Dimensões de cavacos industriais de eucalipto e relações com polpação, resistência e morfologia de fibras na polpa
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Data
2012-08-15
Autores
Grande, João Paulo [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A celulose de fibra curta branqueada produzida no Brasil é toda proveniente de madeira de florestas de Eucalyptus spp. A qualidade dos cavacos usados na produção de celulose é considerada um fator importante para operabilidade da indústria e para a qualidade da polpa. Os cavacos desejáveis são aqueles que apresentam poucas variações nas características físicas e químicas, isentos de contaminantes, alta densidade a granel, impregnação homogênea, baixa degradação de polissacarídeos e alto rendimento na transformação em polpa celulósica. Na indústria a classificação do tamanho dos cavacos passou a ser adotada depois que estudos demonstraram que os cavacos muito grandes e/ou muito pequenos poderiam interferir no processo de deslignificação e na qualidade da polpa celulósica, mas os cavacos utilizados pela indústria ainda apresentam variações no tamanho depois da classificação industrial. O objetivo do estudo foi identificar nos cavacos classificados industrialmente, dimensões que favoreçam ou desfavorecem o processo de deslignificação e a resistência da polpa. Para tanto, foi coletada uma amostra de cavacos em uma indústria de celulose, a amostra foi separada em sete frações, e mensurada às dimensões (comprimento, largura e espessura), determinado à densidade básica, densidade a granel, e composição química dos cavacos. As frações também foram deslignificadas e determinado o rendimento bruto, rendimento depurado, rejeitos base celulose, rejeitos base madeira e o número Kappa da polpa marrom. As fibras dos cavacos grande e pequenos foram classificadas pelo comprimento, e determinado algumas características físico-mecânicas da celulose. As dimensões dos cavacos variaram entre as frações, houve aumento do teor de holocelulose nas duas frações com as menores dimensões dos...
Bleached hardwood pulp produced in Brazil is entirely from wood of Eucalyptus spp forests. The quality of the chips used in pulp production is considered an important factor in the industry operability and the pulp quality. Desirable chips have few variations of physical and chemical characteristics are free of contaminants, and present high bulk density, homogeneous uptake, low degradation of polysaccharides and high milling yield in kraft pulp. In manufacturing, the chip size classification has been adopted after studies have shown that very large and / or very little chips could interfere in the delignification process and pulp quality; however, the chips used by the industry still vary in size after industrial grading. The aim of this study was to identify, among the industrially classified chips, dimensions that favor or not the delignification process and pulp strength. Thus, a chip sample was collected in a pulp mill, then the chips were separated into seven fractions and their dimensions (length, width and thickness) were measured, and the chip basic density, bulk density, chemical composition were determined. The chips were also delignified, and the total yield, screening yield, pulp-based wastes, wood- based wastes, and Kappa number of unbleached pulp were determined. The fibers of large and small chips were classified by length, and some physical and mechanical properties of cellulose were determined. The chip dimensions varied among fractions, and there was an increase of holocellulose content in the two fractions that had the smallest chips. The total yield, screening yield, and pulp-based waste content did not differ significantly, but, when the chip size dimension decreased, the waste content and kappa number were likely to reduce and the specific wood use was likely to increase. The fiber length... (Complete abstract click electronic access below)
Bleached hardwood pulp produced in Brazil is entirely from wood of Eucalyptus spp forests. The quality of the chips used in pulp production is considered an important factor in the industry operability and the pulp quality. Desirable chips have few variations of physical and chemical characteristics are free of contaminants, and present high bulk density, homogeneous uptake, low degradation of polysaccharides and high milling yield in kraft pulp. In manufacturing, the chip size classification has been adopted after studies have shown that very large and / or very little chips could interfere in the delignification process and pulp quality; however, the chips used by the industry still vary in size after industrial grading. The aim of this study was to identify, among the industrially classified chips, dimensions that favor or not the delignification process and pulp strength. Thus, a chip sample was collected in a pulp mill, then the chips were separated into seven fractions and their dimensions (length, width and thickness) were measured, and the chip basic density, bulk density, chemical composition were determined. The chips were also delignified, and the total yield, screening yield, pulp-based wastes, wood- based wastes, and Kappa number of unbleached pulp were determined. The fibers of large and small chips were classified by length, and some physical and mechanical properties of cellulose were determined. The chip dimensions varied among fractions, and there was an increase of holocellulose content in the two fractions that had the smallest chips. The total yield, screening yield, and pulp-based waste content did not differ significantly, but, when the chip size dimension decreased, the waste content and kappa number were likely to reduce and the specific wood use was likely to increase. The fiber length... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Celulose, Madeira - Densidade, Eucalipto, Polpa de madeira, Madeira - Quimica, Residuos de madeira - Exploração, Wood-pulp
Como citar
GRANDE, João Paulo. Dimensões de cavacos industriais de eucalipto e relações com polpação, resistência e morfologia de fibras na polpa. 2012. viii, 77 f. Dissertação (mestrado) - Universidade Estadual Paulista, Faculdade de Ciências Agronômicas de Botucatu, 2012.