Applications

Interesting Facts

Discovery

French chemist, painter, sculptor and musician Georges Urbain discovered lutetium in 1907 (Urbain, 1907). Using fractional crystallization of an impure ytterbium nitrate, Urbain precipitated two oxides from nitric acid, one he called neoytterbia, which Jean-Charles Galissard de Marignac had discovered in 1878, and the other new “earth” he named lutecia (Urbain, 1908, 1909). The spelling was later changed to lutetia (Weeks and Leicester, 1968, p. 692). Georges Urbain named the element lutetium, after the ancient Latin name for Paris, his native city in France.

Definition

Lutetium is a bright silvery lustrous metal that is relatively stable in air. The metal is soft, malleable, and ductile. It has a hexagonal close-packed structure, a density of 9.840 gm/cm³, a melting point of 1663 °C, and a boiling point of 3402 °C. Lutetium oxide, or lutetia, occurs as a sesquioxide with the formula Lu₂O₃. The oxide is a white to beige powder with a specific gravity of 9.420 gm/cm³, a melting point of 2487 °C, and a formula weight of 397.94.

Preparation of Metal

Lutetium metal is typically prepared by calciothermic reduction of the trihalide, typically LuF3, in a tantalum crucible. Lutetium has a high melting point (highest melting point of the rare earths) and is vacuum melted at a temperature of about 1800 °C, similar to Y, Gd, and Tb. The high vacuum melting temperature necessitates a distillation step to remove tantalum impurities introduced during the high temperature reduction and vacuum melting steps, however, sublimation is used to purify lutetium. Lutetium is the only one of the group that can be significantly purified with respect to oxygen if a very slow rate of sublimation is applied. A vacuum of better than 1.3 x 10^-6 Pa is needed (Beaudry and Gschneidner, Jr., 1978). Lutetium metal is formed when the fluoride preferentially separates from lutetium fluoride at high-temperature and combines with calcium metal forming calcium fluoride and a high-purity lutetium metal.

Source

Resources of lutetium are in xenotime, synchisite-(Y), eudialyte-(Y), and ion adsorption ores. They are available worldwide in ancient and recent placer deposits, igneous alkalic deposits, uranium ores, and weathered clay deposits (ion-adsorption ore). It occurs in the Earth’s crust at an average concentration of 0.5 parts per million. Additional subeconomic resources of lutetium occur in apatite-magnetite-bearing rocks, deposits of niobium-tantalum minerals, non-placer monazite-bearing deposits, and sedimentary phosphate deposits. Additional resources in Canada are contained in allanite, apatite, and britholite at Eden Lake, Manitoba; allanite and apatite at Hoidas Lake, Saskatchewan; fergusonite and xenotime at Nechalacho (Thor Lake), Northwest Territories; and eudialyte-(Y), mosandrite, and britholite at Kipawa, Quebec. It occurs in various minerals in differing concentrations and occurs in a wide variety of geologic environments, including alkaline granites and intrusives, hydrothermal deposits, laterites, placers, and vein-type deposits (Hedrick, 2010).

Mining

Lutetium is mined from a variety of ore minerals and deposits using various methods. Xenotime, with Lu₂O₃ contents of 1.0% to 1.8% of the total REO content, is recovered from heavy-mineral sands (specific gravity >2.9) deposits in various parts of the world as a byproduct of mining zircon and titanium-minerals or tin minerals. Heavy mineral sands are recovered by surface placer methods from unconsolidated sands. Many of these deposits are mined using floating dredges which separate the heavy-mineral sands from the lighter weight fraction with an on-board wet mill through a series of wet-gravity equipment that includes screens, hydrocyclones, spirals, and cone concentrators. Consolidated or partially consolidated sand deposits that are too difficult to mine by dredging are mined by dry methods. Ore is stripped by typical earth-moving equipment with bulldozers, scrapers, and loaders or by water jet methods. Ore recovered by these methods is crushed and screened and then processed by the wet mill described above. Wet mill heavy-mineral concentrate is sent to a dry mill for processing to separate the individual heavy-minerals using a combination of scrubbing, drying, screening, electrostatic, electromagnetic, magnetic, and gravity processes (Hedrick, 1991). Vein monazite has been mined by hard-rock methods in South Africa and the United States, and as a byproduct of tungsten mining in China (Hedrick, 2010).

