Method and system for producing lignin

A method for separation of lignin from an aqueous slurry containing lignocellulosic biomass material comprising:

• providing the aqueous slurry having an initial pH level to at least one precipitation phase for precipitating lignin;
• performing the at least one precipitation phase during reaction times including adding at least one acidifier, wherein a decrease in the pH value of the aqueous slurry from said initial pH level to respective lower pH levels are created;
• separating the precipitated lignin in a first separation phase;
• performing an acidification phase including:
• performing a re-slurry step including mixing lignin from the first separation phase with an acidifier to form an acidic slurry;
• establishing a reaction temperature in a range of 65-95 degrees Celsius in the acidic slurry;
• and
• performing a retention step including maintaining the acidic slurry at the reaction temperature for a reaction time period of 30-60 minutes;
• and
• separating the treated lignin content from the acidic slurry in a second separation phase.

A system for separation of lignin from an aqueous slurry containing lignocellulosic biomass material comprising:

• at least one precipitation vessel configured to carry out at least one precipitation phase comprising precipitating lignin from the aqueous slurry during predetermined reaction times including adding at least one acidifier, wherein a decrease in the pH value of the aqueous slurry from said initial pH level to respective lower pH levels are created;
• a first separation device configured to carry out a first separation phase comprising separating the precipitated lignin;
• a suspension vessel configured to carry out an acidification phase comprising performing a re-slurry step including mixing lignin from the first separation phase with an acidifier to form an acidic slurry;
• at least one heat generating device configured to establish a reaction temperature in a range of 65-95 degrees Celsius of the acidic slurry;
• wherein the suspension vessel or a retention vessel is configured for carrying out a retention step comprising maintaining the acidic slurry at the reaction temperature for a reaction time period of 30-60 minutes;
• and
• a second separation device configured for carrying out a second separation phase comprising separating the treated lignin content from the acidic slurry.

A computer-readable medium having stored therein computer-readable instructions for a processor, wherein the instructions when read and implemented by the processor, cause the processor to:

• control at least one precipitation phase for precipitating lignin in an aqueous slurry containing lignocellulosic biomass material during reaction times including adding at least one acidifier, wherein a decrease in the pH value of the aqueous slurry from said initial pH level to respective lower pH levels are created;
• control a separation of precipitated lignin in a first separation phase;
• control an acidification phase including:
• performing a re-slurry step including mixing lignin from the first separation phase with an acidifier to form an acidic slurry;
• establishing a reaction temperature in a range of 65-95 degrees Celsius in the acidic slurry;
• and
• maintaining the acidic slurry at the reaction temperature for a reaction time period of 30-60 minutes;
• and
• control a separation of treated lignin content from the acidic slurry in a second separation phase.