Discovered in 1817, cadmium occurs in nature with zinc. Cadmium is softer, more malleable and ductile than zinc. Chemically, it is less reactive than zinc. Cadmium is obtained primarily from zinc smelters and from the sludge produced by the electrolytic refining of zinc. Removal of cadmium in zinc is very important since cadmium salts are poisonous. Galvanized iron is used for water tanks and any residual cadmium in the zinc would slowly enter the water reservoir as Cd2+ ions. Modern day tanks show that there is no danger to health from this source. But older tanks contain significant cadmium levels.

Cadmium and cadmium-containing compounds are used in a variety of ways. These include:

  1. rechargeable nickel-cadmium batteries.
  2. the artist's paint pigment, cadmium yellow.
  3. Wood's metal, a low-melting alloy which is 50% Bi, 25% Pb, 12.5% Sn and 12.5 % Cd.
  4. antifriction bearings (Cd-Ni) that have high melting points.
  5. control rods that contain boron or cadmium. These control rods are effective neutron absorbers. With them in place, chain reactions can be kept to proceed at a steady rate.

BCIT Chemistry Resource Center
http://nobel.scas.bcit.ca/resource/