Electrolysis of alkali metal chloride solution with subsequent production of alkali metal carbonates and hypochlorites

A process for the production of chlorine by the electrolysis of an aqueous alkali metal chloride solution which process comprises the steps of

• (1) contacting an alkali metal carbonate with an aqueous alkali metal chloride solution which contains a polyvalent metal or metals in solution, precipitating therein compounds of polyvalent metals, and removing said precipitated compounds therefrom,
• (2) electrolysing the solution from step (1) in an electrolytic cell to produce an aqueous alkali metal hydroxide solution and a gaseous stream containing chlorine and carbon dioxide,
• (3) contacting the gaseous stream from step (2) containing chlorine and carbon dioxide, or a part thereof, with aqueous alkali metal hydroxide solution, in which step (3) of the process is effected in a plurality of reaction vessels, the gaseous stream containing chlorine and carbon dioxide, or a part thereof, being passed into a first reaction vessel or vessels and thence into a second reaction vessel or vessels and aqueous alkali metal hydroxide solution being charged to the first reaction vessel or vessels and aqueous alkali metal hydroxide solution being separately charged to the second reaction vessel or vessels, the process comprising the additional steps of
• (4) removing an aqueous solution containing alkali metal hypochlorite from the first reaction vessel or vessels, and
• (5) removing an aqueous solution containing alkali metal carbonate from the second reaction vessel or vessels.