Niobium production process

Niobium production methods
Niobium metal is mainly produced by carbon thermal reduction, aluminum thermal reduction and sodium thermal reduction, followed by molten salt electrolysis and niobium halide reduction.
Vacuum Carbon Reduction
Vacuum carbon reduction is one of the main methods for the production of niobium metal at home and abroad. Carbon reduction is generally carried out in a vacuum carbon tube furnace. This method utilizes the affinity of carbon for oxygen to be greater than that of niobium for oxygen, and uses carbon as a reducing agent to reduce Nb2O5 to produce niobium strips. The advantages are high product yield (>96%), cheap reductant, low production cost, no sodium reduction and other methods of by-products need to be wet treatment of the problem, you can get high purity niobium strip and metal powder.
There are two industrial processes: direct carbon reduction and indirect carbon reduction. The niobium produced by direct carbon reduction is spongy, with a large surface area, low metal impurities and nitrogen content, which is favorable to the specific capacity of niobium powder, so this process is suitable for the production of capacitor-grade niobium powder. Indirect reduction is characterized by large production capacity of the equipment, stable process, the resulting metal niobium strip is denser, more regular dimensions, suitable for niobium strips, niobium ingots and niobium processing materials.
Aluminum thermal reduction
Aluminum thermal reduction is more often used outside the furnace. The reduction and smelting reaction is carried out in a vessel without external heating, and after the reaction is completed, the vessel is dismantled, the product is removed, and the metal and slag are separated outside the furnace. Aluminum thermal reduction produces niobium metal with a high content of aluminum, which can then be removed from aluminum and other impurities by vacuum heat treatment (1800°C), electrolytic refining and electron beam furnace smelting. The niobium after two electron beam furnace melting can reach very high purity. Aluminum thermal reduction method does not need to be carried out under vacuum conditions, the equipment is simple and easy to implement, but the product purity is low, the niobium in the high content of aluminum, need to be further purified through the electron beam melting in addition to impurities.
Sodium thermal reduction
Niobium is seldom used in the manufacture of capacitors, so the sodium reduction method is less used.
Electrolysis
Niobium electrolysis method has a molten salt electrolysis and aqueous solution electrolysis two methods, molten salt electrolysis method for the production of niobium powder with simple equipment, production costs are low.
Nitriding method
In addition to the above methods, in recent years, the development of niobium nitriding method of production of niobium, the method of niobium oxide or ferro-niobium as raw materials, so that the first and ammonia or nitrogen, carbon reaction to generate niobium nitride, niobium nitride and then in a vacuum and 2103 ~ 2373K temperature thermal decomposition into metallic niobium.