Scandium rare earth element metal REE Collection

Scandium

Scantily scant scandium aptly describes the availability of this, the first member of the rare-earth group of elements.

Applications

  • High-intensity discharge (HID) lamps use scandium iodide for sports stadium and arena lighting to provide daytime-like color for television.
  • Russian MiG fighter jets use scandium-aluminum airframes to make the aircraft lighter and more maneuverable.
  • Scandium-aluminum high-strength lightweight alloy is also used in bicycle frames, lacrosse sticks, golf clubs, and baseball bats.
  • Laser crystals of gadolinium-scandium-gallium garnet (GSGG) are used in strategic defense applications.
  • Dentists use Erbium, chromium: yttrium-scandium-gallium garnet (Er,Cr:YSGG) lasers for cavity preparation and in endodontics.
  • Smith and Wesson make a lightweight, high-strength revolver frame using Scandium-aluminum.

Interesting Facts

  • Scandium is more abundant in the Moon than on Earth.
  • The blue color of the gemstone aquamarine is attributed to the presence of scandium.
  • Scandium is widely dispersed in the Earth but is rarely found in any large concentrations, thus it is "rare".
  • Scandium-aluminum in baseball and softball bats creates a "trampoline effect" that deflects the ball off the bat faster and farther.

Discovery

The element was discovered in 1879 by Lars Fredrik Nilson, a professor of analytical chemistry at the University of Uppsala at Uppsala, and the Royal Academy of Agricultural in Stockholm, Sweden. Several kilograms of the rare-earth minerals gadolinite (Ytterby, Sweden) and euxenite (Arendal, Norway) were decomposed and the rare-earth content extracted. Nilson separated the rare earths by fractional distillation and precipitation to obtain 63 grams of concentrate. Of this amount, a 0.35 gram sample of an unknown weakly basic earth (an early term for oxide) was procured (Nilson, 1879, p. 642). Nilson named the new element scandium in honor of the locations where the two minerals were found, Scandinavia (Nilson, 1879, p. 645).

Definition

Scandium is a silvery-white metal that oxidizes in air to a yellowish or pinkish tint. The metal is lightweight, soft, and ductile. It has a hexagonal close-packed structure, a density of 2.992 gm/cm3, a melting point of 1541 °C, and a boiling point of 2836 °C. Scandium oxide, or scandia, occurs as a trivalent ion and forms a sesquioxide with the formula Sc2O3. The oxide is a white powder with a specific gravity of 3.86 gm/cm3 and a formula weight of 137.9.

Preparation of Metal

Scandium metal is typically prepared by calciothermic reduction of the trihalide, typically ScF3. Although its melting point is similar to Y, Gd, Tb, and Lu, its vapor pressure at the melting point is much higher. This makes purification of Sc, and similar elements Dy, Ho, and Er with high vapor pressures, comparatively easy. Common interstitial impurities which form stable compounds with nitrogen, carbon, and oxygen remain in the residue when the metal is sublimed at a slow rate (Beaudry and Gschneidner, Jr., 1978).

Source

Scandium is rarely concentrated in nature because it lacks affinity to combine with the common ore-forming anions (Hedrick, 2010). It occurs in the Earth's crust at an average concentration of 22 parts per million. Scandium has not been found in significant grade or tonnage to be classified as a reserve. It is widely dispersed in the lithosphere and forms solid solutions in more than 100 minerals. In the Earth's crust, scandium is primarily a trace constituent of ferromagnesium minerals. Concentrations in these minerals (amphibole-hornblende, biotite, and pyroxene) typically range from 5 to 100 parts per million, equivalent scandium oxide. Ferromagnesium minerals commonly occur in the igneous rocks basalt and gabbro. Enrichment of scandium also occurs in aluminum phosphate minerals, beryl, cassiterite, columbite, garnet, muscovite, rare-earth minerals, and wolframite.

Mining

Scandium previously produced in the United States was primarily from the scandium-yttrium silicate mineral thortveitite, and from byproduct leach solutions from uranium operations. The rare thortveitite and associated scandium-bearing minerals from Ravalli County, Montana, USA, are believed to be of magmatic origin and occur in association with a fluorite-bearing granitic pegmatite and host melagabbro within the Crystal Mountain fluorite deposit (Foord, Birmingham, Demartin, Pilati, Gramaccioli, and Lichte, 1993). Thortveitite contains ~34% Sc2O3, ~10% HREE, and ~2% LREE (Horowitz, Gschneidner, Jr., Melson, Youngblood, and Schock, 1975). Scandium was also previously produced as a byproduct during uranium processing at the Bingham Canyon copper mine, Bingham Canyon, Utah. At Climax, Colorado, scandium was recovered from tungsten raffinates during wolframite processing. Some Idaho batholith-derived heavy mineral placers are reported to contain from 200 ppm to 1,500 ppm scandium, mainly in tantalite, columbite, euxenite, and ilmenite (Parker and Adams, 1973).

Selected scandium minerals (all considered rare)

Thortveitite (Sc,Y)2Si2O7
Bazzite Be3Sc2(Si6O18)
Kolbeckite ScPO4 2H2O
Sc-Ixiolite (Nb,Ta,Ti,Sc,Fe,Mn)4O8
Sc-Perrierite (Ce,Ca, Th)4(Fe2+,Sc)Fe23+(Ti,Fe3+)2(Si2O7)2O8
Magbasite KBa(Al,Sc)Fe2+Mg5F2Si6O20

References

Ahmad, Zaki, 2003, The properties and application of scandium-reinforced aluminum: Journal of Metals v. 55, no. 2, p. 35.

Beaudry and Bernard J. and Karl A. Gschneidner, Jr., 1978, Preparation and Basic Properties of the Rare Earth Metals: chapter 2 in Handbook of the Physics and Chemistry of Rare Earths-Volume 1:Metals, (Gschneidner, Jr. and Eyring, editors), North-Holland, New York, p. 173-232.

Ford, Eugene E., Scott D. Birmingham, Francesco Demartin, Tullio Pilati, Carlo M. Gramaccioli, and Frederick E. Lichte, 1993, Thortveitite and associated Sc-bearing minerals from Ravalli County, Montana: Canadian Mineralogist, v. 31, p. 337-346.

Hedrick, James B., 2010, Scandium: chapter in Mineral commodity summaries 2010, U.S. Geological Survey, p. 140-141.

Horowitz, Chaim T. (ed.), Karl A. Gschneidner, Jr., Gordon A. Melson, David H. Youngblood, and Hans H. Schock, 1975, Scandium?ts occurrence, chemistry, physics, metallurgy, biology, and technology: Academic Press, New York, 598 p.

Nilson, Lars F. 1879, Sur l’ytterbine, terre nouvelle de M. Marginac: Comptes rendus, March 24, no. 88, p. 642-645.

Nilson, Lars F., 1879, Sur le scandium, élément nouveau: Comptes rendus, March 24, no. 88, p. 645-648.

Parker, R.L, and J.W. Adams, 1973, Niobium (columbium) and tantalum: chapter in United States Mineral Resources, (D.A. Brobst and W.P. Pratt, eds.) U.S. Geological Survey Professional Paper 820, p. 443-454.

Electrons per shell:
2, 8, 9, 2
Atomic number,
Protons, Electrons:
21
Number of Neutrons:
24
Atomic Mass:
44.95591 amu
Melting Point:
1541 °C
Boiling Point:
2836 °C
Density @ 293 K:
2.992 g/cm3
Crystal structure:
hexagonal
Color:
silvery