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Se K-edge XANES spectrum collected from sample 3-5 compared to the spectra obtained for selenite and selenate model compounds showing that selenium dominant redox state is 4+ in the mine waste material, despite the perceptible occurrence of selenide anions
Source publication
Selenium is an essential nutrient for humans, animals and microorganisms, but it becomes toxic at concentrations slightly above the nutritional levels. This naturally occurring trace element can be released to the environment from various anthropogenic sources such as mining, agricultural, petrochemical and industrial processes and its toxicity is...
Contexts in source publication
Context 1
... view of clearly perceptible differences in the degree of selenium oxidation, the Se K-edge XANES spectra of the three mine waste materials are separately compared with the spectra obtained for Se-O model compounds (a selenite, Na 2 SeO 3 , and a selenate, Na 2 SeO 4 , in the case of sample 3-5, Figure 6) and for the model selenide minerals (guanajuatite/paraguanajuatite, Bi 2 (Se 1-y S y ) 3 , and galena, Pb(S 1-x Se x ), in the case of the other two samples, Figure 7). Vol. 3, No. 4;2014 The energy of the strong absorption maximum -the so-called white line -was highlighted along with other spectral details to allow for an easy comparison of collected Se K-edge XANES spectra. ...
Context 2
... for Se = , 12658.0 eV for Se 4+ , 12661.5 eV for Se 6+ (Pickering, Brown & Tokunaga, 1995;Ryser et al., 2006;Scheinhost et al., 2008;Kavshnina et al., 2009;Wiramanaden, Liber & Pickering, 2010). The result is in good agreement with the sequence of experimental values obtained for the studied mining waste materials (Figures 6 and 7). ...
Citations
... There is an emerging consensus that a sustainable approach to waste management requires further development of secondary raw material markets [23]. Despite Portugal having already conducted some previous studies into secondary raw materials, namely, indium [24], selenium [25], rhenium [26] and tetrahedrite-tennantite [27], it is with these reminders as props that as part of the Geological Service for Europe (GSEU) Project, Portugal is revisiting the old mines in the south of the country located in the Ossa-Morena and South Portuguese Zones (including the Iberian Pyrite Belt (IPB) [28]), seeking to define and characterize the (critical) mineral contents of the mine waste dumps. ...
A steady supply of mineral raw materials is vital for the transition to a low-carbon, circular economy. The number of active mines in Europe has severely declined over the last century and half, giving rise to many abandoned mining waste sites and corresponding geological heritage. Also, the rise in minerals demand for large-scale deployment of renewable energy requires the continued and steady availability of key minerals. The supply risk associated with unpredicted geopolitical events needs to be eliminated/mitigated. Historical mine waste sites are the answer but evaluating mine waste is a lengthy and costly exercise. The study, undertaken in the Lousal Mine, used small unmanned aerial systems (sUASs) to model and determine mine waste volumes by generating orthomosaic maps with quick, inexpensive, and reliable results. Calculated mine waste volumes between 308,478 m3 and 322,455 m3 were obtained. XRD and p-XRF techniques determined the mineralogy and chemistry of waste, which varied from mineralization and host rocks with hydrothermal alteration and numerous neogenic sulphates (mostly gypsum, rhomboclase, ferricopiapite, coquimbite, and jarosite) related with supergene processes and weathering. The study shows the viability of using these sUASs to successfully model historical mine waste sites in an initial phase and for future monitoring programs.
