Preparation of niobium

Preparation of niobium

Niobium can be produced by electrolytic melting of potassium heptafluoroniobate, reduction of potassium heptafluoroniobate by sodium metal or niobium pentoxide by aluminum. Pure niobium is used to remove residual gas in electron tube. Niobium doping in steel can improve the oxidation resistance of steel at high temperature and improve the welding performance of steel. Niobium is also used in the manufacture of high temperature cermets.

Tantalum pentoxide (Ta2O5) and niobium pentoxide (Nb2O5) are separated from other minerals through separation process. The first step in the process is to react with hydrofluoric acid

Ta2O5+ 14 HF → 2 H2[TaF7] + 5 H2O

Nb2O5+ 10 HF → 2 H2[NbOF5] + 3 H2O

Jean Charles galisa de marinia invented an industrial scale separation method that took advantage of the water solubility differences of the fluoride complexes of niobium and tantalum. In the new method, fluoride is extracted from aqueous solution with organic solvent similar to cyclohexanone, and then niobium and tantalum complexes are extracted from organic solvent with water. Niobium pentoxide can be precipitated by adding potassium fluoride, while niobium pentoxide can be precipitated by adding ammonia

H2[NbOF5] + 2 KF → K2[NbOF5]↓ + 2 HF

then:

2 H2[NbOF5] + 10 NH4OH → Nb2O5↓ + 10 NH4F + 7 H2O

There are several ways to reduce compounds to metallic states. One is to electrolyze the molten mixture of K2 [nbof5] and sodium chloride, and the other is to reduce niobium fluoride with sodium. The niobium obtained by this method has high purity. In large-scale production, Nb2O5 is usually reduced by hydrogen or carbon. The other method uses thermite reaction, in which iron oxide and niobium oxide react with aluminum

3 Nb2O5+ Fe2O3+ 12 Al → 6 Nb + 2 Fe + 6 Al2O3

A small amount of oxidation additive similar to sodium nitrate can enhance the above reaction. This produces alumina and ferroniobium alloys, which can be used in steel production. Ferroniobium generally contains 60% to 70% niobium. If iron oxide is not added, niobium will be produced by aluminothermic reaction, but high purity niobium alloy with superconductivity can be made only after purification. The method used by the two largest niobium distributors in the world is vacuum electron beam melting.

As of 2013, Brazil metallurgy and Mining Co., Ltd. (Portuguese: CIA. Brasileira de metalurgia & minera à Φ o) controlled 85% of the world's niobium production. The U.S. Geological Survey estimates that niobium production rose from 38700 tons in 2005 to 44500 tons in 2006. The global stock of niobium resources is estimated to be 4.4 million tons. Between 1995 and 2005, production more than doubled from 17800 tons. From 2009 to 2011, the output remained stable at 63000 tons per year.