Because scandium is difficult to make, its use has not been shown for 100 years since its discovery With the increasing improvement of rare earth element separation methods, there has been a fairly mature process for purifying scandium compounds After obtaining pure scandium compound, convert it into ScCl3, co melt it with KCl and LiCl, use molten zinc as cathode for electrolysis, so that scandium will precipitate on the zinc electrode, and then evaporate the zinc to obtain metal scandium
In the past 30 years, scandium metal has achieved a lot of application practices at home and abroad, and achieved excellent results
At present, scandium metal has been widely used in laser (Gd3Sc2Ga3O12 laser material, GSGG, new laser), electric light source (scandium sodium halide lamp), alloy (Al Sc alloy, Ga Sc alloy are used in aerospace, missile, automobile, ship and other structural parts; scandium neutron filter) and civil (Ga Sc alloy cermet binder and advanced coating material; ScB2 material is used in light temperature resistant alloy, electron gun cathode parts, scandium battery)
Scandium is a typical dispersed lithophile element, but it is not rare Its average abundance in the crust is 22-30ppm (i.e. 22-30g/t, converted to 35-48g/t scandium trioxide), much higher than Ag, Au, Pb, Sb, Mo, Hg, W and Bi, but equivalent to B, Br, Sn, Ge and As
In nature, scandium is not affected by oxidation and reduction, and is difficult to be reduced to metals. It can rarely form a significant enrichment group (ore deposit), but is widely dispersed in various rock forming minerals (especially magnesium and iron silicate) and scandium bearing minerals
There are more than 800 kinds of scandium minerals in the nature, but few minerals with scandium trioxide content>0.05%. At present, the known independent scandium minerals are scandium yttrium ore ((Sc, Y) 2Si2O7, Sc2O3 content 33.8% - 42.3%), water phosphorus scandium ore (ScPO4.2H2O, Sc2O3 content 39.22%), beryllium silicon scandium ore (Be3 (Sc, Al) 2Si6O18, Sc2O3 content 14.6%), zirconium scandium yttrium ore ((Sc, Zr) 2Si2O7) and titanium silicic acid rare gold ore (Sc (Nb, Ti, Si) 2O5, Sc2O3 content is 18.0% - 20.0%), and there are few ore sources, It is rare in nature
Scandium mainly exists in the form of isomorphism in minerals such as ilmenite, zircon, zircon, bauxite, rare earth ore, titanopyroxene, vanadium titanium magnetite, tungsten ore, tin ore, uranium ore and coal Goldschmidt et al. believed in the 1930s that Sc3+was enriched in rocks and minerals, which was closely related to isomorphic replacement, especially the isomorphic replacement of Sc3+with Fe3+, Mg2+and Al3+ Later, Ringwood added that it was the generation of oxygen or hydroxyl containing complexes, especially the enrichment of scandium in crystalline rocks and greisens The comprehensive similarity between scandium and its coexisting elements, such as ionic radius, coordination number and electronegativity, determines that scandium can undergo isomorphic replacement with many other ions
Scandium content in various rocks, pyroxenite (containing 200-300g/t Scandium trioxide) and gabbro are the highest in magmatic rocks (76g/t) The metasomatic altered rocks are mainly granite pegmatite, tungsten tin bearing greisen, albitization rock and mica rock, and the scandium content in bauxite and coal is also quite high. Especially in coal ash, the scandium trioxide content can reach 40-600g/t
Scandium content of raw ore (scandium trioxide, g/t) is as follows: bauxite 40-150; Phosphate rock 10-25; Tungsten ore 78-337; Vanadium titanium magnetite 13-40; Iron niobium rare earth ore 50; Low manganese ore 181; Ion type rare earth ore 20-50; Scandium is also contained in bastnaesite, tantalum niobium ore and uranium ore (according to Lin Hecheng, 2010)
Scandium content in concentrate (scandium trioxide, g/t): wolframite>500; Ilmenite 60; Bauxite 95; Titanium tailing 77; Cassiterite 100 (according to Lin Hecheng, 2010)
The scandium content of raw material for scandium extraction (scandium trioxide, g/t) is 150-600 for tungsten smelting slag; Aluminum smelting red mud 40-150; Titanium tailing 77; The mother liquor of titanium white hydrolysis 25-100; Chlorinated fume from high titanium slag 736 (according to Lin Hecheng, 2010)
The world is extremely rich in scandium resources, with industrial reserves of about 2 million tons (in terms of scandium metal, the statistics are incomplete). China is also rich in scandium resources, with industrial reserves of about 650000 tons (according to incomplete statistics), accounting for 33% of the world's total industrial reserves
