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 T2 - Proceedings / EMC 2019, European Metallurgical Conference 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 T2 - Mineralische Nebenprodukte und Abfälle 6 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 -