H. W. Gudenau

Effect of coke reactivity and nut coke on blast furnace operation

Abstract Two measures for coke saving and increase in blast furnace efficiency related to coke characteristics – reactivity and size – are discussed in this paper. Modern blast furnace operation with low coke rate and high injection rate causes a change in coke quality requirements. A discussion has arisen recently about highly reactive coke. Here, a theoretical analysis of influence of coke reactivity on the thermal reserve zone, direct reduction and carbon consumption in the blast furnace has been undertaken. Experiments have been performed using non-standard test scenarios that simulate coke behaviour under real blast furnace operating conditions. Coke reactivity and microstructure have also been investigated under the impact of alkali and pulverised coal ash and char. Operation of many blast furnaces has proved the possibility of coke saving and increase in productivity when using small-sized coke (so-called nut coke) mixed with the burden, but the reasons for this phenomenon, and consequently the limit for nut coke consumption, are still not very clear. An analytical method and cold model simulations have been used to quantify the change in shaft permeability and furnace productivity when using nut coke.

Influence of nut coke on iron ore sinter reducibility under simulated blast furnace conditions

Abstract One of the most important factors to increase the economic efficiency of the blast furnace process is to reduced coke losses (undersieve product known as nut coke). In recent years there has been increased interest in mixing nut coke in the sinter layers. In order to clarify the influence of nut coke on sinter reducibility, sinter and sinter–nut coke mixtures were isothermally reduced with 30%CO–70%N2 at 1173–1523 K using a muffle furnace supported by an on-line gas analyser. Reflected light microscopy, scanning electron microscopy and X-ray technique were used to characterise the microstructure and the different phases developed in the original and reduced sinter. Sinter reduced without nut coke participation exhibited reduction retardation at elevated temperatures (>1373 K) while the presence of nut coke prevented such phenomena. The rate controlling mechanism of sinter and sinter–nut coke mixture was predicted from the correlation between apparent activation energy calculations, mathematical modelling derived from gas–solid reaction model and microstructure examination.

Der Lehrstuhl für Metallurgie von Eisen und Stahl an der RWTH Aachen anhand des Forschungsbeispiels „Metallurgischer Einsatz von Stäuben”

ZusammenfassungBreites Feld der Forschung und Lehre der Eisen- und Stahlerzeugung von Rohstoffen zum kontinuierlich gegossenen Zwischenprodukt — Entwicklungen der Prozessmetallurgie und Untersuchungen metallurgischer Mechanismen auf der Mikrometerskala — Großlaboranlagen aktualisiert, z. B. 2004/05 Inbetriebnahme des VakuumStahlZentrums — Darstellung der Arbeitsweise an drei Beispielen der Staubverwendung in metallurgischen Prozessen: Problemanalyse, Modellbildung, experimentelle und mathematische Simulation, betriebliche ErprobungAbstractWide range of research and higher education in the field of iron and steel metallurgy from resources to continuously cast products — Developments of process metallurgy and investigations of fundamental mechanisms on micro scale — Three examples of working methods concerning application of dusts in iron and steel metallurgy: problem analysis, modelling, experimental and mathematical simulation, industrial application