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The preparation of metal tantalum


The preparation of metallic tantalum is a process in which a pure tantalum compound is reduced to metallic tantalum by a reducing agent. The raw materials of the pure tantalum compound used are tantalum pentoxide, tantalum pentachloride, tantalum pentafluoride and fluorine salts (e. g., K2TaF7). The reducing agent has sodium, magnesium and other active metals and carbon and hydrogen. The melting point of tantalum is as high as 3669K, so the powder or sponge metal is obtained after reduction. Further smelting or refining is required to obtain dense metal.
The preparation methods of metal tantalum mainly include sodium thermal reduction method to produce tantalum powder, carbon thermal reduction method to produce tantalum and molten salt electrolysis method to produce tantalum powder. Sodium thermal reduction of potassium fluorotantalate is the most commonly used tantalum production method in the world. The tantalum powder produced has complex particle shape and large specific surface area, which is suitable for the manufacture of capacitors. Carbothermal reduction of tantalum pentoxide is a mature tantalum production method in industry, but because the product purity is not high enough, it is not as widely used as sodium reduction method. The molten salt electrolysis method is divided into oxygen-containing electrolyte electrolysis and oxygen-free electrolyte electrolysis according to the electrolyte composition. Molten salt electrolysis generally can only produce metallurgical grade tantalum powder. Tantalum pentafluoride hydrogen reduction is considered to be one of the most promising tantalum production methods, but due to the high requirements of equipment materials and environmental protection, it has not been used in industrial production.
Most tantalum is directly used in the form of tantalum powder for the manufacture of tantalum capacitors for the electronic industry, so the tantalum powder making process, such as capacitor grade tantalum powder making, hydrogenation of tantalum powder and vacuum heat treatment of tantalum powder, also belongs to the category of metal tantalum making.