Method for producing solid lignin
AssigneeValmet Technologies Oy
InventorsEric Enqvist, Ville Tarvo, Panu Tikka, Tobias Wittmann, Henrik Wallmo, Anders Littorin
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Abstract
Lignin-rich starting material is suspended in a first medium, which is acidic and aqueous, to form a aqueous acidic suspension, which is heated and allowed to form two continuous phases, a thermoplastic lignin phase and an aqueous phase. The thermoplastic lignin phase is separated from the aqueous phase and passed through a shape giving process into a second medium which is at a temperature lower than that of the thermoplastic lignin phase and in which the thermoplastic lignin phase is essentially insoluble. Solid lignin formed in the second medium is recovered.
Claims19
A method for producing solid lignin from lignin-rich starting material, characterized by
- suspending the starting material in a first medium, which is an aqueous solution of an inorganic acid having a pH in the range of from 0 to 5, to form an aqueous acidic suspension having a dry solid content of 10-25 weight percent;
- heating the aqueous acidic suspension to a temperature in the range of 120 to 180° C. and allowing the suspension to form two continuous phases, a phase comprising thermoplastic lignin and an aqueous phase;
- separating the phase comprising thermoplastic lignin from the aqueous phase;
- passing the separated phase comprising thermoplastic lignin through a shape giving process into a second medium, which is at a temperature lower than that of the thermoplastic lignin phase and in which the phase comprising thermoplastic lignin is essentially insoluble, whereby the lignin solidifies in a form of granules when it is brought in contact with the cooler second medium;
- and
- recovering the solid lignin formed in the second medium;
- wherein the separated phase comprising thermoplastic lignin is introduced to the second medium through one or several nozzles and the second medium is water.
A method for producing solid lignin granules from lignin-rich starting material, characterized by
- suspending alkaline spent pulping liquor or black liquor in a first medium, which is an aqueous solution of an inorganic acid having a pH in the range of from 0 to 5, to form an aqueous acidic suspension having a dry solid content of 10-25 weight percent;
- heating the aqueous acidic suspension to a temperature in the range of 120 to 180° C. and allowing the suspension to form two continuous phases, a phase comprising thermoplastic lignin and an aqueous phase;
- separating the phase comprising thermoplastic lignin from the aqueous phase by an acceleration selected from gravity and centripetal;
- and
- passing the separated thermoplastic lignin phase through at least one nozzle into water having a temperature lower than that of the phase comprising thermoplastic lignin and in which the phase comprising thermoplastic lignin is essentially insoluble, such that the phase comprising thermoplastic lignin forms droplets which solidify in the shape of granules with a selected size distribution controlled by the at least one nozzle.
Dependencies are inferred from the claim text.