Method for lignin purification
AssigneeLigneasy Oy
InventorsEric Enqvist, Ville Tarvo, Panu Tikka
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Abstract
The invention is directed to a method for producing a purified lignin salt from alkaline spent liquor from the chemical cooking of lignocellulosic raw materials. The method comprises the steps of decreasing the spent liquor pH to form a lignin precipitate suspension; filtering the lignin precipitate to form a lignin filter cake and a filtrate; mixing the lignin filter cake into a dilution liquid to form an alkalilignin agglomerate colloid; subjecting the alkalilignin agglomerate colloid to large-pore membrane filtration; and recovering a purified lignin salt concentrate.
Claims14
A method for producing purified lignin salt from alkaline spent liquor from chemical cooking of lignocellulosic raw materials, comprising the steps of
- decreasing the spent liquor pH to form a lignin precipitation suspension,
- filtering the lignin precipitation suspension to form a filter cake comprising lignin, and a filtrate,
- mixing the filter cake into a dilution liquid to form an alkalilignin agglomerate colloid,
- subjecting the alkalilignin agglomerate colloid to large-pore membrane filtration, and
- recovering a purified lignin salt concentrate,
- wherein the nominal cut-off value of the large-pore membrane filtration is at least 40 kDa.
Dependencies are inferred from the claim text.