About Cobalt

Cobalt is one of the world's essential elements. Of all elements, 27 are essential to man. Cobalt is one. It has many strategic and irreplaceable industrial uses but it is as the central component of Vitamin B12 that it is VITAL. Cobalt has many uses based on several of its unique properties:

• It has a high melting point (1493°C) and retains its strength to a high temperature - Cutting tools, superalloys, surface coating, high speed steels, cemented carbides, diamond tooling
• Cobalt is ferromagnetic (nickel and iron are as well) and retains this property to 1100°C, a higher temperature (Curie Point) than any other material - Alnico magnets, recording tape, soft magnetic materials, samarium cobalt, NdBFe + cobalt
• Cobalt in conjunction with silica, etc., produces intense blue colours - Cobalt Blue in paints, glazes, enamels, etc.
• Cobalt is multivalent - Catalytic action is enhanced - OXO reaction, Fischer-Tropsch, oil desulphurisation, paint and ink driers, tyre adhesives

Sources of Co

Cobalt is not a particularly rare metal and it ranks 33 in abundance. It is however widely scattered in the Earth’s crust but is found in potentially exploitable quantities in several countries, 17 of which currently produce. Cobalt is only extracted alone from the Moroccan and Canadian Arsenide ores. It is normally associated with copper or nickel. In 2003 about 44% of world production came from nickel ores.

Table 1 - Where Cobalt is Mined - shows the current situation. Significant resources of cobalt are also present in the deep-sea nodules and crusts which occur in the Mid-Pacific and are estimated to contain anywhere from 2.5-10 million tonnes of cobalt. At a world production level of 42,000 tonnes, this is 60 to 230 years of usage. Current land sources are estimated at over 100 years, so no long-term shortage is in sight.

Main properties

Cobalt is a transition metal appearing in the first long period of the Periodic Table between iron and nickel.

The ground state atom is s22s22p63s23d74s2

This leads to cobalt’s commonest valency, i.e. Co2+, by removal of the two 4s electrons. Other valencies exist however in some complex salts and mixed valencies occur in Co3O4 for example (Co2+ and Co3+).

Cobalt is shiny, grey, brittle metal with a close packed hexagonal (CPH) crystal structure at room temperature but which changes at 421°C to a face centred cubic form. The metal is rarely used as a structural material in the pure form but almost always as an alloy or a component of another system

Cobalt uses

The use of cobalt goes back to 2-3000 BC. Although it had not been identified, its addition to glass to give traditional cobalt blue was known. The name however seems to arise from the Erzgebirge region of Saxony which was a silver mining area. The term “Kobald” applied to spirits (gnomes) who frequented the mines causing trouble (as per “gremlins” in air force slang). The problems were due to cobalt interfering with the silver smelting and causing some respiratory problems with the miners (cobalt here is arsenical). The term seems to have passed to and been held by the metal but the stories are varied.

The main use of cobalt remained as a colouring agent right up to the 20th Century and in fact, before 1914, cobalt was really only available or used as the oxide.

The modern uses blossomed with the work of Elwood Haynes on StelliteR alloys, the development of Alnico magnets in Japan, and the use of cobalt to bind tungsten carbide in Germany. These uses are outlined here.

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