Future Pulping Technologies, 1992 TAPPI Conference Proceedings

Increasing environmental concerns have been the driving force for the development and implementation of new pulping technologies. Future pulping technologies will include both modifications to kraft pulping and non-conventional pulping technologies.

In conventional kraft pulping, the kappa number was limited to 30 for softwoods due to the severe loss in pulp strength at kappa numbers less than 30. Modifications to the kraft process have been aimed at lowering the kappa number by changing the process conditions. With these changes it is possible to cook to a kappa number of 15 as compared to 30 for conventional kraft, with no loss in pulp quality. The major benefit is the reduction in the environmental impact of bleaching. Future research is aimed at lowering the kappa number even further, with improved bleachability and yield.

Non-conventional technologies include the use of pure solvents to remove the lignin from wood (ALCELL, ACETOSOLV, MILOX), inorganic-organic solvent processes (ORGANOCELL, ASAM) and even biopulping. These processes aim to produce pulps with qualities similar to kraft, which being environmentally benign with respect to odors. Biopulping in its present stage of development provides for a method to pretreat the chips in mechanical pulping.