TY - CONF A1 - Sichler, Theresa A1 - Adam, Christian A1 - Montag, D. A1 - Ehm, J. A1 - Barjenbruch, M. A1 - Pinnekamp, J. ED - Holm, O. ED - Thomé-Kozmiensky, E. ED - Quicker, P. ED - Kopp-Assenmacher, S. T1 - Auswirkungen der novellierten AbfKlärV auf die Kreislaufführung von Pflanzennährstoffen N2 - Because of the longstanding oversupply of nutrients in Germany, waste and fertilization legislation has been amended in 2017. As the new laws do still not meet the European nitrate ordinance, fertilization laws must be tightened again. In consequence, there is a rising competition for land between sewage sludge and organic fertilizers. Furthermore, the new sewage sludge ordinance (AbfKlärV) contains stricter thresholds and a ban on agricultural sewage sludge utilization for WWTPs > 50,000 p.e. from 2029. WWTPs which do not use their sludge for agriculture have to recover phosphorus from then on. However, sludges with less than 2% P content are not affected by that obligation. Every federal state of Germany must report amounts and quality of agricultural utilized sewage sludge yearly. An evaluation of raw data from 10 federal states shows that nearly 40% of both WWTPs and sewage sludge volume fall below the recovery limit of 2%. On the other hand, this means less than 30% of the P potential. In addition, there is no information whether the sludges fall reliably below the limit as required by the ordinance. This project aims to investigate this reliability by regarding the variations in the P content of sewage sludge. For this reason, samples will be taken monthly at 10 representative WWTPs over a year. Whereas phosphorus will still mostly be subject of recovery other nutrients are not affected by this. As a result, large amounts of N, K, Mg and Ca will be increasingly removed from the cycle. In 2017, WWTPs > 50,000 p.e. accounted for 30-60% of the nutrient potentials. These potentials will probably get lost to a large extent due to the fertilization ban. Many small WWTPs are also currently changing their utilization strategy from agriculture to incineration to ensure a safe disposal in future. Therefore, we can expect that even larger amounts of nutrients apart from phosphorus will be discharged from the circular economy. In comparison to the domestic sales volume of mineral fertilizers these other nutrients do only account for a very small fraction. A recovery could nevertheless replace parts of the mineral fertilizers, thus reducing environmental impacts. Energy consumption for technical nitrogen fixation is high and nutrient cycles are strongly anthropogenic influenced with diverse consequences such as eutrophication, acidification and endangered groundwater resources. Sewage sludge contains several micronutrients next to the macronutrients P, N, K, Mg, Ca and S. Because of lacking information on the actual German need for micronutrients contents and freights cannot evaluated. Moreover, former sewage sludge fertilization was probably not needs-based. It is therefore not possible to estimate a true loss in micronutrients due to the amended sewage sludge ordinance. N2 - Die landwirtschaftliche Klärschlammverwertung ist in der Bundesrepublik Deutschland seit Jahren rückläufig, hatte im Jahr 2017 jedoch noch einen Anteil von rund 18 % [20]. Diese Art der Verwertung wird kontrovers diskutiert, da der Klärschlamm im Rahmen der Abwasserreinigung eine Schadstoffsenke darstellt. In vergangenen Jahrzehnten wurden insbesondere die hohen Gehalte an Schwermetallen im Klärschlamm als kritisch für eine landwirtschaftliche Verwertung eingestuft. Diese Belastung konnte allerdings durch Absenkung der Einträge von Schmermetallen in das Abwasser signifikant gesenkt werden. Neben Schwermetallen kamen jedoch auch organische Schadstoffe wie Pharmazeutika, Kosmetika und Haushaltschemikalien in den Fokus der Diskussion über den Einsatz von Klärschlamm auf Agrarflächen. Heute geraten zunehmend weitere Inhaltsstoffe in den Fokus, deren Auswirkungen noch nicht abschließend geklärt sind, weshalb eine einheitliche Bewertung über Grenzwerte nicht darstellbar ist. Beispiele für diese neuen Stoffgruppen sind Mikroplastik, Nanopartikel, Antibiotikaresistenzen und persistente organische Spurenstoffe. Neben den angesprochenen Risiken gibt es in Deutschland Regionen mit einem stark erhöhten Nährstoffüberschuss. In der Kritik steht vor allem eine nicht ordnungsgemäße Düngung mit Stickstoff, welche mit Nitratauswaschungen in das Grundwasser einhergeht. Um diese Grundwasserbelastung zu verhindern wurde u.a. das Düngerecht erneut verschärft, was die Flächenkonkurrenz zwischen Klärschlamm und Wirtschaftsdünger weiter vergrößern wird. Auf Druck der EU-Kommission stehen zudem weitere Anpassungen im Düngerecht bevor, da die beschlossenen Änderungen aus Kommissionssicht nicht ausreichen, um die Nitratrichtlinie einzuhalten. Vor dem Hintergrund der angeführten