Efeito da lixiviação ácida de cavacos de eucalipto no processo Kraft / Effects of acid leaching of wood chips on the Kraft process

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The goal of the present work was assessing the influence of acid leaching of wood chips before Kraft cooking, on the yield of the pulping process, the bleachability of the pulp and on its physical and mechanical properties. At first, a study was made to determine optimum conditions to be used in the leaching process: time, temperature and pH. The wood chips leached at the chosen conditions (3 hours, 70 C and pH 2,0) went through a conventional Kraft pulping process, the pulp obtained was pre-delignificated with oxygen and bleached using three sequences: AZDP, with 0,5% and 2% of CIO2 and A/Z/EDP. Its properties were then tested. The acid leaching reduced significantly the metal content in the wood chips. It was determined that, unlike temperature, the variables time and pH have great influence on the removal rate, and that the acid treatment did not lower yield on the cooking process, even though it generated pulp with a lower Kappa number. The leached pulp showed improved performance during the oxygen pre-delignification stage and its behavior during bleaching was, in certain aspects, better than the reference material. There was great reduction in the use of chemicals in the last stage and no significant difference in the physical and mechanical properties of the leached pulp was observed, leading to the conclusion that the acid leaching did not affect adversely these properties.

ASSUNTO(S)

branqueamento polpa de madeira wood pulp effect of metals kraft pulping process efeitos dos metais polpação kraft tecnologia de celulose e papel bleaching

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