Secondary Copper Processing

The secondary processing of copper from scrap has many of the same processes as conventional processing except for the mineral processing steps. The process involved in recovering copper from scrap material depends on the grade. High-grade scrap is virtually pure copper, which needs only to be re-melted and cast into useful shapes. Lower grade material is processed by pyrometallurgical methods and electrorefining (See Pyrometallurgical Processing of Copper). While the furnaces are slightly different than those used to smelt sulfide concentrates, the processing is essential the same. A significant difference can occur in the resulting composition of the copper anode because scrap can contain large amounts of other metallic elements. This results in higher impurity loading in the anode than those produced from clean ores, which can aggravate problems during electrorefining. To illustrate this point two anode compositions are listed in Table 1. The two anodes were submitted by the same electrorefinery. The anode form ore was produced by the company's smelter. The other was being toll refined for a secondary copper producer. It should not be assumed that dirtier anodes come from a secondary producer. By blending different grades of scrap, secondary smelters can achieve anode impurity levels lower than anodes produced from complex ores.

Table 1

Comparison of Anode Compositions from Ore and Scrap

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