Comparison of Different TCF Bleaching Sequence for Eucalyptus Kraft pulp

This paper compared Z-Eo- Q-PO, Z-Eop- Q-PO, Z-Eop- Q-PO with MgSO(4) addition in Eop-stage and Z-Q-Eop-Q-PO with MgSO(4) addition in Eop-stage. The results denoted that Z-Eop- Q-PO bleaching sequence decreased viscosity clearly compared with Z-Eo- Q-PO. Using magnesium sulphate as protectant in Eop-stage remarkably lightened degradation of pulp, Pre-treatment of chelating agent improved viscosity clearly and decreased noneffective decomposition of hydrogen peroxide extremely. Combination of both was very effective way for improving hydrogen peroxide bleaching efficiency. To obtain full brightness (89%ISO), it needed only 11.5kg hydrogen peroxide consumption for one ton unbleached pulp and gave very good pulp quality.