Molybdenum is a metallic element which is most frequently used as an alloying addition in alloy and stainless steels. Its alloying versatility is unmatched because its addition enhances strength, hardenability, weldability, toughness, elevated temperature strength and corrosion resistance. Although molybdenum is primarily used in steels, its complex and unique properties have proved invaluable in a constantly expanding range of other alloy systems and chemicals.

One of the unique features of molybdenum, as distinct from other heavy metals, is that laboratory tests have shown its compounds to be of low toxicity.

Molybdenum plays a vital part in everyday life, particularly in relation to many aspects of the protection of human health and the environment. The toxicity of molybdenum is low, reducing concerns about the presence of trace amounts in water and soils which may enter the human food chain.

Further, this low toxicity enables molybdenum to play a significant part in lubricants used for food processing machinery, minimising the consequences of accidental contamination. There has been much concern about the generation of fumes when materials such as those used for carpets and furniture, made from artificial fibres, ignite. Molybdenum compounds in certain polymers have been found to be particularly good smoke suppressants
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Molybdenum-containing catalysts are used in the production of petroleum products to remove sulphur, thereby minimising emissions. This applies not only to the internal combustion engine but also to gas turbines, large combustion plants for power generation and fired heaters in the chemical, petrochemical and process industries. Molybdenum plays a most important part in processes developed to treat pollutants, such as the desulphurisation of flue gases generated by combustion of sulphur containing fossil fuels and the cleaning of gases from the incineration of municipal and other wastes. Here, full advantage is taken of the classical role of molybdenum in enhancing the corrosion resistance of stainless steels and nickel-base alloys to withstand extreme conditions of corrosion attack. Cost effective applications of molybdenum containing materials are demonstrable, taking advantage in design of inherent characteristics of strength, corrosion resistance and integrity.

Sponsored by IMOA and conducted in accordance with internationally accepted protocols and Good Laboratory Practice, toxicity tests have shown molybdenum oxide, ammonium dimolybdate and sodium molybdate to be non-toxic (based on EU
criteria of a ‘harmful’ substance) following acute oral, inhalation and dermal exposures. These materials were also found to be non-irritating to the skin and eyes and non-sensitising.