ANTHRAQUINONE AND POLYSULFIDE-APPLICABILITY FOR USE IN PULP MILL OPERATIONS, 2002 Kraft Pulp Yield Symposium

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Anthraquinone has been touted as the wonder chemical for the kraft pulping process for the past twenty years. Claims of increased yield, increased profits, reduced kappa numbers to the bleach plant, and reductions in operating cost have been made, but these benefits have been difficult to prove. As a result, anthraquinone and polysulfide cooking have not gained a wide following in North America. While anthraquinone has not proven itself in the United States, Japanese mills have accepted these chemicals into their cooking processes and have achieved the favorable results mentioned above. Why is that? This paper will explore the reasons for switching to anthraquinone/polysulfide pulping and ways to quantify the results. In addition, the cost of installing a polysulfide system into an existing causticizing line will be explored. The drawbacks or possible problems with anthraquinone/polysulfide pulping will also be discussed.