Modelling the mechanical entrainment of metal droplets by solid particles in liquid slags

A variety of pyrometallurgical industries encounters production losses due to the mechanical entrainment of metallic droplets, i.e. the droplets are attached to solid particles in slags. The attached metal cannot settle, decreasing the efficiency of the phase separation. This results in inadequate decantation and eventually production losses in e.g. industrial Cu smelters and Pb reduction melting furnaces. Recent experimental results on this interaction indicate the importance of interfacial energies. Simulations can give a more systematic insight into the observed phenomenon and the phase field modelling technique is well-suited for modelling microstructural evolution. In the present work, a phase field model describes a solid-liquid binary system with spinodal decomposition in the liquid near a non-reacting solid particle. The influence of the interfacial energies and the particle morphology on the attachment of metallic droplets to solid particles was investigated. Depending on the relative magnitudes of the interfacial energies, four different regimes were found, namely, non-wetting, low wettability, high wettability and full wettability. In the case of full or high wettability, the perimeter of the particle determines the amount of attached metal. Moreover, the space available around the particle, determined by the shape and proximity of other particles, can restrict the amount of attached metal. In practice, fewer but larger solid particles close to each other would provide less attached metal and thus a better phase separation.status: publishe