Pure tantalum powder has been produced by combining Na as a reducing agent, K₂TaF₇ as feed material, KCl and KF as a diluent in a stainless steel (SUS) bomb, using the method of metallothermic reduction. The present study investigated the effect of the temperature and the amount of the reductant on the characteristics of tantalum powder in the production process and on the yield. The temperature applied in this study ranged from 800 to 980°C, and the amount of the additional reductant varied from −10%, 0%, 5%, and 10% of the theoretical amount used for the reduction of the entire K₂Ta F₇. The results showed that as the temperature and the additional reductant increased, the yield of the powder increased from 57 to 94%, and the particle size also increased from 0.4 to 5.0 μm. On the other hand, the amount of minute tantalum powder decreased significantly, from 93 to 60%, with the increase of temperature and the amount of the reductant. At the reduction temperature of 920°C and with the 5% excess of the reductant, the average size of the particle, 2-4 μm, was closest to that of the particle commonly used, 2-5 μm. Also, under this condition, impurities contained in the powder were within the limit allowed for the commonly used product.
The present study concluded that the optimal condition for manufacturing tantalum powder of the best quality was the reduction temperature of 920°C and the reductant of 5% excess.