Refractory aspects of Egyptian alum-waste material

The material studied was Egyptian alum-waste, which consists mainly of SiO2 and Al2O3. Mixes were made with appropriate additions of magnesia to bind SiO2 as forsterite (2MgO·SiO2) and Al2O3 as spinel (MgO·Al2O3), in an attempt to asses their suitability as a refractory forsterite material. The formation of spinel in these materials helped in the improvement of the quality of the prepared forsterite bodies. The phase reactions that may occur during the firing at 1550 °C of the prepared mixes, which belong to the five component system CaO–MgO–SiO2–R2O3 were investigated. The mineral composition of the resulting forsterite bodies were determined theoretically by calculations from their thermal equilibrium data and experimentally by means of X-ray analysis and scanning electron microscopy. The technological properties of the resulting refractory bodies were determined and correlated with their mineral composition. Such properties were found to compare favourably with those of the parallel imported types.