On the interactions of iron sulphide with alumina and silica

The hypothesis that matte will only react with certain constituents of a refractory brick, as opposed to the entire brick, was tested by observing the extent of possible reactions between iron sulphide (FeS) and the refractory oxides silica and alumina. The main aim was to identify the components of the alumina-chrome refractory brick which are most reactive with the matte. Pellets comprised of FeS and either SiO₂ or Al₂O₃ were enclosed in a graphite crucible and reacted in a horizontal tube furnace for one hour at 1200°C, 1350°C, or 1500°C in an argon atmosphere. The specimens were analysed with SEM and XRD to determine the extent of any reactions. Results showed that FeS penetration into the silica grain was more prominent with increasing temperature, while alumina was not penetrated by FeS at all temperatures. At 1200°C, no significant reactions were observed for both reaction couples; however, at 1350°C and 1500°C intermediate products were observed. For example, an FeS FeO mixture, SiS-O, and nonstoichiometric oxides with excess oxygen were detected in the products. SiO₂ was also more reactive towards FeS. Thus, the postulation that brick components may individually be reactive towards matte was proved to be true.