In the copper industry dusts are generated in various processes and separated from the off-gas by filters. Depending on the dust composition different options for processing of the dusts can be taken into account: recycling into the metallurgical process and hydrometallurgical processes or pyrometallurgical processes. The main components in the dust from a secondary copper smelting furnace were Zn and Pb. But there was also some Cu contained in this dust. Air classification of this dust showed that Cu was enriched in the coarse fraction while in the finest fraction Cu was depleted. In contrast, Zn and Pb were enriched in the finest fraction. Thus, air classification could be considered for separation of the filter dust into two fractions: a coarse fraction for recovery of Cu and a fine fraction which is discharged for recovery of Zn.