TY - CONF A1 - Hoffmann, Marie A1 - Vogel, Christian A1 - Adam, Christian A1 - Stephan-Scherb, Christiane A1 - Hecht, Lutz T1 - Novel approaches to Sc species investigation in bauxite residues by x ray absorption near edge structure spectroscopy N2 - In a rapidly evolving world, the demand on raw materials is increasing steadily and many technologies are dependent on a secure supply of hi-tech metals. Recently, scandium (Sc) has attracted attention since its use in high strength Al-alloys and solid-oxide-fuel-cells strongly improves the performance of those materials. The element Sc is not exceptionally rare but quite resistant to geochemical enrichment processes, it is scarcely found enriched to high concentrations and is recovered as a by-product. Since Sc enrichment in Greek bauxite residues was shown by Ochsenkühn-Petropoulou et. al (1994), intensive research on this material and development of efficient Sc-recovery methods is ongoing. This study investigates Sc-bearing species in bauxite residues from alumina production. It aims to provide direct evidence about the Sc-speciation’s in those secondary resources and tries to find the link to speciation’s in primary resources, e.g. bauxites and laterites. Therefore, Sc K edge XANES (X-ray absorption near edge structure) spectroscopy is performed using synchrotron radiation to determine the presence of certain Sc-components and distinguish between adsorbed and chemically bonded Sc as was shown for lateritic deposits in Australia by Chassé et al. 2016. For comparison, reference standards of Sc-bearing and Sc-adsorbed species are synthesized. Indirect inferences from leaching behavior of bauxites, in cases supported by analyses with LA-ICP-MS, suggest Sc to be associated with either iron- or aluminum phases (Vind et al. 2017); (Suss et al.). It remains unclear how different primary materials influence Sc-speciation in the bauxite residue. Therefore, a comparison between different European bauxite residues is made in this study. The investigations should help to understand Sc chemistry and behavior in different primary and secondary materials and provide fundamentals for metallurgical processing. The research is incorporated in the SCALE project (GA No. 730105) funded by EU Horizon 2020 research and innovation program. T2 - DMG Tagung GeoMünster CY - Westfälische Wilhelms-Universität Münster, Germany DA - 22.09.2019 KW - Scandium KW - Bauxite Residue KW - Red Mud KW - XANES PY - 2019 AN - OPUS4-49389 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, Marie A1 - Adam, Christian T1 - Scandium and scandium-aluminium alloy production from European metallurgical by-products N2 - The SCALE Project is a Horizon2020 Project (GA°730105) that aims to develope a secure supply chain for Scandium in Europe. To achieve that, the whole value chain is investigated and new methodologies and techniques are being developed. In BAM we are characterizing potential Scandium-bearing industrial by-products. T2 - Poster presentation during Exploration Geology Short Course DMG CY - Freiburg, Germany DA - 19.02.2018 KW - Scandium KW - Red Mud KW - Aluminium KW - SCALE PY - 2018 AN - OPUS4-46539 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, Marie A1 - Adam, Christian T1 - Scandium in industriellen Reststoffen - Die Suche nach der Nadel im Heuhaufen N2 - Im Zusammenhang mit dem Horizon2020 geförderten Projekt SCALE (GA°730105) untersuchen wir an der BAM die Scandium Spezies in industriellen Restsoffen wie zum Beispiel Rotschlamm. Dabei kommen Methoden wie Elektronenmikroskopie, LA-ICP-MS und auch X-ray Adsorption near edge structure an Synchrotron-Lichtquellen zum Einsatz. Das Verständnis der Bindungsformen des Scandiums soll im Weiteren helfen, metallurgische Gewinnungsmethoden zu verbessern und anzupassen. T2 - Posterpräsentation während des Themenfeldtags Umwelt CY - Berlin, Germany DA - 18.10.2018 KW - Scandium KW - Rotschlamm KW - Aluminium KW - SCALE PY - 2018 AN - OPUS4-46540 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Vogel, Christian