Ta - Tantalum

Properties

Tantalum is a shiny, silvery metal, which is soft when pure and is a member of Group 5 of the Periodic Table. It is the 51st most abundant element within the Earth’s crust. Due to its tendency to form a protective oxide surface layer, it is highly corrosion resistant to most acids, but it is attacked by hydroflouric acid and molten alkalis.  It is hard, ductile, and can be easily fabricated.

History

Tantalum was reported as a new metal in 1802 by the Swedish chemist Anders Gustav Ekeberg, who was Professor of Chemistry at Uppsala University. However, when William Wollaston, the eminent British chemist, analysed minerals from which it had been extracted, he declared it was indentical to the new metal niobium which had been discovered the previous year. These two elements often occur together and are chemically very similar, which makes them difficult to separate even today, and especially so by the methods available two centuries ago.  More than 40 years passed before Heinrich Rose separated tantalum and niobium and proved conclusively that they were different. That was in 1846, and yet pure tantalum was not produced until Werner von Bolton of Charlottenburg finally accomplished it in 1903. No-one now doubts that Ekeberg had isolated tantalum, and so was the discoverer of a new element, thanks to his exceptional skills as a chemist, yet even his samples must have contained quite a lot of niobium.

Sources

The major primary source is Australia, although both here and in Canada the main mines are shut down or on care and maintenance. Other producing regions include Brazil, Ethiopia, central Africa, Nigeria, Mozambique, and China.
There is limited large scale mining and consequently much ore comes from artisanal and small scale mining (60-70% of total supply).

As regards secondary supply, there are three main sources:  i) old low tantalum grade tin slags, primarily from South East Asia, on-processed either hydrometallurgically in China or pyrometallurgically in Germany;  ii) mineral from the US national stockpile;  iii) scrap.

Uses

Tantalum’s main use is in capacitors for consumer electronics, where it faces competition from aluminum, niobium, and multi-layer ceramics.  This sector used to account for >60% of demand, but is now less than half.  Due to miniaturization and operating temperatures, capacitors made of tantalum remain optimum for various applications.

Tantalum is also used in sputtering targets, corrosion-resistant mill products (implants), superconductors, carbides for cutting tools, chemicals for high end optics and is also frequently used as an addition in nickel-base super alloy castings for turbine blades in jet engines and industrial gas turbines (IGT).

Overall demand has fluctuated recently between 1,400-2,000mt tantalum per year, but following the downturn of 2009 demand fell to just over 1,000mt.  Meanwhile, China has become the main world processor (20 installations), with only 10 others in the rest of the world concentrating on high-end capacitor production.