Rhenium in Transition

Did you know that rhenium (pronounced ri-neum) was the next-to-last naturally occurring element to be discovered?

Its name derives from the Latin term rhemus meaning Rhine. Those who know their world geography will deduce from its name that it was discovered in . . . Germany, in the year 1925.

Rhenium is clingy and reclusive. It is not found free; rather, it is detected in ores, like platinum and porphyry copper, and minerals, like columbite. It's favorite companion is molybdenum. Rhenium is recovered as a byproduct from roasting molybdenum concentrates.

Recovering rhenium is an expensive process, which lends to rhenium's distinction of making the list of the top 10 most expensive transition metals. During 2006, average rhenium metal price was a whopping $1,170 per kilogram, but it rose as high as $5,000 per kilogram when Kazakhstan refused to supply it to the U.S. for several months!

Rhenium is a component of platinum-rhenium catalysts that are used primarily in producing lead-free, high-octane gasoline and in high-temperature superalloys used for jet engine components.

The largest producer of rhenium has always been Chile. Kazakhstan has become the second largest producer. The United States relies heavily on rhenium imports, as it produces rhenium from only six mines in the U.S.: Two in Arizona and one each in Montana, Nevada, New Mexico and Utah.