Patent ID: 7270726

Claim:
A method for the production of green liquor in association with a causticizing process during recovery of chemicals during the manufacture of sulphate paper pulp, comprising: providing a smelt of chemicals consisting essentially of Na 2 S and Na 2 CO 3 from a soda boiler, conveying the smelt from a soda boiler to a dissolving tank, providing a weak liquor in a vessel that contains dissolved NaOH and CaO, the weak liquor having a first concentration of NaOH of not higher than 25 g/l, adding a solution of NaOH to the weak liquor in the vessel in such an amount that the first concentration of NaOH in the weak liquor increases to a second concentration of NaOH that is at least 20% higher than the first concentration and until a main portion of the dissolved CaO starts precipitating into particles in the weak liquor, conveying the weak liquor and the particles to the dissolving tank, and dissolving the smelt in the weak liquor in the dissolving tank to form a green liquor.