Metal losses in slags occur in pyrometallurgical production processes and limit the overall process efficiency. The metal losses are generally subdivided in two types: chemical losses referring to dissolved copper in the slag and mechanical losses referring to entrained copper droplets in the slag.

For the mechanical losses, several causes can be found, one of them being the attachment of metal droplets to spinel particles in the slag. The spinel particles hinder the sedimentation process of the metal droplets. However, no fundamental understanding of this phenomenon is available.

First, a suitable methodology was developed, consisting of two complementary approaches, as illustrated in the figure below:

• The different interactions (copper-spinel, slag-spinel and slag-copper-spinel) were studied in separately by a sessile drop methodology.
• The complete system (metal-slag-spinel) was also studied during smelting experiments: for this, two experimental set-ups were developed to study the attachment of copper droplets to spinels in the slag. One set-up allowed studying the influence of the sedimentation time, while the other one allowed an evaluation as a function of the slag height.