Newsprint content

Paper recycling has greatly increased in Canada, from one mill making recyded-content newsprint in 1989 to 60 paper recycling operations in 1995... 

Lin and Kringstad (7) confirmed Leary s results in an experiment with a solution of milled wood lignin (MWL) in methylcellusolve water. Irradiation of this solution in a vacuum produced no colour. This solution, opened to air and irradiated, produced the same amount of colour as a solution of milled wood lignin initially irradiated in air. The effect of oxygen on light-induced yellowing of newsprint is further illustrated by the accompanying effect on methoxyl content. Leary found that the methoxyl content of newsprint after irradiation in a vacuum decreased by only 0.1% whereas the same irradiation in air decreased the methoxyl content by 0.4% (6). 

Solvent Extraction (1A, IB). A single frozen book was set in a container and submerged in precooled anhydrous solvent. The container was then sealed and stored in a freezer. As the ice dissolved, the water-solvent mixture was replaced with anhydrous solvent until the moisture content in the book was reduced to that known for the original preflooded book. At this point, excess solvent was removed, and the book was interleaved with newsprint and stored at room temperature. During this storage, fresh paper was interleaved several times to remove the solvent. Both samples A and B were treated by the same technique however, it was used at two different times. In this set of experiments, absolute anhydrous ethyl alcohol was used. 

Table II shows the calcium content in paper from the chemical feeder process. With the addition of 9.2 ppm Ca in DI water, the treated newsprint papers calcium content doubled in comparison with the control. The treated Foldur Kraft paper contained three times more calcium than did the unwashed paper. The more calcium that was added in the DI water, the higher the amounts of calcium absorbed in the papers during the washing and deacidification process. However, the absorption of calcium in the paper reached a saturation point. This is the reason why newsprint and Foldur Kraft papers that are treated with 36.4 ppm Ca in the Dl-Ca water imbibed the same amount of calcium as the papers washed with 112.8 ppm Ca in the Dl-Ca water.

Product quality is much superior (e.g., newsprint, which yields superior strength properties in steam and permits use of lower chemical pulp content to attain same strength and runnability). 

The deinking plant is located in Quebec. It uses 80 % old news paper and 20 % old magazines furnish to produce deinked pulp. The plant is located next to a thermo mechanical pulp newsprint mill to which part of the deinked pulp is sent to produce 30 % recycled content paper. The recycling facility was built in the early nineties, and was subsequently modernized at the end of the decade in order to increase its production capacity. During the upgrade, several modifications were made to the pulp treatment sequences and the process water circulation layout. It is estimated that the fresh water intake has been reduced from approximately 21 to IS tons per ton of oven dried pulp produced. Figure 1 shows a simplified layout of the present day plant. 

Poirier and Sparkes [78] have successfully run a two-roll impulse drying unit at PAPRICAN pilot paper machine at speeds up to 800 m/min. Solids contents of 60% have been achieved with newsprint using this single-nip arrangement. 

Improved newsprint has a high filler content and is calendered to obtain a more closed surface. It is used, e. g., for book and offset printing. The ISO brightness is about 10 units higher than the mean brightness of standard newsprint [14],... 

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