Preparation of alkali metal silicates

Abstract From the Canadian patent

The ratio of silicate to alkali in silicate liquors is increased, for example to convert alkaline grades to neutral grades, by passing the liquors through an electrodialysis stack comprising alternating anion exchange membranes and cation-exchange membranes mounted between an anode and a cathode the membranes, being spaced apart to provide cells through which a fluid can be passed, the method comprising passing the silicate liquor through those cells having their anion exchange membranes on the anode side and passing water or an aqueous solution through the other cells whereby, the silicate liquor is caused to lose alkali metal ions.