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Tungsten Strategic Metal
Oct 19, 2017

Tungsten, a metal element. Atomic number 74, atomic weight 183.84. Steel gray or silver white, high hardness, high melting point, at room temperature from air erosion; the main purpose for the manufacture of filament and high-speed cutting alloy steel, super-hard mold, also used for optical instruments, chemical equipment. China is the world's largest tungsten storage country.

Tungsten is a metal element. The chemical element of tungsten is W, the atomic number is 74, the relative atomic mass is 183.85, the atomic radius is 137 dm, the density is 19.35 g / cm3, and belongs to the sixth cycle (second long period) of the periodic table VIB family. Tungsten in the nature of the main hexavalent cation, the ion radius of 0.68 × 10-10m. As the W6 + ion radius is small, the price is high, the polarization ability is strong, easy to form the network anion, so the tungsten mainly in the form of anion [WO4] 2-, with the solution of Fe2 +, Mn2 +, Ca2 + and other cations to form wolframite or white Tungsten ore precipitation. After smelting tungsten is silver and shiny metal, melting point is very high, hardness is very large, low vapor pressure, evaporation speed is also small, the chemical properties are relatively stable.

Metal type

Nonferrous metals

Tungsten is a nonferrous metal. Usually people according to the color and nature of metal metal into two categories: ferrous metals and non-ferrous metals. Black metal mainly refers to iron, manganese, chromium and its alloys, such as steel, pig iron, ferroalloy, cast iron and so on. Ferrous metals other than metal are called non-ferrous metals. Tungsten belongs to the category of nonferrous metals. The strength and hardness of the colored alloy are generally higher than pure metal, the resistance is larger than that of pure metal, the temperature coefficient of resistance is small, and it has good comprehensive mechanical properties. Thus, as a nonferrous metal, tungsten has a very high strength and hardness. Because of this feature, with a high hardness, wear resistance of tungsten carbide is a large-scale application in cutting tools, mining tools.

Refractory metal

Tungsten is the highest melting refractory metal. Generally, the metal with a certain melting point above 1650 ° C and the melting point above the melting point of zinc (1852 ° C) is called refractory metal. Typical refractory metals are tungsten, tantalum, molybdenum, niobium, hafnium, chromium, vanadium, zirconium and titanium. As a refractory metal, tungsten is the most important advantage is a good high temperature strength, the molten alkali metal and steam have good corrosion resistance, tungsten only at 1000 ℃ above only oxide evaporation and liquid oxide. However, it also has a plastic - brittle transition temperature is higher, at room temperature is difficult to plastic processing shortcomings. Tungsten as the representative of the refractory metal in the metallurgical, chemical, electronics, light, machinery industry and other departments have been widely used.

Rare metal

Tungsten is a rare metal. Rare metals usually refer to metals that are less or less dispersed in nature. Tungsten is a widely distributed element, almost all over the various types of rocks, but the content is low. The content of tungsten in the crust is 0.001%, and the average content of granite is 1.5 × 10-6. This characteristic leads to its extraction difficulty. It can only be extracted and extracted by organic solvent extraction and ion exchange. With the development of science and technology and the development of metallurgical technology, equipment and analytical detection technology and the expansion of rare metal production scale, the purity of tungsten has been improved, the performance has been improved continuously and the variety has been increasing, thus expanding the application field of tungsten. China's tungsten ore is rich in resources, tungsten production and total exports accounted for the world's first.

Strategic metal

Tungsten is a strategic metal. It is well known that rare metals are an important strategic resource for the country, and tungsten is a typical rare metal and has a very important use. It is an important part of contemporary high-tech new materials, a series of electronic optical materials, special alloys, new functional materials and organometallic compounds are required to use a unique performance of tungsten. Although the amount is not big, but it is essential, lack it can not. And thus widely used in contemporary communications technology, electronic computers, aerospace development, medicine and health, photographic materials, optoelectronic materials, energy materials and catalyst materials.

There are a dozen tungsten ore, there are two main in China; wolframite (manganese and iron tungstate) and scheelite (calcium tungstate).

1. Black tungstenite (FeMn) WO4. Color dark gray, reddish brown, light brown black, brown and iron brown and other colors. Semi-metallic luster, metallic luster and resin luster. Usually leaf-like, curved sheet, granular and dense; and some are thick plate, pointed and other monoclinic crystal, often with white quartz together with the form of filling in the form of granite and its nearby rock cracks. Hardness 5-5.5, specific gravity 7.1-7.5. Fracture. Brittle, weakly magnetic. Black tungsten ore is the main raw material for refining tungsten and producing tungstate. The traditional process uses alkali melting.

2. Scheelite CaWO4. Color is gray, there are yellow brown, green and light red and so on. Grease shiny. It is a tetragonal system, the formation of double-cone pseudo-octahedral or plate-like crystals, crystal surface sometimes visible oblique stripes, which inserted the twin crystal are more common. And some of the crystal was crust-like, kidney-like, granular and dense block. Hardness 4.5-5; Specific gravity 5.9-6.2. Brittle, shelly or staggered. When exposed to fluorescent lamps, scheelite can emit beautiful light blue fluorescence. Scheelite mineral in China Jiangxi more than Yu, Xiushui, Hunan Rucheng, Anhua, Linwu, Henan Luanchuan, Yunnan Wenshan and other places. More into sand,

The above tungsten minerals can be re-election (shaker, jig, etc.), flotation, chute, Amoy sand method and other methods to get black tungsten concentrate or white tungsten concentrate

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