in environmentally significant elements with several hosted by iron oxides and iron-oxyhydroxides. Leaching of these gossan materials was performed using three extractants to represent different conditions which may be experienced in a surficial environment (i.e., deionized water, hydrogen peroxide and sulfuric acid). Results from these experiments indicated that under ambient surface conditions all analyzed elements will not be A. Parbhakar-Fox (&) N. Fox School of Physical Sciences, University of Tasmania, Private Bag 79, Hobart, TAS 7001, Australia e-mail: [email protected] N. Fox e-mail: [email protected] J. Hunt GeMMe, University of Liege, Sart Tilman B52, 4000 Liege, Belgium e-mail: [email protected] B. Lottermoser Institute of Mineral Resources Engineering, RWTH Aachen University, Wüllnerstrasse 2, 52062 Aachen, Germany e-mail: [email protected] E.M. van Veen Camborne School of Mines, Environment and Sustainability Institute, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, UK e-mail: [email protected] © Springer International Publishing Switzerland 2017 B. Lottermoser (ed.), Environmental Indicators in Metal Mining, DOI 10.1007/978-3-319-42731-7_13
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released from their goethite and hematite hosts. However, under ARD conditions, elements such Co, Cu, Pb and Zn will be mobilized.
Introduction The Iberian Pyrite Belt (IPB) is one of the world’s largest massive sulfide provinces with a total estimated tonnage of 1600 Mt of massive sulfides, and approximately 250 Mt in the underlying sub-economic stockwork (Tornos 2006). It has been continuously explored and mined since prehistoric times resulting in more than 80 mines across Spain and Portugal, including the large Rio Tinto and Neves Corvo deposits (e.g. Leistel et al. 1998; Sáez et al. 2003; Nocete et al. 2005; Pérez-López et al. 2011). Associated with these deposits are gossans (typically up to 70 m thick; Núñez et al. 1987), which formed as a result of supergene oxidation of such massive sulfide deposits (Velaso et al. 2013; Fig. 1). In the IPB, gossanous rocks are characterized by a high content of hematite, amorphous and poorly crystalline Fe oxyhydroxides, goethite and quartz (Romero et al. 2006; Velaso et al. 2013). In additi
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