Métodos indiretos para avaliar a perda de rendimento do branqueamento de polpa kraft

• Autor(a) principal: Gomes, Regina Maria
• Data de Publicação: 2012
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/3109
• topic: Branqueamento; Medição rendimento; Polpa kraft; Bleaching; Performance measurement; Kraft pulp; CNPQ::CIENCIAS AGRARIAS::RECURSOS FLORESTAIS E ENGENHARIA FLORESTAL::TECNOLOGIA E UTILIZACAO DE PRODUTOS FLORESTAIS

The cellulosic pulp bleaching aims to either remove or transform the chromophore groups of the pulp, so the final product reaches the desired brightness but the bleaching causes an inevitable loss of yield. Therefore, this work was done with the intention of proposing the use the dissolved solids content (SD), the chemical oxygen demand (DQO) and the total organic carbon (TOC) of each bleaching stage as indirect techniques to qualify the yield loss. It was used industrial eucaliptus kraft pulps (unbleached pulp and Oxygen predelignified pulp). The industrial brown pulp was used to analyze the yield losses during the oxygen deslignification. The Oxygen predelignified eucalyptus kraft pulp was subjected to the D*(EP)D bleaching sequence and the first stage D* was done with five kappa factors (0,12; 0,16; 0,20; 0,24; 0,28). Stages (EP) and D were done at two different temperatures (75°C and 90°C). The gravimetric yield loss of each stage bleaching stage was determined. The filtrate for each stage and the combined filtrate for each sequence were evaluated by the SD, DQO and TOC technique. Correlations were established among the three measurement methods (gravimetric, COD and TOC) and it was tested with an identity test. Analyzing the results it can be concluded that all of three proposals can be used for an indirect determination for the yield loss. The SD and TOC techniques are the most indicated in order to determine the yield loss in the Pre-O2 and in the D*(EP)D bleaching, respectively. Every SD percentual unit corresponds to 2,19% of yield loss in the Pre-O2. Each unit of TOC (kg C/t pulp dry) corresponds to 0,27% of yield loss, considering the temperatures of 90°, 90° and 75° C in the stages D*, (EP) and D, respectively, and independently of the kappa factor in D* in the range of 0,12 to 0,28. The yield losses in every stage and in the whole sequence are influenced by the employed conditions, therefore there is not a general equation which provides this indirect determination.