Effect of chemical charges in cooking and their effectiveness on pulp bleaching

The screened Eucalyptus camendulensis chips were cooked in the laboratory at various alkalinities (14, 16, 18 and 20 per cent) and sulphidity (20, 30 and 40 per cent). Due to the variation in chemical charge, the pulp yield was found to be different. The average pulp yield was 50.6 per cent after washing and the final yield was obtained 40 per cent, which followed the normal kraft yield trend. Bleaching was done with the pulp of maximum final yield obtained. By avoiding oxygen delignification stage, pulp was bleached directly by using D0ED1 sequence of elementary chlorine free bleaching. The average brightness and viscosity after final stage were 79.9 per cent ISO and 614 mL/g, respectively. Improvement in brightness was remarkable, but the viscosity decreased.