Institute of Metallurgy at the Ural Branch of the Russian Academy of Sciences, Yekaterinburg, Russia:

A. S. Vusikhis, Senior Researcher, Candidate of Technical Sciences, e-mail: vas58@mail.ru
+E. N. Selivanov, Head of the Laboratory, Doctor of Technical Sciences
L. I. Leontiev, Principal Researcher, Doctor of Technical Sciences, Academican of RAS, e-mail: leo@presidium.ras.ru

A thermodynamic modelling procedure has been developed that enables to predict the results of metal reduction from oxide melt in bubbling units by building an almost-true-to-real-process model. The procedure involves determining an equilibrium for each introduced portion of gas while taking the concentrations of target metal oxides in every modelling cycle from the previous data. The resultant metal phases and gases are excluded from the following calculations. This approach helps make the models most true to real processes and analyze how complete the reactions are that take place in pyrometallurgical units. The authors use the above procedure to describe the processes of combined iron and lead reduction from the B₂O₃ – CaO – FeO – PbO melt by carbon monoxide and hydrogen. This paper includes a comparative analysis of how the temperature T and the amount of V СО or VН₂ gas introduced can impact the reduction of lead and iron from an oxide melt. The B₂O₃/CaO ratio taken for the modelling purposes is equal to 3, which corresponds to eutectic composition. The initial concentration of components, wt. %: 58.5 В₂О₃; 19.5 СаО; 20.0 FeO; 2 PbО; the temperature range: 1273–1773 К. The calculations were carried out based on the disproportionation of FeO into Fe and Fe₃O₄. The interaction of FeO and Fe with PbO ensures a partial transition of lead in metallic state. Depending on the temperature, the degree of lead metallization can vary from 76.8 (at 1,273 К) to 19.4 % (at 1,773 К). As the temperature rises, the concentration of FeO and PbO in the melt tends to increase whereas that of Fe₃O₄ tends to decrease. The authors analyzed how the concentration of lead and iron oxides in the melt and their reduction degree changed depending on the amount of reducing agent introduced. In the case of lead and iron reduction, no difference in the resulting products was found when using hydrogen versus carbon monoxide as the reducing agent. At the same time, hydrogen reduction results in a more complete reaction compared with carbon monoxide reduction. Thus, a smaller amount of gas is required to achieve a close-to-100% reduction of lead: СО — 10÷13 dm³/kg, Н₂ — 5.8÷10.1 dm³/kg. Higher temperatures lead to the transition of some of the lead in gas phase. The obtained data indicate that one should account for the disproportionation of FeO into Fe₃O₄ and Fe when analyzing the interaction between the reducing agent (carbon monoxide or hydrogen) and the B₂O₃ – CaO – FeO – PbО oxide melt in the bubbled layer, which is associated with the changing composition of the melt.
The work was conducted according to the State assignment of the Institute of Metallurgy of the RAS Ural branch (State registration of the theme No. 122020100404-2).

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