ISSN ………… - International Network for Bamboo and Rattan

presence of hydrogen peroxide) at 140-150 0 C and high oxygen pressures in the range of 20-40 bar.
The pressure cooking is carried out at low consistency to maintain the temperature level. To avoid
insufficient oxygen penetration into the wood very thin chips (< 1.5 mm) must be used. The pulps are
generally obtained in high yields and good brightness, but the strength properties are usually not
comparable to those of kraft pulps. Strength improvements can be obtained by sodium hydrogen
carbonate pre-cooking, increasing the carbon dioxide content in the gas phase, and by addition of
potassium iodide or other metal compounds as cellulose protectors (Fujii and Hannah 1978).
In the alkaline–AQ-peroxide process, delignification is carried out in two stages with a refining step
in between. The first stage is a high-yield soda-AQ cook down to kappa numbers of 50-60. The
second delignification step is performed as a medium to high consistency (>10%) hydrogen peroxide
bleaching (