摘要 |
<p>The present invention relates to a method for manufacture of cooking liquors and like liquids with different sulphidities in the recovery processes of chemicals in a pulp mill. The chemicals recovered in the combustion of black liquor are dissolved, and the temperature of the thus obtained green liquor is decreased to crystallize the sodium carbonate; and the sodium carbonate crystals are separated from the green liquor to manufacture a green liquor with a high sulphidity, which may be utilized in the impregnation stage of the cooking and the sodium carbonate crystals are dissolved to manufacture an alkaline solution having a low sulphide content. The cooling crystallization of green liquor is carried out by expansion in two or more stages and vapor generated in the expansion is brought into contact with green liquor after the separation of sodium carbonate crystals to recover heat. The alkaline solution may be causticized to produce sodium hydroxide solution which may be used in different places in the pulp mill.</p> |