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The Composition of Electronic Equipment

The materials contained in scrap electronic equipment are large in number and value; some are valuable and some are toxic or hazardous. Typical chemical elements found include:Precious metals such as gold, silver and palladium, and to a lesser extent, platinum and ruthenium

1. Base and special metals such as iron,copper, aluminium, nickel, zinc, tin, cobalt, indium, gallium and selenium
2. Hazardous metals such as mercury,beryllium, cadmium, arsenic and antimony
3. Halogens – bromine, fluorine and chlorine
4. Other substances such as organics/plastics, glass and ceramics.

If such scrap is landfilled or not treated in an environmentally sound way, then it poses a high risk of environmental damage. The valuable materials that it contains are not recovered and reused, and so this increases the need to mine new metals from primary resources.

Table.1

Typical compositions of a number of electronic items are shown in the upper part of Table 1. We should note that these figures are indicative; actual content can vary significantly but the magnitude is correct. In terms of weight, plastics and steel tend to dominate, but in terms of value, the lower part of Table 1, gold and the other precious metals dominate.

Gold and other precious metals makes up more than 80% of the value in PC boards, cell phones and calculators, and around 50% of the value in TV boards and DVDs. We note copper is next in value terms.

Hence, it is very evident that any net decrease in precious metal content substantially reduces the net recoverable value from the electronic scrap and, thus, the motivation to recycle scrap. It is worth noting that the complete recycling chain needs to be renumerated, as Hagel√ľken and Corti discuss in their paper.

The recycling requirements – technical processes and emission controls – depend on the composition of the scrap, and taking the various values between types of scrap into account, means that the mixing of different types of scrap in the collection and pre-processing stages can influence the recycling returns in a negative manner.