Estudo comparativo da branqueabilidade de polpas kraft de Pinus radiata e de uma mistura de Eucalyptus globulus e Eucalyptus nitens

• Autor(a) principal: Andrade, Marcela Freitas
• Data de Publicação: 2010
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5934
• topic: Aperfeiçoamento; Branqueamento ECF; Dióxido de cloro; Polpa Kraft; Pinho; Eucalipto; Improvement; ECF bleaching; Chlorine dioxide; Kraft pulp; Pine; Eucalyptus; CNPQ::CIENCIAS AGRARIAS::RECURSOS FLORESTAIS E ENGENHARIA FLORESTAL::TECNOLOGIA E UTILIZACAO DE PRODUTOS FLORESTAIS::TECNOLOGIA DE CELULOSE E PAPEL

In recent decades, the pulp industry has been changing and improving its manufacturing processes in order to improve production capacity, product quality and environmental performance. The bleaching unit at Valdivia, Arauco Group, operates pulps of Pinus radiata (Pine) and a mixture (30/70%) of Eucalyptus globulus and Eucalyptus nitens (Eucalyptus) in a same D(EPO)DD bleaching sequence. The aim of this study was to optimize the D(EPO)DD sequence to reduce the consumption of chlorine dioxide (ClO2) and the cost of reagents for the two types of pulp. Results of the improved process were compared with those obtained in the operating conditions existing at the mill for the use of ClO2, bleaching cost, physicochemical properties of the pulps and effluent pollution load. Pulps from pine and eucalyptus were pre- delignified with oxygen kappa numbers 10 and 9 respectively. The study consisted of the evaluation of the carryover, kappa factor, temperature and pH of the first stage of deoxidation, temperature and doses of H2O2 and O2 of the (EPO) stage, and pH and ClO2 dose of the second and third stages of deoxidation of the D (EPO) DD sequence. The improved condition allowed a reduction of 1.60 kg ClO2/odt for pine pulp and 4.50 kg ClO2/odt for eucalyptus pulp, without loss of pulp and effluent quality, comparing with the reference values (current operating conditions at the mill). The bleaching cost in the improved condition was US$ 2.90/odt and US$ 8.70/odt lower than the reference values for pine and eucalyptus pulps respectively. The study showed that the variables that most influenced the cost of bleaching chemical reagents were the pH of the second stage of deoxidation and the temperature of the (EPO) stage for Eucalyptus pulp. For the pine pulp, the most important variables were the kappa factor of the first stage of deoxidation and the temperature of the (EPO) stage.