Abstract: A method for pulp processing used in connection with a pre-hydrolysis kraft process (PHKP) includes adding wood chips or similar material to a reaction vessel, performing pre-hydrolysis, and neutralizing the mixture with a first quantity of white liquor followed by a different solution such as a cold caustic extraction alkaline filtrate optionally enriched with white liquor. The neutralization fluids are replaced with a cooking fluid comprising a hot black liquor and alkaline filtrate, optionally enriched with white liquor. The cooking fluid may have a relatively high effective alkali concentration. The cooked pulp may exhibit very low residual hemicelluloses and a kappa number within an optimal range.

Abstract: A method for pulp processing used in connection with a pre-hydrolysis kraft process (PHKP) includes adding wood chips or similar material to a reaction vessel, performing pre-hydrolysis, and neutralizing the mixture with a first quantity of white liquor followed by a different solution such as a cold caustic extraction alkaline filtrate optionally enriched with white liquor. The neutralization fluids are replaced with a cooking fluid comprising a hot black liquor and alkaline filtrate, optionally enriched with white liquor. The cooking fluid may have a relatively high effective alkali concentration. The cooked pulp may exhibit very low residual hemicelluloses and a kappa number within an optimal range.

Abstract: A method for pulp processing includes a cold caustic extraction stage in which the spent cold caustic solution and the spent liquid used to wash the extracted pulp are concentrated by an evaporation system. The concentrated liquid can be used as part of the neutralization and cooking liquor in the pulp process, leading to increased efficiency without significant reduction in pulp quality. Highly concentrated filtrate from the cold caustic extraction stage may help reduce hemicellulose deposition on wood fiber during the cooking step.

Abstract: A method for pulp processing used in connection with a pre-hydrolysis kraft process (PHKP) includes adding wood chips or similar material to a reaction vessel, performing pre-hydrolysis, and neutralizing the mixture with a first quantity of white liquor followed by a different solution such as a cold caustic extraction alkaline filtrate optionally enriched with white liquor. The neutralization fluids are replaced with a cooking fluid comprising a hot black liquor and alkaline filtrate, optionally enriched with white liquor. The cooking fluid may have a relatively high effective alkali concentration. The cooked pulp may exhibit very low residual hemicelluloses and a kappa number within an optimal range.

Abstract: A method for pulp processing includes a cold caustic extraction stage in which the spent cold caustic solution and the spent liquid used to wash the extracted pulp are concentrated by an evaporation system. The concentrated liquid can be used as part of the neutralization and cooking liquor in the pulp process, leading to increased efficiency without significant reduction in pulp quality. Highly concentrated filtrate from the cold caustic extraction stage may help reduce hemicellulose deposition on wood fiber during the cooking step.