Electrical conductivity of pbo-siO₂ liquids containing pb precipitates

The phenomena of dispersion and growth of metallic lead from lead silicate melts in the composition range X_pbo = 0.45 to X_pbo = 0.6 at 1103 K were studied utilizing conductivity measurements. The conductivity of the molten silicate was found to be independent of the partial pressure of oxygen. However, in the presence of a reducing atmosphere viz CO or H₂-Ar mixtures, dispersion and growth of metallic lead take place causing a change in the composition of the lead silicate melt and a change in the conductivity. The increase in the observed conductivity of the PbO-SiO₂ melt during the initial stages of reduction is attributed to the emission of electrons from the dispersed lead particles, an effect which was further verified by Seebeck measurements. Also, the decrease in the observed conductivity during the subsequent period of reduction is attributed to the change in the composition of the molten silicate coupled with the growth and settling of lead particles.