A PROCESS FOR THE RECOVERY OF ALKALI FROM AQUEOUS SOLUTION CONTANING CARBONATES, HYDROXIDES, PHOSPHATES, SILICATES AND ALUMINATES.

摘要

A process for the recovery of alkali from aqueous solutions by adding an oxide, hydroxide or carbonate characterized in that an oxide, hydroxide or carbonate of an alkaline earth metal is added to an aqueous solution containing alkali carbonates, hydroxides, phosphates, silicates and aluminates to precipitate, phosphates, silicates and aluminates as sparingly soluble salts of alkaline earth metal, filtering the clear solution containing alkali metal hydroxide and a small quantity of alkaline-earth metal ion, removing the latter as its carbonate by the addition of sodium carbonate and separating the clear solution containing essentially alkali metal hydroxide which i subsequently concentrated and recovered for reuse,