Advertisement

Removal of Shives

Chapter

Abstract

Cleanliness is a very important quality parameter of a bleached chemical pulp. The main objective of bleaching kraft pulp to full brightness is to produce a white, strong, clean, and stable pulp that is suitable for high-quality grades of printing paper. It is natural to stress brightness and cleanliness while properties such as strength are given a lower priority. However, for most purposes, cleanliness is more critical than brightness and the advantages of bleaching to a very high brightness are, therefore, not always evident. The reason for bleaching to a very high brightness is that this indirectly guarantees an acceptable cleanliness or that customer demands are not always necessarily related to the end product demand. For many paper grades, a significantly lower bleached pulp brightness can be accepted if the cleanliness is sufficient. During most of the bleaching operation, the shives decrease significantly. Normally, bleaching to make market pulp removes 95–99% of the shives. Better cleanliness is obtained using bleaching in short sequences. Some advances in mill techniques such as whole tree utilization intensify the cleanliness problems. Another is closing up of the screening department including recycling the screenings. On the other hand, improved bleaching techniques with more extensive use of chlorine dioxide permit prolonged cooking without excessive carbohydrate degradation during cooking and bleaching. The resulting pulp has fewer and probably less shives. Xylanase enzymes have also been found to be effective in removing shives. By treating the brown stock with xylanases, mills can substantially increase the degree of shive removal in the subsequent bleaching. Xylanase enzymes can increase the degree of shive removal by 50% in the subsequent bleaching. At a given bleached brightness, Xylanase treatment results in a lower shive count. Xylanase treatment, therefore, helps to remove shives from the pulp beyond the associated gain in the brightness. Removal of shives and ease of pulp bleaching by the use of xylanases also helps in reducing the energy requirement.

Keywords

Shives Cleanliness Enzymes Xylanases Brightness Bleaching Shivex Shives removal 

References

  1. Annergren GE, Lindblad PO (1996) Shives/brightness: a problem of bleaching optimization. Tappi J 59(11):95–98Google Scholar
  2. Axegard P (1980) Effect of prebleaching with chlorine and chlorine dioxide on the cleanliness of softwood kraft pulp. Svensk Papperstidn 83(10):284Google Scholar
  3. Axegard P (1990). Bleaching shives and dirt—an overview. Paper presented at 1990 Bleach Plant Operations Short Course held 17–22 June, 1990 at Hilton Head, SC, USA, pp 27–34Google Scholar
  4. Axegard P, Teder A (1976) Model experiments in bleaching of shives and bark particles. In: 1976 International of Pulp Bleaching Conference 2–6 May 1976, pp 35–43Google Scholar
  5. Bajpai P (2004). Biological bleaching of chemical pulps. Criti Rev Biotechnol 24(11):1–58Google Scholar
  6. Bajpai P (2009) Xylanases. In: Schaechter M, Lederberg M (eds) Encyclopedia of microbiology, 3rd edn, vol 4. Academic Press, San Diego, California, USA, pp 600–612Google Scholar
  7. Bajpai P, Bajpai PK (1992) Biobleaching of kraft pulp. Process Biochem 27:319–325CrossRefGoogle Scholar
  8. Bajpai P, Bajpai PK (1997) Realities and trends in enzymatic prebleaching of kraft pulp. Adv Biochem Engg/Biotechnol 57:1–31Google Scholar
  9. Bruun H, Henricson K, Kronlof T (1993) Particles in bleached softwood sulphate pulp and their reduction. Pap Puu 10(3):126Google Scholar
  10. Germgard U, Sjogren B (1985) Ozone prebleaching of a modified cooked and oxygen bleached softwood kraft pulp. Svensk Papperstidn 88(15):R127Google Scholar
  11. Grant R (1994) Enzymes future looks bright, as range improves and expands. Pulp Pap Int 36(8):20Google Scholar
  12. Grant R (1995) Enzymes help to increase pulp and paper production. Pulp Pap Int 37(8):26Google Scholar
  13. Hancock B, Esteghlalian AR (2007) New technology tools discover enzyme products to enhance pulp bleaching. In: 2007 Engineering, pulping and environmental conference, 21–24 Oct 2007, Jacksonville, FL, USA, 4 ppGoogle Scholar
  14. Lavielle P (1993) Xylanase prebleaching. Asia Pac Papermaker 3(5):29Google Scholar
  15. Pedersen LS, Choma PP, Holm HC, Kihlgren P, Munk N, Nissen AM (1992) Enzymatic bleach boosting of kraft pulp: laboratory and mill scale experiences. Paper presented at 1992 Pulping Conference held 1–5 Nov 1992 at Boston, MA, USA, Book 1, pp 31–37Google Scholar
  16. Robitaille MA (1991) Policing dirt and plastic contamination Bleach Plant Operations Short Course Notes, Tappi Press, Atlanta, p 39Google Scholar
  17. Senior DJ, Hamilton J (1992) Use of xylanases to decrease the formation of AOX in kraft pulp bleaching. J Pulp Pap Sci 18(5):J165–J169Google Scholar
  18. Skerker PS, Farrell RL, Chang HM (1991). Chlorine free bleaching with Cartazyme HS treatment. In: Proceedings of the international pulp bleaching conference, Stockholm, vol 2, pp 93–105Google Scholar
  19. Tolan JS (1992a) The use of enzymes to decrease the chlorine requirements in pulp bleaching. In: 78th CPPA annual meeting, preprints, Montreal, pp A163–A168Google Scholar
  20. Tolan JS (1992b) The use of enzymes to enhance pulp bleaching. In: Proceedings of Tappi pulping conference, Boston, MA, Nov 6–10, pp 13–17Google Scholar
  21. Tolan JS, Guenette M, Thebault L, Winstanley C (1994) The use of a novel enzyme treatment to improve the efficiency of shive removal by bleaching. Pulp Pap Canada 95(12):T488Google Scholar
  22. Viikari L, Tenkanen M, Buchert J, Ratto M, Bailey M, Siika-aho M, Linko M (1993) Hemicellulases for industrial applications. In: Saddler JN (ed) Bioconversion of forest and agricultural plant residues, CAB International, Wallingford, pp 131–182Google Scholar
  23. Viikari L, Kantelinen A, Sundquist J, Linko M (1994) Xylanases in bleaching: from an idea to the industry. FEMS Microbiol Rev 13:335–351CrossRefGoogle Scholar

Copyright information

© Springer Nature Singapore Pte Ltd. 2018

Authors and Affiliations

  1. 1.Pulp and Paper ConsultantKanpurIndia

Personalised recommendations