Recycled metal produced by the extraction and refining of metallic wastes is called secondary metal while metal produced from primary ores is called primary metal. There are two types of secondary metal producer: the secondary alloy producer who blends and refines the scrap to produce an alloy of required composition, and the secondary metal extractor who generally extracts one metal from the waste and sells any valuable by-products to other metal extractors or chemical processors. Both types of processor need to deal with a large range of size, shapes and compositions of the waste materials. In this respect the processing route and plant must be flexible in order to cope with a constantly changing input material.