A1 - Hoffmann, Marie A1 - Krüger, O. A1 - Murzin, V. A1 - Caliebe, W. A1 - Adam, Christian T1 - Chromium (VI) in phosphorus fertilizers determined with the diffusive gradients in thin-films (DGT) technique N2 - Phosphorus (P) fertilizers from secondary resources became increasingly important in the last years. However, these novel P-fertilizers can also contain toxic pollutants such as chromium in its hexavalent state (Cr(VI)). This hazardous form of chromium is therefore regulated with low limit values for agricultural products even though the correct determination of Cr(VI) in these fertilizers may be hampered by redox processes, leading to false results. Thus, we applied the novel diffusive gradients in thin-films (DGT) technique for Cr(VI) in fertilizers and compared the results with the standard wet chemical extraction method (German norm DIN EN 15192) and Cr K-edge X-ray Absorption near-edge structure (XANES) spectroscopy. We determined an overall good correlation between the wet chemical extraction and the DGT method. DGT was very sensitive and for most tested materials selective for the analysis of Cr(VI) in P-fertilizers. However, hardly soluble Cr(VI) compounds cannot be detected with the DGT method since only mobile Cr(VI) is analyzed. Furthermore, Cr K-edge XANES spectroscopy showed that the DGT binding layer also adsorbs small amounts of mobile Cr(III) so that Cr(VI) values are overestimated. Since certain types of the P fertilizers contain mobile Cr(III) or partly immobile Cr(VI), it is necessary to optimize the DGT binding layers to avoid aforementioned over- or underestimation. Furthermore, our investigations showed that the Cr K-edge XANES spectroscopy technique is unsuitable to determine small amounts of Cr(VI) in fertilizers (below approx. 1% of Cr(VI) in relation to total Cr). KW - Phosphorus fertilizer KW - Sewage sludge ash KW - Diffusive Gradients in thin films (DGT) KW - Chemical extraction KW - XANES spectroscopy PY - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-509578 SN - 0944-1344 VL - 27 SP - 24320 EP - 24328 PB - Springer AN - OPUS4-50957 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Vogel, Christian A1 - Hoffmann, Marie A1 - Taube, Mareike A1 - Krüger, O. A1 - Baran, R. A1 - Adam, Christian T1 - Uranium and thorium species in phosphate rock and sewage sludge ash based phosphorus fertilizers N2 - Phosphorus (P) is an essential element for all forms of life and is thus often applied as phosphate rock-based P-fertilizers in agriculture to enable continuous farming. However, these P-fertilizers contain also hazardous uranium (U) and thorium (Th), up to 660 and 220 mg/kg, respectively. On the contrary, novel P-fertilizers made from sewage sludge (ash) contain only low mass fractions of U and Th. In addition to the total amount of U and Th in P-fertilizers, their mobility and bioavailability is important, which depends to a large extent on their chemical state, especially oxidation state and chemical bonding. Thus, we analyzed their chemical state in various P-fertilizers by U and Th L3-edge HERFD-XANES spectroscopy. Phosphate rocks and sewage sludge-based P-fertilizers contain mainly U(IV) compounds which have only a low bioavailability. In contrast, acidic treatment of phosphate rock to produce super phosphates lead to an oxidation to U(VI) compounds (including formation of uranium phosphates) with a strongly increased bioavailability. On the contrary, all analyzed P-fertilizers contain Th in form of strongly insoluble phosphates and oxides with a low bioavailability. Additionally performed water extractions and Diffusive Gradients in Thin-films (DGT) experiments support these findings. KW - Phosphorus fertilizer KW - Sewage sludge KW - X-ray absorption near-edge structure (XANES) spectroscopy KW - Diffusive Gradients in Thin-films (DGT) KW - Extraction PY - 2020 U6 - https://doi.org/10.1016/j.jhazmat.2019.121100 SN - 0304-3894 VL - 382 SP - 121100, 1 EP - 6 AN - OPUS4-48872 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -