| Abstract: | The use of Zn- and Pb-contaminated scrap in steelmaking has led to a significant increase of the zinc and lead contents in dusts and sludges, especially produced in the electric arc furnace melting shops. To understand the behaviour of Zn and Pb, fundamental research on the thermodynamics and kinetics of zinc and lead reactions under steelmaking conditions is helpful. In the first part of the present work, the solubilities of lead and zinc in iron are discussed. Furthermore, the influence of several alloying elements, such as carbon, oxygen, sulfur and chromium on the dissolution behaviour of Zn and Pb was examined and compared with former studies. Measurements of the solubility of lead in liquid iron were made at elevated temperatures in the systems Fe-Pb-O, Fe-Pb-C and Fe-Pb-Cr under argon in a gas-tight Tammann furnace. An increase of lead solubility was found with increasing temperature and increasing oxygen content. On the other hand, higher contents of carbon and chromium led to lower solubilities of lead in liquid iron. In the second part, the partition ratios of zinc and lead between liquid iron and various selected slag compositions were investigated. It is shown that zinc partition is determined by oxygen activity and slag basicity. In SiO2-saturated slags, the partition ratio of zinc is considerably higher than in CaO-saturated slags. In comparison, the partition ratio of lead is significantly lower under the same experimental conditions. |
