Origin and sedimentation of Cu-droplets sticking to spinel solids in pyrometallurgical slags

Cu-droplet losses in slags are an important problem in Cu-industry, limiting the metal recovery. An important cause responsible for the entrainment of copper droplet losses in slags is their sticking behaviour to spinel solids. In the present study, the interaction between spinel solids and Cu-droplets is investigated in an industrially relevant slag system (PbO-CaO-SiO2-Cu2O-Al2O3FeO-ZnO) using two complementary experimental set-ups. Firstly the influence of the sedimentation time is studied and secondly the presence of entrained (sticking) droplets is studied as a function of height in the slag layer. Based on the experimental results, a mechanism that explains the sticking Cu-droplets is proposed. Finally, a model describing the sedimentation of sticking and non-sticking droplets is formulated based on the experimental data.