ORALS
SESSION:
RecyclingSatPM1-R4
| Kozlov International Symposium on Sustainable Materials Recycling Processes and Products (7th Intl. Symp. on Sustainable Materials Recycling Processes and Products) |
| Sat Oct, 26 2019 / Room: Adonis | |
| Session Chairs: Tsuyoshi Hoshino; Alexandra-Georgiana Vatui; Session Monitor: TBA |
14:00: [RecyclingSatPM105]
Slag Basicity Variation at Block Smelting for the Recycling of Tantalum Dominik
Hofer1 ; Stefan
Luidold
1 ; Tobias
Beckmann
2 ;
1Montanuniversitaet Leoben, Leoben, Austria;
2H.C.Starck Tantalum & Niobium GmbH, Laufenburg, Germany;
Paper Id: 228
[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 Ta<sub>2</sub>O<sub>5</sub> 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 Al<sub>2</sub>O<sub>3</sub>, CaO, MgO, SiO<sub>2</sub>, TiO<sub>2</sub> and ZrO<sub>2</sub> 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 % Ta<sub>2</sub>O<sub>5</sub>. 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.
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/SiO<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub> 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.
