Stretching the Fiber Supply With Improved Bleaching Technology, 1997 Pulping Conference Proceedings
This paper is a review of the current and emerging bleaching technology for recycled fiber and investigates ways to stretch the current fiber supply. Lower quality grades of recycled fiber furnishes were examined. The current technology in using various oxidative-reductive type bleach sequences was examined. The Eop-FAS bleaching system was investigated to determine what its limitations are, and how the system can be stretched. High temperature peroxide at 110 o C (P110) was found to be more effective than an oxygen-peroxide combination (Eop) for brightening and color stripping of MOW furnishes. For ONP / OMG recycled fiber furnishes, lower temperature peroxide bleaching at 60 o C (P60) is the most effective and provides the greatest cost savings.
If an improved bleaching sequence is not an option at a MOW mill, higher dosages of chemicals and higher bleaching temperatures, or diluting the furnish with sorted white ledger, can achieve the required brightness on some furnishes. New, more powerful bleaching sequences will need to be developed for the lowest quality furnishes. To stretch the fiber supply, lower quality grades of recycle fiber furnishes can be utilized, bleaching conditions for each stage of a sequence, and the type of sequence must be optimized for brightening and color stripping, and chemical, equipment, and process cost savings must be examined.