Superalloys: The cobalt metal is mixed with many metals to create high performance alloys called superalloys which are resistant to high temperatures, corrosion, and wear. They are used in Fisher-Tropsch process, Hydroformylation of alkene, to make terepthalic acid, to make paints, varnishes, as drying agents, to accelerate growth of polyester resins, in hydrodesulfurization of petroleum, etc. Catalysts: Cobalt compound based catalysts are widely used in chemical and related industries. Relevance in Chemical and Related Industries Aluminothermic reaction: In order to obtain metallic cobalt, the products obtained from the above processes is oxidised to cobalt oxide and then the metallic cobalt is recovered using aluminothermic reaction. The residue is further leached with sulphuric acid. Water is used as a leaching solvent to extract sulphates and arsenates. Leaching: The cobalt sulphate solutions may be leached fur further refining. The cobalt sulphate has many applications and can be sold directly in market. The enriched ore is then roasted to oxidise copper and iron to its subsequent oxides and obtain cobalt sulphate solution. The surfactants get bound to components of the ore in such a way that it leads to enrichment of the cobalt metal in the ore. Froth flotation: The ore is subjected to surfactants. Cobalt reacts with all the halogens at high temperatures to yield binary halides. Cobalt easily gets attacked by halogens and sulfur. Metallic cobalt is weakly reducing in nature. Cobalt reacts slowly with mineral acids. Cobalt reacts very slowly with the moist air at ambient conditions it does not react with dry air. If cobalt is exposed to air then a passivation oxide layer forms on the surface of the metal. There are 22 radioisotopes of cobalt which has been characterized till now. Cobalt-59 is the only stable isotope of cobalt which is naturally found on earth. Metallic cobalt occurs in two structures face-centred cubic (fcc) and hexagonal close packing (hcp). 
Cobalt is a silvery-blue lustrous metal which is magnetic in nature.Several tonnes of cobalt are also found in deepest parts of the ocean in manganese rich nodules these nodules contain many transition metals.
The most common minerals which contain cobalt are cobaltite, skutterudite, and erythrite. It makes up to 0.0029% of the Earth’s crust.
COBALT PERIODIC TABLE OF ELEMENTS FREE
Cobalt is found in nature in combined form except for very small deposits of free cobalt found in alloys of natural meteoric iron.
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