Contribution Oral Presentation
ANALYSIS OF THE ALKALI DISTRIBUTION IN IRONMAKING REACTORS BY THERMOCHEMICAL MODELLING
- ANTON PICHLER
- ANTON PICHLER (Chair of Ferrous Metallurgy, Montanuniversitaet Leoben)
Due to their physical and thermochemical properties, alkali metals as potassium and sodium show a specific behavior in ironmaking processes. The reduction and oxidation of alkali compounds as well as their evaporation and condensing behavior lead to the formation of an alkali cycle. Furthermore, an enrichment of harmful K- and Na-compositions takes place. This affects refractory material, fuel rate, dust & cyanide emissions and the formation of scaffolds. To predict the influence of different process parameters on the creation of this alkali cycle, a multi stage model was developed for ironmaking processes. A special slag model and thermochemical calculations connected with the pressure, temperature and gas composition leads to a prediction of the alkali distribution. Main findings of the calculations are the influences of process parameters on the alkali flow inside different reactors. A comparison between the conditions in the blast furnace and the melter-gasifier (Finex®/Corex®-process) confirms the influence of temperature, pressure and gas composition on the formation of cyanides and carbonates. The model enables an evaluation of mass balances based on industrial data and contributes new information and ideas about the fundamental reactions in ironmaking reactors.