Metals are used in a wide variety of applications. They will therefore be in a wide variety of states when they are sent for recycling.

Sorting and processing of metal scrap is essential, because when melted, mixtures of metals may become alloys. Without careful separation the quality of the final product will be reduced. This issue is explored and explained later in this TLP.

In this section, four examples of sorting and processing are investigated:–

1. the Eddy current separation method (electromagnetic induction)
2. the leaching and electrolysis of tin from steel cans (electrochemistry)
3. the theoretical cryogenic separation of copper from steel motors (ductile-brittle transition)
4. the chemical oxidation of tramp elements from molten steel scrap (Ellingham diagram)

Phase diagrams are also used to illustrate the problems that can occur when not all contaminants are removed.

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