Niobium Basics

Niobium is a silver-gray metal that turns slightly blue when exposed to room temperature air. Its appearance is similar to polished steel or platinum.

It is a transition metal belonging to Group V of the Periodic Table with an atomic weight of 92.9064 and an atomic symbol of Nb. It has 28 isotopes with known half-lives and mass numbers between 83 and 110. The natural niobium is its stable isotope niobium 93.

Niobium is also a refractory metal. Refractory metals are a special group of metals that retain their hardness and strength even when subjected to extreme heat and exhibit several other unique properties that make them useful for a range of manufacturing processes. Other refractory metals include:

Tungsten (W)
Molybdenum (Mo)
Tantalum (Ta)
Rhenium (Re)
Titanium (Ti)
Several other exotic metals
Niobium cannot be found alone in nature. Instead, it is found in a group of minerals known as the columbite-tantalite group. In addition to the obvious columbite-tantalite, this group contains pyrochlore, pyroxene, tantalite and columbite, also known as columbite. Large quantities of niobium have been found to be associated with carbon silicate rocks (also known as carbonatites) and sodium calcium niobate. Some of the largest known deposits are located in Canada, Brazil, Russia, Nigeria and the Democratic Republic of Congo.

These minerals also often contain tantalum. Niobium and tantalum share many properties, but there is one major difference. Tantalum is about twice as heavy as niobium.

Niobium is also 10 times more abundant than tantalum in the Earth's crust. Its content in the earth's crust is about 17 parts per million by weight or 3.7 parts per million by mole. This means that there is more niobium in the earth's crust than lead, but less than copper. The cost per 100 grams is about 18 dollars.

The process used to produce niobium is quite complex, mainly because it needs to be separated from tantalum.

Niobium can be separated from these other substances by forming an oxide and then reducing it with hydrogen and carbon. The separation process uses solvents to extract the elements in a liquid-liquid process and then precipitates the niobium. The processor must then bake it to niobium pentoxide (Nb2O5), which is then reduced to a powder using hydrogenation and metallothermic processes. Vacuum sintering or electron beam melting further consolidates and purifies the powder.

Another method of obtaining niobium includes electrolysis of molten salts or reduction of fluorine complexes using reactive metals.

Niobium is usually alloyed with metals, including iron, nickel and cobalt, prior to use.