How Is Scandium Metal Made?

How is scandium metal made?
After obtaining the pure scandium compound, convert it into ScCl3, co-melt it with KCl and LiCl, use the molten zinc as the cathode for electrolysis, so that scandium will precipitate on the zinc electrode, and then evaporate the zinc to obtain scandium metal.
The natural production state of scandium: scattered but not scarce
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/ton, converted to 35-48g/ton of scandium trioxide), which is much higher than Ag, Au, Pb, Sb, Mo, Hg, W and Bi, and is equivalent to the abundance of B, Br, Sn, Ge and As.
In nature, scandium is not affected by oxidation-reduction and is difficult to be reduced to metal. It rarely forms a significant rich aggregate (deposit), but is widely dispersed in various rock-forming minerals (especially magnesium and iron silicate) and scandium-bearing minerals.
There are more than 800 minerals containing scandium in nature, but few minerals with scandium trioxide content>0.05%. At present, the only known independent minerals of scandium are scandium yttrium ore ((Sc, Y) 2Si2O7, Sc2O3 content 33.8% - 42.3%), water scandium phosphate ore (ScPO4.2H2O, Sc2O3 content 39.22%), beryllium scandium (Be3 (Sc, Al) 2Si6O18, Sc2O3 content 14.6%), zirconium scandium yttrium ore (Sc, Zr) 2Si2O7) and titanium silicate rare gold (Sc (Nb, Ti, Si) 2O5, Sc2O3 content 18.0% - 20.0%) It is rare in nature.
Scandium mainly exists in minerals such as ilmenite, zircon, zircon, bauxite, rare earth ore, titanopyroxene, vanadium-titanium magnetite, tungsten ore, tin ore, uranium ore and coal in the form of isomorphism. Goldschmidt et al. believed in the 1930s that the enrichment of Sc3+in rocks and minerals was closely related to isomorphism replacement, especially the isomorphism replacement of Sc3+with Fe3+, Mg2+and Al3+. Later, Ringwood added that it was the formation of oxygen-containing or hydroxyl complexes, especially the enrichment of scandium in crystalline rocks and dolomites. The comprehensive similarity of the ionic radius, coordination number and electronegativity of scandium and its associated elements determines that it can be isomorphic with many other ions.
The content of scandium in various rocks is higher than that of pyroxenite (containing 200-300 g/t of scandium trioxide) and gabbro (76 g/t). The metasomatic altered rocks are enriched with granitic pegmatite, tungsten-tin bearing greisenite, albite and micitite *, and the bauxite and coal also contain high scandium. In particular, coal ash contains scandium trioxide up to 40-600 g/t.
Scandium content of raw ore (scandium trioxide, g/t) is as follows: bauxite ore 40-150; Phosphate rock 10-25; Tungsten ore 78-337; Vanadium-titanium magnetite 13-40; Fe-Nb rare earth ore 50; Lean manganese ore 181; Ion-type rare earth ore 20-50; Bastnaesite, tantalum niobium ore and uranium ore also contain scandium (according to Lin Hecheng, 2010).
Scandium content of concentrate (scandium trioxide, g/t): wolframite ＞ 500; Ilmenite 60; Bauxite 95; Titanium tailings 77; Cassiterite 100 (according to Lin Hecheng, 2010).
Scandium content of scandium extraction raw material (scandium trioxide, g/t): 150-600 tungsten slag for tungsten smelting; 40-150 red mud for aluminum smelting; Tailings of titanium separation 77; 25-100 hydrolysis mother liquor for titanium dioxide refining; Smoke and dust from chlorination of high-titanium slag 736 (according to Lin Hecheng, 2010).
The world's scandium resources are extremely rich, with an industrial reserve of about 2 million tons (calculated by 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.