Anthraquinone effect on kraft cooking curve for the wood of Eucalyptus grandis x Eucalyptus urophylla hybrid

Abstract

This study aimed to evaluate the effects of anthraquinone addition in the cooking curve, with different loads of reagents, through the kraft pulping process, of Eucalyptus grandis x Eucalyptus urophylla wood, to infer about the process parameters. The wood was transformed into chips and classified to conduct the kraft cooking curves. The applied loads were from 10% to 24% of active alkali, with an anthraquinone charge of 0.05% (on dry wood). We evaluated raw and screened yield, reject content, kappa number (delignification level) and residual active alkali. We observed that the addition of anthraquinone did not affect the process raw yield, but increased the screened yield by reducing reject content, especially for low loads of active alkali (10% and 12%). Another effect observed was the reduction of the kappa number with the addition of anthraquinone, which indicates the increase of the wood delignification rate. This is reinforced by the lower residual active alkali, which implies greater use of reagents in the process.