Why a Tungsten Thread?
This little known mineral is one of the two metals mined by Avocet.
They may sell the business, but until they do, it comprises an important
minor asset in their business mix. Few know much about this metal
(including myself). This thread and the Links on it will help you learn more.
Tungsten (elemental symbol: W) is a vital and environmentally safe metal, which replaces hazardous lead in many products, including automobiles. It is also used in industrial tools, chemicals, super alloys, lightbulbs and electrical equipment.
Additional new applications for tungsten include the following:
Golf ball centers and golf clubs
Heat sinkers for computer chips
Metal Cutting tools (blades, drill and general purpose tools)
High Temperature Alloys (Enhanced Alloys that are used in jet engines, commercial smeltures, furnaces, welding electrodes)
Miltary Usage (Bullets, armour plating, armor-piercing projectiles)
It has not only the highest melting point of all elements except carbon - sources in scientific literature vary between 3,387°C and 3,422°C - but also excellent high temperature mechanical properties and the lowest expansion coefficient of all metals. A temperature of about 5,700°C is needed to bring tungsten to boil - which corresponds approximately to the temperature of the sun’s surface. With a density of 19.25 g/cu.cm, tungsten is also among the heaviest metals. Its electrical conductivity at 0°C is about 28% of that of silver which itself has the highest conductivity of all metals.
The word tungsten means "heavy stone" in Swedish. The chemical symbol for tungsten is W, which stands for wolfram. The name came from medieval German smelters who found that tin ores containing tungsten had a much lower yield. It was said that the tungsten devoured the tin "like a wolf." Tungsten occurs in the natural state only in the form of chemical compounds with other elements. Although more than 20 tungsten-bearing minerals are known, only two of them are important for industrial use, namely wolframite and scheelite.
Tungsten is usually mined underground. Scheelite and/or wolframite is frequently located in rather narrow veins which are slightly inclined and often widen with the depth. Open pit mines exist but are rare. Most tungsten ores contain less than 1.5% WO3 and ore dressing plants are always in close proximity to the mine. The ore is first crushed and milled to liberate the tungsten mineral crystals. Scheelite ore can be concentrated by gravimetric methods, often combined with froth flotation, whilst wolframite ore can be concentrated by gravity, sometimes in combination with magnetic separation.
Metal Bulletin's Summary (1998, still useful): http://www.amm.com/ref/tung.HTM
More Detail (from ITIA): http://www.itia.org.uk/images/Itiatab4.gif
Annual Global Tungsten Mine Production (tonnes of contained tungsten trioxide (WO3))
Global Tungsten Production
China ........ 85% incl. Pangushan Tungsten Mine and Xiamen Tungsten Co
................ including 2500 tons p.a. Shizhuyuan Mine in Hunan
Russia ....... xx% Two Mines: X and “Lermontovskaya”
Vietnam....... xx% Tiberon Minerals (v.TBR)
Portugal...... xx% xxx, Avocet Mining (L.AVM)
Canada ........ 8% North American Tungsten (v.NTC)
Osram Sylvania, US Based
Sandvik, Sweden based
Supply and Demand
Low tungsten prices over the past 15 years have lead to the closing of a large number of tungsten mines, and virtually no exploration. The main cause of low prices was primarily a combination of Chinese overproduction and liquidation of strategic stockpiles predominately from the former USSR. Throughout much of the 1990s, over 20% of world tungsten consumption has been supplied by stockpile liquidations. In 2000, it is estimated that world mine production was approximately 45,000 tonnes of WO3 per year, while consumption of primary tungsten was over 50,000 tonnes per year; the difference being met by stockpile supplies.
The Vancouver-based company closed CanTung in 1986 when China began dominating the tungsten market. But the company said supplies there and in Russia had become depleted, which had pushed prices up and made it worthwhile to resume mining.
U.S.-based Osram Sylvania and Sweden's Sandvik have agreed to purchase the entire production from CanTung and advanced start-up funds.
"We are prudent and seasoned mine operators and start-up takes more than just pushing a button and expecting a mine that has been idling for 15 years to turn on like a tungsten light bulb," said Udo von Doehren, company chief executive in a statement.
The company, which also owns the MacTung deposit in the NWT, said that the two tungsten assets represent the Western world's largest high-grade proven tungsten reserves and comprise some 15 percent of global proven resource base.