Elements in steel are considered as impurities or alloy elements depending on where in the process the element is added or if it is added intentionally. For example: -
“Copper in significant amounts is detrimental to hot-working steels. Copper negatively affects forge
welding, but does not seriously affect arc or oxyacetylene welding. Copper can be detrimental to surface quality. Copper is beneficial to atmospheric corrosion resistance when present in amounts exceeding 0.20%. Weathering steels are sold having greater than 0.20% Copper.”
The elements that have lower oxygen affinity than iron, such as Cu, Sn, Co and Ni, remain in the final alloy. Utilisation of low quality scrap can result in the production of off-specification steel and in addition to the direct impact of this on the steelmaker it could also be considered to be a loss of these valuable elements. To date there exists no economically viable way of removing these elements from steels.
Many steel scrap specifications quote limits for copper which are particularly important for post consumer scrap grades since these are prone to contamination with copper because some steel components are associated with copper (e.g. electric motors). The general distribution of elements found in EAF furnaces during meltdown is illustrated below (adapted from Jernkontoret, 2007).