Digester additives are used to improve the cooking process in chemical pulping: Anthraquinone (AQ) is used to improve yield, improve pulp quality or debottlenecking; dispersing agents or wetting agents may be used as replacement for tall oil or to improve homogeneity and improve pulp quality.
Anthraquinone (AQ) is delivered as a 50 % waterborne dispersion, containing small amounts of emulsifier and stabiliser, that gives easier handling properties. AQ can be used in alkaline or neutral cooking processes such as kraft, soda and NSSC (Neutral Sulphite Semi Chemical). The AQ goes through a redox cycle that gives a catalytic effect that reduces peeling and increases the delignification speed. This lowers Kappa, H-factor and chemical demand and increases yield.
Digester aids are surface active chemicals that improve penetration of cooking liquors and drive air out of the wood chips. They can also disperse and stabilise neutral extractives in the wood. Digester aids can be used in all chemical and semi-chemical pulping processes and can be used as a replacement for tall oil. The effect is a more homogenous cook and the level of extractives in the pulp out of the digester is reduced. Synergy effects with AQ are often seen.
Nopco has years of experience in digester additives and will help you to find the correct solution to your individual needs.