High-capacity capacitor tantalum powders from production waste

The possibility of producing high-quality high-capacity tantalum powder from certain types of tantalum wastes by their oxidation and subsequent magnesium thermal reduction is discussed. Capacitor powders with a specific charge of 100000—150000 µC·g–1 and leakage current less than 0.001 μA·μC–1 were obtained.

Extraction of Tantalum Powder via the Magnesium Reduction of Tantalum Pentoxide

The metallic tantalum powder was successfully synthesized via reduction of tantalum pentoxide (Ta2O5) with magnesium gas at 1073~1223 K for 10 h inside the chamber held under an argon atmosphere. The powder obtained after reduction shows the Ta–MgO mixed structure and that the MgO component was dissolved and removed fully via stirring in a water-based HCl solution. The particle size in the tantalum powder obtained after acid leaching was shown to be in a range of 50~300 nm, and the mean internal crystallite sizes measured by the Scherrer equation varied from 11.5 to 24.7 nm according to the increase in reduction temperatures. The temperature satisfactory for a maximal reduction effect was found to be 1173 K because the oxygen content was minimally saturated to about 1.3 wt %.