Reduction of tantalum and niobium with sodium

Berzelius reported on the results of the first reduction of tantalum from K2TaF7 using metallic potassium in 1825 [574]. About thirty years later, Rose obtained sufficiently pure tantalum in an interaction between Na2TaF7 and metallic sodium [575]. The methods elaborated by Berzelius and Rose provided a basis for the development of the industrial-scale production of tantalum by the reduction of K2TaF7 using metallic sodium. 

The sodium reduction process was first implemented in Germany by Siemens and Halske A.G. and it remained a principally European method, while the American tantalum industry was founded exclusively on the electrolysis of molten fluorides [28, 576], The production of tantalum by sodium reduction has gained worldwide acceptance and currently, nearly 90% of the world s tantalum is produced by the sodium reduction method [538]. 

The main reason for the tantalum industry s drive toward the sodium reduction process is an increasing demand for tantalum powder by tantalum capacitor manufacturers. The modem tendency of the electronics industry to miniaturize their components calls for the improvement of tantalum powder 

The interaction in Equation (173) is exothermic and occurs with the generation of 713 Kcal of heat per 1 kg of mixture, as reported by Bose and Gupta [538]. Kolchin and Vol dman [577] investigated the thermal effects of tantalum and niobium reduction by sodium from molten K2TaF7 and K2NbF7, respectively. The interaction with K2NbF7 is similar to that shown is Eqaution (173). It was found that the thermal effects in the case of tantalum and niobium correspond to 385 cal/g and 510 cal/g at 1000°C, respectively. 

Despite the above disadvantages, some investigations show possible directions for further improvement and development of the process for the production of tantalum powder suitable for the manufacture of capacitors with no additional electron-beam melting and special crushing. 

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