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Cobalt
| Atomic Number |
27 |
| Atomic Symbol |
Co |
| Atomic Weight |
58.9332 |
| Electron Configuration |
[Ar]4s23d7 |
| History |
(Kobald, from the German, goblin or evil
spirit, cobalos, Greek, mine) Brandt discovered cobalt in about 1735. |
| Production/Sources |
Cobalt occurs in the minerals cobaltite,
smaltite, and erythrite, and is often associated with nickel
, silver
, lead
, copper
, and iron
ores, from which it is most frequently obtained as a by-product. It is
also present in meteorites.
Important ore deposits are found in
Zaire, Morocco, and Canada. The U.S. Geological Survey has announced
that the bottom of the north central Pacific Ocean may have cobalt-rich
deposits at relatively shallow depths in water close to the the Hawaiian
Islands and other U.S. Pacific territories. |
| Properties |
Cobalt is a brittle, hard metal,
resembling iron and nickel in appearance. It has a metallic permeability
of about two thirds that of iron. Cobalt tends to exist as a mixture of
two allotropes over a wide temperature range. The transformation is
sluggish and accounts in part for the wide variation in reported data on
physical properties of cobalt. |
| Isotopes |
Cobalt-60, an artificial isotope, is an
important gamma ray source, and is extensively used as a tracer and a
radiotherapeutic agent. |
| Uses |
It is alloyed with iron, nickel and other
metals to make Alnico, an alloy of unusual magnetic strength with many
important uses. Stellite alloys, containing cobalt, chromium
, and tungsten
, are used for high-speed, heavy-duty, high temperature cutting tools,
and for dies.
Cobalt is also used in other magnetic
steels and stainless steels, and in alloys used in jet turbines and gas
turbine generators. The metal is used in electroplating because of its
appearance, hardness, and resistance to oxidation.
The salts have been used for centuries to
produce brilliant and permanent blue colors in porcelain, glass,
pottery, tiles, and enamels. It is the principal ingredient in Sevre's
and Thenard's blue. A solution of the chloride is used as a sympathetic
ink. Cobalt carefully used in the form of the chloride, sulfate,
acetate, or nitrate has been found effective in correcting a certain
mineral deficiency disease in animals.
Soils should contain 0.13 to 0.30 ppm of
cobalt for proper animal nutrition. |
| Cost |
Single compact sources of Cobalt-60 vary
from about $1 to $10/curie, depending on quantity and specific activity. |
| Handling |
Exposure to cobalt (metal fumes and dust)
should be limited to 0.05 mg/m3
(8-hour time-weighted average 40-hour week). |
Source: Los Alamos National Laboratory
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