Experimental and Thermodynamic Modeling Study of Phase Equilibria in the FeO–Fe ₂ O ₃ –SnO–SnO ₂ –SiO ₂ System

ABSTRACT Experimental investigation and thermodynamic modeling of the phase equilibria in the FeO–Fe 2 O 3 –SnO–SnO 2 –SiO 2 system have been undertaken to characterize Sn behavior in iron silicate slags for recycling of waste electrical and electronic materials (WEEE) through black copper process. Phase equilibria data at 865–1740°C were obtained through equilibration of synthetic mixtures in sealed silica ampoules or open crucibles, on Ir wires, or Pt–Ir foils, followed by rapid quenching and electron probe x‐ray microanalysis. Phase equilibria and liquidus isotherms of the “FeO”–“SnO”–SiO 2 system in equilibrium with Sn metal, “Fe 2 O 3 ”–“SnO 2 ”–SiO 2 system in air and 1 atm oxygen, FeO–Fe 2 O 3 –SnO–SnO 2 –SiO 2 –Au 2 O in equilibrium with Au–Fe–Sn metal, and hematite(spinel)–cassiterite equilibria in the Fe–Sn–O system at various p(O 2 ) in the presence of CaO–SiO 2 or PbO–SiO 2 flux were measured in the tridymite/cristobalite SiO 2 , cassiterite SnO 2 , hematite (Fe,Sn) 2 O 3 , spinel (Fe,Sn) 3 O 4+ x , and fayalite Fe 2 SiO 4 phase fields. New data were used for developing a self‐consistent set of thermodynamic parameters for all phases to describe the Pb/Zn/Cu/Fe‐containing complex system for characterizing Sn behavior in industrial primary smelting and recycling slags.