Cadmium metallurgy

(metallurgy) The extraction of cadmium from zinc ores, or from complex ores as a by-product of zinc, lead, and copper smelting.

Most cadmium occurs in solid solution in the zinc sulfide mineral called sphalerite. Although cadmium may be recovered from some lead and copper ores, it is associated with the zinc which is also found in these ores. Since cadmium is entirely a by-product metal, the supply available is closely aligned with zinc production, averaging about 0.4% of zinc production.

All cadmium recovery processes involve the dissolution of cadmium-bearing feed material, followed by various purification and cadmium displacement steps. Methods of processing can be grouped conveniently into two basic categories, electrolytic and electromotive. In the former case, cadmium is recovered by electrolyzing purified solutions; in the latter case, cadmium in the form of a metallic sponge is displaced from purified solutions by a less noble metal, zinc being used in every known commercial application, and the sponge is melted or distilled, or both.

Major end uses for cadmium are in corrosion-resistant plating and in cadmium compounds for use as pigments in paints, ceramics, and plastics. Cadmium is also used in alloys, plastic stabilizers, batteries, and television picture tube phosphors. In view of the changing world energy situation, uses for cadmium are anticipated in applications such as solar energy cells and energy storage systems. See also Cadmium.