Recycling of Tantalum Capacitors Via Sulfide Chemistry

The fabrication of tantalum capacitors represents more than 35 pct of the total consumption of metallic tantalum with an increasing demand for the high-technology sector. Tantalum capacitors contain a large concentration of tantalum, and the absence of niobium leads to interesting economic outcomes for potential recycling processes. The article discusses such recycling using sulfur, where an AB2O6 crystal structure analogous to the orthorhombic columbite-tantalite series is sulfidized. Sulfide affinities differences between A (Mn, Fe) and B (Nb, Ta) effectively separate the ternary oxide, capitalizing on the distinct chemical properties between A and B elements, in the absence of fluoridic acids. To bypass the fluoride-based chemistry process entirely, a proof of concept of tantalum disulfide (TaS2) production via sulfidation of Ta2O5 and its subsequent metallic reduction via molten sulfide electrolysis are also presented.