The Isa smelting furnace discharges the matte and slag in the same tapping
hole. As a result, an electric furnace needs to clean the slag. In the
present study, the copper slag cleaning in an electric furnace, particularly
the separation of the matte from the slag during the reduction process, was
investigated. For Fe3O4 to FeO, the foaming slag in the melt disappeared
when the Fe3O4 content was less than 10%. With the formation of the metallic
iron, the foaming slag formed again, hindering the sedimentation of the
matte. When the anthracite dosage increased to 2.61%, the copper content in
the slag increased to 9.46%. The microstructure of the slag and the
existence of the metallic iron found in the slag were analyzed in detail.
The results obtained in this study provide a theoretical basis for the
reasonable control of the transformation of Fe3O4 during the copper slag
cleaning.