Influence of Grain Size Distributions and Spinel Content on the Properties of Low Cement Alumina-Spinel Castables

Alumina-Spinel castables are widely used and replaced instead of traditional refractory bricks for many industrial application. That is because of the best resistance to slag penetration and other properties. This study aims to make Alumina-Spinel castables and evaluate the effects of grain size distributions and Spinel on the properties. Aggregates used were tabular alumina while fine and ultra fine aluminas were of calcined type. the alumina cement cotained 17 wt % CaO and synthetic spinel (MAS 76) microsilica, dead burnt magnesia (M99) and additives were used. After making the samples, the properties such as flowability, CMOR, CCS, bulk density, were measured. Microstructural and phase analysis were conducted by SEM and XRD. The data showed that flow value of castables slightly was increased with fine addition. The grain size distributions and shape of grains influence on rheological behavior and flowability of castables. Addition of fine particles into the composition decreased the interference between coarse particles. Fine particles decreased the viscosity of castable matrix therefore flowability increased. The results showed that the strength decreases by increasing fine grain size due to increasing requaird water. Cold crushing strength after firing at 1500