The History of Tungsten

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 Taming Tungsten: From inauspicious to awesome

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Tungsten production and pricing

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    The strongest metal on earth came from the stars. As rare as it’s strong, tungsten is thought to be formed when a massive star goes supernova.

    Tin and Tungsten

    Tungsten’s history dates back to the Middle Ages. In the mid 1500s tin miners in the Ore (Erz) Mountains of Saxony-Bohemian Erzgebirge in Germany noticed a certain mineral often accompanied tin ore. The frustrated miners found this mineral reduced the tin yield during the smelting process and increased slagging.

    Foam would appear on the tin melt surface and a heavy slag would form in the smelter that retained the valuable tin. An observer using the symbolic language of those times, described the unknown mineral: “It tears away the tin and devours it like a wolf devours a sheep”.

    Miners gave the mineral German nicknames like “wolform”, “wolffshar” and “wolffram” (which means wolf froth, in part because of the mineral’s black colour and hairy appearance). Hardly a salubrious start for a metal destined to become the enabler of countless engineering and technological breakthroughs.

    Heavy metal roots

    In the mid to late 1750’s, the Swedish chemist and mineralogist, Axel Fredrik Cronstedt, discovered an unusually heavy mineral in Bispberg´s iron mine in the Swedish province of Dalecarlia. He referred to this heavy mineral as “tung-sten” which in Swedish means “heavy-stone”.

    Cronstedt was convinced that this mineral contained a new, and as yet, undiscovered element. In 1781, a fellow Swedish chemist named Carl Wilhelm Scheele, succeeded in isolating a still unknown acid, which he called tungstic acid (tungsten trioxide) and published the results of his experiments. Torbeen Bergman, a professor in Uppsala, suggested preparing the corresponding metal by charcoal reduction of the obtained acid. In 1781/82, a Spanish Nobleman, Juan Jose’ de D’Eluyar who studied metallurgical chemistry with Professor Bergman produced a review of the work carried out by Scheele on the mineral Tungsten.

    Upon return to Spain in 1783 Juan Jose analyzed a sample of wolfram from a tin mine in Saxony and concluded that wolfram contained the same acid as what Scheele had gained from Tungsten. He then reduced the oxide to a new metal by heating it with charcoal as had been previously suggested by Professor Bergman. The new metal was then named “Wolfram” after the mineral from which it was derived.

    Thereafter, a number of scientists explored and experimented on the new chemical element and its compounds. In 1821, K.C. von Leonhard proposed the name “Scheelite” for the mineral CaWO4 (Calcium Tungstate). In 1847, a patent for the manufacture of sodium tungstate, tungstic acid and tungsten from tinstone was granted to Robert Oxland. Additional patents were granted to Oxland for his work in tungsten-containing steels in 1858 and self-hardening steels in 1868. The work established an important step in modern tungsten chemistry and opened the way to industrialization. Tungsten light bulbs were patented in 1904 and rapidly displaced the less efficient carbon filament lamps, thus revolutionizing artificial lighting.

    The drive to produce drawing dies and other tools with diamond–like hardness and improved toughness and wear resistance led to the development of cemented carbides during the 1920’s.
    A patent for hardmetal (cemented carbide) was granted to Osram Studiengesellschaft in Berlin in 1923. Tungsten became a strategic metal during World War II as its resistance to high temperatures and its strengthening of alloys made it an important raw material for the arms industry. The Post-WWII industrial boom caused the demand for cemented carbides which was used extensively as cutting tool material and construction of industrial equipment/machinery to soar and has resulted in the present day market where tungsten carbide is the primary application for tungsten.

    From light bulbs to bullets

    Tungsten’s diverse properties and uses

    Pure tungsten is a shiny white metal and in its purest form is quite pliant and can easily be processed. However, it usually contains small amounts of carbon and oxygen, which give tungsten metal its considerable hardness and brittleness. 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.

    Pure scheelite has blue-white fluorescence in ultraviolet light, a property which is utilised in prospecting. Wolframite is a general term for iron and manganese tungstates where the iron/manganese ratio can vary. A mineral with more than 80% FeWO4 is called Ferberite and a mineral with more than 80% MnWO4 (Manganese Tungstate) is called Hübnerite.

    Fast Facts
    • Tungsten is the heaviest engineering material with a density of 19.25 g/cm3.
    • It has the highest melting point of all metals at 3410∞C with a boiling point of 5700∞C.
    • It has the lowest vapour pressure of all metals.
    • It has the highest modulus of elasticity of the metals (E = 400GPa).
    • It is the hardest pure metal.
    • Excellent high temperature strength characteristics.
    • It has the highest tensile strength at temperatures above 1650∞C.
    • It has a low thermal expansion co-efficient (4.4 x 10-6 m/m/∞C) similar to that of borosilicate glass, and therefore makes it useful for glass to metal seals.
    • It does not oxidise in air and needs no protection from oxidation at elevated temperatures.
    • Its corrosion resistance is excellent, and it is not attacked by nitric, hydrofluoric, or sulphuric acid solutions.
    • Environmentally friendly, does not break down or decompose.

