Chlorine dioxide bleaching of soda-anthraquinone jute pulp to a very high brightness.
Bleaching of soda-anthraquinone jute pulp by chlorine dioxide (ClO2) was studied to reach a target brightness of above 88% for the purpose of using less bleaching chemicals. The performance of either chlorine dioxide or peroxide in the final bleaching to boost brightness was also studied. The experimental results revealed that the final brightness depended on ClO2 charge in the Do and D1 stages. The brightness reversion was lower when the final stage brightening was done by peroxide. The use of Mg(OH)2 in the D1 and D2 stages improved the final brightness due to the formation of less chlorate and chlorite during the Mg(OH)2- based ClO2 brightening stages. The strength properties of pulp bleached by peroxide in the final stage was slightly better than that from ClO2 as the final ClO2 bleaching stage.
The Effect of Pulp Pad Dryness in Determining Brightness using Non-Standard Fast Drying Methods
In integrated pulp and paper mills a rapid pulp brightness determination method is needed at the pulp mill for quality and process control. In this study, the effect of dryness on the brightness reading of pulp pads has been studied. The results showed that in comparison with that from the TAPPI standard test procedure, the brightness was significantly lower when the pulp pad dryness was lower than 50%, implying that at pulp mills, the pulp pads should be dried quickly to a dryness of about 50% or higher in order to give rapid, yet reproducible brightness results. For this purpose, a forced hot air dryer was designed to dry the pulp pads to 50 to 60% dryness in about 15 minutes. The pulp pads which were dried with the forced hot air dryer had similar brightness readings to those prepared and dried by following the TAPPI standard method. Alternatively, a microwave oven can be used for the same purpose, and the pulp pads can be dried to about 50% dryness in 2.5 minutes.
P-RC alkaline peroxide mechanical pulping of hardwood, part 1 : aspen, beech, birch, cottonwood and maple. Birch gives the highest strength properties
Les proprietes physiques intrinseques de feuilles d'essai de pâtes APMP P-RC a partir de peuplier faux-tremble, hetre a grandes feuilles, bouleau et peuplier deltoide ont fait l'objet d'une etude. Les resultats ont indique que lorsqu'il est compare au meme degre de resistance a la traction, le bouleau offre le bouffant le plus eleve, suivi du peuplier deltoide, puis des trois autres a environ un meme degre. Les pâtes APMP et P-RC d'erable argente et de peuplier faux-tremble presentaient un degre eleve de resistance a la traction a la meme densite, ou un bouffant plus eleve a la meme resistance a la traction, que les pâtes kraft fabriquees a partir des memes essences. Les raisons de la difference sont discutees.