Sodalite-type seeds are proved as efficient desilication agents for desilication in highly alkaline silica containing sodium aluminate solution. The structure information of desilicaiton agents from different synthesis conditions and desilication products were studied by means of measurements such as XRD, FTIR, Si-29 MAS NMR, Al-22 MAS NMR and so on. The desilication result shows that the final concentration of SiO2 was efficiently decreased below 2 g/L from the initial silica concentration of 5 g/L under highly alkaline condition (C-Na2O > 500 g/L). The stability of sodalite-type desilication agent in highly alkaline sodium aluminate solution provides the possibility to recycle the desilication agent in production of alumina industry. (C) 2016 Elsevier Inc. All rights reserved.