Scandium

Mig-29 on landing

Scandium is a chemical element with the symbol Sc and atomic number 21. A silvery-white metallic d-block element, scandium has historically been classified as a rare earth element, together with yttrium and the lanthanides. It was discovered in 1879 by spectral analysis of the minerals euxenite and gadolinite by Swedish scientist Lars Fredrik Nilson. Scandium is present in most of the deposits of rare earth and uranium compounds, but it is extracted from these ores in only a few mines worldwide. Due to its scarcity and the difficulty in extracting the metal, scandium was not used in significant quantities until the 1970s, when methods to produce it more economically were developed.

Properties

Scandium is a soft metal with a high melting point. It exhibits a high specific gravity and is resistant to corrosion. When exposed to air, scandium forms a pink or yellow oxide layer that prevents further corrosion. It has a much lower density than most metals, making it attractive for use in lightweight materials for aerospace and military applications. Scandium, when added in small quantities to aluminum, significantly strengthens the metal without adding much weight, leading to its use in aircraft and spacecraft.

Applications

The primary application of scandium is in aluminum-scandium alloys. These alloys are used in the aerospace industry in components such as aircraft wings and fuselage parts. The addition of scandium to aluminum also improves the metal's weldability and durability at higher temperatures. Scandium is also used in the production of high-intensity lights, in electronic ceramics, and as a tracer in studies of oil wells and pipelines.

Occurrence

Scandium is not found free in nature but is found in small amounts in over 800 mineral species. The most common sources of scandium are the rare earth minerals thortveitite, euxenite, and gadolinite. It is also found in residual clays from the weathering of aluminous rocks. The extraction of scandium from these sources is challenging, making the element relatively rare and expensive.

History

Scandium was discovered in 1879 by Lars Fredrik Nilson, who named it after Scandinavia. Its discovery was notable because it was predicted to exist by Dmitri Mendeleev's periodic table, which had a gap for an element with properties that scandium was later found to possess. Mendeleev's prediction and Nilson's discovery were significant validations of the periodic table.

Production

The production of scandium is a complex process, typically involving the extraction of the element from uranium ore residues or from the minerals thortveitite and euxenite. The extracted scandium is then purified through various chemical processes. The global production of scandium is estimated to be only around 10 to 15 tonnes per year, with the primary producers being China, Russia, and Ukraine.

Health and Safety

Scandium compounds should be handled with care, as they can be hazardous to human health if ingested or inhaled. Scandium has no known biological role, and its compounds are generally considered to be of low toxicity. However, safety precautions should be taken to avoid exposure.

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