Probleme wurde im Koalitionsvertrag der 18. Legislaturperiode (2013) festgeschrieben, „die Klärschlammausbringung zu Düngezwecken [zu] beenden und Phosphor und andere Nährstoffe zurück[zu]gewinnen“ [5]. Die novellierte AbfKlärV beinhaltet allerdings kein grundsätzliches Aufbringungsverbot und eine Rückgewinnungspflicht besteht lediglich für den Nährstoff Phosphor. Es ist davon auszugehen, dass sich die neuen Regelungen im Düngerecht und der Klärschlammverordnung massiv auf die landwirtschaftliche Verwertung von Klärschlamm und damit auf die Kreislaufwirtschaft verschiedener Nährstoffe auswirken werden. Zur Ermittlung dieser Auswirkungen wird seit Oktober 2018 im Auftrag des Umweltbundesamtes das REFOPLAN-Projekt „extraWERT“ (FKZ 3718 26 330 0) von der Bundesanstalt für Materialforschung und -prüfung (BAM) in Kooperation mit dem Institut für Siedlungswasserwirtschaft (ISA) der RWTH Aachen durchgeführt. In diesem Beitrag werden erste Ergebnisse dieses Projekts vorgestellt. T2 - Klärschlammkonferenz CY - Berlin, Germany DA - 04.11.2019 KW - Klärschlammdüngung KW - Landwirtschaft KW - Makronährstoffe PY - 2019 SN - 978-3-944310-49-7 VL - 2 SP - 362 EP - 374 PB - Thomé-Kozmiensky Verlag CY - Neuruppin AN - OPUS4-49603 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schraut, Katharina A1 - Adamczyk, Burkart A1 - Simon, Sebastian A1 - von Werder, Julia A1 - Meng, Birgit A1 - Stephan, D. A1 - Kargl, F. A1 - Adam, Christian T1 - Formation and chemical stabilisation of tricalcium-silicate during solidification from the melt of post-treated metallurgical slags N2 - Tricalcium-silicate (C3S) or Alite is the most important mineral in Portland cement. Since pure tricalcium-silicate is only stable above temperatures of 1250 °C, its decomposition has to be prevented technically by fast cooling after the sintering process. At room temperature, the decomposition velocity is very slow so that metastable tricalcium-silicate is obtained. Although the mechanisms of clinker phase formation during burning process of Portland cement in a rotary kiln were solved and improved over the years, in view of possible economic and ecological benefits current projects aim to produce clinker phases from metallurgical slags. Recent studies discovered that the mineral phase which remained after a reducing treatment and separation of formed metallic iron from molten Linz-Donawitz (LD-) slags contained about 60 wt.% Alite despite it was cooled slowly. Because the results could be verified using slags from different origins and varying cooling velocities a chemical stabilisation of the Alite can be assumed. First tests in mortars indicate that workability, hardening and solid state properties are comparable with an ordinary Portland cement. An application of the observed phenomenon in cement production requires enhanced knowledge about formation and stabilisation conditions of Alite during crystallisation from melts in contrast to the sintering reactions in conventional Portland cement production. Therefore, this study focuses on the stabilisation mechanisms of Alite in consolidating melts. Samples from different melting experiments are analysed to determine stabilising factors. T2 - 15th International Congress on the Chemistry of Cement CY - Prag, Czech Republic DA - 16.09.2019 KW - Tricalcium-silicate KW - Portland Cement KW - Alite KW - Steelmaking slag PY - 2019 SP - Paper 492, 1 EP - 10 AN - OPUS4-49050 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Taube, Mareike Carolin A1 - Adam, Christian A1 - Adamczyk, Burkart A1 - Beckmann, T. A1 - Reuter, M. A1 - Stelter, M. T1 - Influence of carbon feeding on a pyrometallurgical tantalum and niobium recycling process and the formation of carbides N2 - An existing pyrometallurgical process for tantalum and niobium recovery, mainly from low grade pyrometallurgical residues, was investigated. Series of melting experiments were carried out in a pilot-scale electric arc furnace to study how the amount, the grain size and the way of feeding affect the activity of carbon as a reducing agent. During the pyrometallurgical treatment refractory metals such as tantalum and niobium are reduced to their carbide form and enriched in the molten iron-based metal phase. The cooled down slag and metal phase were analysed to investigate thermodynamic and kinetic conditions of the carbide formation. FACT Sage simulations were also used to investigate the material system in state of thermodynamic equilibrium. Results show that mass transfer and kinetics may play an important role if compared to equilibrium analyses using FACT Sage. T2 - Euopean Metallurgical Conference (EMC) 2019 CY - Düsseldorf, Germany DA - 23.06.2019 KW - Pyrometallurgy KW - Tantalum KW - Carbide formation KW - Reduction process KW - Carbon feeding PY - 2019 SN - 978-3-940276-87-2 VL - 1 SP - 371 EP - 386 PB - GDMB Verlag GmbH CY - Clausthal-Zellerfeld AN - OPUS4-48363 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Taube, Mareike Carolin A1 - Adam, Christian A1 - Adamczyk, Burkart A1 - Beckmann, T. A1 - Reuter, M. A1 - Stelter, M. ED - Thiel, S. ED - Thomé-Kozmiensky, E. ED - Pretz, T. ED - Senk, D. G. ED - Wotruba, H. T1 - Tantal-Rückgewinnung aus Zinnschlacken und weiteren Reststoffen N2 - Since the recycling of tantalum bearing post-consumer waste is practically not existent, metallurgical residues are the most important feed for the tantalum recycling. Most tin ores naturally contain significant quantities of refractory metals. During the smelting process in primary tin production these elements are enriched in the slag phase. This slag is a highly valuable raw material for tantalum production due to its considerable concentration of tantalum and its functioning as an additional slag former in further pyrometallurgical treatment. In this paper the first process stage of an existing pyrometallurgical process for tantalum recovery, mainly from low grade pyrometallurgical residues, is discussed. Smelting trials were carried out in a pilot-scale electric arc furnace to analyse the effect of feeding on the activity of carbon as a reducing agent. Therefore, blowing petroleum coke through an iron lance and the manual adding of coke into the melting bath were tested. During the pyrometallurgical treatment elements with a high affinity to carbon were reduced to their carbide form and enriched in the molten iron-based metal phase. The objective of the process was to reduce the oxidic tantalum completely and to enrich it into the metal phase. Furthermore, the transfer of unwanted elements such as titanium into the metal phase was aimed to be avoided. Spoon test specimens were taken from the liquid mineral melt to follow the evolution of the reduction process. The cooled down solidified melting bath was investigated by using the XRD and EDX method to characterise the slag system and to identify relevant mineral phases. T2 - Berliner Konferenz Mineralische Nebenprodukte und Abfälle CY - Berlin, Germany DA - 13.05.2019 KW - Zinnschlacke KW - Tantal KW - Recycling KW - Pyrometallurgie KW - Lichtbogenofen PY - 2019 SN - 978-3-944310-47-3 VL - 6 SP - 378 EP - 393 PB - Thomé-Kozmiensky Verlag GmbH CY - Neuruppin AN - OPUS4-48357 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hamann, Christopher A1 - Adam, Christian A1 - Stolle, Dirk A1 - Spanka, M. A1 - Auer, G. T1 - Thermochemical treatment of waste products from iron and steel production N2 - Blast furnace (BF) sludge and electric arc furnace (EAF) dust are typical wastes that incur from iron and steel production. In addition to iron, calcium, carbon, and silicon they usually contain high concentrations of heavy metals such as zinc, lead, and cadmium that are potentially hazardous to the environment, rendering disposal in landfills ecologically problematic and costly. Consequently, pyrometallurgical, hydrometallurgical, and hybrid methods for selective elimination of non-ferrous heavy metals from BF sludge and EAF dust have been conceived, of which only the carbothermic reduction route taken in the so-called Waelz rotary kiln process has been proven to be economically successful. However, this process has several drawbacks regarding efficiency of heavy-metal removal and recovery of iron, and it does not allow processing of BF sludge. In this study, we investigated the efficiency and feasibility of selective chlorination and evaporation of non-ferrous heavy metals, particularly zinc and lead, in both BF sludge and EAF dust as an alternative, thermochemical processing route. To this end, hydrochloric acid and iron(II) chloride solution have been used as chlorinating agents, and the process of heavy-metal chlorination and evaporation has been investigated under inert operating conditions, at variable chlorine concentrations, and at temperatures between 500 and 1200 °C. High zinc and lead removal efficiencies of > 99.5 % were achieved with both chlorinating agents, but iron(II) chloride turned out to be overall more efficient for removal of zinc and lead from BF sludge and EAF dust. Interestingly, and in contrast to previous studies, the iron was completely retained in the processed solid residue, therefore rendering the processed residues virtually zinc- and lead-free raw materials that may either be used internally (e.g., feeding processed BF sludge and EAF dust back into the respective furnaces) or externally (e.g., for cement production). T2 - European Metallurgical Conference 2019 CY - Düsseldorf, Germany DA - 23.06.2019 KW - Blast furnace sludge KW - Electric arc furnace dust KW - Recycling KW - Selective chlorination KW - Zinc PY - 2019 SN - 978-3-940276-89-6 VL - 3 SP - 1267 EP - 1282 PB - GDMB CY - Clausthal-Zellerfeld AN - OPUS4-48362 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -