Compared with yttrium and lanthanide, scandium metal has a very small ion radius and a very weak alkalinity of hydroxides. Therefore, when scandium and rare earth elements are mixed together, they are treated with ammonia (or very dilute alkali), and scandium will be precipitated first. Therefore, it can be easily separated from rare earth elements by using the "graded precipitation" method. The other method is to use the polar decomposition of nitrate for separation. Because scandium nitrate is easy to decompose, the purpose of separation is achieved.
Scandium metal can be prepared by electrolysis. ScCl3, KCl and LiCl are co melted during scandium smelting, and the molten zinc is used as cathode for electrolysis to separate scandium on the zinc electrode, and then the zinc is evaporated to obtain scandium metal. In addition, scandium can be easily recovered when processing ores to produce uranium, thorium and lanthanide elements. Comprehensive recovery of scandium associated with tungsten and tin ores is also one of the important sources of scandium. Scandium is mainly in the 3-valent state in the compound, which is easy to be oxidized to Sc2O3 in the air and lose its metallic luster and become dark gray.
Scandium reacts with hot water to release hydrogen, which is also soluble in acid and is a strong reducing agent. Scandium oxides and hydroxides are only alkaline, but their salt ash can hardly be hydrolyzed. Scandium chloride is white crystal, easily soluble in water and deliquescent in air. In the metallurgical industry, scandium is often used to make alloys (alloy additives) to improve the strength, hardness, heat resistance and performance of alloys. For example, adding a small amount of scandium to molten iron can significantly improve the properties of cast iron, and adding a small amount of scandium to aluminum can improve its strength and heat resistance.
In the electronic industry, scandium can be used as various semiconductor devices, such as the application of scandium sulfite in semiconductors has attracted attention at home and abroad, and scandium containing ferrites have a bright future in computer cores. In the chemical industry, scandium compounds are used as dehydrogenation and dehydration agents for alcohol to produce ethylene and efficient catalysts for producing chlorine from waste hydrochloric acid. In the glass industry, special glass containing scandium can be manufactured. In the electric light source industry, scandium sodium lamp made of scandium and sodium has the advantages of high efficiency and positive light color.
