Cobalt as a pollutant

Inhalation of cobalt fumes and absorption of cobalt salts produces systemic poisoning with myocardial disorders and irritant effects on the eyes, and on the respiratory and digestive tracts; inhalation of cobalt dust produces an asthma-like disease and fibrotic pulmonary lesions; and allergic dermatitis has been reported in workers exposed to cobalt. In the process of concentration of the cobalt ore, workers are exposed to dust and fumes containing both cobalt and other metals and metalloids such as arsenic and nickel. Carbon monoxide is formed during melting, and hydrogen sulphide is used for the precipitation of copper. Melting and pouring cobalt before pelletizing also produces cobalt fumes. Dust containing cobalt together with tungsten, titanium and tantalum is a potential hazard in the production of cemented tungsten carbides and the grinding and sharpening of cemented carbide tools. Radioactive cobalt does not exist in nature but is prepared in nuclear reactors and is used as a gamma-emitter in industry and medicine.

Cobalt is a relatively rare metal. The most important mineral sources are the arsenides, the sulphides, and various oxidized forms. The main producers are Zaire, Canada, Morocco, Finland, the USSR and Zambia. The principal consumer of cobalt is the USA which uses about half of world production.