Microwave-assisted recycling of tantalum and manganese from end-of-life tantalum capacitors

Abstract

Abstract Critical elements such as tantalum (Ta) and manganese (Mn) are in high demand and subject to supply chain disruptions, underscoring the importance of effective recycling strategies. Tantalum capacitors (TCs), which can contain up to 50% Ta and 18% Mn, represent a significant source of Ta-bearing electronic scrap (e-scrap). Here, we develop a selective carbothermal reduction method driven by 2.45 GHz microwave heating to recover Ta and Mn from end-of-life TCs. Guided by Ellingham and phase diagrams using the CALPHAD approach, the capacitors underwent a three-stage process at varying temperatures and pressures. XRD and ICP-MS analyses confirmed the formation of stable TaC with 97% purity, while Mn was reduced to lower oxide forms. This scalable, selective, and energy-competitive technique offers a new route for the secondary mining of critical metals from heterogeneous e-scrap.