In Russia, loparite is mined by underground methods using room and pillar methods. Ore is drilled and blasted and hauled to the mill. At the mill the blasted ore is crushed, screened, and processed by flotation to produce a loparite concentrate with a 0.15% Lu₂O₃ REO grade. Russian eudialyte has a grade of 0.3% Lu₂O₃. In Kyrgyzstan, synchysite-(Y) concentrate with a Lu₂O₃ content of 0.25% to 0.50% of the total REO was mined by hard-rock methods from the open-pit Kutessai-II deposit near Aktyuz (Hedrick, Sinha, and Kosynkin, 1997). Argillaceous marine sediments enriched in fossil fish remains at the Melovie deposit in Kazakhstan were previously recovered for their uranium and rare-earth content, including lutetium. The main source of the world’s lutetium is the ion-adsorption lateritic clays with Lu₂O₃ contents of 0.1% to 0.3% in the Xunwu ore and 0.4% to 0.5% in the Longnan ore’s total REO grade. Although the Lu₂O₃ grade is lower than in xenotime, larger volumes of the ion-adsorption ore are mined. These ores are mined in the southern provinces of China, primarily Fujian, Guangdong, and Jiangxi, with a lesser number of deposits in Guangxi and Hunan. These deposits are mined by leaching methods (Hedrick, 2010).

Selected ytterbium-bearing minerals

Gadolinite-(Y)	Y2Fe2+Be2(Si2O10)
Xenotime	Y(PO4)
Synchysite-(Y)	Ca(Y,Ce)(CO3)2F
Eudialyte-(Y)	Na4(Ca,Ce)2(Fe2+,Mn,Y)ZrSi8O22(OH,Cl)2
Mosandrite	Na2Ca4(REE)(Si2O7)2OF3
Britholite-(Y)	Ca2(Y,Ca)3(SiO4,PO4)3(OH,F)
Ion adsorption lateritic clays	Y-enriched lateritic clays

References

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.

Cordier, Daniel J., 2009, Rare earths: chapter in Minerals Yearbook 2009, U.S. Geological Survey, (Advance Release), p. 60.1-60.15.

Gschneidner, Karl A. Jr., 2011, The Rare Earth Crisis—The Supply/Demand Situation for 2010-2015: article in Material Matters, Aldrich Chemical Co., Milwaukee, Wisconsin, v. 6, no. 2, p. 34-35.

Hedrick, James B., 2010, Rare earths: chapter in Mineral commodity summaries 2010, U.S. Geological Survey, p. 128-129.

Hedrick, James B., 1990, Rare earths—The lanthanides, yttrium, and scandium: chapter in Minerals Yearbook 1990, U.S. Geological Survey, v. 1, p. 903-922.

Hedrick, James B., 1991, Rare earths—The lanthanides, yttrium, and scandium: chapter in Minerals Yearbook 1991, U.S. Geological Survey, v. 1, p. 1211-1237.

Hedrick, James B., Shyama P. Sinha, and Valery D. Kosynkin, 1997, Loparite—a rare-earth ore (Ce,Na,Sr,Ca)(Ti,Nb,Ta,Fe+3)O3: Journal of Alloys and Compounds, v. 250, p. 467-470.

Urbain, Georges, 1907, A new element, lutecium, obtained by splitting up Marignac’s ytterbium: Chemical News, December 6, v. 96, p. 271-272.

Urbain, Georges, 1908, Lutetium and neoytterbium: Chemical News, April 3, v. 97, p. 157.

Urbain, Georges, 1909, Europium, gadolinium, terbium, neoytterbium, and lutecium: Chemical News, August 13, v. 100, p. 73-75.

Weeks, Mary E., and Henry M. Leicester, 1968, Discovery of the Elements (7th ed.): Easton, Pennsylvania, Journal of Chemical Education, 896 p.