Abstract :
Five refractory cement mixes were prepared from different proportions of barite, zirconia and calcined alumina by sintering at 1500–1550 °C for 3 h. The obtained cements were composed of barium aluminate and barium zirconate minerals in addition to comparable proportions of di-barium silicate.
Cement mix prepared from 70 wt.% barite, 10 wt.% zirconia and 20 wt.% alumina and containing comparable proportions of barium aluminate and barium zirconate minerals (≈38 and ≈29 wt.%, respectively) shows a comporomise between good cementing, sintering and refractory properties.
Refractory concretes prepared from 20 wt.% of this cement and 80 wt.% of either bauxite or fused spinel aggregate are composed mainly of mullite, barium aluminate, barium zirconate and α-corundum in case of bauxite aggregate or magnesium aluminate spinel in addition to barium aluminate and barium zirconate in case of fused spinel aggregate. These assemblages of minerals exhibit compact and homogenous microstructure and results in outstanding technological properties that meet the requirements of international standard specifications, i.e., good volume stability (permanent linear change is only 0.62 and 0.28%, respectively) good mechanical properties (680 and 610 kg/cm2), high spalling resistance (>30 cycles), high refractoriness (>1700 °C) as well as high load bearing capacity (ta: 1560 and 1590 °C). The combination of these advantages in such refractory concretes makes them suitable for use in severe conditions at high temperature applications especially in steel-making industries.
