Qualidade da madeira de eucalipto para produção de celulose kraft

• Ano de defesa: 2012
• Autor(a) principal: Fantuzzi Neto, Humberto
• Orientador(a): Gomide, José Lívio
• Banca de defesa: Carvalho, Ana Márcia Macedo Ladeira , Oliveira, José Tarcisio da Silva , Silva, Teresa Cristina Fonseca da
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Ciência Florestal
• Departamento: Manejo Florestal; Meio Ambiente e Conservação da Natureza; Silvicultura; Tecnologia e Utilização de
• País: BR
• Palavras-chave em Português: Eucalyptus; Qualidade; Madeira; Densidade básica; NIRS; Palpação
• Palavras-chave em Inglês: Eucalyptus; Quality; Wood; Basic density; NIRS; Palpation
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::RECURSOS FLORESTAIS E ENGENHARIA FLORESTAL::TECNOLOGIA E UTILIZACAO DE PRODUTOS FLORESTAIS
• Link de acesso: http://locus.ufv.br/handle/123456789/572

In Brazil, planted forests are the main source of supply wood for the forest-based industry. The planted area corresponds to 6.5 million hectares in which 73% of the area is constituted of Eucalyptus and 23% with Pinus. The planted area for pulp and paper production reached 2.2 million hectares in which 1.7 million hectares corresponds to Eucalyptus plantation and 500,000 hectares to Pinus plantation. Brazil stands out worldwide in pulp production currently occupying the fourth position, with a production of 14.2 million tons of pulp per year. The territorial extension of the country, the climate and the investment in breeding research which allowed high levels of forest productivity with an average of 45 m3/ha of wood per year, contributed to the lower cost of the worldwide production attracting the attention of investors. The breeding program aims to generate clones with high wood quality and high forest productivity. The wood shows significant variability in quality, influencing the entire industrial process which can cause decrease in yield, affect the quality of the final product, increase the costs and decrease the profit. Despite the knowledge of the wood chemical composition, it is difficult to predict its behavior during the pulping, then it is needed to associate the results of wood chemical analyzes with the results of pulping and the aspects of forest growth, treating pulp production as an integrated forest-mill process to reduce costs and increase the production. The criteria of the analysis of wood quality of Eucalyptus for kraft pulp production were evaluated based on statistical analysis. It was demonstrated that an active alkali charge, wood lignin and extractive contents presented a significant effect on pulping yield. The wood basic density did not present a significant effect on pulping yield but it affected wood consumption for pulp production (m3 of wood/ton of pulp). The wood basic density, the lignin content and the extractive content were recommended as criteria to establish wood quality prior to pulping characteristics. The effect the wood basic density on pulping yield was not statistically observed. Two Eucalyptus clones with low and high basic wood densities (426 e 520 kg/m3) and similar chemical constitutions were studied. Kraft cooking was carried out with temperature, time and alkali charge adjusted to obtain pulps with kappa number 17. This study aimed to evaluate the real effect of wood basic density on pulping yield, since their chemical constitutions were similar and the difference of density attributed only anatomical characteristics of the wood. For similar conditions of pulping, the high wood basic density resulted in pulps with kappa number higher than woods with low basic density. The pulping of woods with high basic density could result in similar yield of woods with low density if lower temperatures and longer cooking times were used for high density wood. This gain on pulping yield may be important if the digester capacity would allow longer cooking time without jeopardizing the production. The determination of wood quality by carrying chemical analysis laboratory and kraft pulping is expensive and require a longer time of analysis. An alternative technique to evaluate this quality is the near infrared spectroscopy (NIRS), which has a lower cost, higher processing speed and does not require chemical reagents. Seventy five Eucalyptus clones were used in this study, the selected NIRS models presented 0.87, 0.95 and 0.90 as determination coefficients (R²) for basic density, total lignin and extractive contents, respectively. Twenty four samples were used for external validation of the selected models. The models showed good predictive abilities, resulting in 83% of the predictions with residues between +/-17 kg/m³ for basic density of wood, 82% of the predictions with residues between +/- 1% for lignin and 76% of the predictions with residues between +/-0.6% for extractives. For the kraft pulping parameters, the coefficients of determination (R2) for NIRS models were 0.84 for active alkali, 0.88 for pulping yield and 0.90 for specific wood consumption (m³ of wood/ton pulp). For active alkali, 96% of the predictions presented residues between +/- 1.0%. For pulping yield, 96% of the predictions presented residues between +/- 1% and for specific wood consumption, 92% of all predictions presented residues between +/-0.20 m³ wood/ton pulp. Results have shown that the NIRS technology could be applied as a tool for characterization of the Eucalyptus wood quality for pulping. Considering the results presented sought to develop NIRS general model to predict the wood basic density and chemical characteristics of Eucalyptus clones grown in Brazil. The objectives of this study was the development of NIRS models using a large number of Eucalyptus wood samples (2900 samples) and compare them with models developed using less number of samples. The Eucalyptus wood samples were evaluated for density, lignin content and extractives content. The statistical parameters of NIRS models developed with 250 wood samples were close to the one developed using the total number of available samples (2900) in terms of prediction accuracy. The reduced samples models presented good predictive abilities for all three characteristics demonstrating that use of some representative samples can be as precise as using large number of samples. Today, all studies involving wood quality by destructive methods or nondestructive methods are performed on clones that were improved by different cloning techniques. However, polyploidy induced by colchicine is an unusual technique for Eucalyptus wood and publications related to its effect on wood quality are difficult to find, so in the last chapter of this study the goal was to evaluate the wood quality of the Eucalyptus grandis polyploidies x Eucalyptus urophylla clones. The Eucalyptus clones were evaluated for wood basic density, chemical composition, anatomical characteristics and kraft pulping performance. Clones derived from polyploidies presented longer fibers, higher wood basic density, lower lignin content, higher syringyl/guaiacyl ratio, lower alkali charge for same kappa level and higher screened yield. These results demonstrate that the polyploidy technique can be used as an important tool in Eucalyptus forest improvement programs for pulping process. The analyzes described in seven chapters of this study indicate that the physicochemical characteristics of the wood, silvicultural aspects and process variables determine the potential of an eucalyptus clone for kraft pulp production.