Scintillating, stimulating, and expensive, lutetium is the last of the heavy-group rare-earth elements (HREE), the 15th and final lanthanide, and the 17th and closing climax to the rare-earth saga, an epic Norse battle of discovery and conquest. As the heaviest rare earth, lutetium is endowed with properties of medical diagnostics on the molecular level, nanometer lithography of integrated circuits, high-energy treatment of cancer, and laser detection of weather vectors including dust in the wind.
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).
Lutetium is mined from a variety of ore minerals and deposits using various methods. Xenotime, with Lu2
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).
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