Recovering good fibers from rejects for the sulfite pulping process

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University of New Brunswick


In the pulp and paper industry, sulfite pulping makes up less than 4% of the global market. In New Brunswick, Twin Rivers Paper is the only bisulfite chemical pulping mill that produces specialty paper grades including labels, packaging, publishing paper. In order for Twin Rivers Paper to remain competitive in the sulfite pulping industry, it must continue to produce high quality pulp while ensuring the process is optimized to achieve a high pulping yield. For this reason, recovering good pulpable fibers from rejected chips would be economically beneficial for the mill to increase their pulp yield while decreasing costs associated with waste. The objective of this research is to treat the rejected chips mechanically to recover the fibers. The proposed process concept is to use a mechanical disintegration followed by a screening process to recover the good fibers. Different pre-treatments including additional mechanical action and a rinsing process step are examined in order to further increase the yield. Once the good fibers were recovered, the pulp was bleached and the strength was tested. After completing the experiment, the optimal process for adding the recovered fibers to the pulp mainline has been evaluated.