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 coatings, cadmium stabilisers, 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, coatings and stabilisers to a growing demand of Ni-Cd batteries in industrial applications. Annual worldwide consumption is estimated at 25 000 tonnes.(2019 estimate)
Reference Year: 2019
1.2 Nickel-Cadmium Batteries
Cadmium is utilized as the principal material for negative electrodes in Ni-Cd batteries. These batteries demonstrate superior reliability, they are able to withstand severe mechanical and electrical abuse, they operate with limited loss of performance under both low and high temperatures as well as in setting with wide temperature swings, they do not suffer from the “sudden death” syndrome which plague the standard technology, and their service life in industrial applications, in excess of 15 years, remains unmatched.
Thanks to these unique characteristics, industrial Ni-Cd batteries are the batteries of choice for back-up power aboard both civilian and military aircrafts with over 70% of the market, in this use they supply power to the avionics systems in case of power failure and ensure engine starting on the ground. Industrial Ni-Cd batteries are also commonly used to provide back-up power for railways and metro systems as well as in trackside signaling systems under harsh climate conditions. They are also used in other mission critical settings to protect industrial assets or human life, such as nuclear power plants, offshore oil rigs and refineries.
The use of Ni-Cd batteries in consumer applications is now essentially limited to cordless power tools. Moreover, in the EU the placing on the market of portable Ni-Cd batteries has been prohibited since 2008, the power tool exemption was terminated in December 2016 and today in Europe, these portable Ni-Cd batteries may only be used for the limited market of safety and alarm systems.
1.3 Cadmium Pigments
Cadmium zinc-sulphide and cadmium sulphoselenide pigments find niche applications in market segments where their unique blend of properties of clean colour shade, intensity, opacity, heat and light resistance and long-term stability are paramount. These properties make Cd pigments unique. Being difficult to substitute, they are typically the yellow to deep red pigments of choice for ceramic, glass and metal decoration, plastic colouration and for the professional artist including restoration work.
1.4 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.
In the EU, the use of cadmium coatings is restricted to articles used in the aeronautical, aerospace, mining, offshore and nuclear sectors whose applications require high safety standards and in safety devices in road and agricultural vehicles, rolling stock.
1.5 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 based stabilizers are banned in the EU. The European PVC industry has put in place commercially viable alternatives to cadmium and lead-based compounds.
Cadmium alloys find applications where electrical conductivity or heat conductivity is required in combination with abrasion resistance, corrosion resistance or strength. Due to its low melting point it is also applied in brazing alloys, fusing alloys and decorative castings.
The CdTe photovoltaic technology is based on the use of a thin film of CdTe to absorb and convert sunlight into electricity. CdTe is growing rapidly in acceptance and now represents the second most utilized solar cell material in the world. The semi-conducting properties of cadmium-mercury-telluride are exploited in infrared detectors.
1.8 Minor Uses
Cadmium applications 2019
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The International Cadmium Association (ICdA) is a non-profit association representing the interests of the world’s cadmium industry. Its Members include producers, processors, recyclers and consumers of cadmium metal, cadmium compounds, and products to which cadmium or its compounds have intentionally been added.
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