Production of alkali metal carbonates and/or bicarbonates from alkali metal sulphates

Abstract

The invention provides a method of producing a carbonate or a bicarbonate of an alkali metal, in solid form, from a sulphate of the alkali metal. The method includes, in a first reaction step, reacting, in aqueous medium, a sulphate of an alkali metal with one or more alkaline earth metal sulphides, thus forming an aqueous solution of one or more sulphides of the alkali metal and one or more sulphates of the alkaline earth metal in solid form. The method also includes, in a second reaction step, in the aqueous solution of one or more sulphides of the alkali metal, reacting the one or more sulphides of the alkali metal with carbon dioxide (CO) in gaseous form, thus forming an aqueous solution of a bicarbonate of the alkali metal and gaseous hydrogen sulphide. The method further includes, in a recovery step, recovering a carbonate or the bicarbonate of the alkali metal, in solid form, from the aqueous solution of the bicarbonate of the alkali metal.