Effect of Hercynite Spinel on the Technological Properties of MCZ Products Used for Lining Cement Rotary Kilns

Abstract

Magnesia-calcium zirconate (MCZ) composite products have been tested in the transition zones of cement kilns. Such products are of interest because they are environmentally safe and demonstrate high resistance when exposed to cement clinker at elevated temperatures. Such modifiers as hercynite spinel FeO·Al₂O₃ (FA) can be added in small quantities to MCZ products to enhance elasticity, improve their ability to form a protective coating on the lining surface, and create a reinforced structure. In this study, various FA amounts (2, 4, and 6 wt.%) were added to the MCZ-clinker made from magnesite and ZrO₂ (9.8 wt.%). Next, the material densification parameters, cold compressive strength (CCS), severity of exposure to cement clinker components (CCC), and other technical characteristics of the products made from this material were studied. The maximum product strength was obtained upon introduction of 2 wt.% of FA additive, however, further increase in FA quantity was prevented by an excessive number of micro-cracks and glass-phase formation. The penetration depth of the cement clinker components into the MCZ-FA products decreased with an increase in the FA additive content. In other words, the penetration depth was lower at higher FA quantities. In addition, the behavior of the protective coating and thermal shock resistance of the products improved considerably upon increasing the FA content to 6 wt.%. The products with different FA content can be used for lining the cement rotary kiln zones, in which different protective coating formation conditions are observed.