Cadmium is intentionally added to six major classes of products where it imparts distinct performance advantages and is present as an impurity in five major classes of products where its presence is regarded as an environmental disadvantage but which generally does not affect the performance of the product. The major intentional uses of cadmium are Ni-Cd batteries, cadmium pigments, cadmium stabilisers, cadmium coatings, cadmium alloys and cadmium electronic compounds such as cadmium telluride (CdTe). The major classes of products where cadmium is present as an impurity are non-ferrous metals (zinc, lead and copper), iron and steel, fossil fuels (coal, oil, gas, peat and wood), cement, and phosphate fertilisers (Cook and Morrow 1995).
1.1 Patterns of Consumption
In recent years, the consumption pattern of cadmium in its various end use applications has increasingly shifted away from the traditional market areas of pigments, stabilisers and coatings to rapidly growing applications in Ni-Cd batteries.
Reference Year: 2003
1.2 Nickel-Cadmium Batteries
Cadmium hydroxide is utilised as one of the two principal electrode materials in Ni-Cd batteries which have extensive applications in the railroad and aircraft industry for starting and emergency power and in consumer applications such as cordless power tools, cellular telephones, camcorders, portable computers, portable household appliances and toys. Ni-Cd batteries are cost-effective well suited for high power applications, and have high cycle lives and excellent low temperature and high temperature performance relative to other battery chemistries (Morrow and Keating 1997).
1.3 Cadmium Pigments
Cadmium sulphide and cadmium sulphoselenide are utilised as bright yellow to deep red pigments in plastics, ceramics, glasses, enamels and artists colours. They are well known for their ability to withstand high temperature and high pressure without chalking or fading, and therefore are used in applications where high temperature or high pressure processing is required (Cook 1994).
1.4 Cadmium Stabilisers
Cadmium-bearing stabilisers retard the degradation processes in polyvinylchloride (PVC) which occur upon exposure to heat and ultraviolet light These stabilisers contain organic cadmium salts, usually carboxylates such as cadmium laurate or cadmium stearate, which are incorporated into PVC before processing and which arrest any degradation reactions during subsequent processing and ensure a long service life (Cadmium Association and Cadmium Council 1991).
1.5 Cadmium Coatings
Cadmium coatings are utilised on steel, aluminium, and certain other non-ferrous metal fasteners and moving parts to provide the best available combination of corrosion resistance, particularly in salt and alkali media, and lubricity or low coefficient of friction. They are also employed in many electrical or electronic applications where a good combination of corrosion resistance and low electrical resistivity are required. In addition, cadmium coatings exhibit excellent plating characteristics on a wide variety of substrates, have good galvanic comparability with aluminium, and are readily solderable (Morrow 1996).
1.6 Alloys and Minor Uses
Cadmium alloys include (a) electrical conductivity alloys, (b) heat conductivity alloys, and (c) electrical contact alloys. Other minor uses of cadmium include cadmium telluride and cadmium sulphide in solar cells, and other semiconducting cadmium compounds in a variety of electronic applications (Cadmium Association and Cadmium Council 1991).
Batteries Pigments Stabilisers Coatings Alloys and others