Metal droplet entrainment by solid particles in slags: a combined phase field model and experimental

ir. Inge Bellemansa, ir. Vincent Cnockaerta, dr. Evelien De Wildea,b, prof. dr. ir. Nele Moelansc, prof. dr. ir. Kim Verbekena

Various pyrometallurgical industries (both primary and recycling) encounter production losses due to the mechanical entrainment of metallic droplets, i.e. the droplets are attached to solid particles in liquid slags. The attached metal cannot settle, decreasing the yield of the phase separation. This results in inadequate sedimentation and eventually production losses in e.g. industrial Cu smelters and Pb reduction melting furnaces. Experimental work on this topic remains challenging, but phase field simulations can circumvent this lack of experimental data and allow a more systematic evaluation on the role of different parameters on the observed phenomenon. However, simulations are best interpreted in combination with experiments. The performed experiments are used both for the input microstructure of the solid particles and to validate the simulation results. In the present work, a recently developed phase-field model to simulate the attachment of liquid metal droplets to solid particles in slags considering real microstructures of solid particles in liquid slags is extended to consider movement of the solid particles in the liquid slag. Furthermore, it is investigated which initialization method for the liquid metal droplets corresponds best to the experimental conditions. One of the initialization methods used spinodal decomposition of a supersaturated slag to introduce the metallic droplets, whereas the other initialization consists of positioning metallic droplets in the slag in a random way. The simulations showed that both initialization methods result in microstructures that correspond with experimental observations, which points to the existence of several origins for the attachment of metal droplets to solid particles in slags.