The presence of cobalt in iron alloys results in substantial incr in magnetic retentivity. Slowly attacked by ammonium hydroxide and sodium hydroxide. In normal salts the bivalent form is more stable than the trivalent one, the reverse is true for cobalt complexes. More than a million workers in the USA are potentially exposed to cobalt or its cmpd, many of them, however, to a limited degree, eg, when using cobalt-containing paint driers. Heavier exposure may result from mining processes, in the production of cobalt powder and alloys and in the cemented tungsten carbide industry.
Cobalt is a by product or coproduct of the refining of other mined metals such as copper and nickel.
Some of the commercially mined ores are carrollite, smaltite, cobaltite, siegenite, and sphaerocobaltite. Only a few plant species accumulate cobalt above the 100 ppm which causes severe phytotoxicity. Soil pH is very important in cobalt uptake and phyto-toxicity. More acidic soils sorb cobalt less strongly .Oats and barley grown in an acid sulfate soil area on the coast of the Gulf of Bothnia have exhibited exceptionally high concentrations of cobalt, nickel, and manganese. The objective of this study was to identify the factors contributing to this phenomenon by examinging 63 samples from acid sulfate soils and 35 samples from other soils of the area.