Recovery of Tantalum and Manganese from Epoxy-Coated Solid Electrolyte Tantalum Capacitors through Selective Leaching and Chlorination Processes

Abstract

Electronic products are ever growing in popularity, and tantalum capacitors are heavily used in small electronic products. Spent epoxy-coated solid electrolyte tantalum capacitors, containing about 22 wt.% of tantalum and 8 wt.% of manganese, were treated with selective leaching by hydrochloric acid and chlorination after removing the epoxy resin, and the products converted, respectively, to Mn(OH)2 and TaCl5 . The effects of acid type, acid concentration, liquid–solid ratio, and reaction time were investigated to dissolve the manganese. The optimal selective leaching conditions were determined as 3 mol/L of HCl, 40 mL/g at 25◦ C for 32 min. Next, residues of selective leaching after washing and drying were heated with ferrous chloride to convert to pure TaCl5 . Mixing 48 wt.% of chloride and 52 wt.% of residues for a total of 5 g was conducted to complete the chlorination process in the tube furnace at 450◦ C for 3 h. A total of 2.35 g of Ta was collected and the recovery of Ta achieved 94%. Finally, Mn(OH)2 and TaCl5 were separated and purified as the products.