Fluidized bed reduction as the prestep of smelting reduction

Comparing the four fundamental ironmaking processes the reasons for the development of smelting reduction were derived. Based on bibliographical references a fundamental classification of the main important smelting reduction processes is presented regarding the process engineering principle of both steps, prereduction and final reduction. According to fundamental considerations, the fluidized bed process seems to be optimal for prereduction. Experiments to investigate the influence of process parameters on sticking – the main problem of fluidized‐bed reduction – and their interactions were carried out. Optimal operating conditions to run a fluidized bed as the prereduction unit of smelting reduction process were derived. A special “Reduction‐SEM” to directly observe metallurgical reactions, like the precipitation behaviour of iron during iron ore reduction, is presented. With the results of such investigations it is possible to show the influence of precipitation behaviour on sticking and to assign the different types of precipitates to the Baur‐Glaessner‐Diagram. The influence of hydrogen addition on surface morphology is sketched out.