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Effect of pulping conditions on deinking of wood-containing recovered paper grades

Pulp & paper Canada, 1999-04, Vol.100 (4), p.37-41

1999 INIST-CNRS ;Copyright Southam Business Communications, Inc. Apr 1999 ;ISSN: 0316-4004 ;EISSN: 1923-3515 ;CODEN: PPCADD

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  • Title:
    Effect of pulping conditions on deinking of wood-containing recovered paper grades
  • Author: Ackermann, C ; Putz, H.J ; Gottsching, L
  • Subjects: alkaline pulping ; Applied sciences ; Deinking of paper ; Exact sciences and technology ; Paper, paperboard, non wovens ; Polymer industry, paints, wood ; Pulp & paper industry ; Pulp manufacturing ; R&D ; recycling ; Research & development ; waste paper ; Wood. Paper. Non wovens
  • Is Part Of: Pulp & paper Canada, 1999-04, Vol.100 (4), p.37-41
  • Description: The curves of the hyperwashed pulps are similar to the results achieved by flotation, Fig. 3. Therefore, the flotation results are based on a different ink detachment during pulping. Despite the total de-ashing realized by hyperwashing the brightness is on average 2% higher than the brightness of the rotated pulp samples. The brightness difference between hyperwashing and flotation is, in the case of alkaline conditions, the largest at low consistency pulping and becomes smaller with higher consistency. This effect is reversed for neutral pulping conditions where the difference between hyperwashing and flotation is most significant at 18% consistency. Low consistency slushing is advantageous especially for neutral pulping conditions, where the ink detachment is primarily based on the mechanical shear forces,. At alkaline conditions this effect is also influenced by the deinking chemicals (ink detachment effect of alkali and bleaching effect of peroxide). Process combinations: To make an objective comparison possible between alkaline and neutral pulping, the process stages based on a single flotation have to be extended, to include a separate bleaching stage for the treatment of the neutrally deinked pulp. Besides pulping and first flotation, dispersion both with and without addition of bleaching agents was combined with a second flotation stage as well as with post-bleaching. Figure 5 shows the development of brightness for recovered paper processed in both an alkaline and neutral environments. Combinations with optimized consistency ranges for alkaline and neutral pulping were chosen: The absence of alkali in commercial processing is accompanied by a significant reduction in brightness because of poorer printing ink detachment during pulping. The lab trials in this paper show the possibilities on how to improve neutral deinking results by modifications of the mechanical conditions in recovered paper processing. The brightness results depend strongly on pulping consistency. Under alkaline conditions increasing pulping consistency improves brightness. On the other hand, with neutral pulping the trend gets reversed. Low consistency pulping leads to improved flotation as well as wash deinking results. The effect of the type of surfactants seems to be insignificant under these conditions.
  • Publisher: Don Mills, ON: Southam
  • Language: English
  • Identifier: ISSN: 0316-4004
    EISSN: 1923-3515
    CODEN: PPCADD
  • Source: AUTh Library subscriptions: ProQuest Central
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