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The Life and Times of

 Tungsten 

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74

W

183.84

H He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
Cs Ba Lu Hf Ta Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn

 Properties of Tungsten 

 Ores and Extraction 

Mining

Wolframite, named for its high Tungsten content (Tungsten is Wolfram in German), is in an intermediate, between Huebnerite and Ferberite, and so not scientifically classified as a mineral species by the IMA.

Scheelite was named in 1821 by Karl Caesar von Leonhard in honor of Karl Wilhelm Scheele, a Swedish Pomeranian pharmaceutical chemist who discovered Oxygen, Chlorine, Manganese, and Tungsten.

Wolframite and Scheelite mines are usually underground. The minerals are often found in short, narrow veins, and so mines do not produce large amounts of ore (usually less than 2000 tons per day). Because most Tungsten ores contain less than 1.5% Tungsten, dressing plants (where waste material is removed) are usually located close to the mine to reduce transport costs.

Scheelite can be concentrated gravimetrically (using differences in density and mass), and by froth flotation (separating hydrophobic and hydrophilic materials — the ore is ground to grains, water is added to form a slurry, and hydrophobic chemicals are added that adhere to the desired material. The slurry is then aerated, and the hydrophobic chemicals (with the desired materials in tow) attach to the bubbles and rise to the surface). Wolframite is concentrated with gravity (spirals, cones, tables), and sometimes magnetically as well. The Tungsten oxide from this concentrate is then heated to between 550ºC to 850ºC in a stream of hydrogen to form metallic Tungsten powder, which is made into billets through mechanical pressure.

Scheelite found in China
Wolframite found in China
Wolframite mining in the Democratic Republic of Congo
Tungsten rods with evaporated crystals, partially oxidized with colourful tarnish

 Common Uses 

More than half of the world's Tungsten is used in cemented carbides, namely Tungsten carbide. Tungsten Carbide (WC) is used for machining and manufacturing tools, in World War II for armour-piercing ammunition, and for various athletic objects and high-quality surgical tools. Tungsten Carbide has about two times the stiffness of steel, and just under two times the density. It is less dense than pure W, but is much stiffer and more durable.

Pure Tungsten is used electrically because of its high melting point. Incandescent lightbulb filaments are made almost exclusively of Tungsten, having replaced Carbon filaments in 1904.

WC - Tungsten carbide, used for machining tools and armour-piercing ammunition because of its very high hardness and density

WS2 - Tungsten disulfide, used as li-ion battery anodes, and as a dry lubricant

HSS - High speed steel contains about 18% Tungsten, used because it adds hardness and temperature resistivity

Tungsten is used in lightbulbs because of its high melting point and good conductivity.
Tungsten Carbide router bits
Tungsten Carbide inserts

Environmetal Concerns

In 2009, it was found that certain forms of Tungsten can move easily through soil and groundwater, unlike previously thought. Tungstate anions can be biologically harmful — Tungsten sometimes replaces molybdenum in enzymes, rendering them inactive. Tungsten has been used to make “green bullets” instead of lead because of its low reactivity, relatively low toxicity, and high density and strength, but recent studies suggest that these “green” ammunition isn’t actually much better ecologically than lead.

As well, it is very likely that there will be a worldwide scarcity of Tungsten by 2030. Tungsten is essential for today’s industries, but it is a NNR, and we will likely exaust the earth of it fairly soon. That said, Tungsten is recyclable and can be extracted from its applications; it will become increasingly necessary to recycle the metal.

Processing works of Pine Creek Tungsten Mine (also vanadium), at about 9000ft above Rovana, Inyo County CA. Mine shafts mainly high up in valley toward Morgan Pass, but some up Pine Creek. Important during World War II and still some active Tungsten extraction into the 2000's, but now closed. View down from Pine Creek Pass trail.

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