The electro-calciothermic reduction of tantalum sulfide (TaS₂) was applied to open a new pathway for producing high-purity Ta powders applicable for tantalum electrolytic capacitors. The supplied electric charge was varied to electrochemically reduce the sulfide at 900 °C using Ca in molten CaCl₂−xCaS (x = 0.1, 0.5 mol%) salts. The cleaner TaS₂ could also be prepared via the highly efficient carbo-sulfidation of Ta₂O₅ using S₂ gas. The plate-like Ta particles with internal voids and coral structures were obtained through the electrochemical reduction of the sulfides. Sulfur removal was achieved rapidly from TaS₂. Ta powder with 0.08 mass% O and 0.01 mass% S was successfully produced from Ta₂O₅ via clean TaS₂. It was obtained by increasing the electric charge to two times higher than that required to generate the stoichiometric amount of Ca in the CaCl₂ melt. Therefore, the electrometallurgical reduction of TaS₂ could be a promising, cost-effective, and sustainable approach for producing high-purity Ta powders.

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