Rhenium

(L. Rhenus, Rhine) Discovery of rhenium is generally attributed to Noddack, Tacke, andBerg, who announced in 1925 they had detected the element in platinum ore and columbite.They also found the element in gadolinite and molybdenite. By working up 660 kg ofmolybdenite in 1928 they were able to extract 1 g of rhenium.

Rhenium does not occur free in nature or as a compound in a distinct mineral species.It is, however, widely spread throughout the earth's crust to the extent of about 0.001ppm. Commercial rhenium in the U.S. today is obtained from molybdenum roaster-flue dustsobtained from copper-sulfide ores mined in the vicinity of Miami, Arizona, and elsewherein Arizona and Utah.

Some molybdenum contain from 0.002% to 0.2% rhenium. More than 150,000 troy ounces ofrhenium are now being produced yearly in the United States. The total estimated Free Worldreserve of rhenium metal is 3500 tons. Rhenium metal is prepared by reducing ammoniumperrhentate with hydrogen at elevated temperatures.