Recovery of Valuable Materials from Waste Tantalum Capacitors by Vacuum Pyrolysis Combined with Mechanical–Physical Separation

Waste tantalum capacitors (WTCs), dismantled from waste printed circuit boards, are considered a high quality tantalum (Ta) resource. Ta is a rare and strategic material. Nearly half of the Ta consumption is used for manufacturing tantalum capacitors. Furthermore, large amounts of energy and chemicals are consumed during the Ta purification process. Therefore, recovering Ta from WTCs can sustainably utilize the Ta resource and reduce pollution. However, the recycling technology has been poorly developed. This study proposed vacuum pyrolysis (VP) and mechanical–physical separation (MPS) to recover Ta and other materials from WTCs. First, the WTCs were treated by VP to decompose the organics. The suitable VP parameters were considered as 400 °C, 50 Pa, and 60 min. Then, the residues were performed by MPS. Consequently, nickel–iron terminals were recovered by magnetic separation. Ta and silica were separated by corona electrostatic separation. The recovery rate and purity of Ta could reach 97.02 ± 0.85% and 71.35 ± 0.63%, respectively. The optimal parameters were determined as voltage of 28 kV, roll speed of 50 rpm, and particle size of 0.125–0.3 mm, based on the response surface methodology (RSM). This study contributes to the efficient recycling of valuable resources from WTCs.