Characterization of products emanating from conventional and microwave energy roasting of chalcopyrite (CuFeS₂) concentrate

Chalcopyrite concentrate (83% CuFeS₂, 3% FeS₂ and 14% ZnS) which is a typical feed to the matte smelting process for copper extraction via pyro metallurgical route has been roasted with microwaves. Comparison of mineralogical phases obtained was made with the case of conventional roasting. Resulting calcines were characterised with Mössbauer spectroscopy and XRD. It was observed that complete oxidation (dead roasting) of the chalcopyrite was achieved after 10 min with microwaves while 20 min were required in the conventional route. The mineralogical phases found in the dead-roasted calcines produced from microwave roasting of this chalcopyrite concentrate were the hematite (Fe₂O₃), franklinite (ZnFe₂O₄), copper-rich ferrite (Cu_1-xZn _xFe₂O₄, x≤0.5), and copper ferrite (CuFe₂O₄). The findings of this work indicated that it was technologically feasible to oxidize the chalcopyrite with microwaves using a 2.45 GHz multimode applicator.