Patent ID: 8216423

Claim:
An alkaline peroxide mechanical pulping process consisting of the steps of: feeding a lignocellulosic material into a first press; pressing the lignocellulosic material; discharging the lignocellulosic material from the first press; impregnating the lignocellulosic material discharged from the first press with a first sodium hydroxide alkaline peroxide pretreatment solution and maintaining the impregnation for a first reaction time to produce an impregnated lignocellulosic material; feeding the impregnated lignocellulosic material impregnated with said first sodium hydroxide alkaline peroxide pretreatment solution to a refiner having an inlet and a rotating disc within a superatmospheric casing; refining the impregnated lignocellulosic material to form a primary pulp having a temperature of at least about 80° C.; delivering a stream of primary pulp from the superatmospheric casing through a blow valve to a blow line while the primary pulp temperature is at least about 80° C.; adding a sodium hydroxide alkaline peroxide blow line solution to the stream of primary pulp in the blow line while the primary pulp temperature is at least about 80° C.; mixing the blow line solution and the stream of primary pulp to form a reaction mixture in the blow line; discharging the reaction mixture having a temperature of at least about 80° C. into a retention vessel; and retaining the reaction mixture in the retention vessel to produce a bleached material.