Evaluation for improvement of stickies at Utzenstorf Papier
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
The recycling of paper and paper products is an important step in the long‐term development of our society. By recycling the paper a more closed circulation of the compounds and additives used in the refining steps of the production occurs and the accumulation leads to difficulties. One of the difficulties concerns stickies. The primary stickies are directly developed during the pulping of recycled products and the secondary stickies occurs by agglomeration of dissolved and colloidal compounds originating from the recycled paper.
By taking samples from the whole process, the important steps were identified. Concerning macro stickies, the most important step is the fine screening. With two similar de‐inking lines, having their largest difference in how suitable the fine screening, is the differing levels of macro stickies is obvious. The fine screening is the most important step in reducing the load of stickies reaching the paper machine. Re‐arranging DIP 1 into a part‐cascade operation gave a small improvement compared to the potential of an upgraded fine screening. Several trials were made to test the influence of different parameters. An equal air‐pressure in the secondary flotation cells did not eliminate the differences between two parallel lines. Agglomeration of stickies in order to improve the fine screening macro stickie reduction did not show the desired effect. By‐passing of the coarse screening showed a slight quality improvement with less stickies but at the cost of system reliability.Treating the secondary stickies with a de‐activating protein and attaching them to the fiber web with fixing agents makes it possible to lower the stickie load in the white water system. The detackyfying agent had a positive effect on the holes detected by the camera system monitoring the paper web.Continuous measurements of macro stickies and of the colloidal and secondary stickies in the system improve the evaluation of future reconstructions and trials.
Place, publisher, year, edition, pages
2011. , 60 p.
Pulp, Screening, Recycled Fibers, De-inking, Flotation
Massa, silning, retur papper, avsvärtning, flotation
IdentifiersURN: urn:nbn:se:kth:diva-30341OAI: oai:DiVA.org:kth-30341DiVA: diva2:413406
UppsokPhysics, Chemistry, Mathematics