The scrap of used tantalum capacitor is now an important secondary resource of tantalum and the composition of those scraps is simply identical to Ta-Ta₂0₅-Mn0₂ ternary mixture (Ta is above 90%, Mn and oxygen content are a few percent, respectively). In this work, recovery of tantalum metal from tantalum capacitor scraps has been examined by plasma melting process and hydrogen plasma melting was available to obtain ductile pure tantalum (0 < 100, Mn < 20 mass ppm, Hv =90-100) with effective deoxidation and demanganese directly from those scraps.
Manganese was removed rapidly with vaporization of manganese from melt by Ar, H2 -Ar plasma melting and reduced to under 20 mass ppm. Also deoxidation proceeded by H2 -Ar plasma melting and oxygen content reduced to under 100 mass ppm. But oxygen was scarcely removed by Ar plasma. Since the deoxidation rate increased in proportional to the square root of hydrogen content of plasma gas, deoxidation is considered to be caused by dissociated and activated hydrogen atoms in hydrogen plasma. And the addition of carbon within equivalent of oxygen content in the scraps enhanced the deoxidation procedure.
Furthermore the other minor impurities such as nitrogen, iron, nickel in tantalum capacitor scraps were eliminated as much as possible by hydrogen plasma melting.