Method of reducing the viscosity of a black liquor
AssigneeNorth Carolina State University
InventorsRichard J. Spontak, Joanna E. Roberts, Victoria A. Prevysh, Saad A. Khan
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Abstract
A method of recycling sodium-based salts used for digesting wood in a digester during the manufacture of pulp and paper. The method comprises collecting a black liquor from the digester, concentrating the black liquor, and adding a salt to the black liquor in an amount sufficient to reduce the viscosity thereof. Preferred salts are thiocyanate salts. The black liquor is then oxidized to produce a green liquor and a causticizer added to the green liquor to produce a white liquor containing the sodium-based salts to be recycled. The white liquor is then returned to the digester.
Claims6
A method of recycling sodium-based salts used for digesting wood in a digester during the manufacture of pulp and paper, said method comprising:
- collecting a black liquor from said digester;
- concentrating said black liquor;
- and
- adding a salt to said black liquor in an amount sufficient to reduce the viscosity thereof, wherein said salt is selected from the group consisting of thiocyanate, perchlorate, iodide, nitrate, and bromide salts;
- oxidizing said black liquor to produce a green liquor;
- then
- adding a causticizer to said green liquor to produce white liquor containing said sodium-based salts;
- and then
- returning said white liquor to said digester.
Dependencies are inferred from the claim text.