Metals on the leading edge of technological breakthroughs (2)

The major metals may attract most of the attention, but the minor metals have a significant part to play in the industrial world. The minor metals often find themselves near the forefront of technological breakthroughs. A list of such metals is continued from last month.

Tungsten (formerly wolfram): Tung-sten means “heavy stone,” from the Swedish, and is obtained from sheelite and wolframite ores. The current world market is dominated by China.

Tungsten is probably the strongest pure metal in use. The first metallic tungsten was produced by Spain’s d’Elhuyar brothers in 1782. Gas tungsten-arc welding is used in the world of precious metals as a process in which metals are fused together using the heat of the arc between a metal electrode and the work. One of the hardest substances known, tungsten is used for tipping tools. Its hardening effect on other metals has led to its wide use as an unseen but vital alloying element for growing ranges of special tungsten steels for high temperature applications and for cutting tools, as well as in the non-ferrous alloy stellite.

Ordinarily, we see tungsten as a filament in electric incandescent lamps. Their first development was made by Swan and Edison concurrently before 1880 using expensive platinum wires (as in the sparkplugs of early automobiles) with carbon filaments.

In 1907, the world witnessed the first tungsten filament lamps prepared by Austria’s Just and Hanaman. Coolidge’s drawn ductile tungsten greatly improved these by 1912. The next year, Langmuir used inert gases such as nitrogen in the bulb, permitting higher temperatures, thus better light and product life. In improved form, these bulbs make a valuable contribution to our lives today, particularly at home.

Selenium (Selene, goddess of the moon): Discovered by Berzelius in 1817. Canada’s output of this rare element is about 350 tons per year, worth more than $5 million.

Some of the naturally occurring gold and silver ores are selenides, a binary compound of selenium. Chief sources are slimes from electrolytic copper refineries and secondary refining from xerographic scrap. Output levels depend mainly on copper refining.

Our bodies obtain needed selenium from seafood, meat and wheat cereals. It protects cells from damage. Selenium’s main applications are in the manufacture of glass, pigments, chemicals and in electronic and photoelectric components and rectifiers, because of its special electric qualities.

Selenium is a catalyst in the production of aromatic hydrocarbons for the huge cosmetics industry.

Our modern television is an indirect result of a sunbeam falling on selenium. On a cable station off the coast of Ireland in 1861, Irishman Joseph May noticed his instruments malfunctioned in sunlight and he finally traced the disturbance to selenium resistors whose current varied with the amount of light they received. A mosaic of such cells was soon fashioned into an image collector for transmission.

Tellurium (Tellur, “earth” in Latin): Relatively scarce, the metal’s discovery is attributed to von Reichenstein in 1782 and Klaproth in 1798. Canada’s output of 16-20 tons per year is worth $500,000- $700,000.

Some naturally occurring ores of silver and gold, copper or lead contain tellurides, compound salts of divalent tellurium, as in calaverite, sylvanite and hessite. Its chief sources are slimes from copper and lead electrolytic refineries and flue dusts from telluride gold ores.

Early students called it aurum paradoxum (“paradox gold”) because of its peculiar properties. For example, acid solutions of the dioxide have been used for a dip to give a “platinum finish” to certain metals.

The metal is used mainly to enhance the machining and general metal qualities of various types of alloys, particularly ferro-alloys.

The relatively new uses of tellurium include its incorporation into a variety of specialized heat and electric environments as well as in solar energy converter apparatus displays. Some of its semi-conductor compounds are coming into use in technical devices. T. P. (Tom) Mohide, a former president of the Winnipeg Commodity Exchange, served as a director of mining resources with the Ontario Ministry of Natural Resources prior to his retirement in 1986.

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