Tungsten, element symbol W, atomic number 74 in the periodic table, is a VIB group metal. The density is 19.35 g/cm ³, which is close to gold, with a melting point of 3422 ° C and a boiling point of 5927 ° C. Tungsten is a silver-white metal, shaped like steel, with the highest melting point of all metal elements and a slow evaporation rate. Tungsten chemical properties are very stable, does not react with air and water at room temperature, does not react with any concentration of hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, but can be quickly dissolved in hydrofluoric acid and concentrated nitric acid mixed acid, and does not work in alkali solution. Tungsten content in the earth’s crust is 0.001%, there are more than 20 kinds of tungsten minerals and tungsten-containing minerals have been found, but there are only wolframite and scheelite with economic value of mining, wolframite accounts for about 30% of the global total tungsten ore resources, scheelite accounted for about 70%. Tungsten is widely used in alloys, electronics, chemical industry and other fields because of its high melting point, high hardness, high density, good electrical and thermal conductivity, small expansion coefficient and other characteristics.