In the pyrometallurgical process of secondary lead recycling, a desulfurising agent, such as Na2CO3
is added to minimise the emissions of sulfur into the atmosphere, while silica is introduced into the
smelter as a fluxing material. Subsequently, a significant amount of Na2O and SiO2 remains in the
downstream reverberatory furnace and blast furnace slags. However, there is limited understanding
of the thermodynamic behaviour of silicate-based lead slags rich in Na2O, posing challenges in
accurately determining the optimal condition for targeted metal recovery and final slag composition.
In this work, the equilibrium phase relations of the PbO-Na2O-SiO2 system in the primary phase field
of Na2SiO3 are studied from 800 to 1000°C via equilibration-quenching method. Samples with
different compositions were prepared and held in platinum capsules in air at these temperatures to
reach equilibrium. The equilibrated samples were subsequently quenched and the phase
compositions were measured by electron probe microanalysis (EPMA). The results were then
compared to those of previous studies and any discrepancies were resolved.