Process of producing alkali hydroxide, chlorine and hydrogen by the electrolysis of an aqueous alkali chloride solution in a membrane cell

Abstract From the Canadian patent

Alkali hydroxide, chlorine and hydrogen are produced from an aqueous alkali chloride solution by membrane electrolysis. A high-NaCl solid salt, which contains impurities, is dissolved in water in a salt dissolver. Precipitating chemicals are added to the salt solution to precipitate the impurities. The resulting mixture is fed to a thickener from, which precipitates and clarified raw brine are separately withdrawn. The clarified raw brine from the thickener is divided at a ratio between 2:1 and 20:1 into first and second partial streams. The larger first partial stream is mixed with the salt solution and the precipitating chemicals before entering the thickener and the resulting mixture is …