Extraction and Recovery of Tantalum from Capacitors Using Conventional Separation Methods Assisted by Thermal Plasma

The recycling of tantalum contained in waste capacitors from post-production or electronic-waste recycling is an interesting solution to complete primary production. This secondary production unit must meet economic, purity, and environmental criteria to respond to the market. This study proposes a thermal plasma coupled with conventional separation methods to recover pure tantalum. The results show that the dielectric parts containing Ta, Ta2O5, and MnO2 are isolated by a treatment involving thermal plasma pyrolysis, crushing, magnetic separation, and sieving. At the end, tantalum is recovered from the dielectrics by using a neutral Ar and a reductive Ar–H2 plasma atmosphere generated by an electrical power of 13.5 kW. The plasma treatment makes it possible to eliminate Mn/MnO2 by vaporization, to reduce Ta2O5 without any change of the solid state (no melting), and to preserve the Ta metal already present in the dielectrics. This plasma treatment uses atomic hydrogen H at high temperature (>1000°C) with a short treatment time (20 min). At the end of the treatment, it is possible to obtain, with a yield of 80%, usable Ta exhibiting a purity of more than 99%. In addition, the study reports that no valuable metal is lost in the slag, and it may also be possible to recover metal fractions containing Cu, Sn, and Ag by conventional treatments.