Process for separating sulphur in the form of hydrogen sulphide from clarified green liquor obtained from the combustion of waste liquor

In a process for separating sulphur in the form of hydrogen sulphide from clarified green liquor obtained from the combustion of waste liquor, including the steps of precarbonating green liquor with a carbon dioxide rich gas, adding alkali bicarbonate to said precarbonated green liquor, stripping hydrogen sulphide therefrom producing simultaneously alkali carbonate, and preparing alkali bicarbonate to be used in the process by carbonating said alkali carbonate, the improvement comprising carrying out said hydrogen sulphide stripping step producing simultaneously alkali carbonate directly in the solution in said stripping step without crystallizing said simultaneously produced alkali carbonate, preparing said alkali bicarbonate to be used in the process partly from said alkali carbonate solution and partly from alkali carbonate -- alkali sulphide solution obtained in said pre-carbonation step, feeding at least a portion of said alkali carbonate -- alkali sulphide solution through said carbonation step to said hydrogen sulphide stripping step, introducing said carbon dioxide rich gas first into said carbonation step and thereafter passing a portion of the gas escaping from said carbonation step back to said carbonation step, and passing another portion into said precarbonation step, and thereafter removing said gas from the process.