Evaluation of the SuperBatchTM Pulping Process for Pinus taeda, 2007 Engineering, Pulping & Environmental Conference

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In this research was evaluated the efficiency of the SuperBatch™ kraft pulping process in comparison to conventional pulping process as well as the effects of anthraquinone (AQ) aiming the production of unbleachable grades (kappa number 58 ± 2) for Pinus taeda with 9 years old, the main specie used in Brazil to produce long fiber pulp. A study of the impregnation phase in the conventional cooking was performed; the heating up time was variable and the time at the maximum temperature was adjusted to a H-factor of 2300. It was also studied the evolution of the delignification during the SuperBatch™ and conventional process. The pulping results show that in the SuperBatch™ process a smaller amount of rejects was produced than conventional process; the addition of anthraquinone was efficient to reduce the kappa number in the SuperBatch™ process, however without significant gains of selectivity; in the conventional process with the addition of AQ a reduction of 0,5 percentual points in the initial active alkali was possible. During the evaluation of the impregnation phase in the conventional process the adoption of a longer time during the heating up phase results in a reduction of the rejects and an increase in the screened yield. Finally, in the study of the delignification during the cooking, the logistic mathematical model developed showed a good adjustment with three phases identified for all the cases: (i) initial delignification phase when a small amount of lignin is removed, (ii) bulk delignification phase, when the intensity of delignification increases and most of the lignin is dissolved and (iii) residual delignification phase, when the delignification is small again. In the SuperBatch process during the impregnation phase, practically did not happen any reaction between reagents and lignin; during the hot black liquor (HBL) about 25-30% of the lignin is dissolved and in the bulk phase about 50-55%. The addition of AQ in the SuperBatch process increased the intensity of the reactions with the lignin, resulting in a faster delignification during the bulk delignification.