Análise da qualidade da madeira de híbridos de Corymbia para a produção de celulose kraft.

Abstract

Brazil stands out as the largest producer of hardwood pulp in the world and, despite the results achieved through the cultivation of eucalyptus, other crops, such as species of the genus Corymbia, are being studied. The genus Corymbia has been studied in genetic improvement programs aimed at increasing productivity, wood quality and resistance to biotic and abiotic factors. In this context, the present work evaluated the wood quality of hybrid clones of Corymbia torelliana and Corymbia citriodora for the production of kraft pulp. Ten hybrid clones of the genus Corymbia and one clone of Eucalyptus saligna as a control treatment were analyzed, both 6 years old and belonging to the same planting site. The quality of the wood was evaluated in terms of chemical composition and basic density. The quality of wood for pulping was evaluated in terms of screened yield, kappa number, waste content and specific wood consumption. Cooking was carried out with a wood blend in the proportion 50/50 m/m, using E. saligna and the Corymbia hybrid with better pulping results. All clones of the genus Corymbia showed a higher basic density than the control treatment, with results ranging from 509.3 to 607.0kg/m³. For chemical characteristics, the Corymbia hybrids ranged from 2.53 to 8.16% for total extractives, 25.84 to 28.42% for total lignin, 0.5 to 1.17% for ash and 65.35 to 70.84% for holocellulose. In pulping, the Corymbia hybrid with the best performance obtained a screened yield of 53.24%, kappa of 22.2, rejects of 0.91% and specific consumption of 3.11 m³/tSA. The blend proved to be a great alternative as a source of fiber and a reduction in the specific consumption of wood. The increase in the extractives content had a negative influence on the pulp quality, whereas the increase in this parameter resulted in a drop in yield and an increase in the kappa number for the Corymbia hybrids. The study made it possible to perform a ranking and indicate the clones with the greatest potential for commercial pulp production, in order to meet the demand of the company CMPC Celulose Riograndense.