Abstract: The effect of acetate concentration in sodium aluminate solution at 145℃ on the mineral composition， microstructure and precipitation activity of desilication products was studied. The results show that when the acetate exists in sodium aluminate solution， the crystalline sodium aluminosilicate hydrate is comprised of zeolite and methylol-sodalite and the corresponding lattice constant increases with the acetate concentration. Furthermore， with the increasing acetate concentration， the crystallinity of zeolite and methylol-sodalite reduces， and the content of zeolite decreases， in contrast with that of the methylol-sodalite. The effect of the acetate on the structure of functional group and microstructure of desilication products is very little. However， the additive of acetate can increase the molar ratio of Na₂O to Al₂O₃ and decrease the molar ratio of SiO₂ to Al₂O₃. Moreover， with the increasing acetate concentration， the particle size of desilication products decreases and the precipitation activity in sodium aluminate solution increases.

Key words: Bayer process, organic compounds, sodium aluminate solution, desilication products, precipitation activity