History of Molybdenite

Molybdenite—the principal ore from which molybdenum is now extracted—was previously known as molybdena. Molybdena was confused with and often implemented as though it were graphite. Like graphite, molybdenite can be used to black a surface or as a solid lubricant.Even when molybdena was distinguishable from graphite, it was still confused with a common lead ore (now called galena), which took its name from Ancient Greek Μ?molybdos, meaning lead Although apparent deliberate alloying of molybdenum with steel in one 14th century Japanese sword has been reported, that art was never employed widely and was later lost. In 1754, Bengt Andersson Qvist examined molybdenite and determined that it did not contain lead and was thus not the same as galena.

It was not until 1778 that Swedish chemist Carl Wilhelm Scheele realized molybdena was neither graphite nor lead. He and other chemists then correctly assumed that it was the ore of a distinct new element, named molybdenum for the mineral in which it was discovered. Peter Jacob Hjelm successfully isolated molybdenum using carbon and linseed oil in 1781.For about a century following its isolation, there was no industrial use for molybdenum due to its relative scarcity, difficulty extracting the pure metal, and the immaturity of the metallurgical subfield. Early molybdenum steel alloys showed great promise in increased hardness, but efforts were hampered by inconsistent results and a tendency towards brittleness and recrystallization. In 1906, William D. Coolidge filed a patent for rendering molybdenum ductile, leading to use as a heating element for high temperature furnaces and as a support for tungsten filament light bulbs; oxide formation and degradation require that moly be physically sealed or held in an inert gas. In 1913, Frank E. Elmore developed a flotation process to recover molybdenite from ores; flotation remains the primary isolation process.

During the first World War, demand for molybdenum spiked; it was used both in armor plating and as a substitute for tungsten in high speed steels. Some British tanks were protected by 75 mm (3 in) manganese steel plating, but this proved to be ineffective. The manganese steel plates were replaced with 25 mm (1 in) molybdenum-steel plating allowing for higher speed, greater maneuverability, and better protection.[6] After the war, demand plummeted until metallurgical advances allowed extensive development of peacetime applications. In World War II, molybdenum again saw strategic importance as a substitute for tungsten in steel alloys.

From:http://www.rare-metal-metals.com/Rare-metal-product/Molybdenum/