Method for separating lignin from black liquor
AssigneeFPInnovations
InventorsLamfeddal KOUISNI, Michael PALEOLOGOU
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Abstract
A method was developed for: a) improving the filterability of acid-precipitated lignin from kraft black liquors, b) increasing the dry solids content of the final lignin product, c) reducing the acid requirements and d) minimizing or eliminating TRS emissions during the acidification of black liquor to produce lignin and/or the subsequent suspension of the lignin in acid and/or the washing of the lignin with acid. No major difference in the chemical composition, MWD and main functional groups was found in the lignin of the present invention compared with lignins produced by conventional methods.
Claims18
In a process for removing lignin from black liquor by acidifying the black liquor and filtering the acidified black liquor, the improvement wherein the black liquor is oxidized prior to said acidifying.
A process for separating lignin from black liquor comprising:
- a) oxidizing black liquor containing lignin to remove total reduced sulphur (TRS) in the black liquor,
- b) acidifying the oxidized black liquor to precipitate lignin from the black liquor, and
- c) filtering precipitated lignin particles from the acidified liquor.
Dependencies are inferred from the claim text.