Tellurium – the newest critical metal


The Newest Critical Metal

An intriguing, almost throwaway line in a report from the GeoForum conference being held in South Africa: it said one solar energy company “has taken the step of employing geologists to go out and find tellurium to meet projected needs”.

Just how they’re going to manage that is not quite evident, as most tellurium is produced as a by-product of refining of lead or copper. According to the U.S. Geological Survey, production in 2012 is an imprecise matter; Canada produced 10 tonnes, Japan and Russia each 35 tonnes. There is tellurium produced in Texas but how much has been withheld for commercial reasons. It was not known whether any came from the rest of the world but the global total can’t be too far north of 100 tonnes.

There was another throwaway line this week, too, regarding this very minor metal. In his quarterly commodities review, Roger Bade at London broker Whitman Howard, in running through the minor metals, noted in passing that “tellurium prices in Europe are also up sharply”. (He was noting how indium prices were off their lows.)

All this makes one think that we should be giving somewhat more attention to tellurium, that maybe it has been the forgotten critical metal.

Here’s why: tellurium is vital to thin-film cadmium-tellurium solar cells. The report from the South Africa conference noted that if the world suddenly steps up solar energy development, there could be a squeeze on tellurium, citing the figure quoted by Murray Hitzman of the Colorado School of Mines that the U.S, would need 400 tonnes of tellurium for every gigawatt of solar energy, and the known world availability was just 48,000 tonnes (although the U.S. Geological Survey cites 24,000 tonnes — but that takes into account only tellurium contained in copper deposits; after all, some 90% of tellurium used is now recovered from slimes following refining of copper).  The USGS also notes that several materials — including bismuth, calcium, lead, phosphorous, selenium or sulphur — can substitute for tellurium but with loss of efficiency and product characteristics.

Apart form solar energy, tellurium is also used for alloying additive in steel to improve machining characteristics; as a minor additive in copper alloys to improve machinability without reducing conductivity; in lead alloys to improve resistance to vibration and fatigue; in cast iron to help control the depth of chill; and in malleable iron as a carbide stabilizer. It is used in the chemical industry as a vulcanizing agent and accelerator in the processing of rubber, and as a component of catalysts for synthetic fiber production. Other uses included those in photoreceptor and thermoelectric electronic devices, other thermal cooling devices, as an ingredient in blasting caps, and as a pigment to produce various colors in glass and ceramics.

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The above story is reprinted from an article published by Investorintel. The original article was written by Robin Bromby.
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