Mo

Atomic Number:	42
Atomic Weight:	95.94 g
Melting point:	2896 K
Boiling point:	4912 K
Electronegativity	2.16 (pauling)
Density:	10.22 g/cc

· Sources: Found in the minerals molybdenite (MoS₂) and wulfenite (MoO₄Pb).

· Uses: Used in steel, aircraft, missiles, filaments in electric heaters, lubricants and protective coatings in boiler plates.

Isotopes:

Molybdenum (Mo) is a refractory metallic element used principally as an alloying agent in steel, cast iron, and superalloys to enhance hardenability, strength, toughness, and wear and corrosion resistance. To achieve desired metallurgical properties, molybdenum, primarily in the form of molybdic oxide or ferromolybdenum, is frequently used in combination with or added to chromium, columbium (niobium), manganese, nickel, tungsten, or other alloy metals. Few of molybdenum's uses have acceptable substitutions. Molybdenum (often referred to as moly) is a metal that is gaining increasing significance in our industrial world.

Molybdenum is found the world over but only a few deposits warrant the extensive mining, milling and processing facilities necessary for its economic recovery. By far the largest part of world production comes from the Western Hemisphere with the United States contributing the biggest share, Chile in the second place and Canada in third. Outside of a modest output from various locations in China, little molybdenum is mined in the rest of the world.

After crushing, the molybdenum ore is concentrated by flotation to a product consisting largely of molybdenite, which is molybdenite sulfide. It can be purified to give a product used by lubricant manufacturers. Most of the molybdenum concentrate is roasted to remove the sulfur and change the sulfide to oxide. This oxide, which is known as technical molybdic oxide, is the most common means of adding molybdenum to steel as there is almost no loss of molybdenum during the usual melting operations.
A mixture of technical molybdic oxide and iron oxide can be reduced to ferromolybdenum by aluminium in a thermite reaction. Foundries generally use ferromolybdenum for adding molybdenum to cast iron and steel, and steelmills may prefer it to the technical molybdic oxide for some types of steels.
Pure molybdic oxide is made by sublimation of technical oxide or by calcining ammonium molybdate. Pure oxide is suitable for use by chemical and catalyst manufacturers. Molybdenum metal powder is produced by hydrogen reduction of the pure molybdic oxide or ammonium molybdate. In turn, this molybdenum metal powder is consolidated into usable forms by vacuum melting or by pressing and sintering.

Almost everyone uses molybdenum, even when they do not realize it. Superficially molybdenum looks like many other gray metals, and this is one of the reasons many do not appreciate the extent of its use. Everyone knows what copper looks like and can immediately identify a cable as being copper. Not many can look at a light bulb or a TV tube and tell which parts are molybdenum.
The picture becomes even more difficult in the case of the main use of molybdenum as an alloying element added in small amounts to steels, irons and nonferrous alloys. The increasing popularity of lubricants containing Molysulfide has extended from heavy industry to service stations and home workshops. Their black color and the inclusion of the term Moly in the lubricant manufacturer’s trademark can identify these.

Molybdenum is sold on a spot basis in a variety of forms including molybdenum oxide, molybdate (a salt), and ferromolybdenum (an iron alloy containing up to 60 percent molybdenum). In late 1994 and early 1995 molybdenum prices reached a 15-year high of US$18.00/lb as a result of a large world steel demand; by the end of 1995 molybdenum prices had corrected to US$5.00/lb due to increased world production. China has accounted for between 85 and 90 percent of annual world ferromolybdenum exports since 1993, but with its own steel industry growing stronger, China will have less molybdenum to offer on the world market. Besides demand and China's lessened role, experts say the major influence on molybdenum prices will be whether primary producers - like Cyprus Amax Minerals, the world's largest producer, holding 35 percent of the global market - can modify their output to accommodate any shortfall between supply and demand.

