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The Entrepreneur's Guide to Computer Recycling: Basics for starting up a computer recycling business in emerging markets
PC Recycling Guide
Substances of concern

Source: BASEL CONVENTION / OECD

Antimony

Antimony is a component in lead solder. CRTs may contain antimony in the screen and/or cone glass.

Possible adverse effects: Antimony contained in the screen glass may leach out under certain land disposal conditions.

Barium oxide

Barium oxide is contained in the getter plate of the electron gun of CRTs; some of the barium oxide from the getter becomes deposited on the interior surface of the screen and cone glass.

Possible adverse effects: Barium oxide dust can be released during the dismantling and handling of CRTs.

Beryllium

There is a small amount of beryllium, in the form of a copper-beryllium alloy (typically 98% copper, 2% beryllium) in the motherboard, in the slots used for connection to daughterboards.

Possible adverse effects: Beryllium in a copper-beryllium alloy may be released as beryllium oxide dust or fume during high temperature metal processing.

Cadmium

There is a small amount of cadmium in plated contacts and switches, and a very small amount of cadmium may have been used as a stabilizer in PVC wire insulation, which may have been used in a personal computer. Laptop computers often contain a rechargeable nickel cadmium (Ni-Cd) battery.

Possible adverse effects: the small amount of cadmium in plastic may be released in the form of cadmium oxide dust if the plastic is burned prior to or in the course of metal reclamation. Cadmium in plated metal contacts and switches may be released as cadmium oxide dust or fume during high temperature metal processing. Incineration may also result in releases of cadmium to the environment.

Chlorine and/or Bromine

Organic halogenated (brominated) flame retardants and inorganic flame retardants (e.g. antimony chloride) may be present in the plastic in printed circuit boards and cases. There is chlorine in any PVC insulation of wires and cables used in a personal computer.

Possible adverse effects: Bromine in plastics as brominated fire retardants, or chlorine in PVC insulation, may recombine with carbon and hydrogen in various disposal or recovery processes that involve heat, such as combustion or plastics extrusion, to form other halogenated organic compounds of environmental concern, particularly the chlorinated or brominated dibenzodioxins and -furans.

Lead

There is a substantial amount of lead in the CRT, as a rough average perhaps two to three kg in older models and 1 kg in new models, encapsulated in the form of leaded glass. There is also a much smaller quantity of lead in printed circuit boards in the CU, in the form of solder. Printers and miscellaneous peripheral devices will also contain a small amount of lead in solder. Some portable (laptop) computers contain a sealed lead acid battery.

Possible adverse effects: Lead in a CRT or printed circuit board may leach out of the leaded glass under certain land disposal conditions. Incineration can result in release of lead to the air as well as deposition of lead in the ash, which is then land disposed. The lead in a printed circuit board may also be released in the form of lead fume if the board is heated to facilitate harvesting of components, or in the form of fine particulate if the board is burned or shredded prior to metal reclamation. The lead in a CRT or a printed circuit board may be released as lead oxide dust or lead fume during high temperature metal processing, such as smelting.

Lithium

Lithium metal may be present in a small battery on a motherboard.

Possible adverse effects: Lithium in a battery will be released if the battery is shredded with the circuit board to which it is attached. When released, it may react with oxygen and moisture, generating heat and potentially causing fire.

Mercury

In large flat panel displays, a small amount of mercury may be present in a lighting device used to illuminate the screen.

Possible adverse effects: Mercury can be released from certain flat panel displays upon the shredding and subsequent handling of this equipment. Landfilling and incineration of flat panel displays can also result in the release of mercury to the environment.

Phosphors

A phosphor coating, typically zinc sulfide and rare earth metals, are used on the interior of a CRT screen to convert the kinetic energy of an electron beam to light. However, cadmium sulfide has also been used in older CRTs.

Possible adverse effects: Cadmium in the phosphor coating of some older CRT screens could present an inhalation hazard to workers in CRT glass breaking operations. Cadmium can also be leached in a landfill environment.

Although these substances can present risks in recycling or disposal of used personal computers, it is important to note that some of these substances are present in personal computers for the purpose of lowering risks to human health during product use. These include the use of lead shields in CRTs to protect users from harmful x-rays and the use of flame retardants in plastics to reduce the risk of overheating and potential fires. There is no technical substitute for lead in the CRT glass.

Source: Basel Convention