Reduction of Soda Usage for Acacia Kraft Pulp by Mechanical Pretreatment, 2007 Engineering, Pulping & Environmental Conference

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The effect of mechanical pretreatment prior to oxygen delignification was investigated in this study. An Acacia mangium brownstock kraft pulp was used to evaluate the effect of oxygen delignification and mechanical pretreatment with regard to wet zero-span tensile strength (WZSTS), dry zero-span tensile strength (DZSTS) and tensile index of the pulps. A laboratory Quantum mixer was employed to perform mechanical pretreatment at 10 % consistency prior to oxygen delignification. Mechanical pretreatment followed by oxygen delignification was not found, to some extent, to affect pulp DZSTS and tensile index losses. The effect of mechanical pretreated pulp on oxygen delignification process parameters was also studied. The result was analyzed with the Yates’ algorithm analysis and this showed that NaOH addition and temperature were the most detrimental to pulp WZSTS, DZSTS and tensile index losses. Kappa number was affected only by reaction temperature of oxygen delignification. This suggested that the use of NaOH addition could be reduced to compensate the mechanical pretreatment to retain the strength at certain reaction temperature of oxygen delignification. NaOH addition could be reduced as much as 51 % by applying mechanical pretreatment to obtain the same level of selectivity at the oxygen delignification conditions as described in this experiment.