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Mineral Monday: Cadmium

The subject of today’s Mineral Monday is used to protect critical components of oil rigs and aeroplanes, and is a vital part of many batteries. But what is it? Cadmium!

A controversial, yet widely used element, Cadmium was discovered simultaneously in 1817 by Friedrich Stromeyer and Karl Samuel Leberecht Herman, both in Germany, as an impurity in zinc carbonate.

However, it was not to be until the 1930’s that industrial production of Cadmium would be attempted. Its value as a coating of steel and iron to prevent corrosion spurred its production though.

Besides coating Cadmium also found use as red, orange and yellow pigments.

The world of energy generation also makes ample use of Cadmium as it plays a key role in the control rods of nuclear reactors, acting as a ‘neutron poison’ to control neutron flux in nuclear fission. And looking at energy on a smaller scale, Cadmium plays an important role in many batteries. In 2009, 86% of Cadmium was used in batteries, predominantly in rechargeable nickel-cadmium models.

Despite this wide array of uses and applications Cadmium also attracts much criticism and controversy due to its potential to cause poisoning and other harms to humans and other life forms. Cadmium is one of six substances banned by the European Union’s Restriction on Hazardous Substances (RoHS) directive, which bans certain hazardous substances in electrical and electronic equipment but allows for certain exemptions and exclusions. In addition, the International Agency for Research on Cancer has classified Cadmium and Cadmium compounds as carcinogenic to humans.
Where is it produced / mined?
As of 2001, China was the leading producer of Cadmium, producing nearly one-sixth of the world share, with South Korea being the second largest producer. Other significant producers include Japan, Kazakhstan, Canada, Mexico and Russia.
Did you know?
• There are eight isotopes of Cadmium, two of which are radioactive.
• Cadmium electroplating is especially common for aircraft.
• In bulk, Cadmium is non-flammable, but will burn and release poisonous fumes when in powdered form.
• It has been known to take as much as a one ton sample of zinc to produce a mere 6.5 pounds of Cadmium.
• Cadmium is named for the Greek god Cadmus, who led an adventurous life around 2000 BCE.
• Cadmium is a soft, malleable, ductile, bluish-white metal, which is easily cut with a knife. It is an excellent electrical conductor and shows good resistance to corrosion and attack by chemicals.
• Cadmium tarnishes in air and is soluble in acids but not in alkalis.
• The Earth’s crust contains about 0.1 parts per million of Cadmium.

So there you have it! Cadmium, an element that plays a key part in many essential modern industrial processes and applications.