The paper is to study the TCF bleaching of high-yield chemical pulp of NS-AQ aspen(digester yield 63.7%, Kappa number 37.3, brightness 50.0%ISO, intrinsic viscosity 1,340ml/g). Under the suitable conditions(oxygen pre...The paper is to study the TCF bleaching of high-yield chemical pulp of NS-AQ aspen(digester yield 63.7%, Kappa number 37.3, brightness 50.0%ISO, intrinsic viscosity 1,340ml/g). Under the suitable conditions(oxygen pressure 0.6MPa, 85℃, 80min., NaOH 5%, MgSO4 0.3%, consistency 11%), oxygen delignification, can increase the brightness of pulp to 64.9%ISO, substantially decrease Kappa number to 9.11. Before the oxygen delignification pretreating pulp by acidic chelant(Qa)under conditions of pH 3.0, 30min, 40℃, DTPA 0.25%, consistency 15%, and after the Qa strengthening oxygen delignification by H2O2(Op, H2O2 2%)can increase the brightness of pulp to 77.1%ISO, decrease Kappa number and intrinsic viscosity to 6.36 and 984ml/g, respectively. After the Op, pretreat pulp by chelant once again(pH 6.0, 60℃, consistency 12%, other as the Qa), and following this pretreatment do bleach with 1% H2O2, namely using Qa-Op-Q-P bleaching sequence, resulting in the brightness 84.8%ISO, Kappa number 5.01, intrinsic viscosity 792ml/g, total bleaching loss 12.17% for bleached pulp.展开更多
文摘The paper is to study the TCF bleaching of high-yield chemical pulp of NS-AQ aspen(digester yield 63.7%, Kappa number 37.3, brightness 50.0%ISO, intrinsic viscosity 1,340ml/g). Under the suitable conditions(oxygen pressure 0.6MPa, 85℃, 80min., NaOH 5%, MgSO4 0.3%, consistency 11%), oxygen delignification, can increase the brightness of pulp to 64.9%ISO, substantially decrease Kappa number to 9.11. Before the oxygen delignification pretreating pulp by acidic chelant(Qa)under conditions of pH 3.0, 30min, 40℃, DTPA 0.25%, consistency 15%, and after the Qa strengthening oxygen delignification by H2O2(Op, H2O2 2%)can increase the brightness of pulp to 77.1%ISO, decrease Kappa number and intrinsic viscosity to 6.36 and 984ml/g, respectively. After the Op, pretreat pulp by chelant once again(pH 6.0, 60℃, consistency 12%, other as the Qa), and following this pretreatment do bleach with 1% H2O2, namely using Qa-Op-Q-P bleaching sequence, resulting in the brightness 84.8%ISO, Kappa number 5.01, intrinsic viscosity 792ml/g, total bleaching loss 12.17% for bleached pulp.
