Study On The Quality Improvement Of Bagasse Pulp

The bagasse,a by-product in the sugar industry,has been a significant raw material for pulping and paper making.In this study,the bagasse was classified into various fractions by screen with different meshes.The fiber morphology of various fractions,and properties of chemical and chemi-mechanical pulp were studied.Chemical and chemi-mechanical pulping processes of the fraction retained on 40 mesh screen?+40 fraction?were optimized.The main objective of this study was to develop the potentiality of bagasse used for pulping and paper making and improve the quality of bagasse pulp.The results of chemical pulping showed that,in same cooking condition,the kappa numbers and yields of pulps made from various fractions retained on 40 mesh screen had no obvious difference,while the chemical pulping performance of the fraction passing through 40 mesh screen?-40 fraction?was very poor,and the kappa number of unclassified bagasse pulp was higher and its yield was lower than those of pulp made from the +40 fraction.The results of the fiber morphology detection showed that with the increase of the screen meshes,the fiber length of the fraction decreased.With the increase of the screen meshes,the strength properties of chemical pulps decreased,especially the-40 fraction.So the-40 fraction should be removed as more as possible.Investigation on EpDP bleaching process of chemical pulp made from the +40 fraction showed that,the optimal conditions of Ep were as follows:NaOH dosage 2%,H₂O₂ 0.5%,75 ? for 120 min;the optimal conditions of D were:ClO₂ 1%,70'C for 60 min;the optimal conditions of P were:H₂O₂ 2%,MgSO₄ 0.3%,80? for 150 min.Under the optimum bleaching conditions,the brightness of bleached chemical pulp was 87.2%ISO,the yield was 92.49%and the viscosity was maintained at 1196 mL/g.Investigation on pulping and bleaching process of cold alkali chemi-mechanical pulp made from the +40 fraction showed that,the optimal conditions of pre-impregnation were as follows:NaOH 2%,25 ? for 60 min;the optimal conditions of P1 as follows:H₂O₂ 2%,NaOH 2.5%,60? for 120 min;the optimal conditions of P2 were:H₂O₂ 2%,NaOH 1%,60 ? for 120 min.In these conditions,the brightness of bleached cold alkali chemi-mechanical pulp was 61.2%ISOEach fraction of bagasse was used to produce bleached cold alkali chemi-mechanical pulp in the same process conditions.The results of fiber morphology detection showed that with the increase of screen mesh,the fiber length of bleached bagasse cold alkali pulp gradually decreased,while the fiber width and coarseness increased gradually.Comparison of all fractions' physical properties showed that,the tensile index,burst index,ring crush,bending stiffness and bulk of bleached cold alkali chemi-mechanical pulp made from various fractions retained on 40 mesh screen had no obvious difference.The bulk of the-40 fraction was higher than those of other fractions.The dirt count and other strength properties of the-40 fraction were very poor.If brightness is not important,a few parts of the-40 fraction can be retained to increase the bulk of the pulp.