Sustainable valorization of semiconductor industry tantalum scrap using non-hazardous HF substitute lixiviant

Waste Manag. 2022 Apr 12;144:294-302. doi: 10.1016/j.wasman.2022.04.005. Online ahead of print.


Global tantalum production from mines averages 1800 tons per year and hardly increases, but demand for tantalum in the electronics industry consistently increasing. Globally, 50% of total tantalum produced is being used for tantalum capacitors manufacturing, almost all demand from various industries is mainly met by primary resources only. Tantalum production and supply predominantly dominated by Congo and Rwanda which accounts for > 50%, add disadvantages for the strategic and economic competitiveness of other nations. To address the monopoly dominated by Congo and Rwanda, and the disparity of tantalum primary reserve, exploitation of secondary resources can alternatively address the drawbacks of primary resource distribution. Currently, hardly < 1% of tantalum getting recycled, and the poor recycling rate of tantalum is mainly contributed by the lack of efficient and sustainable valorization technology for recycling tantalum-bearing scraps like electronic capacitors and semiconductor industry tantalum scrap. In the current investigation, a sustainable tantalum extraction process from scrap dominated by hydrometallurgical route has been developed. Tantalum scrap which is passive to leach for tantalum recovery was calcinated for oxidation of TaN content and followed by tantalum has been leached using a mixture of NaF and HCl, a specially developed novel lixiviant for the purpose as an HF substituent. Calcination process parameter like temperature and time requirement for oxidation was optimized varying one parameter at a time. Then, the efficient leaching condition was optimized for quantitative leaching of tantalum. The process can achieve 99.99% efficient leaching, the process can successfully be applied for feasible industrial-scale tantalum scrap recycling. The HF substituent lixiviant can add advantages to overcome occupational and industrial operation safety challenges associated with HF lixiviant. The reported valorization process can be a sustainable tantalum recycling process that simultaneously can address UNO sustainable development goal, WEEE directive, and UNEP E-Waste Management goal.

PMID:35427901 | DOI:10.1016/j.wasman.2022.04.005