Refractory Wear Characterization in Lime Recovery Kilns

• A comparison of the laboratory and post-mortem examinations was performed resulting in the following conclusions 1. The lime mud reacted with the brick powder of all three refractory brick compositions with higher temperatures producing more reaction 2. The X-ray diffraction analysis showed that the calcium alumino-silicate phase, anorthite (CaOAl₂O₃2SiO₂), was the dominant mineral formed in the heat-treated pellets, consistent with post-mortem evaluations of used alumina-silica firebrick from rotary lime kiln service 3. Less reaction of the 60% alumina refractories, in comparison to the 70%, is consistent with previous corrosion cup testing that suggested superior wear resistance of 60% alumina bricks in the calcining zone of the kiln 4. It was surmised that liquid formation may begin to occur in these samples as early as 1365-1370◦C (2489- 2498^◦F) based on a eutectic found in the anorthite-silica phase diagram and leading to the behavior observed both experimentally in the laboratory and through post-mortem examinations. • The impact of operating conditions and flame shape on refractory failures was evaluated through modeling and the influence of flame shape on the maximum operating temperatures of the refractory lining, along with the impacts of discharge dams and insulating the refractory linings were addressed • It was found that burner design should promote flame lengths of about 4 kiln diameters long and that the longer flame substantially reduces the refractory temperature. • It was also found that a discharge end dam protects the refractory from overheating due to the increased bed depth of the lime charge in the kiln and both coolers and insulated linings decrease the safety factor for the refractory in terms of the potential for overheating • Finally, it was determined that while levels of alkali play a role, in the end, the temperature of the refractory and interactions with calcium compounds from the lime mud have a larger impact on the service life of the lining.