graduate

Tungsten


Photograph of tungsten powder

U.S. Geological Survey. Via Wikimedia Commons

Tungsten, element number 74, is a scarce heavy metal characterized by its extremely high melting point of 6192 °F (3422 °C), greater than any other pure element. Its Brinnel hardness of 2570 is much greater than that of even the hardest steel armor plate, but tungsten is brittle and would be unsuitable for structural use even if it were not so expensive.  In 1959, it cost almost a dollar per pound.

Tungsten is used in filaments for light bulbs and other instruments and was a vital alloying element for producing high temperature steels for machine tools and advanced aircraft engines (particularly turbocharger blades.)  Steel alloyed with tungsten retains a very high hardness at elevated temperatures.  Tungsten carbide is even harder at high temperature than the metal and is used much like diamond as an embedded abrasive in drill bits.

Large reserves of tungsten were located in China, which was the world's leading producer in the early 20th century and remains so today. Production was severely hindered by the war, dropping from 16,500 tons in 1937 to 9000 tons in 1943. Most of this production was exported to the United States and Britain as partial repayment for pre-Lend-Lease loans to the Chinese government, as well as to Russia for its earlier military assistance.

Significant deposits were also being mined in Burma and Malaya, in the western United States, and in Tasmania, as well as in South America. Small deposits were found in Japan and Korea, but these were inadequate for the Japanese wartime economy, and this contributed to a shortage of machine tools and high-temperature alloys for aircraft after the American submarine blockade cut Japan off from her supplies in southeast Asia.  This was fortunate for the Allies, as the Japanese had produced some excellent aircraft designs by 1945, but these required tungsten alloys that were no longer available. 

Tungsten was a limiting resource even for the Allies, in spite of their access to much greater reserves, since its availability limited how many high-performance aircraft engines could be produced. There was something of a tungsten rush in the western United States from 1941 on, with numerous amateur prospectors seeking promising deposits using mail-order fluorescent lamps. These produced a brilliant glow from scheelite, the principal ore mineral. Prospectors who "struck it rich" found their claims mapped by government geologists at public expense, and then usually sold their claims to established mining companies.

Tungsten mines in the Pacific

Hami

Hsi-k'uang

King Island
Kuala Lumpur

Kukong
Kyoto
Lovelock

Mawchi
Salmon
San Bernardino
Sariwon
Storey's Creek

Tachishan
Tavoy
Toyoha


References

Hsiung and Levine (1992)

Klein (2013)

U.S. Geological Survey (accessed 29 December 2006)

Van Royen and Bowles (1952)



Valid HTML 4.01 Transitional