Applications
Molybdenum is a valuable alloying agent, as it contributes to the hardenability
and toughness of quenched and tempered steels. It also improves the strength of
steel at high temperatures. Molybdenum is used in alloys, electrodes and
catalysts. The Second World War German artillery piece called "Big Bertha"
contains Molybdenum as an essential component of its steel.
It is used in certain Nickel-based alloys, such as the "Hastelloys(R)" which are
heat-resistant and corrosion-resistant to chemical solutions. Molybdenum
oxidizes at elevated temperatures. The metal has found recent application as
electrodes for electrically heated glass furnaces and foreheaths. The metal is
also used in nuclear energy applications and for missile and aircraft parts.
Molybdenum is valuable as a catalyst in the refining of petroleum. It has found
applications as a filament material in electronic and electrical applications.
Molybdenum is an essential trace element in plant nutrition. Some lands are
barren for lack of this element in the soil. Molybdenum sulfide is useful as a
lubricant, especially at high temperatures where oils would decompose. Almost
all ultra-high strength steels with minimum yield points up to 300,000
psi(lb/in. 2 ) contain Molybdenum in amounts from 0.25 to 8%.
Molybdenum powders are used in circuit inks for circuit boards, and in
microwaves devices and heat sinks for solid-state devices.
Molybdenum in the envIronment
Molybdenum differs from the other micronutrients in soils in that it is less
soluble in acid soils and more soluble in alkaline soils, the result being that
its availability to plants is sensitive to pH and drainage conditions. Some
plants can have up to 500 ppm of the metal when they grow on alkaline soils.
Molybdenite is the chief mineral ore, with wulfenite being less important. Some
molybdenite is obtained as a by-product of tungsen and Copper production. The
main mining areas are the USA, Chile, Canada and Russia, with world production
being around 90.000 tonnes per year, and reserves amounting to 12 million tonnes
of which 5 million tonnes are in the USA.
Health effects of Molybdenum
Based on animal experiments, Molybdenum and its compounds are highly toxic. Some
evidence of liver dysfunction with hyperbilirubinemia has been reported in
workmen chronically exposed in a Soviet Mo-Cu plant. In addition, signs of gout
have been found in factory workers and among inhabitants of Mo-rich areas of
Armenia. The main features were joint pains in the knees, hands, feet, articular
deformities, erythema, and edema of the joint areas
Environmental effects of Molybdenum
Molybdenum is essential to all species. As with other trace metals, though, what
is essential in tiny amounts can be highly toxic at larger doses. Animal
experiment have shown that too much Molybdenum causes fetal deformities. Fodder
with more than 10 ppm of Molybdenum would put most livestok at risk.