Tantalum (Ta)

Where Found

Tantalum is moderately uncommon and is about as abundant as uranium in the Earth’s crust. It is almost always found in minerals that also contain niobium and is most commonly found in granite and minerals derived from granite. Tantalum ores are most abundant in Africa and South America. The world’s major producers, in descending order, are Australia, Brazil, Ethiopia, Canada, and Rwanda. Other producers include Burundi, the Democratic Republic of the Congo, Nigeria, Uganda, and Zimbabwe.

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Primary Uses

The most important uses for tantalum are in the manufacturing of capacitors (accounting for more than 60 percent of use in the United States) and in making corrosion-resistant equipment for chemistry laboratories. Tantalum is also used in various electronic devices and in surgical equipment.

Technical Definition

Tantalum (abbreviated Ta), atomic number 73, belongs to Group VB of the periodic table of the elements and resembles niobium (also known as columbium) in its chemical and physical properties. It has one naturally occurring isotope and an atomic weight of 180.95. Pure tantalum is a hard, dense, silver-gray metal. Its density is 16.65 grams per cubic centimeter; it has a melting point of 2,996° Celsius and a boiling point of 5,427° Celsius.

Description, Distribution, and Forms

Tantalum is a fairly rare element resembling niobium. It occurs as the oxide in minerals containing niobium. A small amount of the free metal is found in the former Soviet Union. Tantalum is used in capacitors and chemical equipment.

History

Tantalum was discovered by the Swedish chemist Anders Gustaf Ekeberg in 1802. Because tantalum is so similar to niobium, the two elements were thought to be identical until 1844, when the German chemist Heinrich Rose proved they were different. Tantalum was briefly used for lightbulb filaments during the early twentieth century until it was replaced by tungsten.

Obtaining Tantalum

The most difficult problem in obtaining tantalum is in separating it from the very similar niobium found in its ores. The most common method is known as liquid-liquid extraction. The ore is treated with hydrofluoric acid, which dissolves the tantalum and niobium compounds. This solution is then treated with an organic solvent. This solvent extracts the tantalum compound at a low level of acidity. At a higher acidity the niobium compound is extracted.

The tantalum compound obtained by this method may be electrolyzed in a solid form at about 900° Celsius to produce pure tantalum powder. This powder may also be obtained by treating the tantalum compound with metallic sodium. The powder may be transformed into tantalum metal by heating it in a vacuum.

Uses of Tantalum

Tantalum is used to manufacture equipment for the chemical industry because it is extremely strong and does not react with most chemicals. It has also been used in surgical devices because it does not react with body tissues. Another use is in the manufacture of capacitors, electronic devices that store electric energy. Tantalum capacitors have a greater ability to store energy than any other capacitors of the same size and are thus used in miniaturized components. Tantalum compounds have also been used to manufacture tools used to cut very hard metals, to manufacture special kinds of glass, and as catalysts for various chemical reactions.

Bibliography

Natural Resources Canada. Canadian Minerals Yearbook, 1994: Tantalum. http://www.nrcan.gc.ca/smm-mms/busi-indu/cmy-amc/content/1994/60.pdf

WebElements. Tantalum: The Essentials. http://www.webelements.com/tantalum/