Home - Periodic Tables
For rechargeable batteries.
(L. cadmia; Gr. kadmeia - ancient name for calamine, zinc carbonate) Discovered by
Stromeyer in 1817 from an impurity in zinc carbonate. Cadmium most often occurs in small
quantities associated with zinc ores, such as sphalerite (ZnS). Greenockite (CdS) is the
only mineral of any consequence bearing cadmium. Almost all cadmium is obtained as a
by-product in the treatment of zinc, copper, and lead ores. It is a soft, bluish-white
metal which is easily cut with a knife. It is similar in many respects to zinc. Failure to
appreciate the toxic properties of cadmium may cause workers to be unwittingly exposed to
dangerous fumes. Silver solder, for example, which contains cadmium, should be handled
with care. Serious toxicity problems have been found from long-term exposure and work with
cadmium plating baths. Exposure to cadmium dust should not exceed 0.01 mg/m3 (8-hour time-weighted average, 40-hour
week). The ceiling concentration (maximum), for a period of 15 min, should not exceed 0.14
mg/m3. Cadmium oxide fume
exposure (8-hour, 40-hour week) should not exceed 0.05 mg/m3, and the maximum concentration should not
exceed 0.05 mg/m3. These
values are presently being restudied and recommendations have been made to reduce the
exposure. In 1927 the International Conference on Weights and Measures redefined the meter
in terms of the wavelength of the red cadmium spectral line (i.e. 1m = 1.553,164.13
wavelengths). This definition has been changed (see under Krypton).
Cadmium is a component of some of the lowest melting alloys; it is used in bearing
alloys with low coefficients of friction and great resistance to fatigue; it is used
extensively in electroplating, which accounts for about 60% of its use. It is also used in
many types of solder, for standard E.M.F. cells, for Ni-Cd batteries, and as a barrier to
control nuclear fission. Cadmium compounds are used in black and white television
phosphors and in blue and green phosphors for color TV tubes. It forms a number of salts,
of which the sulfate is most common; the sulfide is used as a yellow pigment. Cadmium and
solutions of its compounds are toxic.
The current price of cadmium is about $12/lb. It is available in high purity form.
Sources: CRC Handbook of Chemistry
and Physics and the American Chemical Society.
[an error occurred while processing this directive]