Foaming during reduction of iron oxide in molten slag

Abstract

Coal based direct liquid ironmaking processes, also known as smelting reduction (SR) processes, are now receiving serious consideration in the industry. However, although several processes have reached pilot plant trials, only one, namely Corex, has been commercialised. In all SR processes, most of the iron oxide is reduced in the molten slag phase and foaming is an important phenomenon. Better understanding of the foaming behaviour will result in design of a more efficient and economic reactor. Accordingly, some basic studies on the foaming behaviour of some typical SR process slags have been undertaken in this work. Experimental data on foaming in a 50 kW capacity plasma reactor are discussed in this paper. The data generated are analysed in terms of foaming index, which is equal to the residence time or travelling time of the gas in the foam layer. The influence of FeO percentage in the slag, slag basicity, crucible surface area, initial slag height, and CaF2 addition in the slag on foaming has been studied.