Molybdenum Minerals Have Long Been Known
Ferro molybdenum is an important iron molybdenum alloy
, with a molybdenum content of 60-70% It is the main source for molybdenum alloying of HSLA steel. The molybdenum is mined and is subsequently transformed into the molybdenum(VI) oxide MoO3. This oxide is mixed with iron oxide and aluminium and is reduced in the an aluminothermic reaction to molybdenum and iron. The ferromolybdenum can be purified by electron beam melting or used as it is. For alloying with steel the ferromolybdenum is added to molten steel before casting. Among the biggest suppliers of
Ferro molybdenum in Europe is the German trading house Grondmet in Dsseldorf, Germany.
Molybdenum (pronounced /mlbdinm/ mol-ib-DEE-nm, from Neo-Latin Molybdaenum, from Ancient Greek molybdos, meaning lead), is a Group 6 chemical element with the symbol Mo and atomic number 42. The free element, which is a silvery metal, has the sixth-highest melting point of any element. It readily forms hard, stable carbides, and for this reason it is often used in high-strength steel alloys. Molybdenum does not occur as the free metal in nature, but rather in various oxidation states in minerals. Industrially, molybdenum compounds are used in high pressure and high temperature applications, as pigments and catalysts.
Molybdenum minerals have long been known, but the element was "discovered" (in the sense of differentiating it as a new entity from minerals salts of other metals) in 1778 by Carl Wilhelm Scheele. The metal was first isolated in 1781 by Peter Jacob Hjelm.
Most molybdenum compounds have low water solubility, but the molybdate ion MoO24 is soluble and will form if molybdenum-containing minerals are in contact with oxygen and water. Recent theories suggest that the release of oxygen by early life was important in removing molybdenum from minerals into a soluble form in the early oceans, where it was used as a catalyst by single-celled organisms. This sequence may have been important in the history of life, because molybdenum-containing enzymes then became the most important catalysts used by some bacteria to break into atoms the atmospheric molecular nitrogen, allowing biological nitrogen fixation. This, in turn allowed biologically driven nitrogen-fertilization of the oceans, and thus the development of more complex organisms.
At least 50 molybdenum-containing enzymes are now known in bacteria and animals, though only the bacterial and cyanobacterial enzymes are involved in nitrogen fixation. Due to the diverse functions of the remainder of the enzymes, molybdenum is a required element for life in higher organisms (eukaryotes), though not in all bacteria.
In its pure form,
Molybdenum Powder is silvery white metal with a Mohs hardness of 5.5. It has a melting point of 2,623 C (4,753 F); of the naturally occurring elements, only tantalum, osmium, rhenium, tungsten and carbon have higher melting points. Molybdenum burns only at temperatures above 600 C (1,112 F).[4] It has one of the lowest coefficient of thermal expansion among commercially used metals. Tensile strength of molybdenum wires increases about 3 times from about 10 to 30 GPa when their diameter decreases from ~50100 nm to 10 nm.
There are 35 known isotopes of molybdenum ranging in atomic mass from 83 to 117, as well as four metastable nuclear isomers. Seven isotopes occur naturally, with atomic masses of 92, 94, 95, 96, 97, 98 and 100. Of these naturally occurring isotopes, only molybdenum-92 and molybdenum-100 are unstable. All unstable isotopes of molybdenum decay into isotopes of niobium, technetium and ruthenium.
Molybdenum-98 is the most abundant isotope, comprising 24.14% of all molybdenum. Molybdenum-100 has a half-life of about 1019 y and undergoes double beta decay into ruthenium-100. Molybdenum isotopes with mass numbers from 111 to 117 all have half-lives of approximately 150 ns.
As also noted below, the most common isotopic molybdenum application involves molybdenum-99, which is a fission product. It is a parent radioisotope to the short-lived gamma-emitting daughter radioisotope technetium-99m, a nuclear isomer which is used in various imaging applications in medicine.
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