Microstructure and properties of hercynite–magnesia–calcium zirconate refractory mixtures

Refractory manufacturers have focused their investigations on the development of chrome-free products that suitably meet the refractory lining requirements of cement rotary kilns. The experimental development of refractory mixtures based on magnesia and calcium zirconate, to which electrofused hercynite was added, was carried out in this work. Formulations, in which various amounts of hercynite were added to study its influence on MgO–CaZrO3 microstructure and properties, were prepared. Samples were obtained by compacting powders and sintering in an industrial tunnel kiln. The samples were characterized via XRD and SEM. The strength of the refractory was determined at room temperature. Resistance to attack by cement raw meal at 1300 °C was studied. According to the results, formulations with the addition of hercynite show superior cold crushing strength compared to those without the additive, moreover, all compositions showed good chemical resistance to the presence of cement raw meal.