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Tungsten Strategic Metals
Oct 10, 2017

Tungsten, a metal element. Atomic number 74, atomic weight 183.84. Steel gray or silver white, high hardness, high melting point, free from air erosion under normal temperature; The main purpose is to manufacture filament and high speed cutting alloy steel, super hard molds, also for optical instruments, chemical instruments. China is the world's largest depository of tungsten.

Tungsten is a metal element. Tungsten chemical symbol W, atomic number is 74, the relative atomic mass is 183.85, the atomic radius of 137 meters, the density of 19.35 g/per cubic centimeter, belongs to the periodic table 6 cycles of VIB (second) for a long period of time. In nature, tungsten is mainly a six-valent cation with an ion radius of 0.68 x 10-10m. Due to the small W6 + ion radius, electricity price is high, the polarization ability strong, easy to form the complex anion, thus tungsten is mainly in the form of complex anion (WO4) 2 -, and solution of Fe2 +, Mn2 + and Ca2 + cation form black tungsten or scheelite ore precipitation. After smelting, tungsten is silver and white luster metal, melting point is very high, hardness is very big, the vapor pressure is very low, evaporation speed is also small, chemical character also is relatively stable.

Non-ferrous metal

Tungsten is a nonferrous metal. Metals are usually divided into two groups based on the color and nature of metals: ferrous and nonferrous metals. Black metal mainly refers to iron, manganese, chromium and its alloys, such as steel, pig iron, iron alloy, cast iron, etc. Metals other than black metals are called nonferrous metals. Tungsten is a nonferrous metal category. The strength and hardness of nonferrous alloys are generally higher than pure metal, the resistance is larger than the pure gold, the resistance temperature coefficient is small, and has good comprehensive mechanical properties. Therefore, as a nonferrous metal, the strength and hardness of tungsten are very high. Because of this characteristic, tungsten carbide with high hardness and wear resistance is widely used in cutting tools and mining tools.

Refractory metal

Tungsten is the most refractory metal in the melting point. Generally higher than the melting point 1650 ℃ and a storage amount of metal zirconium and melting point higher than the melting point (1852 ℃) of metal is called refractory metal. Typical refractory metals are tungsten, tantalum, molybdenum, niobium, hafnium, chromium, vanadium, zirconium and titanium. As a kind of refractory metal, tungsten is the most important advantage is good high temperature strength, good corrosion resistant to molten alkali metals and steam performance, tungsten is only appear in more than 1000 ℃ oxide volatilization and liquid oxide. However, it also has a plastic - brittle transition temperature, which is difficult to plastic machining at room temperature. The refractory metals represented by tungsten are widely used in metallurgy, chemical, electronics, light source and mechanical industries.

Rare metal

Tungsten is a rare metal. A thin metal usually refers to a metal that has little or no distribution in nature. Tungsten is a widely distributed element that is found almost in all kinds of rocks but is low in content. Tungsten content of 0.001%, in the earth's crust in the flower post the content in rock is an average of 1.5 x 10-6, the characteristic causes its extraction difficulty is very big, usually only by organic solvent extraction and ion exchange method extraction. With the progress of science and technology and the metallurgical process, equipment and analysis of the development of detecting technology and expansion of the rare metals production scale for the purity of tungsten, increasing varieties and performance improved, so as to expand the application fields of tungsten. China's tungsten mineral resources are rich, and the production and export of tungsten are the world's largest.

Strategic metals

Tungsten is a strategic metal. As is known to all, rare metals are an important strategic resource for the state, while tungsten is a typical rare metal and has a very important purpose. It is an important part of modern high-tech new materials, and a series of electronic optical materials, special alloys, new functional materials and organic metal compounds are required to use the unique performance of tungsten. Dosage is not great, but it is vital. Therefore, it is widely used in modern communication technology, electronic computer, aerospace development, medicine and health, photosensitive materials, photoelectric materials, energy materials and catalyst materials.

There are a dozen main tungsten mines, China has two main kinds; Wolframite (tungsten and iron tungstate) and white tungsten (calcium tungstate).

1. Black tungsten ore (FeMn) WO4. It has dark grey, reddish brown, light brown, brown and iron brown. Semi - metallic luster, metallic gloss and resin gloss. Usually leaf shaped, curved flaky, granular and dense; There are also some thickened plates, pointed columnar crystals, often with white quartz in the form of the veins in granite and its adjacent rock cracks. Hardness 5-5.5, proportion 7.1-7.5. The differential fracture. Crispy, weak magnetism. Wolframite is the main raw material for refining tungsten and producing tungstate acid salts. The traditional process USES alkali fusion method.

2. White tungsten mine CaWO4. The color is gray, and there are brown, green and light red. Grease sheen. It is a dipyramidal pseudooctahedral or plate-like crystal, which can be seen with oblique streaks. Some crystals are crust, kidney, granular and dense. Hardness is 4.5 5; The proportion of 5.9 6.2. Sexual embrittlement, shell or differential fracture. When illuminated by fluorescent lamp, white tungsten ore can emit beautiful light blue fluorescence. The white tungsten deposit is produced in China's jiangxi province, water repair, hunan rucheng, anhua, linwu, henan luanchuan, yunnan wenshan and other places. Much mortars,

The above tungsten minerals can be used for reelection (shaking bed, jigging, etc.), flotation, chute, and heavy sand, etc., to get the concentrate of black tungsten concentrate or white tungsten concentrate.

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