Photoelectric measurement of the foaming process in the reduction of slags containing iron oxide

A measuring method for determining foaming volume is being developed. The volume increase and the progress of the foaming process can be continuously determined and quantified by optical means through evaluation of brightness differences. The influences of various reducing agents on the foaming process are considered. CO evolution resulting from the reaction between liquid iron oxide and carbon constitutes the decisive factor for foaming of this type. In contrast, the temperature‐dependent formation of O 2 which occurs during conversion of haematite to magnetite only produces a small increase in volume during the melting process. No foaming is observed during reduction by the gas phase at the surface of the specimen. The foaming behaviour of slags in the basic FeO n ‐CaO‐SiO 2 system is investigated. Maximum foaming occurs in the moderate basicity range. Similarly, foaming may also be maximized with moderate gangue contents in the oxide melt. Relatively high volume increases are likewise achieved within certain temperature ranges. The rate of gas formation constitutes the main criterion determining the foaming intensity. The highest volume increase values observed lie in the region of 1100% related to the initial volume. The foaming process always exhibits a reliable degree of reproducibility.