GB382167A - Improved process for manufacture of sodium bicarbonate - Google Patents

Abstract

Sodium bicarbonate is obtained by the action of ammonia and carbon dioxide or ammonium bicarbonate on a sodium salt in the presence of a soluble salt of an amine whereby the sodium bicarbonate is precipitated by the conjoint action of amine and ammonium bicarbonates. The process may be carried out in a cycle by adding to a solution containing soluble salts of amines and ammonium, a soluble sodium salt and ammonia and carbon dioxide or ammonium carbonate, an amount of ammonium salt corresponding to the sodium salt introduced being precipitated and removed. Carbon dioxide or ammonia and carbon dioxide, is then added to the remaining solution, sodium bicarbonate being precipitated and a solution of the same composition as that initially employed remaining. This is returned to the first step of the process. According to one example sodium chloride is added to a solution containing sodium chloride and trimethylamine chloride and saturated with ammonium chloride. The solution is treated with ammonia and carbon dioxide whereby ammonium chloride equivalent to the freshly introduced sodium chloride is precipitated and separated. The remaining solution is treated with carbon dioxide or carbon dioxide and ammonia, sodium bicarbonate being precipitated leaving a solution of the same composition as that originally employed for starting a new cycle. According to a second example the starting solution is saturated with ammonium chloride and contains mono-, di- or trimethyl ammonium nitrate or a double nitrate of amine and ammonium. Sodium chloride, ammonia, and carbon dioxide are added and the cyclic process is carried out as in the previous example. Ammonia for the process may be obtained by decomposing the ammonium chloride produced. Wash water from a previous operation may be used for replenishing the water lost in the process.