2019-Sustainable Industrial Processing Summit
SIPS2019 Volume 4: Kozlov Intl. Symp. / Sustainable Materials Recycling Processes and Products
| Editors: | F. Kongoli, S.V. Alexandrovich, D.V. Grigorievich, L.L. Igoryevich, I. Startsev, T.A. Vladimirovich |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2019 |
| Pages: | 193 pages |
| ISBN: | 978-1-989820-03-2 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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Slag Basicity Variation at Block Smelting for the Recycling of Tantalum
Dominik Hofer1; Stefan Luidold1; Tobias Beckmann2;1MONTANUNIVERSITAET LEOBEN, Leoben, Austria; 2H.C.STARCK TANTALUM & NIOBIUM GMBH, Laufenburg, Germany;
Type of Paper: Regular
Id Paper: 228
Topic: 7
Abstract:
Tantalum rich ores containing oxidic minerals like tantalite or columbite are primarily mined by artisanal and small scale practices. [1] Major sources located in countries around the African Great Lakes like Congo and Rwanda control global output with a 60 % share. [2] Direct treatment of concentrates with a Ta2O5 content higher than 25 % takes place via leaching followed by liquid-liquid extraction. Recycling, chlorination and processing of low grade residues, slags, sludges or dusts represent aspiring alternatives accounting for approximately 30 % of the tantalum world production. [3] The pyrometallurgical manufacturing of synthetic tantalum concentrate (syncon) in a multi-stage process constitutes an established procedure for various input materials. [4] Within this study, the first step (smelting and reduction) is recreated in a small scale induction furnace as well as a DC-EAF. Huge amounts of high melting slag comprising mostly Al2O3, CaO, MgO, SiO2, TiO2 and ZrO2 arise whilst Nb and Ta concentrate in the metal phase. Previous flow behaviour investigations [5] and viscosity calculations reveal low viscous slag to be crucial for good metal/slag separation at elevated CaO content. Therefore, a variation of slag basicity is tested for further process optimization and to attain technical standard regarding treatment time, tapping procedure and slag composition of < 0.2 % Ta2O5. Accumulation of value components was successfully realized and validated by SEM/EDX. Thus, yield, energy saving potential and other process adjustments for the syncon production can be investigated at the laboratory scale before upscaling to industrial quantity.
Keywords:
Non-Ferrous; Processing; Recycling; Slag; Temperature;References:
[1] Killiches F. et al.: Sorgfaltspflichten in den Lieferketten von Zinn, Tantal, Wolfram und Gold. DERA Deutsche Rohstoffagentur Commodity TopNews 46, 2014.[2] Reichl C., M. Schatz and G. Zsak: World Mining Data. Minerals Production, 2017.
[3] Andersson K., K. Reichert and R. Wolf: Tantalum and Tantalum Compounds: Ullmann's Encyclopedia of Industrial Chemistry (2000), 1-15.
[4] Schulenburg F., H. Rossel and U. Bartmann: Tantalrecycling: Thiel, Thome-Kozmiensky et al. (Hg) 2017 - Recycling und Rohstoffe, 137-154.
[5] Hofer D. et al.: Influence of CaO/SiO2/Al2O3 Ratio on the Melting Behaviour of SynCon Slags. In: Minerals, Metals and Materials Society, TMS Annual Meeting & Exhibition (Hg.): TMS 2019 148th Annual Meeting & Exhibition supplemental proceedings. Cham: Springer, 1139-1148.