    Uses

    Due to the unique properties of tungsten, tungsten alloys and some tungsten compounds listed above, the metal cannot be substituted in many important applications in different fields of modern technology.

    Tungsten is an additive in the production of specialty alloys; filament wire for lighting (2%); and specialty uses for mobile phone handsets, military, ballistics (defense equipment) automotive parts, aerospace components, drilling, boring & cutting equipment, logging equipment, electrical & electron- ics appliances, chemical applications and other end-uses.

    Today, the majority of tungsten is used in manufacturing cemented carbides or hard metals. These are materials made by cementing tungsten carbide grains in a binder matrix of a tough nickel or cobalt alloy using the process of sintering. Tungsten carbide is the most popularly used form of the product which has hardness close to diamond. It is denser than steel and titanium, twice as hard as any steel grade, and has extremely high wear resistance. Due to these characteristics, the product is widely used in construction, metalworking applications and mining. The global mining industry’s usage of tungsten carbide as drilling, boring, and cutting tools will likely propel the tungsten market growth as the demand for precious metals in China and other developing countries increases.

    Also, pure tungsten metal products used in the electronics industry such as electrodes, lighting filaments, electrical and electronic contacts, sheets, wires, rods, etc. will be a major factor driving the mill tungsten market growth, not to mention, future applications of tungsten that are being developed as an alternative to lead.

    Fast Facts
    • Filaments for electric lamps – electrical and electronic contacts, wire, rods and so on.
    • Inert gas welding electrodes.
    • Metal evaporation work.
    • As an alloy (steels) it is used for high-speed steel tools, weights and counterbalances, radiation shielding, cutting/grinding tools.
    • Magnets.
    • Heavy metals.
    • Electronic applications such as electric contacts points for automobile distributors, heat sinks, electrochemical machining and electrodes for electrical-discharge machining (EDM).
    • X-ray targets.
    • Windings and heating elements for electric furnaces.
    • Electroplating.
    • Space missiles, rocket nozzles and high-temperature applications as a coating.
    • As yarn it is used for reinforcement in metal, ceramic and plastic composites.
    • Magnetrons for microwave ovens.
    • Television sets.
    • Chemical catalysts.
    • Metalworking, mining, cutting tools bits, heat- and erosion-resistant parts, coatings, seal rings and petroleum.
      Calcium and magnesium tungstates are widely used in fluorescent lighting.
    • Other tungsten salts are used in tanning industries.
      Tungsten disulphide is used as a dry high temperature lubricant (stable to 500∞C).
    • Tungsten bronzes and other compounds are used as pigments for paints.

    Chinese dominance

    The global tungsten market is mainly driven by China, which will continue to dominate both tungsten supply and  consumption. However, China has now become a net importer of tungsten concentrate. This change is due to the Chinese government’s increased regulation and restriction of tungsten ore exports, plus increased domestic demand due to manufacturing of value-added tungsten products.

    These factors, along with China’s high growth in the automotive, aerospace, mining and electronics sectors are the main reasons behind its dominant market position.

    The global demand for tungsten is forecasted to rise annually (3-7% per annum according to the British Geological Survey) and is predicted to outstrip available supply which will place continued upward pressure on prices in the near-term. Tungsten alloys will experience the fastest growth of any major product category, stimulated largely by increasing aerospace manufacturing demands. However, cemented carbides will continue to account for the largest share of processed tungsten consumption as increased production in the construction, mining, aerospace, machinery and metal products industries will spur demand for tungsten-containing cutting tools, dies, drills, weights and wear parts, among others.

    Tungsten mill products (pure tungsten metal products) such as electrodes, lighting filaments, electrical and electronic contacts, sheets, wires, rods, etc. will have steady growth, fueled by the demand for tungsten’s usage in a multitude of electrical and electronic applications.

    Global Supply & Demand

    Tungsten is typically priced according to Metric Ton Units (MTU) of Ammonium Para Tungstate (APT) – the main form of raw tungsten material traded.

    One MTU equals 10 kg and an MTU of APT contains approximately 7.93 kgs of tungsten. APT and concentrate prices are mainly based on quotations published twice weekly by London’s metal bulletin and other trade journals (ITIA).

    Tungsten Supply & Demand

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