Tungsten [W] (formally known as Wolfram) 1
Translated from Swedish, Tungsten means heavy stone. 1
Tungsten is a period 6/group 6 transition metal and has an [Xe] core. 1
It has the hightest melting point (mp) of any metal - 3,695K (When metals Al, Fe, Cu, or Ti reach this temperature they vaporize.) 4
The half filled 5d orbital allows for a high binding energy in it standard Body Centered Cubic Lattice 4
- 1 Where Does tungsten come from?4
- 2 What form is tungsten found in and how is tungsten extracted? 4
- 3 Uses of Tungsten
- 4 The Availability of Tungsten
- 5 Global Impact
- 6 Environmental Effects
- 7 Future Outcomes of Tungsten
- 8 References
Where Does tungsten come from?4
Officially tungsten was discovered in an iron ore mine in Sweden.
During the Middle Ages a tungsten compound, Wolframite, was found to inhibit tin (Sn) smelting. It devored the tin like a wolf.
China followed at a distance by Canada and Russia holds the largest deposits of Tungsten compounds. However, China, Russia, Boliva, Vietnam, and Austria provide the largest amounts of Tungsten compounds for processing. Looking at a map each of these countries contains a young mountain range (Himayalas, Urals, Andes, Annamite, and Alps).
What form is tungsten found in and how is tungsten extracted? 4
Tungsten is not found in its elemental form.
The main forms of tungsten found are wolframite[(Fe,Mn)WO4] and scheelite[CaWO4].
These compounds are mainly mined underground from veins. The ores are crushed at processing facilities close to the mine and due to the high atomic mass of tungsten, gravity separation is used to obtain more pure wolframite, scheelite and tungsten.
Wolframite and scheelite are then treated with NaOH or similar alkali. Sodium tungstenate is produced. Ammonium is added and the transport form of tungsten is obtained, ammonium-paratungstate [(NH4)10(H2W12O42).4H2O].
Tungsten oxides can be obtained from APT through calcination, the thermal treatment of metal compounds in the absence of air. Tungsten oxides can then be reduced with hydrogen gas to obtain tungsten in a powder form. This form of tungsten is mixed with carbide to form a hard metal compound.
Uses of Tungsten
Tungstens high melting point of 3695K makes it quite suitable for conducting extreme heat and high amounts of electric power. This property is what makes tungsten most commonly used in light bulb filaments and as heating elements in electrical components.
It can also be formed into a tungsten-carbide alloy that is used for surgical cutting tools and machine parts especially in drill bits and saw blades.Tungsten is a very dense element and the hardness of the alloy gives it a very long lifetime of use.
This tungsten-carbide alloy is sometimes used to cut diamond
More miscellaneous uses of tungsten are in making bullets, as weights for fishing lures and sporting equipment ranging from the spikes in bicycle tires to hiking and trekking poles that have to be put under heavy strain.
Tungsten is also used for making jewelry. Mainly rings but also some bracelets and necklace pendants are made from tungsten. Tungsten-carbide does not fade or bend and is being used more as replacement jewelry for the more expensive gold and platinum.
The Availability of Tungsten
On a broad scale
Tungsten can only be attained from the refining and processing of wolframite[(Fe,Mn)WO4] and scheelite[CaWO4]. Tungsten is not too rare as China was able to produce about 51,000 tonnes of tungsten concentrate in 2009.
Elemental tungsten is the most readily available and cheapest of the metals that share similar physical properties to gold and platinum. This enables it to be used as a substitute for these metals especially in jewelry making.
In the 1980's there were counterfeiting issues of tungsten bars being plated with gold and then being sold as 100% gold. Tungsten is only 0.36% less dense than gold and counterfeiters used this to their advantage. At the time the test for gold involved the archimedes method which is pretty much the water displacement method and since tungsten was just about as dense as gold it displaced very similar amounts of water as gold.
Platinum, although not as hard or as durable as tungsten, is a lot more expensive and jewelers have begun to use tungsten carbide alloy more because of its availaibilty, durability and beauty.
Importance to the World's Supply
As of 2012 the United States, Europe and Japan use about 55% of the world's tungsten and produce only about 5%. African and South American countries produce approximately 5% and about 7.5% of the worlds tungsten supply is distributed over 70 countries. Russia and Canada, being the second and third major producers respectively, jointly have less than 8% and as stated earlier China holds the vast majority with close to 85% of the worlds total tungsten production.
The supply and production of tungsten has always been on a general upward trend as manufacturers especially in China have learnt to streamline their mining processes. As more than 85% of the world's tungsten comes from China they tend to be able to monopolize the market and set the prices in their favor.
Due to the fact that tungsten is not mined heavily in the United States, its availabilty is quite limited unless shipped from other major mining areas. China being the worlds major supplier of tungsten controls the avaliability.
Restrictions from China have caused the trading price of tungsten to increase from about $185 per MTU to $335 per MTU (MTU - Metric ton Unit). Also a decrease in supply from the DRC (Democratic Republic of Congo) due to the bill passed on conflict minerals has caused a slight reduction in the worlds supply of tungsten.
China, being the main producer of tungsten, usually trades to larger economies like the USA, Japan, and the EU. In recent years, to keep their domestic tungsten industry functioning, China has become one of the significant importer of tungsten ores and other intemediate products like APT and tungsten oxides. China has gradually reduced exporting tungsten. The main exporters of tungsten are Canada, Russia, Portugal and Bolivia, while the USA and Germany, remain the main importers behind China.
For decades, tungsten was considered environmentally benign, soluable and non-toxic. It served as a less toxic substitute to lead in the production of munitions. After many years of research, its potential environmental impact was evaluated again and the researchers from Stevens Institute of Technology found that it was not a benign as previously assumed 6 . In their experiments, they wanted to see if dissolved forms of tungsten were released during munitions and they found just that. When alloy pieces were exposed to anything aqueous, they found large amounts of dissolved tungsten, meaning that it is not actually souluble as thought.
Even though previous studies showed that tungsten may be stable in environmental conditions, biologically, tungsten could act as a substitute for molybedenum in some enzymes, inhibiting them.Another reseracher at the same institute proved that tungsten alloys are not environmentally inert by watching the degradation of tungsten alloys in environmental conditions. In general, tungsten can have a negative environmental impact.
Tungsten Poisoning 5
Actute tungsten poisoning, common in the French army tradition, is usually gotten from alcoholic drinks which have been rinsed in recently fired gun barrel. This is a ritual done when they are celebrating victory where everyone takes a sip of the drink from the gun. Such poisoning could lead to sudden seizures, coma, renal failure, hypercalcaemia etc. Even after recovery, biochemical abnormalities can still occur five months after ingestion.
Chronic tungsten posioning is usually common amongst hard metal workers and soliders who have constant exposure to the element. These people are at a high risk of pulmonalry fibrosis (lung disease), interstitial pneumonitis, from inhaling the dust from manufacture of the metal. It could also cause memory dysfunction and lung cancer.
Future Outcomes of Tungsten
Tungsten, one of the world's hardest metals has been increasingly introduced into new technologies beacause of its great properties. There is trouble maintaining a balanced supply and demand for tungsten. The world is running low on Tungsten and is considered as one of the important disappearing resource that will affect us all. The reason for its disappearance is that it is a hard metal that is difficult to extract. Also, with China restricting their exports to other countries and buying from other counties, it has caused the demand to keep rising.