Experimental and thermodynamic modeling study of phase equilibria in the MgO‐SnO‐SnO ₂ ‐SiO ₂ system

Abstract Experimental investigation and thermodynamic modeling of the phase equilibria in the MgO‐SnO‐SnO 2 ‐SiO 2 system have been undertaken to characterize the effect of Sn‐rich slags, typical for recycling of waste electrical and electronic materials through black copper process, on MgO‐based refractories. Phase equilibria data at 1000–1750°C were obtained through equilibration of synthetic mixtures in sealed silica ampoules, MgO crucibles, on Ir wires, Pt‐Ir or Re foils, followed by rapid quenching, and electron probe X‐ray microanalysis. Phase equilibria and liquidus isotherms of the MgO‐“SnO”‐SiO 2 system in equilibrium with Sn metal, MgO‐“SnO 2 ”‐SiO 2 system in air, and MgO‐SnO‐SnO 2 ‐SiO 2 in equilibrium with Au‐Sn metal were measured in the tridymite/cristobalite SiO 2 , cassiterite SnO 2 , pyroxene (proto‐ and ortho‐enstatite) MgSiO 3 , olivine (forsterite) Mg 2 SiO 4 , monoxide (periclase) MgO, and spinel Mg 2 SnO 4 phase fields. New data were used for developing a self‐consistent set of thermodynamic parameters for all phases to describe the Pb/Cu‐containing complex system for characterizing Sn behavior in industrial primary smelting and recycling slags.