Experimental Study of Liquidus of the “FeO”-SiO2-PbO Slags in Equilibrium with Air and with Metallic Lead

Abstract

Limited data are available on phase equilibria of the "FeO"-SiO2-PbO slag system at conditions used in the lead smelting due to difficulties from lead vaporization and interactions with metal and ceramic crucibles. Recently experimental procedures have been developed and successfully applied to complex industrial slag-metal-matte systems involving high temperature equilibration on a primary phase substrate and rapid quenching followed by the electron probe X-ray microanalysis. The liquidus isotherms and invariant lines in the "FeO"-SiO2-PbO slag system in equilibrium with air and with metallic lead have been constructed. Preliminary data compared to the FactSage package predictions demonstrate differences in some aspects, indicating the possibility for further improvement of the thermodynamic database. The present work is a part of the integrated experimental and thermodynamic modelling research program on multi-phase lead systems in support of the optimization and development of complex lead smelting, refining and recycling technologies.

Experimental and thermodynamic modeling study of phase equilibria in the PbO–NiO–SiO2 system

“…Achievement of equilibrium in the samples was ensured by using the four‐point test approach 26,30 : (i) variation of equilibration time, (ii) assessment of the compositional homogeneity of phases by EPMA, (iii) approaching the final equilibrium point from different starting conditions, and (iv) consideration of reactions specific to this system that may affect the achievement of equilibrium or reduce the accuracy. Among the latter reactions, the one of primary concern was evaporation of lead oxide.…”

Phase Diagram Study for the PbO-ZnO-CaO-SiO2-"Fe2O3" System in Air with CaO/SiO2 in 1.1 and PbO/(CaO+SiO2) in 2.4 Weight Ratios

“…It must be stressed that it is possible to confirm the equilibrium achievement by changing the equilibration time variation to confirm that no further changes take place with time. Another test of the equilibrium achievement is by confirming the chemical homogeneity of phases and samples 10 .…”