Study of the Effect of Spinel Composition on Metallic Copper Losses in Slags

In both primary and secondary copper production, copper losses in slags are a decisive factor confining the process efficiency. An important cause for mechanical entrainment of metal droplets in slags is their attachment to solid spinel particles present in the slag phase, hindering sedimentation. To further optimize the production process, it is important to gain insights in the fundamental mechanisms governing this attachment. In the present study, the influence of the spinel composition on the attachment of copper droplets is investigated. First, the attachment is studied in an industrially relevant synthetic PbO-CaO-SiO2-Cu2O-Al2O3-FeO-ZnO slag system. Second, the wetting of copper on two spinel substrates (ZnFe2O4 and MgAl2O4) has been studied in the absence of a slag system, by sessile-drop experiments. Based on the results of both types of experiments, a clear influence of the spinel composition on the sticking behavior of copper droplets is noted. These observations might be transferred to industrial processes to adapt processing parameters to diminish copper losses in industrial slags.