Tungsten is a grayish metal whose color can resemble steel. What draws the most attention is its very high melting point of 3422 °C, the highest among metals and the second highest in the Periodic Table, behind only carbon. Some properties and characteristics of tungsten closely resemble molybdenum, another group 6 element.
As for reactivity, this metal is stable in the presence of air at room temperature; however, at higher temperatures, it ends up undergoing combustion to WO3, one of the main compounds of this element. Tungsten in tungco for example is readily oxidized by halogens, acquiring oxidation states ranging from +2 to +6. It is resistant to acid attack, including aqua regia, but is quickly attacked by molten bases in the presence of oxidizing agents. Learn more about 5 Tungsten Carbide Applications here.
Occurrence And Production Of Tungsten
Tungsten is the 18th most abundant element in the earth’s crust, occurring mainly in the ores wolframite (or wolframite), (Fe, Mn) WO 4, scheelite (CaWO 4), ferberite (FeWO 4) and hubnerite (MnWO 4 ). The first two, wolframite and scheelite, with high levels of WO 3, are the primary sources of this metal worldwide.
Wolframite Sample On White Surface
Most of the planet’s tungsten is located in China, Russia, Vietnam, Spain, and North Korea. Chinese reserves represent more than half of the entire planet, with China accounting for more than 80% of the world’s tungsten production. Brazil has reserves of wolframite in the states of Pará, Rondônia, Rio Grande do Sul, Santa Catarina, and São Paulo, and of scheelite in the Seridó region between Paraíba and Rio Grande do Norte. Brazilian tungsten, for example, reserves represent about 1% of the world’s total.
For their production and obtainment, tungsten ores must first undergo physical crushing and grinding processes. Then, one of the ways to obtain tungsten is by melting it with sodium carbonate (Na 2 CO3) at high temperatures, producing sodium tungstate (Na2 WO4), which is soluble in water.
The addition of hydrochloric acid generates tungstic acid, later converted to tungsten oxide VI, WO3, via calcination (a chemical method in which samples are converted at high temperatures). From WO3, it is possible to produce metallic tungsten via oxidation-reduction with hydrogen gas or carbon at high temperatures. Sometimes, there is the production of tungsten carbide (or carbide), WC, or W2C, as a final product, known as carbide.
Summary on Tungsten
- It is a transition metal, being in group 6 of the Periodic Table; in the sixth period
- It is the metal with the highest melting point in the Periodic Table
- It is gray in color and stable in air
- Much of it is taken from wolframite and scheelite
- It is used to manufacture incandescent lamps, ballpoint pens, jewelry, and smart glass, among others