The demands of industry are becoming constantly more severe. Engineers want stronger, tougher materials with better hot strength, superior properties at low temperatures, more corrosion resistance and added wear resistance so they can design and build more efficient equipment to give us a better life. Molybdenum helps meet these demands.
Just like other common alloying elements such as chromium and nickel, molybdenum additions give alloy steel and iron a combination of strength, toughness and wear resistance not possible with unalloyed steels. Its extensive use is proof that, under many conditions, its inclusion (alone or with other alloys) results in a more economical and serviceable part. Moreover, molybdenum makes a unique contribution to hot strength, corrosion resistance and toughness.

Increasing temperature raises the efficiency of most types of equipment from steam turbines in central power stations to gas turbines in jet planes and eventually automobiles. Relatively small molybdenum additions are in many cases the best means of increasing hot strength. This applies not only to steel but also to the nonferrous super-alloys with nickel or cobalt as a base. In some aerospace and metalworking applications, molybdenum metal – either pure or with small additions of other alloys – is needed as it stands up even at temperatures where steel melts.

Because it keeps its strength and structure at high temperatures, molybdenum is used largely in alloys as a hardening agent. Steel-molybdenum alloys are used to make high-speed cutting tools, as well as aircraft and automobile parts. Thus, there is no substitute for molybdenum in its major application as an alloying element.

Molybdenum in sheet or wire form is used in X-ray tubes and electric furnaces. Molybdenum has key nuclear-energy applications, and is found in critical rocket and missile parts. It is also a catalyst in petroleum refining, filament material in electrical applications, and an essential trace element in plant nutrition.

Molybdenum is a silverish-white trace element with metallic properties. It is found most often in soils and is usually absorbed through the consumption of plant material. The human body contains about nine milligrams of molybdenum, with the highest concentrations found in the liver, kidneys, bones and skin.

Molybdenum is essential for the proper function of certain enzyme-dependent processes, including the metabolism of iron. It also forms part of several body enzymes and is needed to convert a substance called purine into uric acid. Molybdenum has been used to treat copper toxicity in conditions such as Wilson's disease. Preliminary evidence has suggested that molybdenum might prevent certain types of asthma attacks. It has also been used with fluoride to treat dental decay.

There is currently no recommended daily allowance (RDA) for molybdenum. However, the National Academy of Sciences has deemed the following amounts to be safe and adequate in a normal diet:

Large amounts of molybdenum are found in milk, beans, dark green leafy vegetables, unrefined cereals and grains. Hard tap water can also supply molybdenum to the diet.

Molybdenum deficiency is virtually nonexistent in the U.S. and is usually seen only in people who have been on prolonged tube or intravenous feeding or have a genetic inability to metabolize molybdenum. Symptoms of deficiency include rapid heartbeat and breathing, headaches, night blindness, anemia, mental disturbances, nausea and vomiting. Some studies conducted in Japan and China have linked low levels of molybdenum with an increased risk of stomach and esophageal cancers.

Molybdenum toxicity is extremely rare in the United States. Most health experts agree that an intake of as much as 15 milligrams per day is safe; however, large amounts can interfere with the absorption of copper. In rare cases, excessive molybdenum consumption can cause nausea, diarrhea, or gout-like symptoms such as joint pain and swelling.

Molybdenum is an essential trace mineral. It is needed for the proper function of certain enzyme-dependent processes, including the metabolism of iron. Preliminary evidence indicates that molybdenum, through its involvement in detoxifying sulfites, might reduce the risk of sulfite-reactive asthma attacks. However, a physician should be involved in the evaluation and treatment of sulfite sensitivity.

The amount of molybdenum in plant foods varies significantly and is dependent upon the mineral content of the soil. The best sources of this mineral are beans, dark green leafy vegetables, and grains. Hard tap water can also supply molybdenum to the diet.

Isotope	Half Life
Mo-91	15.5 minutes
Mo-92	Stable
Mo-93	3500.0 years
Mo-94	Stable
Mo-95	Stable
Mo-96	Stable
Mo-97	Stable
Mo-98	Stable
Mo-99	2.74 days
Mo-100	Stable
Mo-101	14.6 minutes