The Development History of Niobium and Tantalum

image_pdfimage_print

In the middle of the 17th century, a heavy black mineral was discovered in North America, and sent to the British Museum for preservation and exhibition. About 150 years later, until 1801, British chemist C. Hatchet (1765-1847) accepted the task of analyzing this mineral from the British Museum, and discovered a kind of new element from it. He named it “Columbium” in honor of Columbia, the place where this mineral was discovered the first time. In 1802, Swedish chemist A. G. Ekeberg (1767-1813) separated another new element from similar mineral in Sweden and Finland. Referring to Tantalus, the name of the son of Zeus, this element is named Tantalum. Due to the similar property of columbium and tantalum, it was once misunderstood by people that they are the same element. Until 1844, German analytical chemist Heinrich Rose (1795-1864) chemically identified them as two different kinds of elements. Referring to Niobe, the name of the daughter of Tantalus, he changed the original name of “Columbium” by C. Hatchett into “Niobium”. From the sources of these two names “tantalum” and “niobium” in the periodic table of the elements, the 41st element and the 73rd element are father and daughter relationships. In this way, the 41st element has two names: “Cb” and “Nb”. The name of Niubium was formally adopted until 1949 by the International Union of Pure and Applied Chemistry. However, so far, “Columbium” is still used by some people in America.

Tantalum and niobium are both high melting rare metals, and they are in fact twin sisters. They are pretty close in nature, and usually coexist in the crystalline mineral. The most important minerals of tantalum and niobium are tantalite and columbite, with (Fe,Mn)(Ta,Nb)2O6 as main components. Both of them contain Ta and Nb. When the content of Ta is larger than Nb, it is called tantalite; otherwise, it is called columbite.

In periodic table of the elements, tantalum and niobium both belong to subgroup of Class V (vanadium family). Their atomic radius and ionic radius are almost the same(For example, Nb5+7.0nm,Ta5+7.1nm). The properties of these two elements are very similar to each other in many aspects. The elementary substance of tantalum and niobium are both silver metals. Under indoor temperature, both of them can react with fluorine, and do not have obvious effects with oxygen, nitrogen, chlorine and other gases. When heated, they can react with chlorine, oxygen, or nitrogen. Tantalum and niobium both have excellent corrosion resistance ability. Tantalum is said to be the champion in the metal corrosion resistance competition, and niobium is the runner-up. Niobium powder can react with hydrofluoric acid and dissolve into it under indoor temperature, while Ta can only react slowly with hydrofluoric acid when above 150℃. However, both of them are easily dissolved in the mixture of nitric acid and hydrofluoric acid. Under indoor temperature, concentrated sulfuric acid has no obvious reaction with Nb and Ta, when over 150℃, Nb can dissolve in concentrated sulfuric acid, but Ta can just dissolve slowly. Other acids and aqua regia can not react with Nb and Ta.

Tantalum and niobium was discovered in the early 19th century, but metal tantalum was made until 1903. Industrial production of Ta began from 1922; metal niobium was made in 1907, its industrial production began in 1929. Since the 1940’s, they caught people’s attention after their heatproof ability, anti-corrosion ability, and electrical performance were known by people. Their output and demand also soared. In 1958, America only produced 33 tons of metal niobium and 96 tons of metal tantalum. However, in 1978, metal tantalum’s international demand has already exceeded 1200 tons; the demand of metal niobium has passed 5000 tons. Tantalum and niobium jumped into the important rare metals of great promises.