Abstract:The reaction behavior of CaO during desilication process of sodium aluminate solution was systematically investigated by analyzing the producing quantity, phase composition and morphology of desilication products with XRD and SEM-EDS methods. The results show that the amount of desilication products rise gradually with the increase of calcium ratio and reaction time. The desilication products mainly include four phases, i.e., tricalcium aluminate hexahydrate, hydrogarnet, zeolite-A and zeolite. The increasing of calcium ratio and reaction time is beneficial to the conversion of desilication products tricalcium aluminate hexahydrate to hydrogarnet, and the corresponding lattice constant and unit cell volume of desilication products increase continuously. The morphology of different types of desilication products is quite different, and the precipitation sequence of desilication products is as follows: tricalcium aluminate hexahydrate, hydrogarnet, zeolite-A, and zeolite.