Effect of Al(OH)3 and La2O3 on the sintering behavior of CaO granules via CaCo3 decomposition

Abstract

Hydration resistance of CaO aggregates is the key to the successful application of lime-based refractories. Granulation technology on limestone with additives and one step calcination method was used in this study to investigate the effects of Al(OH)3 and La2O3 on the sintering behavior and the hydration resistance of CaO granules. The result showed that the hydration resistance of CaO granules was improved significantly by adding Al(OH)3 and La2O3. The shell of sintered CaO granules was relatively dense after calcination and the specific surface area of CaO granules decreased from 7.5?10-2 m2/g to 1.2?10-2 m2/g. The average pore size of CaO granular was decreased from 3.54 ?m to 0.83 ?m due to the liquid phase sintering when Al(OH)3 additive was used. La2O3 promoted the densification of CaO compact by the ion substitution and solution with CaO. La3+ approached into CaO lattices, which enlarged the vacancy concentration of Ca2+ and accelerated the diffusion of Ca2+.