Positive and negative aspects of soda/anthraquinone pulping of hardwoods
2008
Francis, R.C. | Bolton, T.S. | Abdoulmoumine, N. | Lavrykova, N. | Bose, S.K.
The positive aspects of the non-sulfur soda/anthraquinone (SAQ) process are mostly tied to improved energy efficiency while lower pulp brightness after bleaching is its most significant drawback. A credible method that quantifies bleachability as well as an approach that solves the problem for SAQ pulps from hardwoods will be described. A straight line correlation (R ² =0.904) was obtained between O₂ kappa number and final light absorption coefficient (LAC) value after standardized OD₀EpD₁ bleaching of nine hardwood kraft pulps from three laboratories and one pulp mill. The bleachability of pulps from four different soda processes catalyzed by anthraquinone (AQ) and 2-methylanthraquinone (MAQ) was compared to that of conventional kraft pulps by comparing O₂ kappa number decrease and final LAC values. It was observed that a mild hot water pre-hydrolysis improved the bleachability of SAQ pulps to a level equal to that of kraft.
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