Method for producing synthetic sodium aluminosilicate ion-exchange material from calcined kaolin clay

Abstract From the Canadian patent

Kaolin clay is dehydrated at a temperature in excess of about 600°C. and below 980°C. and the dehydrated clay is chlorinated in a gas-solid reaction at elevated temperature to remove colored iron impurities as volatile chlorides. The dehydrated clay is then cooled and reacted with an aqueous solution of sodium hydroxide, optionally containing additional sources of alumina and silica, to produce high purity hydrated sodium aluminosilicates such as sodium zeolite A in the form of white crystals useful as ion exchange materials (water softening agents) in detergent compositions.