A process is proposed for the recycling of Ta capacitor scrap containing 4-7% MnO2 as solid electrolyte. This paper describes the removal leaching of MnO2 with various agents and disscusses the dissolution reaction of MnO2 in FeSO4-H2SO4 aqueous solution from thermodynamic and kinetic aspects. In leaching of block Ta anode scrap, H2O2 and Na2SO3 solution were the most effective leaching agents, with more than 90% of Mn extraction at room temperature after 24 hours. When the sample was ground to -200 mesh, MnO2 was almost completely removed in a short time by use of H2O2 solution. FeSO4 solution also showed a satisfactory result. The overall reaction of the primary per was controlled by mass transfer of Fe2+ ions through the boundary layer between the solution and the surface of MnO2 inside the capacitor. Dissolution of Fe(OH)3 and other reaction products was the rate determining step in the secondary per Hermetic seal type Ta capacitor scrap was upgraded by applying the Fe3+/Fe2+ oxidative-reductive leaching method.
ASJC Scopus subject areas