Abstract: In order to utilize silicon in the coal gangue to prepare sodium silicate，the gangue powder was calcined at 750 ℃ for 2 h firstly，then the organic matters were removed and the crystal structures of the minerals，such as kaolin in the gangue were destroyed.The calcined gangue powder was leached in sulfuric acid with mass fraction of 40% and liquid to solid ratio of 8∶1 at 95 ℃ for 5 h.The total removal ratio of impurity metal ions，such as iron and aluminum was 86.93%；the influences of the alkali melting activation conditions on the dissolution ratios of silicon element were investigated，then the suitable activation conditions were obtained:the mass ratio of acid leaching powder to sodium carbonate was 1∶1.5，the alkali melting temperature was 800 ℃，and the alkali melting time was 2 h.Under these conditions silicon element dissolution ratio was more than 75% and the sodium silicate solution was obtained finally. 

Key words: gangue, purification, alkali melting, sodium silicate