ORALS

Strategic, critical or high-tech metals are indispensable ingredients for the development of technologically sophisticated products. Modern cars, flat-screen televisions, mobile phones, and countless other products rely on a range of materials, such as cobalt, lithium, PGM’s, tantalum, tungsten, gold, gallium and more particularly REE. This group of high-tech metals is also fundamental to new environmentally friendly products, with electric cars requiring lithium and neodymium, turbine wind with neodymium and dysprosium, high performance aluminium alloys, lighting or hard ceramics requiring scandium, and computer/mobile phones with tantalum, gold, palladium and rare earths. To meet the challenges of dwindling resources and the growth of needs, as well as in a perspective of a secure supply approach, three options are considered today based on the extraction of metals from primary resources (old mines or new deposits), from secondary resources (mining and industrial wastes) or from end of life materials (urban mine). Understanding this challenges facing strategic metals supply today requires consideration not only of the sources (whether from mines or waste streams), but of the development of eco-friendly and always more efficient processes. Here, we propose a process based on the use of ionic liquids such as N-butyl-N-ethyl-piperidinium bis(trifluoromethylsulfonyl)imide (EBPiP-NTf2), N-octyl-N-ethyl-piperidinium bis(trifluoromethylsulfonyl)imide (EOPiP-NTf2) for the extraction and the recovering of tantalum, palladium and gold initially contained in the capacitors and connectors of printed circuit boards [1-3]. The perfect extractability of ILs for Ta, Au and Pd was demonstrated and under the experimental conditions, the more promising properties have been highlighted for EOPiP-NTf2. Back extraction of Ta followed by precipitation with an ammonia solution or direct electodeposition from the loaded ionic liquid phase was also performed and showed that quantitative recovery of metals was possible, allowing thus to recover the Ta, Pd and Au, and to recycle the ionic liquid.

References:
[1] G. Arrachart, R. Turgis, M. Lejeune, M. Draye, S. Michel, S. Legeai, S. Pellet-Rostaing ACS Sustainable Chemistry & Engineering 8 (2019) 1954-1963.
[2] Raphaël Turgis, Guilhem Arrachart, Stéphane Pellet-Rostaing, Micheline Draye, Sophie Legeai, David Virieux, Faidjiba Loe-Mie, FR1557636A, WO2017025547A1.
[3] G. Arrachart, M. Draye, M. Lejeune, S. Legeai, S. Michel, S. Pellet-Rostaing, C. Thomas, R. Turgis. FR. 20 00667