Molybdenum is a silvery-white, metallic element that features an extremely high melting point, high strength and the ability to enhance the properties of steel and other alloys. It is relatively rare in the universe and ranks only 53rd or 54th in abundance in the earth's crust.
Molybdenum is an essential trace element for all higher eukaryote organisms, which includes all animals, plants, fungi, protozoa, etc. It is a vital component of numerous enzymes which perform essential biological functions including with regard to metabolism, cellular waste removal and nitrogen fixation.
Molybdenum in greater than trace quantities can be moderately toxic for humans, but the incidence of such toxicity is not common and is usually the result of high exposure levels from supplements and occupational sources. However, it is a much more frequent problem for ruminants, such as cattle and sheep, mainly due to its interference with their copper metabolism, leading to a copper deficiency.
Molybdenum is of great industrial importance because of its unique properties. Approximately 86 percent of its industrial consumption is in metallurgy, primarily for use in various steel and other high-performance alloys. Structural steel and stainless steel account for about 60 percent of global molybdenum use, for which molybdenum improves strength, corrosion resistance, weldability and high-temperature performance. Only about six percent is used in its pure form, for applications such as radiation shielding, electrical contacts and equipment resistant to molten metals.
As with many other types of mining, molybdenum mining is often associated with significant environmental problems, including soil and water contamination, soil erosion, habitat loss, and the release of other metals, such as copper, lead, cadmium and zinc, some of which are highly toxic. Moreover, the flotation process used in the extraction of molybdenum from its ores can introduce additional toxic substances to the environment and also requires large amounts of water.