Tungsten
Tungsten is a silver-white metal, shaped like steel. Tungsten has high melting point, low vapor pressure and low evaporation rate. The chemical properties of tungsten are very stable. It does not react with air or water at room temperature. Without heating, any concentration of hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid or Wang Shui does not act on tungsten. When the temperature rises to 80 °-100 °C, among these acids, In addition to hydrofluoric acid, other acids have a weak effect on tungsten. At room temperature, tungsten can be rapidly dissolved in the mixed acid of hydrofluoric acid and concentrated nitric acid, but it has no effect in alkali solution. In the presence of air, the molten alkali can oxidize tungsten to tungstate, and in the presence of oxidant (NaNO3,NaNO2,KClO3,PbO2), the reaction to form tungstate is more violent. At high temperature can combine with chlorine, bromine, iodine, carbon, nitrogen, sulfur and so on, but not with hydrogenation. Associated ores: there are more than a dozen major tungsten ores and two major types in China; wolframite (tungstenite) and scheelite (calcium tungstate). 1. Wolframite (FeMn) WO4. The color has dark gray, light red brown, light brown black, hair brown and iron brown and other colors. Semi-metallic, metallic and resin gloss. It is usually blade shaped, curved flake, granular and compact, while others are thick platelike, pointed columnar and monoclinic crystals, often filled with white quartz in the form of choroid in granite and its adjacent rock fractures. Hardness 5-5.5, specific gravity 7.1-7.5. A staggered fracture. Brittle and weakly magnetic. Wolframite is the main raw material for tungsten smelting and tungstate manufacture. 2. Scheelite MnWO4. The color is gray and white, but also yellow and brown, green and light red and so on. Grease gloss It belongs to the square crystal system and forms a double cone pseudooctahedron or a plate crystal with oblique stripes on the surface of the crystal, in which the intercalation of double crystals is more common. Some crystals are crust-shaped, renal-shaped, granular and compact. Hardness 4.5-5; specific gravity 5.9-6.2. Brittle, shell-like or staggered fracture. When exposed to fluorescent lamps, scheelite can emit beautiful light blue fluorescence. Scheelite occurs in Dageng, Jiangxi, Dashun, Hunan, Wenshan, Yunnan, etc. Scheelite ore can be obtained by scouring and heavy sand washing. [1] Resource distribution: the abundance of tungsten in the crust is 1.2X10-4. Twenty-four kinds of tungsten minerals have been found, of which there are two kinds of wolframite and scheelite of industrial value. The resources of the world are mainly concentrated in the two major metallogenic regions of the Pacific Rim Zone and the Eurasian-North American Continental Belt. World tungsten reserves 2.8169 million tons, mainly produced in China, Canada, North Korea, Russia, the United States, Australia and other countries. China is located in the above two tungsten ore areas, the ore quality is good, the ore variety is complete, the reserve ranks first in the world, reaches 2.32 million tons, the main production Jiangxi, Hunan, Fujian, Guangdong, Yunnan, Guangxi and so on province. China is a large tungsten producing country, with reserves of 5.2 million tons of tungsten, more than three times of the total reserves (1.3 million tons) of 30 countries producing tungsten abroad. The output and export volume are the first in the world. The reserves of tungsten in Hunan, Jiangxi and Henan provinces are among the top three in the country, of which Hunan and Jiangxi provinces account for 55.48 percent of the countryundefineds total reserves. White tungsten is the main resource in Hunan province and black tungsten in Jiangxi province, which accounts for 42.40% of the total amount of black tungsten resources in China. Tungsten deposits in China are mainly distributed along the eastern coast of Guangdong on the two sides of the Nanling Mountains in China, especially in the southern part of Jiangxi Province, accounting for more than 1/2 of the worldundefineds reserves. In addition, Jiangxiundefineds Dayu, Hunanundefineds Rucheng, Zixing, Qiling and other provinces, as well as Guangxi and Yunnan provinces also have tungsten deposits. Besides China, other countries with tungsten resources are Canada, Austria, Russia, Australia and Vietnam.
