Papermaking Properties of Aspen NSAQ Pulp, 1999 Pulping Conference Proceedings

Al Wong

Arbokem Inc.

Although kraft pulping is the de facto industry standard, neutral sulphite pulping offers unique advantages in the pulping of hardwoods such as aspen (Populus tremuloides). Higher yield and higher brightness of unbleached pulp could be achieved. Moreover, neutral sulphite pulping can provide an opportunity to establish a chemical-grade pulp mill that could be sustained with a smaller wood supply base and concomitant economic viability.

Samples of aspen chips from the Lac St. Jean region of Quebec were pulped and bleached in the laboratory. The neutral sulphite-anthraquinone (NSAQ) pulping technique was used. An unbleached pulp yield of 62% was achieved at a screened Kappa number of 16.7. The pulp was subsequently bleached in two-stages: medium-consistency oxygen followed by chlorine dioxide. The final pulp brightness was 88.4 points Elrepho.

The pulp strengths were tested and compared against those of commercial hardwood kraft pulps, viz., Alberta aspen, Brazillian eucalyptus and Korean mixed hardwood. Preliminary test results showed that aspen NSAQ pulp had strength characteristics that are comparable to the hardwood kraft pulps evaluated.